01-17-2014 02:28 PM - edited 03-04-2019 10:06 PM
Hi,
There are totally three Autonomous configured, OSPF running on AS 2. Router 3(as2) has directly connection with R1(As1) and Router 5(As2) has directly connected with R2(AS3). now the problem is R3 and R5 know AS1 and AS2 routes but they don't exchange their external routes with ebgp. if R3 know about 2.2.2.2(AS3) it should send this to AS 1.
here is my results:-
R5#sh ip bgp
Network Next Hop Metric LocPrf Weight Path
* i1.1.1.1/32 192.168.13.1 0 100 0 1 i
*> 2.2.2.2/32 192.168.52.2 0 0 3 i
R3#sh ip bgp
Network Next Hop Metric LocPrf Weight Path
*> 1.1.1.1/32 192.168.13.1 0 0 1 i
* i2.2.2.2/32 192.168.52.2 0 100 0 3 i
AS 3
R2#sh ip bgp
Network Next Hop Metric LocPrf Weight Path
*> 2.2.2.2/32 0.0.0.0 0 32768 i
AS 1
R1#sh ip bgp
Network Next Hop Metric LocPrf Weight Path
*> 1.1.1.1/32 0.0.0.0 0 32768 i
Solved! Go to Solution.
01-17-2014 04:07 PM
Can't see anything wrong with your config but i did a quick search and it seems like it is dynamips/GNS3 issue.
Are you using that for your setup ?
If so the solutions are either to save the lab, stop and it and reload it or use a different router/IOS.
As for the route issue. When an EBGP router receives a route from an EBGP peer it advertises the route to an IBGP peer with the next hop set to the EBGP peer it received the route from ie.
1) R2 in AS 3 advertises 2.2.2.2 to R5 in AS 2 so this is EBGP. The next hop for the route is R2 ie. 192.168.52.2.
2) R5 then advertises this via IBGP to R3 with the same next hop ie. 192.168.52.2. If you look at your original post 2.2.2.2 is in R3's BGP table with a next hop of 192.168.52.2
3) if you look at R3's route table in your follow up post you can see it has no route to 192.168.52.2 because that subnet is not part of your OSPF domain. So R3 cannot install 2.2.2.2 into the IP routing table because it is not reachable.
And it also cannot advertise to R1 for the same reason.
4) by adding the next-hop self command on R5 (and R3) you are telling R5 that when it advertises the route to R3 it needs to change the next hop of the route from 192.168.52.2 to it's own IP address.
5) once it has done this R3 knows how to get to R5 ie. from its IP routing table so it considers 2.2.2.2 reachable, installs it in the routing table and advertises it to R1.
The same works in reverse ie. R3 advertising to R5 as well.
Hope that makes sense.
Jon
01-17-2014 02:37 PM
From R3 can you post -
1) sh ip route
2) sh ip bgp neighbor
and then also post the full config for R3
Jon
01-17-2014 02:55 PM
i forget to mention that on Router 4 and 6 dont have bgp configured.
R3#sh ip route
Gateway of last resort is not set
1.0.0.0/32 is subnetted, 1 subnets
B 1.1.1.1 [20/0] via 192.168.13.1, 00:04:20
C 192.168.13.0/24 is directly connected, Serial1/0
3.0.0.0/32 is subnetted, 1 subnets
C 3.3.3.3 is directly connected, Loopback0
O 192.168.45.0/24 [110/2] via 192.168.34.4, 00:05:09, FastEthernet0/0
5.0.0.0/32 is subnetted, 1 subnets
O 5.5.5.5 [110/3] via 192.168.36.6, 00:05:09, FastEthernet0/1
[110/3] via 192.168.34.4, 00:05:09, FastEthernet0/0
O 192.168.65.0/24 [110/2] via 192.168.36.6, 00:05:09, FastEthernet0/1
C 192.168.36.0/24 is directly connected, FastEthernet0/1
C 192.168.34.0/24 is directly connected, FastEthernet0/0
R3#sh ip bgp summary
BGP router identifier 3.3.3.3, local AS number 2
BGP table version is 2, main routing table version 2
2 network entries using 264 bytes of memory
2 path entries using 104 bytes of memory
3/1 BGP path/bestpath attribute entries using 504 bytes of memory
2 BGP AS-PATH entries using 48 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
Bitfield cache entries: current 1 (at peak 1) using 32 bytes of memory
BGP using 952 total bytes of memory
BGP activity 2/0 prefixes, 2/0 paths, scan interval 60 secs
Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
5.5.5.5 4 2 14 13 2 0 0 00:06:08 1
192.168.13.1 4 1 10 9 2 0 0 00:06:50 1
R3#sh ip bgp neighbors
BGP neighbor is 5.5.5.5, remote AS 2, internal link
BGP version 4, remote router ID 5.5.5.5
BGP state = Established, up for 00:05:05
Last read 00:00:03, last write 00:00:03, hold time is 180, keepalive interval is 60 seconds
Neighbor capabilities:
Route refresh: advertised and received(new)
New ASN Capability: advertised and received
Address family IPv4 Unicast: advertised and received
Message statistics:
InQ depth is 0
OutQ depth is 0
Sent Rcvd
Opens: 2 2
Notifications: 1 1
Updates: 1 1
Keepalives: 8 8
Route Refresh: 0 0
Unrecognized: n/a 1
Total: 12 13
Default minimum time between advertisement runs is 0 seconds
For address family: IPv4 Unicast
BGP table version 2, neighbor version 2/0
Output queue size : 0
Index 2, Offset 0, Mask 0x4
2 update-group member
Sent Rcvd
Prefix activity: ---- ----
Prefixes Current: 1 1 (Consumes 52 bytes)
Prefixes Total: 1 1
Implicit Withdraw: 0 0
Explicit Withdraw: 0 0
Used as bestpath: n/a 0
Used as multipath: n/a 0
Outbound Inbound
Local Policy Denied Prefixes: -------- -------
Total: 0 0
Number of NLRIs in the update sent: max 1, min 1
Address tracking is enabled, the RIB does have a route to 5.5.5.5
Connections established 2; dropped 1
Last reset 00:05:54, due to BGP Notification sent, header synchronization problems
Transport(tcp) path-mtu-discovery is enabled
Connection state is ESTAB, I/O status: 1, unread input bytes: 0
Connection is ECN Disabled, Mininum incoming TTL 0, Outgoing TTL 255
Local host: 3.3.3.3, Local port: 179
Foreign host: 5.5.5.5, Foreign port: 21868
Connection tableid (VRF): 0
Enqueued packets for retransmit: 0, input: 0 mis-ordered: 0 (0 bytes)
Event Timers (current time is 0x6CC7C):
Timer Starts Wakeups Next
Retrans 8 0 0x0
TimeWait 0 0 0x0
AckHold 7 5 0x0
SendWnd 0 0 0x0
KeepAlive 0 0 0x0
GiveUp 0 0 0x0
PmtuAger 0 0 0x0
DeadWait 0 0 0x0
Linger 0 0 0x0
ProcessQ 0 0 0x0
iss: 2059140500 snduna: 2059140749 sndnxt: 2059140749 sndwnd: 16136
irs: 1335151246 rcvnxt: 1335151495 rcvwnd: 16136 delrcvwnd: 248
SRTT: 200 ms, RTTO: 993 ms, RTV: 793 ms, KRTT: 0 ms
minRTT: 144 ms, maxRTT: 320 ms, ACK hold: 200 ms
Status Flags: passive open, gen tcbs
Option Flags: nagle, path mtu capable
IP Precedence value : 6
Datagrams (max data segment is 536 bytes):
Rcvd: 18 (out of order: 0), with data: 9, total data bytes: 248
Sent: 16 (retransmit: 0, fastretransmit: 0, partialack: 0, Second Congestion: 0), with data: 9, total data bytes: 248
Packets received in fast path: 0, fast processed: 0, slow path: 0
fast lock acquisition failures: 0, slow path: 0
BGP neighbor is 192.168.13.1, remote AS 1, external link
BGP version 4, remote router ID 1.1.1.1
BGP state = Established, up for 00:05:54
Last read 00:00:10, last write 00:00:10, hold time is 180, keepalive interval is 60 seconds
Neighbor capabilities:
Route refresh: advertised and received(new)
New ASN Capability: advertised and received
Address family IPv4 Unicast: advertised and received
Message statistics:
InQ depth is 0
OutQ depth is 0
Sent Rcvd
Opens: 1 1
Notifications: 0 0
Updates: 0 1
Keepalives: 7 7
Route Refresh: 0 0
Total: 8 9
Default minimum time between advertisement runs is 30 seconds
For address family: IPv4 Unicast
BGP table version 2, neighbor version 2/0
Output queue size : 0
Index 1, Offset 0, Mask 0x2
1 update-group member
Sent Rcvd
Prefix activity: ---- ----
Prefixes Current: 0 1 (Consumes 52 bytes)
Prefixes Total: 0 1
Implicit Withdraw: 0 0
Explicit Withdraw: 0 0
Used as bestpath: n/a 1
Used as multipath: n/a 0
Outbound Inbound
Local Policy Denied Prefixes: -------- -------
Bestpath from this peer: 1 n/a
Total: 1 0
Number of NLRIs in the update sent: max 0, min 0
Address tracking is enabled, the RIB does have a route to 192.168.13.1
Connections established 1; dropped 0
Last reset never
Transport(tcp) path-mtu-discovery is enabled
Connection state is ESTAB, I/O status: 1, unread input bytes: 0
Connection is ECN Disabled, Mininum incoming TTL 0, Outgoing TTL 1
Local host: 192.168.13.3, Local port: 20573
Foreign host: 192.168.13.1, Foreign port: 179
Connection tableid (VRF): 0
Enqueued packets for retransmit: 0, input: 0 mis-ordered: 0 (0 bytes)
Event Timers (current time is 0x6D6A8):
Timer Starts Wakeups Next
Retrans 9 0 0x0
TimeWait 0 0 0x0
AckHold 9 7 0x0
SendWnd 0 0 0x0
KeepAlive 0 0 0x0
GiveUp 0 0 0x0
PmtuAger 1 0 0xA9120
DeadWait 0 0 0x0
Linger 0 0 0x0
ProcessQ 0 0 0x0
iss: 3414808598 snduna: 3414808785 sndnxt: 3414808785 sndwnd: 16198
irs: 938062699 rcvnxt: 938062941 rcvwnd: 16143 delrcvwnd: 241
SRTT: 210 ms, RTTO: 904 ms, RTV: 694 ms, KRTT: 0 ms
minRTT: 40 ms, maxRTT: 300 ms, ACK hold: 200 ms
Status Flags: active open
Option Flags: nagle, path mtu capable
IP Precedence value : 6
Datagrams (max data segment is 1460 bytes):
Rcvd: 17 (out of order: 0), with data: 9, total data bytes: 241
Sent: 17 (retransmit: 0, fastretransmit: 0, partialack: 0, Second Congestion: 0), with data: 8, total data bytes: 186
Packets received in fast path: 0, fast processed: 0, slow path: 0
fast lock acquisition failures: 0, slow path: 0
01-17-2014 03:04 PM
On R5 and R3 this message keep gemerating
%BGP-5-ADJCHANGE: neighbor 3.3.3.3 Down BGP Notification sent
R5#
%BGP-3-NOTIFICATION: sent to neighbor 3.3.3.3 1/1 (header synchronization problems) 0 bytes
%BGP-5-ADJCHANGE: neighbor 3.3.3.3 Up
R5#
%BGP-3-NOTIFICATION: received from neighbor 5.5.5.5 1/1 (header synchronization problems) 0 bytes
%BGP-5-ADJCHANGE: neighbor 5.5.5.5 Down BGP Notification received
%BGP-5-ADJCHANGE: neighbor 5.5.5.5 Up
R3#
01-17-2014 03:19 PM
Can you post the full configuration of R3 ?
Jon
01-17-2014 03:22 PM
R3#sh running-config
Building configuration...
Current configuration : 1711 bytes
!
upgrade fpd auto
version 12.4
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname R3
!
boot-start-marker
boot-end-marker
!
logging message-counter syslog
!
no aaa new-model
ip source-route
no ip icmp rate-limit unreachable
ip cef
!
!
!
!
no ip domain lookup
no ipv6 cef
!
multilink bundle-name authenticated
!
!
!
!
!
!
archive
log config
hidekeys
!
!
!
!
!
ip tcp synwait-time 5
!
!
!
!
interface Loopback0
ip address 3.3.3.3 255.255.255.255
!
interface FastEthernet0/0
ip address 192.168.34.3 255.255.255.0
duplex full
speed auto
!
interface FastEthernet0/1
ip address 192.168.36.3 255.255.255.0
duplex full
speed auto
!
interface Serial1/0
ip address 192.168.13.3 255.255.255.0
serial restart-delay 0
!
interface Serial1/1
no ip address
shutdown
serial restart-delay 0
!
interface Serial1/2
no ip address
shutdown
serial restart-delay 0
!
interface Serial1/3
no ip address
shutdown
serial restart-delay 0
!
router ospf 1
log-adjacency-changes
passive-interface Serial1/0
network 3.3.3.3 0.0.0.0 area 0
network 192.168.34.0 0.0.0.255 area 0
network 192.168.36.0 0.0.0.255 area 0
!
router bgp 2
no synchronization
bgp log-neighbor-changes
neighbor 5.5.5.5 remote-as 2
neighbor 5.5.5.5 update-source Loopback0
neighbor 192.168.13.1 remote-as 1
no auto-summary
!
ip forward-protocol nd
no ip http server
no ip http secure-server
!
!
control-plane
01-17-2014 03:27 PM
Add this to your configuration -
router bgp 2
neighbor 5.5.5.5 next-hop self
and then on R5 do the same thing for R3 ie. assuming R3 is 3.3.3.3
router bgp 2
neighbor 3.3.3.3 next-hop self
and then check routing tables on R1/R3.
Jon
01-17-2014 03:34 PM
R1#sh ip bgp
BGP table version is 5, local router ID is 1.1.1.1
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*> 1.1.1.1/32 0.0.0.0 0 32768 i
*> 2.2.2.2/32 192.168.13.3 0 2 3 i
Now its working, but 2.2.2.2 keep coming up and down, check the logs below
*Jan 18 02:24:08.643: %BGP-5-ADJCHANGE: neighbor 5.5.5.5 Up
*Jan 18 02:24:08.871: %BGP-3-NOTIFICATION: received from neighbor 5.5.5.5 1/1 (header synchronization problems) 0 bytes
R3(config-router)#
*Jan 18 02:24:08.875: %BGP-5-ADJCHANGE: neighbor 5.5.5.5 Down BGP Notification received
R3(config-router)#
R3(config-router)#
R3(config-router)#
R3#
*Jan 18 02:24:19.575: %SYS-5-CONFIG_I: Configured from console by console
R3#
*Jan 18 02:24:24.207: %BGP-5-ADJCHANGE: neighbor 5.5.5.5 Up
R3#sh run | sec bgp
router bgp 2
no synchronization
bgp log-neighbor-changes
neighbor 5.5.5.5 remote-as 2
neighbor 5.5.5.5 update-source Loopback0
neighbor 5.5.5.5 next-hop-self
neighbor 192.168.13.1 remote-as 1
no auto-summary
R5#sh run | sec bgp
router bgp 2
no synchronization
bgp log-neighbor-changes
neighbor 3.3.3.3 remote-as 2
neighbor 3.3.3.3 update-source Loopback0
neighbor 3.3.3.3 next-hop-self
neighbor 192.168.52.2 remote-as 3
no auto-summary
01-17-2014 03:41 PM
So the routes are now showing properly ?
So the messages are from R2 showing the neighborship going up and down with R5, is that correct ?
If so you can run "debug ip bgp" on both routers to see what is happening.
Can you also post the BGP config only of R2 ?
Jon
01-17-2014 03:49 PM
Routes no problem now, but not stable keep going up d down
R5#debug ip bgp even
BGP events debugging is on
R5#
R5#
R5#
*Jan 18 02:40:19.471: BGP(4): Import timer expired. Walking from 1 to 1
*Jan 18 02:40:19.471: BGP(5): Import timer expired. Walking from 1 to 1
R5#deb
*Jan 18 02:40:34.475: BGP(4): Import timer expired. Walking from 1 to 1
*Jan 18 02:40:34.479: BGP(5): Import timer expired. Walking from 1 to 1
R5#deb
R5#debug ip bgp
*Jan 18 02:40:49.479: BGP(4): Import timer expired. Walking from 1 to 1
*Jan 18 02:40:49.483: BGP(5): Import timer expired. Walking from 1 to 1
R5#
R5#
R5#
R5#
*Jan 18 02:40:53.947: BGP: 3.3.3.3 reset due to BGP Notification sent
*Jan 18 02:40:53.947: %BGP-5-ADJCHANGE: neighbor 3.3.3.3 Down BGP Notification sent
R5#
*Jan 18 02:40:53.951: %BGP-3-NOTIFICATION: sent to neighbor 3.3.3.3 1/1 (header synchronization problems) 0 bytes
R5#
*Jan 18 02:40:54.023: BGP: service reset requests
*Jan 18 02:40:54.027: BGP: service reset requests
*Jan 18 02:40:54.027: BGP: service reset requests
*Jan 18 02:40:54.031: BGP: service reset requests
*Jan 18 02:40:54.031: BGP: service reset requests
*Jan 18 02:40:54.035: BGP: service reset requests
*Jan 18 02:40:54.035: BGP: service reset requests
*Jan 18 02:40:54.035: BGP: service reset requests
*Jan 18 02:40:54.043: BGP: starting the default originate timer with initial delay of 1 sec
*Jan 18 02:40:54.159: BGP: default originate timer expired
*Jan 18 02:40:54.163: BGP: processing neighbors configured for conditional default route origination
Jan 18 02:41:16.923: %BGP-5-ADJCHANGE: neighbor 3.3.3.3 Up
R5#u all
hostname R2
!
boot-start-marker
boot-end-marker
!
logging message-counter syslog
!
no aaa new-model
ip source-route
no ip icmp rate-limit unreachable
ip cef
!
!
!
!
no ip domain lookup
no ipv6 cef
!
multilink bundle-name authenticated
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
archive
log config
hidekeys
!
!
!
!
!
ip tcp synwait-time 5
!
!
!
!
interface Loopback0
ip address 2.2.2.2 255.255.255.255
!
interface FastEthernet0/0
no ip address
shutdown
duplex half
!
interface Serial1/0
ip address 192.168.52.2 255.255.255.0
serial restart-delay 0
!
interface Serial1/1
no ip address
shutdown
serial restart-delay 0
!
interface Serial1/2
no ip address
shutdown
serial restart-delay 0
!
interface Serial1/3
no ip address
shutdown
serial restart-delay 0
!
router bgp 3
no synchronization
bgp log-neighbor-changes
network 2.2.2.2
network 2.2.2.2 mask 255.255.255.255
neighbor 192.168.52.5 remote-as 2
no auto-summary
!
ip forward-protocol nd
no ip http server
no ip http secure-server
!
01-17-2014 04:07 PM
Can't see anything wrong with your config but i did a quick search and it seems like it is dynamips/GNS3 issue.
Are you using that for your setup ?
If so the solutions are either to save the lab, stop and it and reload it or use a different router/IOS.
As for the route issue. When an EBGP router receives a route from an EBGP peer it advertises the route to an IBGP peer with the next hop set to the EBGP peer it received the route from ie.
1) R2 in AS 3 advertises 2.2.2.2 to R5 in AS 2 so this is EBGP. The next hop for the route is R2 ie. 192.168.52.2.
2) R5 then advertises this via IBGP to R3 with the same next hop ie. 192.168.52.2. If you look at your original post 2.2.2.2 is in R3's BGP table with a next hop of 192.168.52.2
3) if you look at R3's route table in your follow up post you can see it has no route to 192.168.52.2 because that subnet is not part of your OSPF domain. So R3 cannot install 2.2.2.2 into the IP routing table because it is not reachable.
And it also cannot advertise to R1 for the same reason.
4) by adding the next-hop self command on R5 (and R3) you are telling R5 that when it advertises the route to R3 it needs to change the next hop of the route from 192.168.52.2 to it's own IP address.
5) once it has done this R3 knows how to get to R5 ie. from its IP routing table so it considers 2.2.2.2 reachable, installs it in the routing table and advertises it to R1.
The same works in reverse ie. R3 advertising to R5 as well.
Hope that makes sense.
Jon
01-17-2014 04:32 PM
My friend aslo suggest me to check with different ios and router about flapping netwrk , because am using currently router c7200 and Version 12.4(24)T5.
Thanks for your continuous fast replys and explanation really appreciated .
,
Discover and save your favorite ideas. Come back to expert answers, step-by-step guides, recent topics, and more.
New here? Get started with these tips. How to use Community New member guide