BGP AS Path Prepending   AS Path   is the fourth   BGP   attribute, AS Path is well known, mandatory   attribute.   BGP   prefer the shortest AS path to get to destination. In other words   path with shortest AS path list is more desirable.     You can manipulate this by using AS path prepending . Manual manipulation of AS path length is called AS path prepending.     The AS path should be extended with multiple copies of the AS number of the sender.   AS path prepending is used to:                     Ensure proper return path selection.        .     Distribution the traffic load for multi-homed customers.     Results of AS path prepending can be observed on the receiving router.   let see the configuration :-https://www.internetworks.in/2019/03/bgp-as-path-prepending.html   Topology:   Goal:   configure the topology as per the diagram and assign the IP address as per the topology. configure   IBGP and EBGP. configure AS 650014 to ensure that all routes in AS 650014 should exit router_1 to reach AS 650003 (30.0.0.0) prefix. configure AS 650014 to ensure that the traffic from 30.0.0.0 to 10.0.0.0 return traffic should use the same path as forwarding traffic routers_1_2_3.       R1#show ip interface brief   Interface              IP-Address      OK? Method Status                Protocol FastEthernet0/0        10.1.1.1        YES manual up                    up Serial3/0                    1.1.1.1         YES manual up                    up Serial3/3                    4.1.1.2         YES manual up                    up Loopback0               11.0.0.1        YES manual up                    up     R2#show ip interface brief   Interface              IP-Address      OK? Method Status                Protocol FastEthernet0/0        20.1.1.1        YES manual up                    up Serial3/0                    1.1.1.2         YES manual up                    up Serial3/1                    2.1.1.1         YES manual up                    up Loopback0               12.0.0.1        YES manual up                    up     R3#show ip interface brief   Interface              IP-Address      OK? Method Status                Protocol FastEthernet0/0        30.1.1.1        YES manual up                    up Serial3/1                    2.1.1.2         YES manual up                    up Serial3/2                    3.1.1.1         YES manual up                    up Loopback0               13.0.0.1        YES manual up                    up   R4#show ip interface brief Interface              IP-Address      OK? Method Status                Protocol FastEthernet0/0        40.1.1.1        YES manual up                    up Serial3/2                    3.1.1.2         YES manual up                    up Serial3/3                    4.1.1.1         YES manual up                    up Loopback0               14.0.0.1        YES manual up                    up       R1(config)#router bgp 650014 R1(config-router)#neighbor 4.1.1.1 remote-as 650014 R1(config-router)#neighbor 1.1.1.2 remote-as 650002 R1(config-router)#network 10.0.0.0 R1(config-router)#network 1.0.0.0 R1(config-router)#network 4.0.0.0 R1(config-router)#network 11.0.0.0 mask 255.255.255.0 R1(config-router)#exit   R2(config)#router bgp 650002 R2(config-router)#neighbor 1.1.1.1 remote-as 650014   *Mar 13 12:23:30.111: %BGP-5-ADJCHANGE: neighbor 1.1.1.1 Up   R2(config-router)#neighbor 2.1.1.2 remote-as 650003 R2(config-router)#network 20.0.0.0 R2(config-router)#network 1.0.0.0 R2(config-router)#network 2.0.0.0 R2(config-router)#network 12.0.0.0 mask 255.255.255.0 R2(config-router)#exit   R3(config)#router bgp 650003 R3(config-router)#neighbor 2.1.1.1 remote-as 650002   *Mar 13 12:25:42.495: %BGP-5-ADJCHANGE: neighbor 2.1.1.1 Up   R3(config-router)#neighbor 3.1.1.2 remote-as 650014 R3(config-router)#network 30.0.0.0 R3(config-router)#network 3.0.0.0 R3(config-router)#network 2.0.0.0 R3(config-router)#network 13.0.0.0 mask 255.255.255.0 R3(config-router)#exit   R4(config)#router bgp 650014 R4(config-router)#neighbor 3.1.1.1 remote-as 650003   *Mar 13 12:27:46.807: %BGP-5-ADJCHANGE: neighbor 3.1.1.1 Up   R4(config-router)#neighbor 4.1.1.2 remote-as 650014   *Mar 13 12:28:10.663: %BGP-5-ADJCHANGE: neighbor 4.1.1.2 Up   R4(config-router)#network 40.0.0.0 R4(config-router)#network 4.0.0.0 R4(config-router)#network 3.0.0.0 R4(config-router)#network 14.0.0.0 mask 255.255.255.0 R4(config-router)#exit   R1#show ip bgp summary BGP router identifier 11.0.0.1, local AS number 650014 Neighbor        V           AS MsgRcvd MsgSent   TblVer  InQ OutQ Up/Down  State/PfxRcd 1.1.1.2         4       650002      14      16       21    0    0 00:08:00        7 4.1.1.1         4       650014      14      13       21    0    0 00:03:19        7   R2#show ip bgp summary BGP router identifier 12.0.0.1, local AS number 650002 Neighbor        V           AS MsgRcvd MsgSent   TblVer  InQ OutQ Up/Down  State/PfxRcd 1.1.1.1         4       650014      17      15       14    0    0 00:09:06        9 2.1.1.2         4       650003      12      15       14    0    0 00:06:54        9   R3#show ip bgp summary BGP router identifier 13.0.0.1, local AS number 650003 Neighbor        V           AS MsgRcvd MsgSent   TblVer  InQ OutQ Up/Down  State/PfxRcd 2.1.1.1         4       650002      16      13       18    0    0 00:07:58        9 3.1.1.2         4       650014      12      16       18    0    0 00:05:54        9   R4#sh ip bgp summary BGP router identifier 14.0.0.1, local AS number 650014 Neighbor        V           AS MsgRcvd MsgSent   TblVer  InQ OutQ Up/Down  State/PfxRcd 3.1.1.1         4       650003      17      12       18    0    0 00:06:20        7 4.1.1.2         4       650014      15      17       18    0    0 00:05:56        7   R3#show ip bgp BGP table version is 18, local router ID is 13.0.0.1 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,               r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,               x best-external, a additional-path, c RIB-compressed, Origin codes: i - IGP, e - EGP, ? - incomplete RPKI validation codes: V valid, I invalid, N Not found        Network          Next Hop            Metric LocPrf Weight Path  *   1.0.0.0          3.1.1.2                                0 650014 i  *>                   2.1.1.1                  0             0 650002 i  *>  2.0.0.0          0.0.0.0                  0         32768 i  *                    2.1.1.1                  0             0 650002 i  *   3.0.0.0          3.1.1.2                  0             0 650014 i  *>                   0.0.0.0                  0         32768 i  *>  4.0.0.0          3.1.1.2                  0             0 650014 i  *                    2.1.1.1                                0 650002 650014 i  *>  10.0.0.0         3.1.1.2                                0 650014 i  *                    2.1.1.1                                0 650002 650014 i  *>  11.0.0.0/24      3.1.1.2                                0 650014 i  *                    2.1.1.1                                0 650002 650014 i  *   12.0.0.0/24      3.1.1.2                                0 650014 650002 i  *>                   2.1.1.1                  0             0 650002 i      Network          Next Hop            Metric LocPrf Weight Path  *>  13.0.0.0/24      0.0.0.0                  0         32768 i  *   14.0.0.0/24      2.1.1.1                                0 650002 650014 i  *>                   3.1.1.2                  0             0 650014 i  *   20.0.0.0         3.1.1.2                                0 650014 650002 i  *>                   2.1.1.1                  0             0 650002 i  *>  30.0.0.0         0.0.0.0                  0         32768 i  *>  40.0.0.0         3.1.1.2                  0             0 650014 i  *                    2.1.1.1                                0 650002 650014 i   R1#show ip bgp BGP table version is 21, local router ID is 11.0.0.1 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,               r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,               x best-external, a additional-path, c RIB-compressed, Origin codes: i - IGP, e - EGP, ? - incomplete RPKI validation codes: V valid, I invalid, N Not found        Network          Next Hop            Metric LocPrf Weight Path  *   1.0.0.0          1.1.1.2                  0             0 650002 i  *>                   0.0.0.0                  0         32768 i  * i 2.0.0.0          3.1.1.1                  0    100      0 650003 i  *>                   1.1.1.2                  0             0 650002 i  *>i 3.0.0.0          4.1.1.1                  0    100      0 i  *                    1.1.1.2                                0 650002 650003 i  * i 4.0.0.0          4.1.1.1                  0    100      0 i  *>                   0.0.0.0                  0         32768 i  *>  10.0.0.0         0.0.0.0                  0         32768 i  *>  11.0.0.0/24      0.0.0.0                  0         32768 i  *>  12.0.0.0/24      1.1.1.2                  0             0 650002 i  *>i 13.0.0.0/24      3.1.1.1                  0    100      0 650003 i  *                    1.1.1.2                                0 650002 650003 i  *>i 14.0.0.0/24      4.1.1.1                  0    100      0 i      Network          Next Hop            Metric LocPrf Weight Path  *>  20.0.0.0         1.1.1.2                  0             0 650002 i  *>i 30.0.0.0         3.1.1.1                  0    100      0 650003 i  *                    1.1.1.2                                0 650002 650003 i  *>i 40.0.0.0         4.1.1.1                  0    100      0 i   R1#show ip bgp 30.1.1.1 BGP routing table entry for 30.0.0.0/8, version 20 Paths: (2 available, best #1, table default)   Advertised to update-groups:      1   Refresh Epoch 1   650003       3.1.1.1 from 4.1.1.1 (14.0.0.1)       Origin IGP, metric 0, localpref 100, valid, internal, best       rx pathid: 0, tx pathid: 0x0   Refresh Epoch 1     650002 650003       1.1.1.2 from 1.1.1.2 (12.0.0.1)       Origin IGP, localpref 100, valid, external       rx pathid: 0, tx pathid: 0    ( by default AS_650014 EXIT VIA R4 to reach AS 650003 route (30.0.0.0) prefix because of shortest AS-PATH)     R1(config)# access-list 10 permit 30.0.0.0 0.255.255.255   R1(config)#route-map cisco permit 10 R1(config-route-map)#match ip address 10 R1(config-route-map)#set local-preference 300 R1(config-route-map)#exit   R1(config)#route-map cisco permit 20 R1(config-route-map)#exit         R1#show ip bgp 30.1.1.1 BGP routing table entry for 30.0.0.0/8, version 22 Paths: (1 available, best #1, table default)   Advertised to update-groups:      2   Refresh Epoch 2     650002 650003     1.1.1.2 from 1.1.1.2 (12.0.0.1)       Origin IGP,   localpref 300, valid, external, best       rx pathid: 0, tx pathid: 0x0                                                    ( now configure return traffic)     R3#show ip bgp BGP table version is 18, local router ID is 13.0.0.1 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,               r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,               x best-external, a additional-path, c RIB-compressed, Origin codes: i - IGP, e - EGP, ? - incomplete RPKI validation codes: V valid, I invalid, N Not found        Network          Next Hop            Metric LocPrf Weight Path  *   1.0.0.0          3.1.1.2                                0 650014 i  *>                   2.1.1.1                  0             0 650002 i  *>  2.0.0.0          0.0.0.0                  0         32768 i  *                    2.1.1.1                  0             0 650002 i  *   3.0.0.0          3.1.1.2                  0             0 650014 i  *>                   0.0.0.0                  0         32768 i  *>  4.0.0.0          3.1.1.2                  0             0 650014 i  *                    2.1.1.1                                0 650002 650014 i  *>    10.0.0.0         3.1.1.2                                0 650014 i  *                    2.1.1.1                                0 650002 650014 i  *>  11.0.0.0/24      3.1.1.2                                0 650014 i  *                    2.1.1.1                                0 650002 650014 i  *   12.0.0.0/24      3.1.1.2                                0 650014 650002 i  *>                   2.1.1.1                  0             0 650002 i      Network          Next Hop            Metric LocPrf Weight Path  *>  13.0.0.0/24      0.0.0.0                  0         32768 i  *   14.0.0.0/24      2.1.1.1                                0 650002 650014 i  *>                   3.1.1.2                  0             0 650014 i  *   20.0.0.0         3.1.1.2                                0 650014 650002 i  *>                   2.1.1.1                  0             0 650002 i  *>  30.0.0.0         0.0.0.0                  0         32768 i  *>  40.0.0.0         3.1.1.2                  0             0 650014 i  *                    2.1.1.1                                0 650002 650014 i       R3#show ip bgp 10.1.1.1 BGP routing table entry for 10.0.0.0/8, version 13 Paths: (2 available, best #1, table default)   Advertised to update-groups:      1   Refresh Epoch 1     650014     3.1.1.2 from 3.1.1.2 (14.0.0.1)       Origin IGP, localpref 100, valid, external,   best       rx pathid: 0, tx pathid: 0x0   Refresh Epoch 2   650002 650014     2.1.1.1 from 2.1.1.1 (12.0.0.1)       Origin IGP, localpref 100, valid, external       rx pathid: 0, tx pathid: 0   R4(config)#access-list 10 permit 10.0.0.0 0.255.255.255   R4(config)#route-map cisco permit 10 R4(config-route-map)#match ip address 10 R4(config-route-map)#set as-path prepend 650014 650014 650014 650014 R4(config-route-map)#exit   R4(config)#route-map cisco permit 20 R4(config-route-map)#exit   R4(config)#router bgp 650014 R4(config-router)#nei R4(config-router)#neighbor 3.1.1.1 rou R4(config-router)#neighbor 3.1.1.1 route-m R4(config-router)#neighbor 3.1.1.1 route-map cisco out R4(config-router)#end       R3#show ip bgp BGP table version is 19, local router ID is 13.0.0.1 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,               r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,               x best-external, a additional-path, c RIB-compressed, Origin codes: i - IGP, e - EGP, ? - incomplete RPKI validation codes: V valid, I invalid, N Not found        Network          Next Hop            Metric LocPrf Weight Path  *   1.0.0.0          3.1.1.2                                0 650014 i  *>                   2.1.1.1                  0             0 650002 i  *>  2.0.0.0          0.0.0.0                  0         32768 i  *                    2.1.1.1                  0             0 650002 i  *   3.0.0.0          3.1.1.2                  0             0 650014 i  *>                   0.0.0.0                  0         32768 i  *>  4.0.0.0          3.1.1.2                  0             0 650014 i  *                    2.1.1.1                                0 650002 650014 i  *   10.0.0.0         3.1.1.2                                0 650014 650014 650014 650014 650014 i  *>                   2.1.1.1                                0 650002 650014 i  *>  11.0.0.0/24      3.1.1.2                                0 650014 i  *                    2.1.1.1                                0 650002 650014 i  *   12.0.0.0/24      3.1.1.2                                0 650014 650002 i      Network          Next Hop            Metric LocPrf Weight Path  *>                   2.1.1.1                  0             0 650002 i  *>  13.0.0.0/24      0.0.0.0                  0         32768 i  *   14.0.0.0/24      2.1.1.1                                0 650002 650014 i  *>                   3.1.1.2                  0             0 650014 i  *   20.0.0.0         3.1.1.2                                0 650014 650002 i  *>                   2.1.1.1                  0             0 650002 i  *>  30.0.0.0         0.0.0.0                  0         32768 i  *>  40.0.0.0         3.1.1.2                  0             0 650014 i  *                    2.1.1.1                                0 650002 650014 i     R3#show ip bgp 10.1.1.1 BGP routing table entry for 10.0.0.0/8, version 19 Paths: (2 available, best #2, table default)   Advertised to update-groups:      1   Refresh Epoch 3     650014 650014 650014 650014 650014     3.1.1.2 from 3.1.1.2 (14.0.0.1)       Origin IGP, localpref 100, valid, external       rx pathid: 0, tx pathid: 0   Refresh Epoch 3   650002 650014       2.1.1.1 from 2.1.1.1 (12.0.0.1)       Origin IGP, localpref 100, valid, external,   best       rx pathid: 0, tx pathid: 0x0       R1#traceroute 30.1.1.1 Type escape sequence to abort. Tracing the route to 30.1.1.1 VRF info: (vrf in name/id, vrf out name/id)   1 1.1.1.2 52 msec 56 msec 28 msec   2 2.1.1.2 [AS 650002] 120 msec 140 msec 176 msec     R3#traceroute 10.1.1.1 Type escape sequence to abort. Tracing the route to 10.1.1.1 VRF info: (vrf in name/id, vrf out name/id)   1 2.1.1.1 36 msec 44 msec 64 msec   2 1.1.1.1 [AS 650002] 112 msec 92 msec 76 msec   internetworks ... View more

    BGP   Route filter     BGP   updates can be controlled by using a numbers of different filtering methods.   BGP   updates can be filtered based on routes information, on paths information or on   communities. All the methods will achieve the same results choosing one over the other depends on the specific network configuration.    You might need to control exactly which routes are advertised or redistribute or which paths are chosen. Advertise only some specific routes to neighbor (security reasons).Redistribute   specific routes, preventing routing loops, Path manipulation of some specific routes.   Changing metric and metric-type for specific routes. Changing the administrative distance for specific routes with BGP controlling routes to be advertised to ISP. Control routes to get in to routing table Policy based routing.   lets see the methods of BGP route filtering: Distribution-list IP prefix-list Route map    Goal:    configure the topology as per the diagram.  configure EBGP as per the topology and advertise directly connected interfaces configure router 2 to block 30.1.1.1/8 networks. make sure router 2 do not install 30.1.1.1/8 network in its routing table. configure   distribution list   in order to block 30.1.1.1/8 network. R1#show ip interface brief Interface              IP-Address      OK? Method Status                Protocol FastEthernet0/0        10.1.1.1        YES manual up                    up Serial3/0                    1.1.1.1         YES manual up                    up Serial3/3                    4.1.1.2         YES manual up                    up Loopback0              11.0.0.1        YES manual up                    up Loopback1              11.0.1.1        YES manual up                    up Loopback2              11.0.2.1        YES manual up                    up Loopback3              11.0.3.1        YES manual up                    up     R2#show ip interface brief Interface              IP-Address      OK? Method Status                Protocol FastEthernet0/0        20.1.1.1        YES manual up                    up Serial3/0                    1.1.1.2         YES manual up                    up Serial3/1                    2.1.1.1         YES manual up                    up Loopback0              12.0.0.1        YES manual up                    up Loopback1              12.0.1.1        YES manual up                    up Loopback2              12.0.2.1        YES manual up                    up Loopback3              12.0.3.1        YES manual up                    up     R3#show ip interface brief Interface              IP-Address      OK? Method Status                Protocol FastEthernet0/0        30.1.1.1        YES manual up                    up Serial3/1                    2.1.1.2         YES manual up                    up Serial3/2                    3.1.1.1         YES manual up                    up Loopback0              13.0.0.1        YES manual up                    up Loopback1              13.0.1.1        YES manual up                    up Loopback2              13.0.2.1        YES manual up                    up Loopback3              13.0.3.1        YES manual up                    up   R4#show ip interface brief Interface              IP-Address      OK? Method Status                Protocol FastEthernet0/0        40.1.1.1        YES manual up                    up Serial3/2                    3.1.1.2         YES manual up                    up Serial3/3                    4.1.1.1         YES manual up                    up Loopback0              14.0.0.1        YES manual up                    up Loopback1              14.0.1.1        YES manual up                    up Loopback2              14.0.2.1        YES manual up                    up Loopback3              14.0.3.1        YES manual up                    up     R1(config)#router bgp 650001 R1(config-router)#neighbor 1.1.1.2 remote-as 650002 R1(config-router)#neighbor 4.1.1.1 remote-as 650004 R1(config-router)#network 10.0.0.0 R1(config-router)#network 1.0.0.0 R1(config-router)#network 4.0.0.0 R1(config-router)#end   R2(config)#router bgp 650002 R2(config-router)#neighbor 1.1.1.1 remote-as 650001   *Mar  1 14:39:06.207: %BGP-5-ADJCHANGE: neighbor 1.1.1.1 Up   R2(config-router)#neighbor 2.1.1.2 remote-as 650003   *Mar  1 14:39:29.195: %BGP-5-ADJCHANGE: neighbor 2.1.1.2 Up   R2(config-router)#network 20.0.0.0 R2(config-router)#network 2.0.0.0 R2(config-router)#network 1.0.0.0 R2(config-router)#end   R3(config)#router bgp 650003 R3(config-router)#neighbor 2.1.1.1 remote-as 650002 R3(config-router)#neighbor 2.1.1. remote-as 650004   *Mar  1 14:34:49.651: %BGP-5-ADJCHANGE: neighbor 2.1.1.1 Up   R3(config-router)#neighbor 3.1.1.2 remote-as 650004 R3(config-router)#network 30.0.0.0 R3(config-router)#network 3.0.0.0 R3(config-router)#network 2.0.0.0 R3(config-router)#end     R4(config)#router bgp 650004 R4(config-router)#neighbor 3.1.1.1 remote-as 650003   *Mar  1 14:36:26.991: %BGP-5-ADJCHANGE: neighbor 3.1.1.1 Up   R4(config-router)#neighbor 4.1.1.2 remote-as 650001   *Mar  1 14:36:37.771: %BGP-5-ADJCHANGE: neighbor 4.1.1.2 Up   R4(config-router)#network 40.0.0.0 R4(config-router)#network 4.0.0.0 R4(config-router)#network 3.0.0.0 R4(config-router)#end   R1#show ip bgp BGP table version is 16, local router ID is 11.0.3.1 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,               r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,               x best-external, a additional-path, c RIB-compressed, Origin codes: i - IGP, e - EGP, ? - incomplete RPKI validation codes: V valid, I invalid, N Not found      Network          Next Hop            Metric LocPrf Weight Path  *   1.0.0.0          1.1.1.2                  0             0 650002 i  *>                   0.0.0.0                  0         32768 i  *>  2.0.0.0          1.1.1.2                  0             0 650002 i  *                    4.1.1.1                                0 650004 650003 i  *   3.0.0.0          1.1.1.2                                0 650002 650003 i  *>                   4.1.1.1                  0             0 650004 i  *>  4.0.0.0          0.0.0.0                  0         32768 i  *>  10.0.0.0         0.0.0.0                  0         32768 i  *>  20.0.0.0         1.1.1.2                  0             0 650002 i  *   30.0.0.0         1.1.1.2                                0 650002 650003 i  *>                   4.1.1.1                                0 650004 650003 i  *>  40.0.0.0         4.1.1.1                  0             0 650004 i     R2#show ip bgp BGP table version is 14, local router ID is 12.0.3.1 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,               r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,               x best-external, a additional-path, c RIB-compressed, Origin codes: i - IGP, e - EGP, ? - incomplete RPKI validation codes: V valid, I invalid, N Not found        Network          Next Hop            Metric LocPrf Weight Path  *>  1.0.0.0          0.0.0.0                  0         32768 i  *                    1.1.1.1                  0             0 650001 i  *>  2.0.0.0          0.0.0.0                  0         32768 i  *                    2.1.1.2                  0             0 650003 i  *>  3.0.0.0          2.1.1.2                  0             0 650003 i  *                    1.1.1.1                                0 650001 650004 i  *   4.0.0.0          2.1.1.2                                0 650003 650004 650001 i  *>                   1.1.1.1                  0             0 650001 i  *   10.0.0.0         2.1.1.2                                0 650003 650004 650001 i  *>                   1.1.1.1                  0             0 650001 i  *>  20.0.0.0         0.0.0.0                  0         32768 i  *>  30.0.0.0         2.1.1.2                  0             0 650003 i      Network          Next Hop            Metric LocPrf Weight Path  *                    1.1.1.1                                0 650001 650004 650003 i  *   40.0.0.0         2.1.1.2                                0 650003 650004 i  *>                   1.1.1.1                                0 650001 650004 i     R3#show ip bgp BGP table version is 16, local router ID is 13.0.3.1 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,               r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,               x best-external, a additional-path, c RIB-compressed, Origin codes: i - IGP, e - EGP, ? - incomplete RPKI validation codes: V valid, I invalid, N Not found        Network          Next Hop            Metric LocPrf Weight Path  *>  1.0.0.0          2.1.1.1                  0             0 650002 i  *                    3.1.1.2                                0 650004 650001 i  *   2.0.0.0          2.1.1.1                  0             0 650002 i  *>                   0.0.0.0                  0         32768 i  *   3.0.0.0          3.1.1.2                  0             0 650004 i  *>                   0.0.0.0                  0         32768 i  *   4.0.0.0          2.1.1.1                                0 650002 650001 i  *>                   3.1.1.2                                0 650004 650001 i  *   10.0.0.0         2.1.1.1                                0 650002 650001 i  *>                   3.1.1.2                                0 650004 650001 i  *   20.0.0.0         3.1.1.2                                0 650004 650001 650002 i  *>                   2.1.1.1                  0             0 650002 i  *>  30.0.0.0         0.0.0.0                  0         32768 i      Network          Next Hop            Metric LocPrf Weight Path  *   40.0.0.0         2.1.1.1                                0 650002 650001 650004 i  *>                   3.1.1.2                  0             0 650004 i   R4#show ip bgp BGP table version is 15, local router ID is 14.0.3.1 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,               r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,               x best-external, a additional-path, c RIB-compressed, Origin codes: i - IGP, e - EGP, ? - incomplete RPKI validation codes: V valid, I invalid, N Not found        Network          Next Hop            Metric LocPrf Weight Path  *   1.0.0.0          3.1.1.1                                0 650003 650002 i  *>                   4.1.1.2                  0             0 650001 i  *   2.0.0.0          4.1.1.2                                0 650001 650002 i  *>                   3.1.1.1                  0             0 650003 i  *>  3.0.0.0          0.0.0.0                  0         32768 i  *                    3.1.1.1                  0             0 650003 i  *>  4.0.0.0          4.1.1.2                  0             0 650001 i  *>  10.0.0.0         4.1.1.2                  0             0 650001 i  *   20.0.0.0         3.1.1.1                                0 650003 650002 i  *>                   4.1.1.2                                0 650001 650002 i  *>  30.0.0.0         3.1.1.1                  0             0 650003 i  *>  40.0.0.0         0.0.0.0                  0         32768 i   R2#show ip bgp 30.1.1.1 BGP routing table entry for 30.0.0.0/8, version 9 Paths: (2 available, best #1, table default)   Advertised to update-groups:      1   Refresh Epoch 2   650003     2.1.1.2 from 2.1.1.2 (13.0.3.1)       Origin IGP, metric 0, localpref 100, valid, external, best       rx pathid: 0, tx pathid: 0x0   Refresh Epoch 2   650001 650004 650003     1.1.1.1 from 1.1.1.1 (11.0.3.1)       Origin IGP, localpref 100, valid, external       rx pathid: 0, tx pathid: 0   (we are going block 30.1.1.1/8 network by using distribution list)   R2(config)#access-list 30 deny 30.1.1.1 0.255.255.255 R2(config)#access-list 30 permit any R2(config)#exit   R2(config)#router bgp 650002 R2(config-router)#neighbor 2.1.1.2 distribute-list 30 in R2(config-router)#neighbor 1.1.1.1 distribute-list 30 in R2(config-router)#end   R2#clear ip bgp * soft   R2#show ip bgp 30.1.1.1 % Network not in table     let see another method of BGP route filtering. continuing previous configuration :   Topology ... 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    BGP   Route filtering methods     BGP   updates can be controlled by using a numbers of different filtering methods.   BGP   updates can be filtered based on routes information, on paths information or on   communities. All the methods will achieve the same results choosing one over the other depends on the specific network configuration.    You might need to control exactly which routes are advertised or redistribute or which paths are chosen. Advertise only some specific routes to neighbor (security reasons).Redistribute   specific routes, preventing routing loops, Path manipulation of some specific routes.   Changing metric and metric-type for specific routes. Changing the administrative distance for specific routes with BGP controlling routes to be advertised to ISP. Control routes to get in to routing table Policy based routing.   lets see the methods of BGP route filtering: Distribution-list IP prefix-list Route map  Topology :https://www.internetworks.in/2019/03/bgp-route-filtering-methods.html Goal:    configure the topology as per the diagram.  configure EBGP as per the topology and advertise directly connected interfaces configure router 2 to block 30.1.1.1/8 networks. make sure router 2 do not install 30.1.1.1/8 network in its routing table. configure   distribution list   in order to block 30.1.1.1/8 network. R1#show ip interface brief Interface              IP-Address      OK? Method Status                Protocol FastEthernet0/0        10.1.1.1        YES manual up                    up Serial3/0                    1.1.1.1         YES manual up                    up Serial3/3                    4.1.1.2         YES manual up                    up Loopback0              11.0.0.1        YES manual up                    up Loopback1              11.0.1.1        YES manual up                    up Loopback2              11.0.2.1        YES manual up                    up Loopback3              11.0.3.1        YES manual up                    up     R2#show ip interface brief Interface              IP-Address      OK? Method Status                Protocol FastEthernet0/0        20.1.1.1        YES manual up                    up Serial3/0                    1.1.1.2         YES manual up                    up Serial3/1                    2.1.1.1         YES manual up                    up Loopback0              12.0.0.1        YES manual up                    up Loopback1              12.0.1.1        YES manual up                    up Loopback2              12.0.2.1        YES manual up                    up Loopback3              12.0.3.1        YES manual up                    up     R3#show ip interface brief Interface              IP-Address      OK? Method Status                Protocol FastEthernet0/0        30.1.1.1        YES manual up                    up Serial3/1                    2.1.1.2         YES manual up                    up Serial3/2                    3.1.1.1         YES manual up                    up Loopback0              13.0.0.1        YES manual up                    up Loopback1              13.0.1.1        YES manual up                    up Loopback2              13.0.2.1        YES manual up                    up Loopback3              13.0.3.1        YES manual up                    up   R4#show ip interface brief Interface              IP-Address      OK? Method Status                Protocol FastEthernet0/0        40.1.1.1        YES manual up                    up Serial3/2                    3.1.1.2         YES manual up                    up Serial3/3                    4.1.1.1         YES manual up                    up Loopback0              14.0.0.1        YES manual up                    up Loopback1              14.0.1.1        YES manual up                    up Loopback2              14.0.2.1        YES manual up                    up Loopback3              14.0.3.1        YES manual up                    up     R1(config)#router bgp 650001 R1(config-router)#neighbor 1.1.1.2 remote-as 650002 R1(config-router)#neighbor 4.1.1.1 remote-as 650004 R1(config-router)#network 10.0.0.0 R1(config-router)#network 1.0.0.0 R1(config-router)#network 4.0.0.0 R1(config-router)#end   R2(config)#router bgp 650002 R2(config-router)#neighbor 1.1.1.1 remote-as 650001   *Mar  1 14:39:06.207: %BGP-5-ADJCHANGE: neighbor 1.1.1.1 Up   R2(config-router)#neighbor 2.1.1.2 remote-as 650003   *Mar  1 14:39:29.195: %BGP-5-ADJCHANGE: neighbor 2.1.1.2 Up   R2(config-router)#network 20.0.0.0 R2(config-router)#network 2.0.0.0 R2(config-router)#network 1.0.0.0 R2(config-router)#end   R3(config)#router bgp 650003 R3(config-router)#neighbor 2.1.1.1 remote-as 650002 R3(config-router)#neighbor 2.1.1. remote-as 650004   *Mar  1 14:34:49.651: %BGP-5-ADJCHANGE: neighbor 2.1.1.1 Up   R3(config-router)#neighbor 3.1.1.2 remote-as 650004 R3(config-router)#network 30.0.0.0 R3(config-router)#network 3.0.0.0 R3(config-router)#network 2.0.0.0 R3(config-router)#end     R4(config)#router bgp 650004 R4(config-router)#neighbor 3.1.1.1 remote-as 650003   *Mar  1 14:36:26.991: %BGP-5-ADJCHANGE: neighbor 3.1.1.1 Up   R4(config-router)#neighbor 4.1.1.2 remote-as 650001   *Mar  1 14:36:37.771: %BGP-5-ADJCHANGE: neighbor 4.1.1.2 Up   R4(config-router)#network 40.0.0.0 R4(config-router)#network 4.0.0.0 R4(config-router)#network 3.0.0.0 R4(config-router)#end   R1#show ip bgp BGP table version is 16, local router ID is 11.0.3.1 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,               r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,               x best-external, a additional-path, c RIB-compressed, Origin codes: i - IGP, e - EGP, ? - incomplete RPKI validation codes: V valid, I invalid, N Not found      Network          Next Hop            Metric LocPrf Weight Path  *   1.0.0.0          1.1.1.2                  0             0 650002 i  *>                   0.0.0.0                  0         32768 i  *>  2.0.0.0          1.1.1.2                  0             0 650002 i  *                    4.1.1.1                                0 650004 650003 i  *   3.0.0.0          1.1.1.2                                0 650002 650003 i  *>                   4.1.1.1                  0             0 650004 i  *>  4.0.0.0          0.0.0.0                  0         32768 i  *>  10.0.0.0         0.0.0.0                  0         32768 i  *>  20.0.0.0         1.1.1.2                  0             0 650002 i  *   30.0.0.0         1.1.1.2                                0 650002 650003 i  *>                   4.1.1.1                                0 650004 650003 i  *>  40.0.0.0         4.1.1.1                  0             0 650004 i     R2#show ip bgp BGP table version is 14, local router ID is 12.0.3.1 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,               r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,               x best-external, a additional-path, c RIB-compressed, Origin codes: i - IGP, e - EGP, ? - incomplete RPKI validation codes: V valid, I invalid, N Not found        Network          Next Hop            Metric LocPrf Weight Path  *>  1.0.0.0          0.0.0.0                  0         32768 i  *                    1.1.1.1                  0             0 650001 i  *>  2.0.0.0          0.0.0.0                  0         32768 i  *                    2.1.1.2                  0             0 650003 i  *>  3.0.0.0          2.1.1.2                  0             0 650003 i  *                    1.1.1.1                                0 650001 650004 i  *   4.0.0.0          2.1.1.2                                0 650003 650004 650001 i  *>                   1.1.1.1                  0             0 650001 i  *   10.0.0.0         2.1.1.2                                0 650003 650004 650001 i  *>                   1.1.1.1                  0             0 650001 i  *>  20.0.0.0         0.0.0.0                  0         32768 i  *>  30.0.0.0         2.1.1.2                  0             0 650003 i      Network          Next Hop            Metric LocPrf Weight Path  *                    1.1.1.1                                0 650001 650004 650003 i  *   40.0.0.0         2.1.1.2                                0 650003 650004 i  *>                   1.1.1.1                                0 650001 650004 i     R3#show ip bgp BGP table version is 16, local router ID is 13.0.3.1 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,               r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,               x best-external, a additional-path, c RIB-compressed, Origin codes: i - IGP, e - EGP, ? - incomplete RPKI validation codes: V valid, I invalid, N Not found        Network          Next Hop            Metric LocPrf Weight Path  *>  1.0.0.0          2.1.1.1                  0             0 650002 i  *                    3.1.1.2                                0 650004 650001 i  *   2.0.0.0          2.1.1.1                  0             0 650002 i  *>                   0.0.0.0                  0         32768 i  *   3.0.0.0          3.1.1.2                  0             0 650004 i  *>                   0.0.0.0                  0         32768 i  *   4.0.0.0          2.1.1.1                                0 650002 650001 i  *>                   3.1.1.2                                0 650004 650001 i  *   10.0.0.0         2.1.1.1                                0 650002 650001 i  *>                   3.1.1.2                                0 650004 650001 i  *   20.0.0.0         3.1.1.2                                0 650004 650001 650002 i  *>                   2.1.1.1                  0             0 650002 i  *>  30.0.0.0         0.0.0.0                  0         32768 i      Network          Next Hop            Metric LocPrf Weight Path  *   40.0.0.0         2.1.1.1                                0 650002 650001 650004 i  *>                   3.1.1.2                  0             0 650004 i   R4#show ip bgp BGP table version is 15, local router ID is 14.0.3.1 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,               r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,               x best-external, a additional-path, c RIB-compressed, Origin codes: i - IGP, e - EGP, ? - incomplete RPKI validation codes: V valid, I invalid, N Not found        Network          Next Hop            Metric LocPrf Weight Path  *   1.0.0.0          3.1.1.1                                0 650003 650002 i  *>                   4.1.1.2                  0             0 650001 i  *   2.0.0.0          4.1.1.2                                0 650001 650002 i  *>                   3.1.1.1                  0             0 650003 i  *>  3.0.0.0          0.0.0.0                  0         32768 i  *                    3.1.1.1                  0             0 650003 i  *>  4.0.0.0          4.1.1.2                  0             0 650001 i  *>  10.0.0.0         4.1.1.2                  0             0 650001 i  *   20.0.0.0         3.1.1.1                                0 650003 650002 i  *>                   4.1.1.2                                0 650001 650002 i  *>  30.0.0.0         3.1.1.1                  0             0 650003 i  *>  40.0.0.0         0.0.0.0                  0         32768 i   R2#show ip bgp 30.1.1.1 BGP routing table entry for 30.0.0.0/8, version 9 Paths: (2 available, best #1, table default)   Advertised to update-groups:      1   Refresh Epoch 2     650003     2.1.1.2 from 2.1.1.2 (13.0.3.1)       Origin IGP, metric 0, localpref 100, valid, external, best       rx pathid: 0, tx pathid: 0x0   Refresh Epoch 2     650001 650004 650003     1.1.1.1 from 1.1.1.1 (11.0.3.1)       Origin IGP, localpref 100, valid, external       rx pathid: 0, tx pathid: 0   (we are going block 30.1.1.1/8 network by using distribution list)   R2(config)#access-list 30 deny 30.1.1.1 0.255.255.255 R2(config)#access-list 30 permit any R2(config)#exit   R2(config)#router bgp 650002 R2(config-router)#neighbor 2.1.1.2 distribute-list 30 in R2(config-router)#neighbor 1.1.1.1 distribute-list 30 in R2(config-router)#end   R2#clear ip bgp * soft   R2#show ip bgp 30.1.1.1 % Network not in table     let see another method of BGP route filtering. continuing previous configuration :   Prefix-list https://www.internetworks.in/2019/03/bgp-route-filtering-methods.html   Topology ... 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    BGP   Route filtering methods     BGP   updates can be controlled by using a numbers of different filtering methods.   BGP   updates can be filtered based on routes information, on paths information or on   communities. All the methods will achieve the same results choosing one over the other depends on the specific network configuration.    You might need to control exactly which routes are advertised or redistribute or which paths are chosen. Advertise only some specific routes to neighbor (security reasons).Redistribute   specific routes, preventing routing loops, Path manipulation of some specific routes.   Changing metric and metric-type for specific routes. Changing the administrative distance for specific routes with BGP controlling routes to be advertised to ISP. Control routes to get in to routing table Policy based routing.   lets see the methods of BGP route filtering: Distribution-list IP prefix-list Route map  Topology :https://www.internetworks.in/2019/03/bgp-route-filtering-methods.html Goal:    configure the topology as per the diagram.  configure EBGP as per the topology and advertise directly connected interfaces configure router 2 to block 30.1.1.1/8 networks. make sure router 2 do not install 30.1.1.1/8 network in its routing table. configure   distribution list   in order to block 30.1.1.1/8 network. R1#show ip interface brief Interface              IP-Address      OK? Method Status                Protocol FastEthernet0/0        10.1.1.1        YES manual up                    up Serial3/0                    1.1.1.1         YES manual up                    up Serial3/3                    4.1.1.2         YES manual up                    up Loopback0              11.0.0.1        YES manual up                    up Loopback1              11.0.1.1        YES manual up                    up Loopback2              11.0.2.1        YES manual up                    up Loopback3              11.0.3.1        YES manual up                    up     R2#show ip interface brief Interface              IP-Address      OK? Method Status                Protocol FastEthernet0/0        20.1.1.1        YES manual up                    up Serial3/0                    1.1.1.2         YES manual up                    up Serial3/1                    2.1.1.1         YES manual up                    up Loopback0              12.0.0.1        YES manual up                    up Loopback1              12.0.1.1        YES manual up                    up Loopback2              12.0.2.1        YES manual up                    up Loopback3              12.0.3.1        YES manual up                    up     R3#show ip interface brief Interface              IP-Address      OK? Method Status                Protocol FastEthernet0/0        30.1.1.1        YES manual up                    up Serial3/1                    2.1.1.2         YES manual up                    up Serial3/2                    3.1.1.1         YES manual up                    up Loopback0              13.0.0.1        YES manual up                    up Loopback1              13.0.1.1        YES manual up                    up Loopback2              13.0.2.1        YES manual up                    up Loopback3              13.0.3.1        YES manual up                    up   R4#show ip interface brief Interface              IP-Address      OK? Method Status                Protocol FastEthernet0/0        40.1.1.1        YES manual up                    up Serial3/2                    3.1.1.2         YES manual up                    up Serial3/3                    4.1.1.1         YES manual up                    up Loopback0              14.0.0.1        YES manual up                    up Loopback1              14.0.1.1        YES manual up                    up Loopback2              14.0.2.1        YES manual up                    up Loopback3              14.0.3.1        YES manual up                    up     R1(config)#router bgp 650001 R1(config-router)#neighbor 1.1.1.2 remote-as 650002 R1(config-router)#neighbor 4.1.1.1 remote-as 650004 R1(config-router)#network 10.0.0.0 R1(config-router)#network 1.0.0.0 R1(config-router)#network 4.0.0.0 R1(config-router)#end   R2(config)#router bgp 650002 R2(config-router)#neighbor 1.1.1.1 remote-as 650001   *Mar  1 14:39:06.207: %BGP-5-ADJCHANGE: neighbor 1.1.1.1 Up   R2(config-router)#neighbor 2.1.1.2 remote-as 650003   *Mar  1 14:39:29.195: %BGP-5-ADJCHANGE: neighbor 2.1.1.2 Up   R2(config-router)#network 20.0.0.0 R2(config-router)#network 2.0.0.0 R2(config-router)#network 1.0.0.0 R2(config-router)#end   R3(config)#router bgp 650003 R3(config-router)#neighbor 2.1.1.1 remote-as 650002 R3(config-router)#neighbor 2.1.1. remote-as 650004   *Mar  1 14:34:49.651: %BGP-5-ADJCHANGE: neighbor 2.1.1.1 Up   R3(config-router)#neighbor 3.1.1.2 remote-as 650004 R3(config-router)#network 30.0.0.0 R3(config-router)#network 3.0.0.0 R3(config-router)#network 2.0.0.0 R3(config-router)#end     R4(config)#router bgp 650004 R4(config-router)#neighbor 3.1.1.1 remote-as 650003   *Mar  1 14:36:26.991: %BGP-5-ADJCHANGE: neighbor 3.1.1.1 Up   R4(config-router)#neighbor 4.1.1.2 remote-as 650001   *Mar  1 14:36:37.771: %BGP-5-ADJCHANGE: neighbor 4.1.1.2 Up   R4(config-router)#network 40.0.0.0 R4(config-router)#network 4.0.0.0 R4(config-router)#network 3.0.0.0 R4(config-router)#end   R1#show ip bgp BGP table version is 16, local router ID is 11.0.3.1 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,               r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,               x best-external, a additional-path, c RIB-compressed, Origin codes: i - IGP, e - EGP, ? - incomplete RPKI validation codes: V valid, I invalid, N Not found      Network          Next Hop            Metric LocPrf Weight Path  *   1.0.0.0          1.1.1.2                  0             0 650002 i  *>                   0.0.0.0                  0         32768 i  *>  2.0.0.0          1.1.1.2                  0             0 650002 i  *                    4.1.1.1                                0 650004 650003 i  *   3.0.0.0          1.1.1.2                                0 650002 650003 i  *>                   4.1.1.1                  0             0 650004 i  *>  4.0.0.0          0.0.0.0                  0         32768 i  *>  10.0.0.0         0.0.0.0                  0         32768 i  *>  20.0.0.0         1.1.1.2                  0             0 650002 i  *   30.0.0.0         1.1.1.2                                0 650002 650003 i  *>                   4.1.1.1                                0 650004 650003 i  *>  40.0.0.0         4.1.1.1                  0             0 650004 i     R2#show ip bgp BGP table version is 14, local router ID is 12.0.3.1 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,               r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,               x best-external, a additional-path, c RIB-compressed, Origin codes: i - IGP, e - EGP, ? - incomplete RPKI validation codes: V valid, I invalid, N Not found        Network          Next Hop            Metric LocPrf Weight Path  *>  1.0.0.0          0.0.0.0                  0         32768 i  *                    1.1.1.1                  0             0 650001 i  *>  2.0.0.0          0.0.0.0                  0         32768 i  *                    2.1.1.2                  0             0 650003 i  *>  3.0.0.0          2.1.1.2                  0             0 650003 i  *                    1.1.1.1                                0 650001 650004 i  *   4.0.0.0          2.1.1.2                                0 650003 650004 650001 i  *>                   1.1.1.1                  0             0 650001 i  *   10.0.0.0         2.1.1.2                                0 650003 650004 650001 i  *>                   1.1.1.1                  0             0 650001 i  *>  20.0.0.0         0.0.0.0                  0         32768 i  *>  30.0.0.0         2.1.1.2                  0             0 650003 i      Network          Next Hop            Metric LocPrf Weight Path  *                    1.1.1.1                                0 650001 650004 650003 i  *   40.0.0.0         2.1.1.2                                0 650003 650004 i  *>                   1.1.1.1                                0 650001 650004 i     R3#show ip bgp BGP table version is 16, local router ID is 13.0.3.1 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,               r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,               x best-external, a additional-path, c RIB-compressed, Origin codes: i - IGP, e - EGP, ? - incomplete RPKI validation codes: V valid, I invalid, N Not found        Network          Next Hop            Metric LocPrf Weight Path  *>  1.0.0.0          2.1.1.1                  0             0 650002 i  *                    3.1.1.2                                0 650004 650001 i  *   2.0.0.0          2.1.1.1                  0             0 650002 i  *>                   0.0.0.0                  0         32768 i  *   3.0.0.0          3.1.1.2                  0             0 650004 i  *>                   0.0.0.0                  0         32768 i  *   4.0.0.0          2.1.1.1                                0 650002 650001 i  *>                   3.1.1.2                                0 650004 650001 i  *   10.0.0.0         2.1.1.1                                0 650002 650001 i  *>                   3.1.1.2                                0 650004 650001 i  *   20.0.0.0         3.1.1.2                                0 650004 650001 650002 i  *>                   2.1.1.1                  0             0 650002 i  *>  30.0.0.0         0.0.0.0                  0         32768 i      Network          Next Hop            Metric LocPrf Weight Path  *   40.0.0.0         2.1.1.1                                0 650002 650001 650004 i  *>                   3.1.1.2                  0             0 650004 i   R4#show ip bgp BGP table version is 15, local router ID is 14.0.3.1 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,               r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,               x best-external, a additional-path, c RIB-compressed, Origin codes: i - IGP, e - EGP, ? - incomplete RPKI validation codes: V valid, I invalid, N Not found        Network          Next Hop            Metric LocPrf Weight Path  *   1.0.0.0          3.1.1.1                                0 650003 650002 i  *>                   4.1.1.2                  0             0 650001 i  *   2.0.0.0          4.1.1.2                                0 650001 650002 i  *>                   3.1.1.1                  0             0 650003 i  *>  3.0.0.0          0.0.0.0                  0         32768 i  *                    3.1.1.1                  0             0 650003 i  *>  4.0.0.0          4.1.1.2                  0             0 650001 i  *>  10.0.0.0         4.1.1.2                  0             0 650001 i  *   20.0.0.0         3.1.1.1                                0 650003 650002 i  *>                   4.1.1.2                                0 650001 650002 i  *>  30.0.0.0         3.1.1.1                  0             0 650003 i  *>  40.0.0.0         0.0.0.0                  0         32768 i   R2#show ip bgp 30.1.1.1 BGP routing table entry for 30.0.0.0/8, version 9 Paths: (2 available, best #1, table default)   Advertised to update-groups:      1   Refresh Epoch 2     650003     2.1.1.2 from 2.1.1.2 (13.0.3.1)       Origin IGP, metric 0, localpref 100, valid, external, best       rx pathid: 0, tx pathid: 0x0   Refresh Epoch 2     650001 650004 650003     1.1.1.1 from 1.1.1.1 (11.0.3.1)       Origin IGP, localpref 100, valid, external       rx pathid: 0, tx pathid: 0   (we are going block 30.1.1.1/8 network by using distribution list)   R2(config)#access-list 30 deny 30.1.1.1 0.255.255.255 R2(config)#access-list 30 permit any R2(config)#exit   R2(config)#router bgp 650002 R2(config-router)#neighbor 2.1.1.2 distribute-list 30 in R2(config-router)#neighbor 1.1.1.1 distribute-list 30 in R2(config-router)#end   R2#clear ip bgp * soft   R2#show ip bgp 30.1.1.1 % Network not in table     let see another method of BGP route filtering. continuing previous configuration :   Prefix-list https://www.internetworks.in/2019/03/bgp-route-filtering-methods.html   Topology ... 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IP Routing IP routing is basically the process of moving packets from one network to another network using routers. Routing protocols Router use routing protocol to dynamically find all the networks within the great internetwork and to ensure that all router have the same routing table, routing protocols are also employed to determine the best path a packet should through an internetwork to get its destination most effectively. RIP, RIPv2, OSPF, and EIGRP are the most common routing protocols. Routed protocols Routed protocols can be used to send user data (packets) through the established enterprise. Routed protocols are assigned to an interface and determine the method of packet delivery. E.g. IP and IPv6. The three type of routing method. Ø Static routing Ø Default routing Ø Dynamic routing Static Routing Static routing is the process that ensure when you manually add routes in each router’s routing table. There are the advantages and disadvantages of Static Routing. Here the advantages: · There is no overhead on the router CPU. · There is no bandwidth usage between routers. · It adds security because of you, the administrator, can be very exclusive and choose to allow routing access to certain networks only. And here are the disadvantages: · The administrator is must have a vault-tight knowledge of the internetwork and how each router is connected in order to configure routes correctly. If you don’t have a good, accurate map of your internetwork, things will get very messy. · If you add a network to the internetwork, you have to tediously add a route to it on all routers by hand. · It’s just not feasible to use it in most large networks because maintaining it would be a full-time job in itself. Here’s the command syntax you use to add a static route to a routing table from global ip route [destination network] [mask] [next-hop address or exit interface­] [administrative distance] [permanent] ip route- the command used to change the static route. Destination network- the network you’re placing in the routing table Mask-   the subnet mask being used on the network Next-hop address- this is ip address o the next-hop router that will receive packets and forward them to the remote network. Exit interface- used in place o the next-hop address if you want, and show up as a directly connected route. Administrative- distance   by default, static routes have an administrative distance o 1 or 0. Next-hop AD is 1, and exit interface AD is 0. Permanent- if the interface is shut down or the router can’t communicate to the next-hop router, the route will automatically discarded from the routing table by default. Choosing the permanent option keeps the entry in the routing table no matter what happens. Static routing config: IP Routing Topology ... View more

A Trunk link is a point-to-point link between two network devices. Trunk link carry more than one   VLAN. With VLAN trunking, we can extend our configured VLAN across the entire network. Remember, sending information from an access link on one VLAN to another VLAN is not possible without the additional device a router or a external layer 2 bridge connected between the VLAN.   A Trunk link can transport multiple VLANs traffic through a single switch port. A trunk link is not assigned to a specific VLAN.   Types of links/ports. Access links Connecting to end devices (hosts or router) Part of one VLAN   ACCESS LINK Trunk links Do not belong to any VLAN Its Carry multiple VLANs traffic It’s a physical Link between two switches Frame tagging In order to make sure that same VLAN users on different switch communicate with each other there is a method of tagging happens on trunk links. Tag is added before a frame is send and removed once it is received on trunk link. Frame tagging happen only on the trunk links. VLAN Frame Identification   A Trunk link can transport multiple VLANs traffic; a switch must identify frames with their respective VLANs as they are sent and received over a trunk link.   VLAN identification can be performed using    two methods, each using    a different frame identification mechanism: Inter-switch link (ISL) protocol IEEE 802.1Q (Dot1Q) protocol   Inter-switch link   (ISL) is a Cisco-proprietary method for preserving the source VLAN identification of frame passing over trunk link. ISL work with Ethernet, Token ring, FDDI. ISL adds a 26-bytes header and a byte trailer to the frame you can say its adds 30 bytes of tag. The ISL method of VLAN identification or trunking encapsulation no longer is supported across all Cisco catalyst switch platform.   The IEEE 802.1Q   protocol is also used to carry VLAN traffic, dot1q is a open standard trunking protocol, its work only on Ethernet, dot1q introduce us the concept of Native VLAN on a trunk. The frame belong to native VLAN is not encapsulation and with any tag. Dot1q is only adding 4 bytes tag will be added to original frame just after the source address field.   Lets see the configuration: https://www.internetworks.in/2018/12/vlan-trunk.html Topology:- ... View more

PPP Multilinks   Sometimes you notice a network design where you have more than one serial link between two routers.  A single serial link doesn’t provide enough bandwidth or maybe in case you want some extra redundancy. All the interfaces on a router need a different IP address, a design that looks like this:   Multilink PPP allows us to make a combination of multiple physical serial links into a single logical link or MLP bundle. MLP is used to aggregate multiple WAN links into one logical channel for the transportation of traffic from one router to another, MLP enable the load—balancing of traffic from different links  as we and allows some level of redundancy in case of line failure on a single link.MLP Supports a maximum of ten member links per bundle or single logical link.    lets take a look of its configuration:     Multilink point-to-point protocol configuration :-   Topology:https://www.internetworks.in/2018/12/ppp-multilinks.html ... View more

Route Redistribution configuration                           we have already learned what is route redistribution and why we need, if you don't then click here . In this section we see configuration.           R1#show ip interface brief Interface              IP-Address      OK? Method Status                Protocol FastEthernet0/0        10.1.1.1        YES manual up                    up Serial3/0                    1.1.1.1         YES manual up                    up Serial3/3                    4.1.1.2         YES manual up                    up Serial3/6                  15.1.1.1        YES manual up                    up Loopback0              11.0.0.1        YES manual up                    up Loopback1              11.0.1.1        YES manual up                    up Loopback2              11.0.2.1        YES manual up                    up Loopback3              11.0.3.1        YES manual up                    up R2#show ip interface brief Interface              IP-Address      OK? Method Status                Protocol FastEthernet0/0        20.1.1.1        YES manual up                    up Serial3/0                    1.1.1.2         YES manual up                    up Serial3/1                    2.1.1.1         YES manual up                    up Serial3/4                  24.1.1.1        YES manual up                    up Loopback0              12.0.0.1        YES manual up                    up Loopback1              12.0.1.1        YES manual up                    up Loopback2              12.0.2.1        YES manual up                    up Loopback3              12.0.3.1        YES manual up                    up v R3#show ip interface brief Interface              IP-Address      OK? Method Status                Protocol FastEthernet0/0        30.1.1.1        YES manual up                    up Serial3/1                    2.1.1.2         YES manual up                    up Serial3/2                   3.1.1.1         YES manual up                    up Serial3/5                 35.1.1.1        YES manual up                    up Loopback0              13.0.0.1        YES manual up                    up Loopback1              13.0.1.1        YES manual up                    up Loopback2              13.0.2.1        YES manual up                    up Loopback3              13.0.3.1        YES manual up                    up       R4#show ip interface brief Interface              IP-Address      OK? Method Status                Protocol FastEthernet0/0        40.1.1.1        YES manual up                    up Serial3/2                    3.1.1.2         YES manual up                    up Serial3/3                    4.1.1.1         YES manual up                    up Serial3/7                  45.1.1.1        YES manual up                    up Loopback0              14.0.0.1        YES manual up                    up Loopback1              14.0.1.1        YES manual up                    up Loopback2              14.0.2.1        YES manual up                    up Loopback3              14.0.3.1        YES manual up                    up     R5#show ip interface brief Interface              IP-Address      OK? Method Status                Protocol FastEthernet0/0        50.1.1.1        YES manual up                    up Serial3/4                   24.1.1.2        YES manual up                    up Serial3/5                   35.1.1.2        YES manual up                    up Serial3/6                   15.1.1.1        YES manual up                    up Serial3/7                   45.1.1.2        YES manual up                    up Loopback0              150.0.0.1       YES manual up                    up Loopback1              150.0.1.1       YES manual up                    up Loopback2              150.0.2.1       YES manual up                    up Loopback3              150.0.3.1       YES manual up                    up   R1(config)#router eigrp 210 R1(config-router)#network 1.0.0.0 R1(config-router)#network 10.0.0.0 R1(config-router)#no auto-summary R1(config-router)#exit   R1(config)#router rip R1(config-router)#version 2 R1(config-router)#network 15.0.0.0 R1(config-router)#network 11.0.0.0 R1(config-router)#no auto-summary R1(config-router)#exit   R1(config)#router eigrp 140 R1(config-router)#network 4.0.0.0 R1(config-router)#no auto-summary R1(config-router)#exit   R2(config)#router eigrp 210 R2(config-router)#network 1.0.0.0 R2(config-router)#network 20.0.0.0 R2(config-router)#no auto-summary R2(config-router)#exit   R2(config)#router rip R2(config-router)#version 2 R2(config-router)#network 12.0.0.0 R2(config-router)#network 2.0.0.0 R2(config-router)#exit   R2(config)#router ospf 11 R2(config-router)#network 25.0.0.0 0.255.255.255 area 0 R2(config-router)#exit   R3(config)#router rip R3(config-router)#version 2 R3(config-router)#network 2.0.0.0 R3(config-router)#network 13.0.0.0 R3(config-router)#no auto-summary R3(config-router)#exit   R3(config)#router eigrp 53 R3(config-router)#network 35.0.0.0 R3(config-router)#network 30.0.0.0 R3(config-router)#no auto-summary R3(config-router)#exit   R3(config)#router ospf 10 R3(config-router)#network 3.0.0.0 0.255.255.255 area 0 R3(config-router)#exit   R4(config)#router ospf 10 R4(config-router)#network 3.0.0.0 0.255.255.255 a R4(config-router)#network 3.0.0.0 0.255.255.255 area 0 R4(config-router)#exit   R4(config)#router rip R4(config-router)#version 2 R4(config-router)#network 45.0.0.0 R4(config-router)#network 14.0.0.0 R4(config-router)#no auto-summary R4(config-router)#exit   R4(config)#router eigrp 140 R4(config-router)#network 4.0.0.0 R4(config-router)#network 40.0.0.0 R4(config-router)#no auto-summary R4(config-router)#exit   R5(config)#router rip R5(config-router)#ver 2 R5(config-router)#network 45.0.0.0 R5(config-router)#no auto-summary R5(config-router)#exit   R5(config)#router ospf 11 R5(config-router)#network 24.0.0.0 0.255.255.255 a R5(config-router)#network 24.0.0.0 0.255.255.255 area 0 R5(config-router)#network 50.0.0.0 0.255.255.255 area 0 R5(config-router)#exit   R5(config)#router eigrp 53 R5(config-router)#network 35.0.0.0 R5(config-router)#network 150.0.0.0 R5(config-router)#no auto-summary R5(config-router)#exit   R5(config)#router rip R5(config-router)#version 2 R5(config-router)#network 15.0.0.0 R5(config-router)#no auto-summary R5(config-router)#exit   R1#show ip protocols *** IP Routing is NSF aware ***   Routing Protocol is "eigrp 210"   Outgoing update filter list for all interfaces is not set   Incoming update filter list for all interfaces is not set   Default networks flagged in outgoing updates   Default networks accepted from incoming updates   EIGRP-IPv4 Protocol for AS(210)     Metric weight K1=1, K2=0, K3=1, K4=0, K5=0     NSF-aware route hold timer is 240     Router-ID: 11.0.3.1     Topology : 0 (base)       Active Timer: 3 min       Distance: internal 90 external 170       Maximum path: 4       Maximum hopcount 100       Maximum metric variance 1     Automatic Summarization: disabled   Maximum path: 4   Routing for Networks:     1.0.0.0     10.0.0.0   Routing Information Sources:     Gateway         Distance      Last Update     1.1.1.2               90      00:38:42   Distance: internal 90 external 170   Routing Protocol is "rip"   Outgoing update filter list for all interfaces is not set   Incoming update filter list for all interfaces is not set   Sending updates every 30 seconds, next due in 23 seconds   Invalid after 180 seconds, hold down 180, flushed after 240   Redistributing: rip   Default version control: send version 2, receive version 2     Interface             Send  Recv  Triggered RIP  Key-chain     Serial3/6             2     2     Loopback0             2     2     Loopback1             2     2     Loopback2             2     2     Loopback3             2     2   Automatic network summarization is not in effect   Maximum path: 4   Routing for Networks:     11.0.0.0     15.0.0.0   Routing Information Sources:     Gateway         Distance      Last Update   Distance: (default is 120)   Routing Protocol is "eigrp 140"   Outgoing update filter list for all interfaces is not set   Incoming update filter list for all interfaces is not set   Default networks flagged in outgoing updates   Default networks accepted from incoming updates   EIGRP-IPv4 Protocol for AS(140)     Metric weight K1=1, K2=0, K3=1, K4=0, K5=0     NSF-aware route hold timer is 240     Router-ID: 11.0.3.1     Topology : 0 (base)       Active Timer: 3 min       Distance: internal 90 external 170       Maximum path: 4       Maximum hopcount 100       Maximum metric variance 1     Automatic Summarization: disabled   Maximum path: 4   Routing for Networks:     4.0.0.0   Routing Information Sources:     Gateway         Distance      Last Update     4.1.1.1               90      00:20:14   Distance: internal 90 external 170       R2#show ip protocols *** IP Routing is NSF aware ***   Routing Protocol is "eigrp 210"   Outgoing update filter list for all interfaces is not set   Incoming update filter list for all interfaces is not set   Default networks flagged in outgoing updates   Default networks accepted from incoming updates   EIGRP-IPv4 Protocol for AS(210)     Metric weight K1=1, K2=0, K3=1, K4=0, K5=0     NSF-aware route hold timer is 240     Router-ID: 12.0.3.1     Topology : 0 (base)       Active Timer: 3 min       Distance: internal 90 external 170       Maximum path: 4       Maximum hopcount 100       Maximum metric variance 1     Automatic Summarization: disabled   Maximum path: 4   Routing for Networks:     1.0.0.0     20.0.0.0   Routing Information Sources:     Gateway         Distance      Last Update     1.1.1.1               90      00:39:50   Distance: internal 90 external 170   Routing Protocol is "rip"   Outgoing update filter list for all interfaces is not set   Incoming update filter list for all interfaces is not set   Sending updates every 30 seconds, next due in 7 seconds   Invalid after 180 seconds, hold down 180, flushed after 240   Redistributing: rip   Default version control: send version 2, receive version 2     Interface             Send  Recv  Triggered RIP  Key-chain     Serial3/1             2     2   Automatic network summarization is in effect   Maximum path: 4   Routing for Networks:     2.0.0.0     11.0.0.0   Routing Information Sources:     Gateway         Distance      Last Update     2.1.1.2              120      00:00:27   Distance: (default is 120)   Routing Protocol is "ospf 11"   Outgoing update filter list for all interfaces is not set   Incoming update filter list for all interfaces is not set   Router ID 12.0.3.1   Number of areas in this router is 1. 1 normal 0 stub 0 nssa   Maximum path: 4   Routing for Networks:     25.0.0.0 0.255.255.255 area 0   Routing Information Sources:     Gateway         Distance      Last Update   Distance: (default is 110)     R3#show ip protocols *** IP Routing is NSF aware ***   Routing Protocol is "rip"   Outgoing update filter list for all interfaces is not set   Incoming update filter list for all interfaces is not set   Sending updates every 30 seconds, next due in 11 seconds   Invalid after 180 seconds, hold down 180, flushed after 240   Redistributing: rip   Default version control: send version 2, receive version 2     Interface             Send  Recv  Triggered RIP  Key-chain     Serial3/1             2     2     Loopback0             2     2     Loopback1             2     2     Loopback2             2     2     Loopback3             2     2   Automatic network summarization is not in effect   Maximum path: 4   Routing for Networks:     2.0.0.0     13.0.0.0   Routing Information Sources:     Gateway         Distance      Last Update   Distance: (default is 120)   Routing Protocol is "eigrp 53"   Outgoing update filter list for all interfaces is not set   Incoming update filter list for all interfaces is not set   Default networks flagged in outgoing updates   Default networks accepted from incoming updates   EIGRP-IPv4 Protocol for AS(53)     Metric weight K1=1, K2=0, K3=1, K4=0, K5=0     NSF-aware route hold timer is 240     Router-ID: 13.0.3.1     Topology : 0 (base)       Active Timer: 3 min       Distance: internal 90 external 170       Maximum path: 4       Maximum hopcount 100       Maximum metric variance 1     Automatic Summarization: disabled   Maximum path: 4   Routing for Networks:     30.0.0.0     35.0.0.0   Routing Information Sources:     Gateway         Distance      Last Update     35.1.1.2              90      00:29:09   Distance: internal 90 external 170   Routing Protocol is "ospf 10"   Outgoing update filter list for all interfaces is not set   Incoming update filter list for all interfaces is not set   Router ID 13.0.3.1   Number of areas in this router is 1. 1 normal 0 stub 0 nssa   Maximum path: 4   Routing for Networks:     3.0.0.0 0.255.255.255 area 0   Routing Information Sources:     Gateway         Distance      Last Update   Distance: (default is 110)     R4#show ip protocols *** IP Routing is NSF aware ***   Routing Protocol is "ospf 10"   Outgoing update filter list for all interfaces is not set   Incoming update filter list for all interfaces is not set   Router ID 14.0.3.1   Number of areas in this router is 1. 1 normal 0 stub 0 nssa   Maximum path: 4   Routing for Networks:     3.0.0.0 0.255.255.255 area 0   Routing Information Sources:     Gateway         Distance      Last Update   Distance: (default is 110)   Routing Protocol is "rip"   Outgoing update filter list for all interfaces is not set   Incoming update filter list for all interfaces is not set   Sending updates every 30 seconds, next due in 28 seconds   Invalid after 180 seconds, hold down 180, flushed after 240   Redistributing: rip   Default version control: send version 2, receive version 2     Interface             Send  Recv  Triggered RIP  Key-chain     Serial3/7             2     2     Loopback0             2     2     Loopback1             2     2     Loopback2             2     2     Loopback3             2     2   Automatic network summarization is not in effect   Maximum path: 4   Routing for Networks:     14.0.0.0     45.0.0.0   Routing Information Sources:     Gateway         Distance      Last Update     45.1.1.2             120      00:00:11   Distance: (default is 120)   Routing Protocol is "eigrp 140"   Outgoing update filter list for all interfaces is not set   Incoming update filter list for all interfaces is not set   Default networks flagged in outgoing updates   Default networks accepted from incoming updates   EIGRP-IPv4 Protocol for AS(140)     Metric weight K1=1, K2=0, K3=1, K4=0, K5=0     NSF-aware route hold timer is 240     Router-ID: 14.0.3.1     Topology : 0 (base)       Active Timer: 3 min       Distance: internal 90 external 170       Maximum path: 4       Maximum hopcount 100       Maximum metric variance 1     Automatic Summarization: disabled   Maximum path: 4   Routing for Networks:     4.0.0.0     40.0.0.0   Routing Information Sources:     Gateway         Distance      Last Update   Distance: internal 90 external 170     R5#show ip protocols *** IP Routing is NSF aware ***   Routing Protocol is "ospf 11"   Outgoing update filter list for all interfaces is not set   Incoming update filter list for all interfaces is not set   Router ID 150.0.3.1   Number of areas in this router is 1. 1 normal 0 stub 0 nssa   Maximum path: 4   Routing for Networks:     24.0.0.0 0.255.255.255 area 0     50.0.0.0 0.255.255.255 area 0   Routing Information Sources:     Gateway         Distance      Last Update   Distance: (default is 110)   Routing Protocol is "eigrp 53"   Outgoing update filter list for all interfaces is not set   Incoming update filter list for all interfaces is not set   Default networks flagged in outgoing updates   Default networks accepted from incoming updates   EIGRP-IPv4 Protocol for AS(53)     Metric weight K1=1, K2=0, K3=1, K4=0, K5=0     NSF-aware route hold timer is 240     Router-ID: 150.0.3.1     Topology : 0 (base)       Active Timer: 3 min       Distance: internal 90 external 170       Maximum path: 4       Maximum hopcount 100       Maximum metric variance 1     Automatic Summarization: disabled   Maximum path: 4   Routing for Networks:     35.0.0.0     150.0.0.0   Routing Information Sources:     Gateway         Distance      Last Update     35.1.1.1              90      00:30:12   Distance: internal 90 external 170   Routing Protocol is "rip"   Outgoing update filter list for all interfaces is not set   Incoming update filter list for all interfaces is not set   Sending updates every 30 seconds, next due in 20 seconds   Invalid after 180 seconds, hold down 180, flushed after 240   Redistributing: rip   Default version control: send version 2, receive version 2     Interface             Send  Recv  Triggered RIP  Key-chain     Serial3/6             2     2     Serial3/7             2     2   Automatic network summarization is not in effect   Maximum path: 4   Routing for Networks:     15.0.0.0     45.0.0.0   Routing Information Sources:     Gateway         Distance      Last Update     45.1.1.1             120      00:00:01   Distance: (default is 120)   R1(config)#router eigrp 210 R1(config-router)#redistribute rip metric 1000 20000 255 1 1500 R1(config-router)#redistribute eigrp 140 metric 1000 20000 255 1 1500 R1(config-router)#exit   R1(config)#router rip R1(config-router)#version 2 R1(config-router)#redistribute eigrp 210 metric 8 R1(config-router)#redistribute eigrp 140 metric 8 R1(config-router)#exit   R1(config)#router eigrp 140 R1(config-router)#redistribute eigrp 210 metric  1000 20000 255 1 1500 R1(config-router)#redistribute rip  metric  1000 20000 255 1 1500 R1(config-router)#exit   R2(config)#router eigrp 210 R2(config-router)#redistribute ospf 11 metric 1000 20000 255 1 1500 R2(config-router)#redistribute rip  metric 1000 20000 255 1 1500 R2(config-router)#exit   R2(config)#router rip R2(config-router)#version 2 R2(config-router)#redistribute ospf 11 metric 8 R2(config-router)#redistribute eigrp 210  metric 8 R2(config-router)#exit   R2(config)#router ospf 11 R2(config-router)#redistribute eigrp 210 subnets metric-type 1 R2(config-router)#redistribute rip  subnets metric-type 1 R2(config-router)#exit   R3(config)#router rip R3(config-router)#version 2 R3(config-router)#redistribute eigrp 53 metric 8 R3(config-router)#redistribute ospf 10  metric 8 R3(config-router)#exit   R3(config)#router eigrp 53 R3(config-router)#redistribute rip metric 1000 20000 255 1 1500 R3(config-router)#redistribute ospf 10  metric 1000 20000 255 1 1500 R3(config-router)#exit   R3(config)#router ospf 10 R3(config-router)#redistribute rip subnets metric-type 1 R3(config-router)#redistribute eigrp 53  subnets metric-type 1 R3(config-router)#exit   R4(config)#router ospf 10 R4(config-router)#redistribute rip subnets metric-type 1 R4(config-router)#redistribute eigrp 140  subnets metric-type 1 R4(config-router)#exit   R4(config)#router rip R4(config-router)#version 2 R4(config-router)#redistribute eigrp 140 metric 8 R4(config-router)#redistribute ospf 10  metric 8 R4(config-router)#exit   R4(config)#router eigrp 140 R4(config-router)#redistribute rip metric 1000 20000 255 1 1500 R4(config-router)#redistribute ospf 10  metric 1000 20000 255 1 1500 R4(config-router)#exit   R5(config)#router ospf 11 R5(config-router)#redistribute eigrp 53 subnets metric-type 1 R5(config-router)#redistribute rip  subnets metric-type 1 R5(config-router)#exit   R5(config)#router rip R5(config-router)#version 2 R5(config-router)#redistribute eigrp 53 metric 8 R5(config-router)#redistribute ospf 11 metric 8 R5(config-router)#exit   R5(config)#router eigrp 53 R5(config-router)#redistribute ospf 11 metric 1000 20000 255 1 1500 R5(config-router)#redistribute rip  metric 1000 20000 255 1 1500 R5(config-router)#exit   R1#show ip route Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP        D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area        N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2        E1 - OSPF external type 1, E2 - OSPF external type 2        i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2        ia - IS-IS inter area, * - candidate default, U - per-user static route        o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP        + - replicated route, % - next hop override   Gateway of last resort is not set         1.0.0.0/8 is variably subnetted, 2 subnets, 2 masks C        1.0.0.0/8 is directly connected, Serial3/0 L        1.1.1.1/32 is directly connected, Serial3/0 D EX  2.0.0.0/8 [170/8192000] via 4.1.1.1, 00:18:49, Serial3/3 D EX  3.0.0.0/8 [170/8192000] via 4.1.1.1, 00:18:49, Serial3/3       4.0.0.0/8 is variably subnetted, 2 subnets, 2 masks C        4.0.0.0/8 is directly connected, Serial3/3 L        4.1.1.2/32 is directly connected, Serial3/3       10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks C        10.0.0.0/8 is directly connected, FastEthernet0/0 L        10.1.1.1/32 is directly connected, FastEthernet0/0       11.0.0.0/8 is variably subnetted, 9 subnets, 3 masks D EX     11.0.0.0/8 [170/8192000] via 4.1.1.1, 00:18:50, Serial3/3 C        11.0.0.0/24 is directly connected, Loopback0 L        11.0.0.1/32 is directly connected, Loopback0 C        11.0.1.0/24 is directly connected, Loopback1 L        11.0.1.1/32 is directly connected, Loopback1 C        11.0.2.0/24 is directly connected, Loopback2 L        11.0.2.1/32 is directly connected, Loopback2 C        11.0.3.0/24 is directly connected, Loopback3 L        11.0.3.1/32 is directly connected, Loopback3       12.0.0.0/8 is variably subnetted, 5 subnets, 2 masks D EX     12.0.0.0/8 [170/8192000] via 4.1.1.1, 00:09:50, Serial3/3 D EX     12.0.0.0/24 [170/8192000] via 1.1.1.2, 00:09:52, Serial3/0 D EX     12.0.1.0/24 [170/8192000] via 1.1.1.2, 00:09:52, Serial3/0 D EX     12.0.2.0/24 [170/8192000] via 1.1.1.2, 00:09:52, Serial3/0 D EX     12.0.3.0/24 [170/8192000] via 1.1.1.2, 00:09:52, Serial3/0       13.0.0.0/24 is subnetted, 4 subnets D EX     13.0.0.0 [170/8192000] via 4.1.1.1, 00:18:49, Serial3/3 D EX     13.0.1.0 [170/8192000] via 4.1.1.1, 00:18:49, Serial3/3 D EX     13.0.2.0 [170/8192000] via 4.1.1.1, 00:18:49, Serial3/3 D EX     13.0.3.0 [170/8192000] via 4.1.1.1, 00:18:49, Serial3/3       14.0.0.0/24 is subnetted, 4 subnets D EX     14.0.0.0 [170/8192000] via 4.1.1.1, 00:18:59, Serial3/3 D EX     14.0.1.0 [170/8192000] via 4.1.1.1, 00:18:59, Serial3/3 D EX     14.0.2.0 [170/8192000] via 4.1.1.1, 00:18:59, Serial3/3 D EX     14.0.3.0 [170/8192000] via 4.1.1.1, 00:18:59, Serial3/3       15.0.0.0/8 is variably subnetted, 2 subnets, 2 masks C        15.0.0.0/8 is directly connected, Serial3/6 L        15.1.1.1/32 is directly connected, Serial3/6 D     20.0.0.0/8 [90/2172416] via 1.1.1.2, 01:29:11, Serial3/0 D EX  24.0.0.0/8 [170/8192000] via 4.1.1.1, 00:15:10, Serial3/3 D EX  30.0.0.0/8 [170/8192000] via 4.1.1.1, 00:18:49, Serial3/3 D EX  35.0.0.0/8 [170/8192000] via 4.1.1.1, 00:18:49, Serial3/3 D     40.0.0.0/8 [90/2172416] via 4.1.1.1, 01:10:38, Serial3/3 D EX  45.0.0.0/8 [170/8192000] via 4.1.1.1, 00:18:59, Serial3/3 D EX  50.0.0.0/8 [170/8192000] via 4.1.1.1, 00:15:10, Serial3/3       150.0.0.0/24 is subnetted, 4 subnets D EX     150.0.0.0 [170/8192000] via 4.1.1.1, 00:18:49, Serial3/3 D EX     150.0.1.0 [170/8192000] via 4.1.1.1, 00:18:49, Serial3/3 D EX     150.0.2.0 [170/8192000] via 4.1.1.1, 00:18:49, Serial3/3 D EX     150.0.3.0 [170/8192000] via 4.1.1.1, 00:18:49, Serial3/3   R2#show ip route Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP        D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area        N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2        E1 - OSPF external type 1, E2 - OSPF external type 2        i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2        ia - IS-IS inter area, * - candidate default, U - per-user static route        o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP        + - replicated route, % - next hop override   Gateway of last resort is not set         1.0.0.0/8 is variably subnetted, 2 subnets, 2 masks C        1.0.0.0/8 is directly connected, Serial3/0 L        1.1.1.2/32 is directly connected, Serial3/0       2.0.0.0/8 is variably subnetted, 2 subnets, 2 masks C        2.0.0.0/8 is directly connected, Serial3/1 L        2.1.1.1/32 is directly connected, Serial3/1 R     3.0.0.0/8 [120/8] via 2.1.1.2, 00:00:08, Serial3/1 R     4.0.0.0/8 [120/8] via 2.1.1.2, 00:00:08, Serial3/1 D     10.0.0.0/8 [90/2172416] via 1.1.1.1, 00:10:26, Serial3/0       11.0.0.0/8 is variably subnetted, 5 subnets, 2 masks D EX     11.0.0.0/8 [170/8192000] via 1.1.1.1, 00:10:26, Serial3/0 R        11.0.0.0/24 [120/8] via 2.1.1.2, 00:00:08, Serial3/1 R        11.0.1.0/24 [120/8] via 2.1.1.2, 00:00:08, Serial3/1 R        11.0.2.0/24 [120/8] via 2.1.1.2, 00:00:08, Serial3/1 R        11.0.3.0/24 [120/8] via 2.1.1.2, 00:00:08, Serial3/1       12.0.0.0/8 is variably subnetted, 9 subnets, 3 masks D EX     12.0.0.0/8 [170/8192000] via 1.1.1.1, 00:10:26, Serial3/0 C        12.0.0.0/24 is directly connected, Loopback0 L        12.0.0.1/32 is directly connected, Loopback0 C        12.0.1.0/24 is directly connected, Loopback1 L        12.0.1.1/32 is directly connected, Loopback1 C        12.0.2.0/24 is directly connected, Loopback2 L        12.0.2.1/32 is directly connected, Loopback2 C        12.0.3.0/24 is directly connected, Loopback3 L        12.0.3.1/32 is directly connected, Loopback3       13.0.0.0/24 is subnetted, 4 subnets R        13.0.0.0 [120/1] via 2.1.1.2, 00:00:08, Serial3/1 R        13.0.1.0 [120/1] via 2.1.1.2, 00:00:08, Serial3/1 R        13.0.2.0 [120/1] via 2.1.1.2, 00:00:08, Serial3/1 R        13.0.3.0 [120/1] via 2.1.1.2, 00:00:08, Serial3/1       14.0.0.0/24 is subnetted, 4 subnets R        14.0.0.0 [120/8] via 2.1.1.2, 00:00:08, Serial3/1 R        14.0.1.0 [120/8] via 2.1.1.2, 00:00:08, Serial3/1 R        14.0.2.0 [120/8] via 2.1.1.2, 00:00:08, Serial3/1 R        14.0.3.0 [120/8] via 2.1.1.2, 00:00:08, Serial3/1 D EX  15.0.0.0/8 [170/8192000] via 1.1.1.1, 00:10:26, Serial3/0       20.0.0.0/8 is variably subnetted, 2 subnets, 2 masks C        20.0.0.0/8 is directly connected, FastEthernet0/0 L        20.1.1.1/32 is directly connected, FastEthernet0/0       24.0.0.0/8 is variably subnetted, 2 subnets, 2 masks C        24.0.0.0/8 is directly connected, Serial3/4 L        24.1.1.1/32 is directly connected, Serial3/4 R     30.0.0.0/8 [120/8] via 2.1.1.2, 00:00:08, Serial3/1 R     35.0.0.0/8 [120/8] via 2.1.1.2, 00:00:08, Serial3/1 R     40.0.0.0/8 [120/8] via 2.1.1.2, 00:00:08, Serial3/1 R     45.0.0.0/8 [120/8] via 2.1.1.2, 00:00:08, Serial3/1 R     50.0.0.0/8 [120/8] via 2.1.1.2, 00:00:08, Serial3/1       150.0.0.0/24 is subnetted, 4 subnets R        150.0.0.0 [120/8] via 2.1.1.2, 00:00:08, Serial3/1 R        150.0.1.0 [120/8] via 2.1.1.2, 00:00:08, Serial3/1 R        150.0.2.0 [120/8] via 2.1.1.2, 00:00:08, Serial3/1 R        150.0.3.0 [120/8] via 2.1.1.2, 00:00:08, Serial3/1   R3#show ip route Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP        D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area        N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2        E1 - OSPF external type 1, E2 - OSPF external type 2        i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2        ia - IS-IS inter area, * - candidate default, U - per-user static route        o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP        + - replicated route, % - next hop override   Gateway of last resort is not set   R     1.0.0.0/8 [120/8] via 2.1.1.1, 00:00:10, Serial3/1       2.0.0.0/8 is variably subnetted, 2 subnets, 2 masks C        2.0.0.0/8 is directly connected, Serial3/1 L        2.1.1.2/32 is directly connected, Serial3/1       3.0.0.0/8 is variably subnetted, 2 subnets, 2 masks C        3.0.0.0/8 is directly connected, Serial3/2 L        3.1.1.1/32 is directly connected, Serial3/2 O E1  4.0.0.0/8 [110/84] via 3.1.1.2, 00:21:54, Serial3/2 R     10.0.0.0/8 [120/8] via 2.1.1.1, 00:00:10, Serial3/1       11.0.0.0/8 is variably subnetted, 5 subnets, 2 masks R        11.0.0.0/8 [120/8] via 2.1.1.1, 00:00:10, Serial3/1 O E1     11.0.0.0/24 [110/84] via 3.1.1.2, 00:21:54, Serial3/2 O E1     11.0.1.0/24 [110/84] via 3.1.1.2, 00:21:54, Serial3/2 O E1     11.0.2.0/24 [110/84] via 3.1.1.2, 00:21:54, Serial3/2 O E1     11.0.3.0/24 [110/84] via 3.1.1.2, 00:21:54, Serial3/2       12.0.0.0/8 is variably subnetted, 5 subnets, 2 masks R        12.0.0.0/8 [120/8] via 2.1.1.1, 00:00:10, Serial3/1 O E1     12.0.0.0/24 [110/84] via 3.1.1.2, 00:11:03, Serial3/2 O E1     12.0.1.0/24 [110/84] via 3.1.1.2, 00:11:03, Serial3/2 O E1     12.0.2.0/24 [110/84] via 3.1.1.2, 00:11:03, Serial3/2 O E1     12.0.3.0/24 [110/84] via 3.1.1.2, 00:11:03, Serial3/2       13.0.0.0/8 is variably subnetted, 8 subnets, 2 masks C        13.0.0.0/24 is directly connected, Loopback0 L        13.0.0.1/32 is directly connected, Loopback0 C        13.0.1.0/24 is directly connected, Loopback1 L        13.0.1.1/32 is directly connected, Loopback1 C        13.0.2.0/24 is directly connected, Loopback2 L        13.0.2.1/32 is directly connected, Loopback2 C        13.0.3.0/24 is directly connected, Loopback3 L        13.0.3.1/32 is directly connected, Loopback3       14.0.0.0/24 is subnetted, 4 subnets O E1     14.0.0.0 [110/84] via 3.1.1.2, 00:22:05, Serial3/2 O E1     14.0.1.0 [110/84] via 3.1.1.2, 00:22:05, Serial3/2 O E1     14.0.2.0 [110/84] via 3.1.1.2, 00:22:05, Serial3/2 O E1     14.0.3.0 [110/84] via 3.1.1.2, 00:22:05, Serial3/2 R     15.0.0.0/8 [120/8] via 2.1.1.1, 00:00:10, Serial3/1 R     20.0.0.0/8 [120/8] via 2.1.1.1, 00:00:10, Serial3/1 O E1  24.0.0.0/8 [110/84] via 3.1.1.2, 00:16:21, Serial3/2       30.0.0.0/8 is variably subnetted, 2 subnets, 2 masks C        30.0.0.0/8 is directly connected, FastEthernet0/0 L        30.1.1.1/32 is directly connected, FastEthernet0/0       35.0.0.0/8 is variably subnetted, 2 subnets, 2 masks C        35.0.0.0/8 is directly connected, Serial3/5 L        35.1.1.1/32 is directly connected, Serial3/5 O E1  40.0.0.0/8 [110/84] via 3.1.1.2, 00:21:54, Serial3/2 O E1  45.0.0.0/8 [110/84] via 3.1.1.2, 00:22:05, Serial3/2 O E1  50.0.0.0/8 [110/84] via 3.1.1.2, 00:16:21, Serial3/2       150.0.0.0/24 is subnetted, 4 subnets D        150.0.0.0 [90/2297856] via 35.1.1.2, 01:19:24, Serial3/5 D        150.0.1.0 [90/2297856] via 35.1.1.2, 01:19:24, Serial3/5 D        150.0.2.0 [90/2297856] via 35.1.1.2, 01:19:24, Serial3/5 D        150.0.3.0 [90/2297856] via 35.1.1.2, 01:19:24, Serial3/5   R4#show ip route Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP        D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area        N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2        E1 - OSPF external type 1, E2 - OSPF external type 2        i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2        ia - IS-IS inter area, * - candidate default, U - per-user static route        o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP        + - replicated route, % - next hop override   Gateway of last resort is not set   O E1  1.0.0.0/8 [110/84] via 3.1.1.1, 00:25:48, Serial3/2 O E1  2.0.0.0/8 [110/84] via 3.1.1.1, 00:25:48, Serial3/2       3.0.0.0/8 is variably subnetted, 2 subnets, 2 masks C        3.0.0.0/8 is directly connected, Serial3/2 L        3.1.1.2/32 is directly connected, Serial3/2       4.0.0.0/8 is variably subnetted, 2 subnets, 2 masks C        4.0.0.0/8 is directly connected, Serial3/3 L        4.1.1.1/32 is directly connected, Serial3/3 O E1  10.0.0.0/8 [110/84] via 3.1.1.1, 00:25:48, Serial3/2       11.0.0.0/8 is variably subnetted, 5 subnets, 2 masks O E1     11.0.0.0/8 [110/84] via 3.1.1.1, 00:25:48, Serial3/2 D EX     11.0.0.0/24 [170/8192000] via 4.1.1.2, 00:40:04, Serial3/3 D EX     11.0.1.0/24 [170/8192000] via 4.1.1.2, 00:40:04, Serial3/3 D EX     11.0.2.0/24 [170/8192000] via 4.1.1.2, 00:40:04, Serial3/3 D EX     11.0.3.0/24 [170/8192000] via 4.1.1.2, 00:40:04, Serial3/3       12.0.0.0/8 is variably subnetted, 5 subnets, 2 masks O E1     12.0.0.0/8 [110/84] via 3.1.1.1, 00:11:29, Serial3/2 D EX     12.0.0.0/24 [170/8192000] via 4.1.1.2, 00:11:30, Serial3/3 D EX     12.0.1.0/24 [170/8192000] via 4.1.1.2, 00:11:30, Serial3/3 D EX     12.0.2.0/24 [170/8192000] via 4.1.1.2, 00:11:30, Serial3/3 D EX     12.0.3.0/24 [170/8192000] via 4.1.1.2, 00:11:30, Serial3/3       13.0.0.0/24 is subnetted, 4 subnets O E1     13.0.0.0 [110/84] via 3.1.1.1, 00:25:48, Serial3/2 O E1     13.0.1.0 [110/84] via 3.1.1.1, 00:25:48, Serial3/2 O E1     13.0.2.0 [110/84] via 3.1.1.1, 00:25:48, Serial3/2 O E1     13.0.3.0 [110/84] via 3.1.1.1, 00:25:48, Serial3/2       14.0.0.0/8 is variably subnetted, 8 subnets, 2 masks C        14.0.0.0/24 is directly connected, Loopback0 L        14.0.0.1/32 is directly connected, Loopback0 C        14.0.1.0/24 is directly connected, Loopback1 L        14.0.1.1/32 is directly connected, Loopback1 C        14.0.2.0/24 is directly connected, Loopback2 L        14.0.2.1/32 is directly connected, Loopback2 C        14.0.3.0/24 is directly connected, Loopback3 L        14.0.3.1/32 is directly connected, Loopback3 O E1  15.0.0.0/8 [110/84] via 3.1.1.1, 00:25:48, Serial3/2 O E1  20.0.0.0/8 [110/84] via 3.1.1.1, 00:25:48, Serial3/2 R     24.0.0.0/8 [120/8] via 45.1.1.2, 00:00:16, Serial3/7 O E1  30.0.0.0/8 [110/84] via 3.1.1.1, 00:25:38, Serial3/2 O E1  35.0.0.0/8 [110/84] via 3.1.1.1, 00:25:38, Serial3/2       40.0.0.0/8 is variably subnetted, 2 subnets, 2 masks C        40.0.0.0/8 is directly connected, FastEthernet0/0 L        40.1.1.1/32 is directly connected, FastEthernet0/0       45.0.0.0/8 is variably subnetted, 2 subnets, 2 masks C        45.0.0.0/8 is directly connected, Serial3/7 L        45.1.1.1/32 is directly connected, Serial3/7 R     50.0.0.0/8 [120/8] via 45.1.1.2, 00:00:16, Serial3/7       150.0.0.0/24 is subnetted, 4 subnets O E1     150.0.0.0 [110/84] via 3.1.1.1, 00:25:38, Serial3/2 O E1     150.0.1.0 [110/84] via 3.1.1.1, 00:25:38, Serial3/2 O E1     150.0.2.0 [110/84] via 3.1.1.1, 00:25:38, Serial3/2 O E1     150.0.3.0 [110/84] via 3.1.1.1, 00:25:38, Serial3/2   R5#show ip route Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP        D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area        N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2        E1 - OSPF external type 1, E2 - OSPF external type 2        i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2        ia - IS-IS inter area, * - candidate default, U - per-user static route        o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP        + - replicated route, % - next hop override   Gateway of last resort is not set   R     1.0.0.0/8 [120/8] via 45.1.1.1, 00:00:11, Serial3/7 R     2.0.0.0/8 [120/8] via 45.1.1.1, 00:00:11, Serial3/7 R     3.0.0.0/8 [120/8] via 45.1.1.1, 00:00:11, Serial3/7 R     4.0.0.0/8 [120/8] via 45.1.1.1, 00:00:11, Serial3/7 R     10.0.0.0/8 [120/8] via 45.1.1.1, 00:00:11, Serial3/7       11.0.0.0/8 is variably subnetted, 5 subnets, 2 masks R        11.0.0.0/8 [120/8] via 45.1.1.1, 00:00:11, Serial3/7 R        11.0.0.0/24 [120/8] via 45.1.1.1, 00:00:11, Serial3/7 R        11.0.1.0/24 [120/8] via 45.1.1.1, 00:00:11, Serial3/7 R        11.0.2.0/24 [120/8] via 45.1.1.1, 00:00:11, Serial3/7 R        11.0.3.0/24 [120/8] via 45.1.1.1, 00:00:11, Serial3/7       12.0.0.0/8 is variably subnetted, 5 subnets, 2 masks R        12.0.0.0/8 [120/8] via 45.1.1.1, 00:00:11, Serial3/7 R        12.0.0.0/24 [120/8] via 45.1.1.1, 00:00:11, Serial3/7 R        12.0.1.0/24 [120/8] via 45.1.1.1, 00:00:11, Serial3/7 R        12.0.2.0/24 [120/8] via 45.1.1.1, 00:00:11, Serial3/7 R        12.0.3.0/24 [120/8] via 45.1.1.1, 00:00:11, Serial3/7       13.0.0.0/24 is subnetted, 4 subnets R        13.0.0.0 [120/8] via 45.1.1.1, 00:00:11, Serial3/7 R        13.0.1.0 [120/8] via 45.1.1.1, 00:00:11, Serial3/7 R        13.0.2.0 [120/8] via 45.1.1.1, 00:00:11, Serial3/7 R        13.0.3.0 [120/8] via 45.1.1.1, 00:00:11, Serial3/7       14.0.0.0/24 is subnetted, 4 subnets R        14.0.0.0 [120/1] via 45.1.1.1, 00:00:11, Serial3/7 R        14.0.1.0 [120/1] via 45.1.1.1, 00:00:11, Serial3/7 R        14.0.2.0 [120/1] via 45.1.1.1, 00:00:11, Serial3/7 R        14.0.3.0 [120/1] via 45.1.1.1, 00:00:11, Serial3/7       15.0.0.0/8 is variably subnetted, 2 subnets, 2 masks C        15.0.0.0/8 is directly connected, Serial3/6 L        15.1.1.1/32 is directly connected, Serial3/6 R     20.0.0.0/8 [120/8] via 45.1.1.1, 00:00:11, Serial3/7       24.0.0.0/8 is variably subnetted, 2 subnets, 2 masks C        24.0.0.0/8 is directly connected, Serial3/4 L        24.1.1.2/32 is directly connected, Serial3/4 D     30.0.0.0/8 [90/2172416] via 35.1.1.1, 01:20:22, Serial3/5       35.0.0.0/8 is variably subnetted, 2 subnets, 2 masks C        35.0.0.0/8 is directly connected, Serial3/5 L        35.1.1.2/32 is directly connected, Serial3/5 R     40.0.0.0/8 [120/8] via 45.1.1.1, 00:00:11, Serial3/7       45.0.0.0/8 is variably subnetted, 2 subnets, 2 masks C        45.0.0.0/8 is directly connected, Serial3/7 L        45.1.1.2/32 is directly connected, Serial3/7       50.0.0.0/8 is variably subnetted, 2 subnets, 2 masks C        50.0.0.0/8 is directly connected, FastEthernet0/0 L        50.1.1.1/32 is directly connected, FastEthernet0/0       150.0.0.0/16 is variably subnetted, 8 subnets, 2 masks C        150.0.0.0/24 is directly connected, Loopback0 L        150.0.0.1/32 is directly connected, Loopback0 C        150.0.1.0/24 is directly connected, Loopback1 L        150.0.1.1/32 is directly connected, Loopback1 C        150.0.2.0/24 is directly connected, Loopback2 L        150.0.2.1/32 is directly connected, Loopback2 C        150.0.3.0/24 is directly connected, Loopback3 L        150.0.3.1/32 is directly connected, Loopback3     R1#show ip protocols *** IP Routing is NSF aware ***   Routing Protocol is "eigrp 210"   Outgoing update filter list for all interfaces is not set   Incoming update filter list for all interfaces is not set   Default networks flagged in outgoing updates   Default networks accepted from incoming updates    Redistributing: rip, eigrp 140   EIGRP-IPv4 Protocol for AS(210)     Metric weight K1=1, K2=0, K3=1, K4=0, K5=0     NSF-aware route hold timer is 240     Router-ID: 11.0.3.1     Topology : 0 (base)       Active Timer: 3 min       Distance: internal 90 external 170       Maximum path: 4       Maximum hopcount 100       Maximum metric variance 1     Automatic Summarization: disabled   Maximum path: 4   Routing for Networks:     1.0.0.0     10.0.0.0   Routing Information Sources:     Gateway         Distance      Last Update     1.1.1.2               90      00:12:16   Distance: internal 90 external 170   Routing Protocol is "rip"   Outgoing update filter list for all interfaces is not set   Incoming update filter list for all interfaces is not set   Sending updates every 30 seconds, next due in 21 seconds   Invalid after 180 seconds, hold down 180, flushed after 240     Redistributing: eigrp 210, eigrp 140   Default version control: send version 2, receive version 2     Interface             Send  Recv  Triggered RIP  Key-chain     Serial3/6             2     2     Loopback0             2     2     Loopback1             2     2     Loopback2             2     2     Loopback3             2     2   Automatic network summarization is not in effect   Maximum path: 4   Routing for Networks:     11.0.0.0     Interface             Send  Recv  Triggered RIP  Key-chain     15.0.0.0   Routing Information Sources:     Gateway         Distance      Last Update   Distance: (default is 120)   Routing Protocol is "eigrp 140"   Outgoing update filter list for all interfaces is not set   Incoming update filter list for all interfaces is not set   Default networks flagged in outgoing updates   Default networks accepted from incoming updates    Redistributing: eigrp 210, rip   EIGRP-IPv4 Protocol for AS(140)     Metric weight K1=1, K2=0, K3=1, K4=0, K5=0     NSF-aware route hold timer is 240     Router-ID: 11.0.3.1     Topology : 0 (base)       Active Timer: 3 min       Distance: internal 90 external 170       Maximum path: 4       Maximum hopcount 100       Maximum metric variance 1     Automatic Summarization: disabled   Maximum path: 4   Routing for Networks:     4.0.0.0   Routing Information Sources:     Gateway         Distance      Last Update     4.1.1.1               90      00:12:22   Distance: internal 90 external 170   R2#show ip protocols *** IP Routing is NSF aware ***   Routing Protocol is "eigrp 210"   Outgoing update filter list for all interfaces is not set   Incoming update filter list for all interfaces is not set   Default networks flagged in outgoing updates   Default networks accepted from incoming updates   Redistributing: rip, ospf 11   EIGRP-IPv4 Protocol for AS(210)     Metric weight K1=1, K2=0, K3=1, K4=0, K5=0     NSF-aware route hold timer is 240     Router-ID: 12.0.3.1     Topology : 0 (base)       Active Timer: 3 min       Distance: internal 90 external 170       Maximum path: 4       Maximum hopcount 100       Maximum metric variance 1     Automatic Summarization: disabled   Maximum path: 4   Routing for Networks:     1.0.0.0     20.0.0.0   Routing Information Sources:     Gateway         Distance      Last Update     1.1.1.1               90      00:14:01   Distance: internal 90 external 170   Routing Protocol is "rip"   Outgoing update filter list for all interfaces is not set   Incoming update filter list for all interfaces is not set   Sending updates every 30 seconds, next due in 26 seconds   Invalid after 180 seconds, hold down 180, flushed after 240   Redistributing: eigrp 210, rip, ospf 11 (internal, external 1 & 2, nssa-external 1 & 2)     Default version control: send version 2, receive version 2     Interface             Send  Recv  Triggered RIP  Key-chain     Serial3/1             2     2     Loopback0             2     2     Loopback1             2     2     Loopback2             2     2     Loopback3             2     2   Automatic network summarization is in effect   Maximum path: 4     Interface             Send  Recv  Triggered RIP  Key-chain   Routing for Networks:     2.0.0.0     12.0.0.0   Routing Information Sources:     Gateway         Distance      Last Update     2.1.1.2              120      00:00:07   Distance: (default is 120)   Routing Protocol is "ospf 11"   Outgoing update filter list for all interfaces is not set   Incoming update filter list for all interfaces is not set   Router ID 12.0.3.1   It is an autonomous system boundary router  Redistributing External Routes from,     eigrp 210, includes subnets in redistribution     rip, includes subnets in redistribution   Number of areas in this router is 1. 1 normal 0 stub 0 nssa   Maximum path: 4   Routing for Networks:     25.0.0.0 0.255.255.255 area 0   Routing Information Sources:     Gateway         Distance      Last Update   Distance: (default is 110)   R3#show ip protocols *** IP Routing is NSF aware ***   Routing Protocol is "rip"   Outgoing update filter list for all interfaces is not set   Incoming update filter list for all interfaces is not set   Sending updates every 30 seconds, next due in 14 seconds   Invalid after 180 seconds, hold down 180, flushed after 240     Redistributing: rip, eigrp 53, ospf 10 (internal, external 1 & 2, nssa-external 1 & 2)     Default version control: send version 2, receive version 2     Interface             Send  Recv  Triggered RIP  Key-chain     Serial3/1             2     2     Loopback0             2     2     Loopback1             2     2     Loopback2             2     2     Loopback3             2     2   Automatic network summarization is not in effect   Maximum path: 4   Routing for Networks:     2.0.0.0     13.0.0.0   Routing Information Sources:     Gateway         Distance      Last Update     2.1.1.1              120      00:00:19   Distance: (default is 120)   Routing Protocol is "eigrp 53"   Outgoing update filter list for all interfaces is not set   Incoming update filter list for all interfaces is not set   Default networks flagged in outgoing updates   Default networks accepted from incoming updates   Redistributing: rip, ospf 10   EIGRP-IPv4 Protocol for AS(53)     Metric weight K1=1, K2=0, K3=1, K4=0, K5=0     NSF-aware route hold timer is 240     Router-ID: 13.0.3.1     Topology : 0 (base)       Active Timer: 3 min       Distance: internal 90 external 170       Maximum path: 4       Maximum hopcount 100       Maximum metric variance 1     Automatic Summarization: disabled   Maximum path: 4   Routing for Networks:     30.0.0.0     35.0.0.0   Routing Information Sources:     Gateway         Distance      Last Update     35.1.1.2              90      00:15:41   Distance: internal 90 external 170   Routing Protocol is "ospf 10"   Outgoing update filter list for all interfaces is not set   Incoming update filter list for all interfaces is not set   Router ID 13.0.3.1   It is an autonomous system boundary router  Redistributing External Routes from,     rip, includes subnets in redistribution     eigrp 53, includes subnets in redistribution   Number of areas in this router is 1. 1 normal 0 stub 0 nssa   Maximum path: 4   Routing for Networks:     3.0.0.0 0.255.255.255 area 0   Routing Information Sources:     Gateway         Distance      Last Update     14.0.3.1             110      00:15:48   Distance: (default is 110)   R4#show ip protocols *** IP Routing is NSF aware ***   Routing Protocol is "ospf 10"   Outgoing update filter list for all interfaces is not set   Incoming update filter list for all interfaces is not set   Router ID 14.0.3.1   It is an autonomous system boundary router  Redistributing External Routes from,     rip, includes subnets in redistribution     eigrp 140, includes subnets in redistribution   Number of areas in this router is 1. 1 normal 0 stub 0 nssa   Maximum path: 4   Routing for Networks:     3.0.0.0 0.255.255.255 area 0   Routing Information Sources:     Gateway         Distance      Last Update     13.0.3.1             110      00:17:00   Distance: (default is 110)   Routing Protocol is "rip"   Outgoing update filter list for all interfaces is not set   Incoming update filter list for all interfaces is not set   Sending updates every 30 seconds, next due in 16 seconds   Invalid after 180 seconds, hold down 180, flushed after 240   Redistributing: ospf 10 (internal, external 1 & 2, nssa-external 1 & 2)       Redistributing: rip, eigrp 140   Default version control: send version 2, receive version 2     Interface             Send  Recv  Triggered RIP  Key-chain     Serial3/7             2     2     Loopback0             2     2     Loopback1             2     2     Loopback2             2     2     Loopback3             2     2   Automatic network summarization is not in effect   Maximum path: 4   Routing for Networks:     14.0.0.0     45.0.0.0   Routing Information Sources:     Gateway         Distance      Last Update     45.1.1.2             120      00:00:12   Distance: (default is 120)   Routing Protocol is "eigrp 140"   Outgoing update filter list for all interfaces is not set   Incoming update filter list for all interfaces is not set   Default networks flagged in outgoing updates   Default networks accepted from incoming updates    Redistributing: ospf 10, rip   EIGRP-IPv4 Protocol for AS(140)     Metric weight K1=1, K2=0, K3=1, K4=0, K5=0     NSF-aware route hold timer is 240     Router-ID: 14.0.3.1     Topology : 0 (base)       Active Timer: 3 min       Distance: internal 90 external 170       Maximum path: 4       Maximum hopcount 100       Maximum metric variance 1     Automatic Summarization: disabled   Maximum path: 4   Routing for Networks:     4.0.0.0     40.0.0.0   Routing Information Sources:     Gateway         Distance      Last Update     4.1.1.2               90      00:17:04   Distance: internal 90 external 170   R5#show ip protocols *** IP Routing is NSF aware ***   Routing Protocol is "ospf 11"   Outgoing update filter list for all interfaces is not set   Incoming update filter list for all interfaces is not set   Router ID 150.0.3.1   It is an autonomous system boundary router   Redistributing External Routes from,     eigrp 53, includes subnets in redistribution     rip, includes subnets in redistribution   Number of areas in this router is 1. 1 normal 0 stub 0 nssa   Maximum path: 4   Routing for Networks:     24.0.0.0 0.255.255.255 area 0     50.0.0.0 0.255.255.255 area 0   Routing Information Sources:     Gateway         Distance      Last Update   Distance: (default is 110)   Routing Protocol is "eigrp 53"   Outgoing update filter list for all interfaces is not set   Incoming update filter list for all interfaces is not set   Default networks flagged in outgoing updates   Default networks accepted from incoming updates     Redistributing: ospf 11, rip   EIGRP-IPv4 Protocol for AS(53)     Metric weight K1=1, K2=0, K3=1, K4=0, K5=0     NSF-aware route hold timer is 240     Router-ID: 150.0.3.1     Topology : 0 (base)       Active Timer: 3 min       Distance: internal 90 external 170       Maximum path: 4       Maximum hopcount 100       Maximum metric variance 1     Automatic Summarization: disabled   Maximum path: 4   Routing for Networks:     35.0.0.0     150.0.0.0   Routing Information Sources:     Gateway         Distance      Last Update     35.1.1.1              90      00:18:32   Distance: internal 90 external 170   Routing Protocol is "rip"   Outgoing update filter list for all interfaces is not set   Incoming update filter list for all interfaces is not set   Sending updates every 30 seconds, next due in 25 seconds   Invalid after 180 seconds, hold down 180, flushed after 240   Redistributing: ospf 11 (internal, external 1 & 2, nssa-external 1 & 2)     Redistributing: eigrp 53, rip   Default version control: send version 2, receive version 2     Interface             Send  Recv  Triggered RIP  Key-chain     Serial3/6             2     2     Serial3/7             2     2   Automatic network summarization is not in effect   Maximum path: 4   Routing for Networks:     15.0.0.0     45.0.0.0   Routing Information Sources:     Gateway         Distance      Last Update     45.1.1.1             120      00:00:22   Distance: (default is 120) ... 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  Route filtering passive interface Cisco IOS provides several ways to control updates traffic. Passive interface, distribute list, prefix list route maps. In this section we take look at passive interface in RIPv2, EIGRP, and OSPF. Passive interface command is used in al routing protocol to disable sending updates out from a specific interface. However the command behavior varies from one protocol to another. Passive interface in RIPv2 In RIP passive interface command disable sending multicast updates via a specific interface. Allow listening to incoming updates from other RIPv2 speaking routers.   lets see the configure:https://www.internetworks.in/2018/11/route-filtering-passive-interface-ripv2.html Topology: ... View more

    Distribution lists A distribution-list is used to control routing update either coming to your router or leaving from the router. Distribution-lists work on a variety of different IOS routing protocols like EIGRP, RIP, and OSPF. Distribution-list is one of the easiest ways to control routing updates, you can permit or deny routes using access-list or prefix-list or route map. Distribution-list can be applied to transmitted, received, or redistribute routing updates.   Each interface and routing process, Cisco IOS permits the following:   One incoming global distribute list One outgoing global distribute list One incoming interface distribute list One outgoing interface distribute list One outgoing redistribution distribute list     configuration:https://www.internetworks.in/2018/11/distribution-list.html Topology    ... View more

  Policy Based Routing (PBR)   Policy based routing   is use to path manipulation. It is used for implementing policy that causes the packet to take a different direction. Policy based routing allows source based routing. Routing table is destination base.   In short: PBR is a technique used to make routing decisions based on policies implemented by the network administrator.   Here’s the list of some Advantages of policy based routing:- Different users can reach the destination from different direction Load sharing PBR will be implemented on the incoming direction of the source in interface If the packet is match in the route map and it is permit it will be send according to the policy If the packet is match in the route map and route map deny packet will be forwarded according to normal routing table     Lets configure policy based routing.https://www.internetworks.in/2018/11/policy-based-routing-pbr.html Topology:- ... View more

BGP community Local-AS     Local-AS is a well known BGP community and its use in confederations scenarios to prevent the transmit of traffic outside the local-as. If you are not sure about what is BGP communities are and how its work then I advises you to read my introduction to BGP community first before you continue this lab.   Let see the configuration for better understanding, we are continuing our   previous topology.   Topology:-https://www.internetworks.in/2019/01/bgp-community-local-as.html ... View more

BGP Communities_No-advertise configuration   BGP Communities The community attribute is a transitive optional attribute. Communities can be used to mark a set of prefixes that share a common property. Any BGP router can tag routes in incoming and outgoing routing updates or when doing redistribution.By default, communities are stripped in outgoing bgp update. BGP community types:- Well known (pre-defined Own communities Well known communities (predefined) Internet: advertise this route to the internet community, any route belong to this community No-export: do not advertise to EBGP peers; keep this route an AS only. No-advertise: do not advertise this route to any peer, internal or external. Local-AS: use in confederation scenarios, prevent the transmit of packet outside the local sub AS. Topology: ... View more

BGP route reflector (RR) configuration of two RR servers   We have already learned what route reflector is and why we use  route reflector.  In this section we will see the configuration of two RR servers and will learn about deep RR behavior.   A route reflector is a  BGP  router that is allowed to ignore the IBGP loop avoidance rule, such as is allowed to advertise updates received from an IBGP peer to another IBGP peer under specific conditions.  If a router receives an IBGP route with the originate-id  attribute  set to its own router-ID, the route is discarded. If a route reflector (RR) receives a route with a cluster-list  attribute  containing its cluster-ID, the route is discarded.   In our case we have two RR servers and it will establish neighbor with other servers and clients.       Topology:     CCIE   GOAL: Configure the topology as er the diagram and assign the IP address. Configure EIGRP to provide the reachability between BGP speakers (peer) configure router 2 - 4 RR server and router 1 - 3 client.       R1#show ip interface brief Interface              IP-Address      OK? Method Status                Protocol FastEthernet0/0        40.1.1.1        YES manual up                    up Serial3/0                     1.1.1.1         YES manual up                    up Serial3/3                     4.1.1.2         YES manual up                    up Loopback0               11.0.0.1        YES manual up                    up     R2#show ip interface brief Interface              IP-Address      OK? Method Status                Protocol FastEthernet0/0        20.1.1.1        YES manual up                    up Serial3/0                    1.1.1.2         YES manual up                    up Serial3/1                    2.1.1.1         YES manual up                    up Loopback0              12.0.0.1        YES manual up                    up     R3#show ip interface brief Interface              IP-Address      OK? Method Status                Protocol FastEthernet0/0        30.1.1.1        YES manual up                    up Serial3/1                    2.1.1.2         YES manual up                    up Serial3/2                   3.1.1.1         YES manual up                    up Loopback0              13.0.0.1        YES manual up                    up       R4#show ip interface brief Interface              IP-Address      OK? Method Status                Protocol FastEthernet0/0        40.1.1.1        YES manual up                    up Serial3/2                    3.1.1.2         YES manual up                    up Serial3/3                   4.1.1.1         YES manual up                    up Loopback0              14.0.0.1        YES manual up                    up     R1(config)#router eigrp 10 R1(config-router)#network 1.0.0.0 R1(config-router)#network 10.0.0.0 R1(config-router)#network 4.0.0.0 R1(config-router)#network 11.0.0.0 R1(config-router)#auto-summary R1(config-router)#exit   R2(config)#router eigrp 10 R2(config-router)#network 1.0.0.0 R2(config-router)#network 2.0.0.0 R2(config-router)#network 12.0.0.0 R2(config-router)#network 20.0.0.0 R2(config-router)#auto-summary R2(config-router)#exit     R3(config)#router eigrp 10 R3(config-router)#network 2.0.0.0 R3(config-router)#network 3.0.0.0 R3(config-router)#network 30.0.0.0 R3(config-router)#network 13.0.0.0 R3(config-router)#no auto-summary R3(config-router)#exit   R4(config)#router eigrp 10 R4(config-router)#network 3.0.0.0 R4(config-router)#network 4.0.0.0 R4(config-router)#network 40.0.0.0 R4(config-router)#network 14.0.0.0 R4(config-router)#no auto-summary R4(config-router)#exit   R1#show ip eigrp neighbors EIGRP-IPv4 Neighbors for AS(10) H   Address                 Interface              Hold Uptime   SRTT   RTO  Q  Seq                                                    (sec)         (ms)       Cnt Num 1   4.1.1.1                 Se3/3                    14 00:27:43   54   324  0  12 0   1.1.1.2                 Se3/0                    14 00:30:36   48   288  0  24   R2#show ip eigrp neighbors EIGRP-IPv4 Neighbors for AS(10) H   Address                 Interface              Hold Uptime   SRTT   RTO  Q  Seq                                                    (sec)         (ms)       Cnt Num 1   2.1.1.2                 Se3/1                    14 00:29:24   60   360  0  18 0   1.1.1.1                 Se3/0                    12 00:31:07   56   336  0  19       R3#show ip eigrp neighbors EIGRP-IPv4 Neighbors for AS(10) H   Address                 Interface              Hold Uptime   SRTT   RTO  Q  Seq                                                    (sec)         (ms)       Cnt Num 1   3.1.1.2                 Se3/2                    13 00:28:44   64   384  0  11 0   2.1.1.1                 Se3/1                    10 00:29:46   58   348  0  25 R3#   R4#show ip eigrp neighbors EIGRP-IPv4 Neighbors for AS(10) H   Address                 Interface              Hold Uptime   SRTT   RTO  Q  Seq                                                    (sec)         (ms)       Cnt Num 1   4.1.1.2                 Se3/3                    11 00:28:53   53   318  0  20 0   3.1.1.1                 Se3/2                    10 00:29:01   45   270  0  19   R1(config)#router  bgp 100 R1(config-router)#neighbor 12.0.0.1 remote-as 100 R1(config-router)#neighbor 12.0.0.1 update-source loopback 0   R1(config-router)# neighbor 14.0.0.1 remote-as 100 R1(config-router)# neighbor 14.0.0.1 update-source loopback 0   R1(config-router)#network 10.0.0.0 R1(config-router)#no auto-summary R1(config-router)#no synchronization R1(config-router)#exit   R2(config)#router bgp 100   R2(config-router)#neighbor 11.0.0.1 remote-as 100 R2(config-router)#neighbor 11.0.0.1 update-source loopback 0 R2(config-router)#neighbor 11.0.0.1 route-reflector-client   *Jan 23 13:47:51.839: %BGP-5-ADJCHANGE: neighbor 11.0.0.1 Down RR client config change *Jan 23 13:47:51.843: %BGP_SESSION-5-ADJCHANGE: neighbor 11.0.0.1 IPv4 Unicast topology base removed from session  RR client config change   *Jan 23 13:47:52.999: %BGP-5-ADJCHANGE: neighbor 11.0.0.1 Up   R2(config-router)#neighbor 13.0.0.1 remote-as 100 R2(config-router)#neighbor 13.0.0.1 update-source loopback 0 R2(config-router)#neighbor 11.0.0.1 route-reflector-client   R2(config-router)#neighbor 14.0.0.1 remote-as 100 R2(config-router)#neighbor 14.0.0.1 update-source loopback 0 R2(config-router)#neighbor 14.0.0.1 route-reflector-client   R2(config-router)#network 20.0.0.0 R2(config-router)#no auto-summary R2(config-router)#no synchronization R2(config-router)#end     R3(config)#router bgp 100 R3(config-router)#neighbor 12.0.0.1 remote-as 100 R3(config-router)#neighbor 12.0.0.1 update-source loopback 0   *Jan 23 13:50:42.831: %BGP-5-ADJCHANGE: neighbor 12.0.0.1 Up   R3(config-router)#neighbor 14.0.0.1 remote-as 100 R3(config-router)#neighbor 14.0.0.1 update-source loopback 0   R3(config-router)#network 30.0.0.0 R3(config-router)#no auto-summary R3(config-router)#no synchronization R3(config-router)#end     R4(config)#router bgp 100   R4(config-router)#neighbor 11.0.0.1 remote-as 100 R4(config-router)#neighbor 11.0.0.1 update-source loopback 0 R4(config-router)#neighbor 11.0.0.1 route-reflector-client   R4(config-router)#neighbor 12.0.0.1 remote-as 100 R4(config-router)#neighbor 12.0.0.1 update-source loopback 0 R4(config-router)#neighbor 12.0.0.1 route-reflector-client   R4(config-router)#neighbor 13.0.0.1 remote-as 100 R4(config-router)#neighbor 13.0.0.1 update-source loopback 0 R4(config-router)#neighbor 13.0.0.1 route-reflector-client   R4(config-router)#network 40.0.0.0 R4(config-router)#no synchronization R4(config-router)#no auto-summary R4(config-router)#end     R2#show ip bgp summary | begin net 3 network entries using 432 bytes of memory 4 path entries using 320 bytes of memory 2/2 BGP path/bestpath attribute entries using 272 bytes of memory 1 BGP rrinfo entries using 24 bytes of memory 0 BGP route-map cache entries using 0 bytes of memory 0 BGP filter-list cache entries using 0 bytes of memory BGP using 1048 total bytes of memory BGP activity 3/0 prefixes, 5/1 paths, scan interval 60 secs   Neighbor        V           AS MsgRcvd MsgSent   TblVer  InQ OutQ Up/Down  State/PfxRcd 11.0.0.1        4          100      25      26        4    0    0 00:19:31        0 13.0.0.1        4          100      22      23        4    0    0 00:16:41        1 14.0.0.1        4          100      15      12        4    0    0 00:04:00        2     R4#show ip bgp summary | begin network 3 network entries using 432 bytes of memory 4 path entries using 320 bytes of memory 2/2 BGP path/bestpath attribute entries using 272 bytes of memory 1 BGP rrinfo entries using 24 bytes of memory 0 BGP route-map cache entries using 0 bytes of memory 0 BGP filter-list cache entries using 0 bytes of memory BGP using 1048 total bytes of memory BGP activity 3/0 prefixes, 7/3 paths, scan interval 60 secs   Neighbor        V           AS MsgRcvd MsgSent   TblVer  InQ OutQ Up/Down  State/PfxRcd 11.0.0.1        4          100      13      19       11    0    0 00:07:48        0 12.0.0.1        4          100      15      18       11    0    0 00:06:46        2 13.0.0.1        4          100      13      16       11    0    0 00:06:16        1   R2#show ip bgp 30.1.1.1 BGP routing table entry for 30.0.0.0/8, version 3 Paths: (2 available, best #2, table default, RIB-failure(17))   Advertised to update-groups:      2   Refresh Epoch 2   Local,   (Received from a RR-client)     13.0.0.1 (metric 2297856) from 14.0.0.1 (14.0.0.1)       Origin IGP, metric 0, localpref 100, valid, internal       Originator: 13.0.0.1, Cluster list: 14.0.0.1       rx pathid: 0, tx pathid: 0   Refresh Epoch 1   Local     13.0.0.1 (metric 2297856) from 13.0.0.1 (13.0.0.1)       Origin IGP, metric 0, localpref 100, valid, internal, best       rx pathid: 0, tx pathid: 0x0     R4#show ip bgp 20.1.1.1 BGP routing table entry for 20.0.0.0/8, version 7 Paths: (1 available, best #1, table default, RIB-failure(17))   Advertised to update-groups:      2   Refresh Epoch 2   Local,   (Received from a RR-client)     12.0.0.1 (metric 2809856) from 12.0.0.1 (12.0.0.1)       Origin IGP, metric 0, localpref 100, valid, internal, best       rx pathid: 0, tx pathid: 0x0   (from the above output reveal the fact that prefixe 20.1.1.1/8 were recieved from a route reflector client)   R1#show ip bgp 30.1.1.1 BGP routing table entry for 30.0.0.0/8, version 3 Paths: (2 available, best #2, table default, RIB-failure(17))   Not advertised to any peer   Refresh Epoch 1   Local     13.0.0.1 (metric 2809856) from 14.0.0.1 (14.0.0.1)       Origin IGP, metric 0, localpref 100, valid, internal         Originator: 13.0.0.1, Cluster list: 14.0.0.1       rx pathid: 0, tx pathid: 0   Refresh Epoch 1   Local     13.0.0.1 (metric 2809856) from 12.0.0.1 (12.0.0.1)       Origin IGP, metric 0, localpref 100, valid, internal, best       Originator: 13.0.0.1, Cluster list: 12.0.0.1       rx pathid: 0, tx pathid: 0x0   (from the above output reveals the originator-ID  and the cluster- list  of prefix 30.1.1.1/8 ) ... 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BGP Route Reflectors (RR) Route reflectors (RR) are one of the methods to get rid of the full-mesh of IBGP peers in your network. The route reflector allows all IBGP speakers within your autonomous system to learn about the available routes without creating loops.   There are three types of peering in route reflector:   EBGP neighbor IBGP client neighbor IBGP non-client neighbor   When we configure a route reflector (RR), we have to tell the router the other IBGP router is a client or non-client. A     IBGP client is an IBGP router that the route reflector will “reflect” routes to, the non-client is just a regular IBGP neighbor. When a route reflector forwards a route updates, there are a few rules that must follow:   A route learned from an EBGP neighbor can be forwarded to another EBGP neighbor, a client and non-client. A route learned from a client can be forwarded to another EBGP neighbor, client and non-client. A route learned from a non-client can be forwarded to another EBGP neighbor and client, but not to a non-client.   In other words: Route Reflector-RR to advertise route received from an   iBGP peers to other iBGP peers. All the valid client update server Route Reflector-RR and server update to all the valid clients. Each client only establish neighbor relationship with servers, client are not allow to establish neighbor with other clients. Route Reflector (servers) establish neighbor relationship with other servers (if you have more the one servers) and clients.   I hope now you have an idea what is route reflector, so let see the configuration:     Topology: ... View more