01-21-2014 03:30 AM - edited 03-04-2019 10:07 PM
Hi,
I have configured 5 routers with BGP as in the image for testing purpose.
I have assign loopback addresses on each router and each router get all route informations as intended. But when I try to ping from router E to router A it is not success. But when I try sh ip bgp on E it shows Router A's networks can reach trough router C. Router C can ping to loopback of router A. Router A , C, E in different ASs. No ACLs configured due to testings. How can I troubleshoot this?
thank you
Chamara
Thank you for helping on this. Here I listed all the information you need.
thank you again
kind regards
Chamara
A - AS1 , B,C in AS2 , D in AS3, E in AS4
Router A
interface Serial0/0/0
ip address 10.1.1.1 255.255.255.252
!
interface Serial0/0/1
ip address 10.1.2.1 255.255.255.252
!
router bgp 1
bgp log-neighbor-changes
no synchronization
neighbor 10.1.1.2 remote-as 2
neighbor 10.1.2.2 remote-as 2
network 1.1.1.0 mask 255.255.255.0
----
Router#sh ip bgp
BGP table version is 21, 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
*> 1.1.1.0/24 0.0.0.0 0 0 32768 i
*> 2.2.2.0/24 10.1.1.2 0 0 0 2 i
*> 3.3.3.0/24 10.1.2.2 0 0 0 2 i
* 4.4.4.0/24 10.1.2.2 0 0 0 3 4 2 i
*> 10.1.1.2 0 0 0 3 2 i
*> 5.5.5.0/24 10.1.2.2 0 0 0 4 2 i
* 10.1.1.2 0 0 0 4 3 2 i
------------------------
Router B
interface Serial0/0/0
ip address 10.1.1.2 255.255.255.252
clock rate 64000
!
interface Serial0/0/1
ip address 10.1.3.2 255.255.255.252
!
router bgp 2
bgp log-neighbor-changes
no synchronization
neighbor 10.1.3.1 remote-as 3
neighbor 10.1.1.1 remote-as 1
network 2.2.2.0 mask 255.255.255.0
---------------------------------------
Router#sh ip bgp
BGP table version is 11, local router ID is 2.2.2.2
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
*> 1.1.1.0/24 10.1.1.1 0 0 0 1 i
*> 2.2.2.0/24 0.0.0.0 0 0 32768 i
*> 4.4.4.0/24 10.1.3.1 0 0 0 3 i
*> 5.5.5.0/24 10.1.3.1 0 0 0 4 3 i
---------------------------------------
Router C
interface Serial0/0/0
ip address 10.1.2.2 255.255.255.252
clock rate 64000
!
interface Serial0/0/1
ip address 10.1.5.2 255.255.255.252
!
router bgp 2
bgp log-neighbor-changes
no synchronization
neighbor 10.1.2.1 remote-as 1
neighbor 10.1.5.1 remote-as 4
network 3.3.3.0 mask 255.255.255.0
-----------------------
Router#sh ip bgp
BGP table version is 9, local router ID is 3.3.3.3
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
*> 1.1.1.0/24 10.1.2.1 0 0 0 1 i
*> 3.3.3.0/24 0.0.0.0 0 0 32768 i
*> 4.4.4.0/24 10.1.5.1 0 0 0 3 4 i
*> 5.5.5.0/24 10.1.5.1 0 0 0 4 i
Router#ping 1.1.1.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 1.1.1.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 2/4/5 ms
Router#sh ip route
Codes: C - connected, S - static, I - IGRP, 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, E - EGP
i - IS-IS, 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
Gateway of last resort is not set
1.0.0.0/24 is subnetted, 1 subnets
B 1.1.1.0 [20/0] via 10.1.2.1, 07:40:50
3.0.0.0/24 is subnetted, 1 subnets
C 3.3.3.0 is directly connected, Loopback1
4.0.0.0/24 is subnetted, 1 subnets
B 4.4.4.0 [20/0] via 10.1.5.1, 07:40:50
5.0.0.0/24 is subnetted, 1 subnets
B 5.5.5.0 [20/0] via 10.1.5.1, 07:40:50
10.0.0.0/30 is subnetted, 2 subnets
C 10.1.2.0 is directly connected, Serial0/0/0
C 10.1.5.0 is directly connected, Serial0/0/1
-------------------------
Router D
interface Serial0/0/0
ip address 10.1.3.1 255.255.255.252
clock rate 64000
!
interface Serial0/0/1
ip address 10.1.4.2 255.255.255.252
!
!
router bgp 3
bgp log-neighbor-changes
no synchronization
neighbor 10.1.4.1 remote-as 4
neighbor 10.1.3.2 remote-as 2
network 4.4.4.0 mask 255.255.255.0
!
----------------------------------------
Router#sh ip bgp
BGP table version is 16, local router ID is 4.4.4.4
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
* 1.1.1.0/24 10.1.4.1 0 0 0 1 2 4 i
*> 10.1.3.2 0 0 0 1 2 i
*> 2.2.2.0/24 10.1.3.2 0 0 0 2 i
*> 3.3.3.0/24 10.1.4.1 0 0 0 2 4 i
*> 4.4.4.0/24 0.0.0.0 0 0 32768 i
*> 5.5.5.0/24 10.1.4.1 0 0 0 4 i
-----------------------------------------
Router E
interface Serial0/0/0
ip address 10.1.5.1 255.255.255.252
clock rate 64000
!
interface Serial0/0/1
ip address 10.1.4.1 255.255.255.252
clock rate 64000
!
!
router bgp 4
bgp log-neighbor-changes
no synchronization
neighbor 10.1.4.2 remote-as 3
neighbor 10.1.5.2 remote-as 2
network 5.5.5.0 mask 255.255.255.0
------------------------------------------------------
Router# sh ip bgp
BGP table version is 15, local router ID is 5.5.5.5
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
*> 1.1.1.0/24 10.1.5.2 0 0 0 1 2 i
* 10.1.4.2 0 0 0 1 2 3 i
*> 2.2.2.0/24 10.1.4.2 0 0 0 2 3 i
*> 3.3.3.0/24 10.1.5.2 0 0 0 2 i
*> 4.4.4.0/24 10.1.4.2 0 0 0 3 i
*> 5.5.5.0/24 0.0.0.0 0 0 32768 i
Router#ping 1.1.1.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 1.1.1.1, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)
Router#traceroute 1.1.1.1
Type escape sequence to abort.
Tracing the route to 1.1.1.1
1 10.1.5.2 4 msec 1 msec 3 msec
2 * * *
3 * * *
4 * * *
5 * * *
6 * * *
Router#sh ip route
Codes: C - connected, S - static, I - IGRP, 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, E - EGP
i - IS-IS, 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
Gateway of last resort is not set
1.0.0.0/24 is subnetted, 1 subnets
B 1.1.1.0 [20/0] via 10.1.5.2, 07:42:36
2.0.0.0/24 is subnetted, 1 subnets
B 2.2.2.0 [20/0] via 10.1.4.2, 07:42:36
3.0.0.0/24 is subnetted, 1 subnets
B 3.3.3.0 [20/0] via 10.1.5.2, 07:42:36
4.0.0.0/24 is subnetted, 1 subnets
B 4.4.4.0 [20/0] via 10.1.4.2, 07:42:36
5.0.0.0/24 is subnetted, 1 subnets
C 5.5.5.0 is directly connected, Loopback1
10.0.0.0/30 is subnetted, 2 subnets
C 10.1.4.0 is directly connected, Serial0/0/1
C 10.1.5.0 is directly connected, Serial0/0/0
------------------------------------------------------
Solved! Go to Solution.
01-21-2014 07:47 AM
Hi Chamara,
John is right.
you means Do I have to configure all connection IPs with network command? if it is like that how can I configure this kind of scenario with ISPs?
Well you don't have to since you don't care about advertising the internal 10.X.X.X that are used only for neighbor definition and p2p connections with other routers, right?
The only reason that you think you have a problem is because your routers do not know about other than connected 10.X.X.X networks and that's why the ping/traceroute fails. If you would do it as John suggests, you will find no problems in the setup. If you intended the other routers to know about 10.X.X.X network as well then do so via static or dynamic routing but that is not necessary if you want just the loopbacks (and other networks specified in bgp through the network command as well) to communicate with each other.
Best regards,
Jan
01-21-2014 03:37 AM
Chamara
It would help us if your post included -
1) a diagram showing which routers were in which AS together with IP addresses
2) the "sh ip bgp" and "sh ip route" for routers which you are having problems with
3) the BGP configurations of all routers. Note without knowing the IPs (see 1)) it can be hard to make sense of the configurations.
Jon
01-21-2014 05:19 AM
Let assume. All are in same autonmous system..
Kindly share the BGP configuration in each router.
U able to see the Router A ip address and Router E. But u not able to reach the Router A.
Check the Router E have route to reach the Router A by Sh Ip route command on Router A.
BGP can learn the routes through BGP. But it can reach Router A through routing table only.
Configure static Route to overcome this issue or advertise the Loop back ip address under bgp through Network Command.
01-21-2014 06:39 AM
You'll need to source your ping from your loopback interface. The bgp table doesn't have a route back to your 10.1.x.x address:
Router#ping 1.1.1.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 1.1.1.1, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)
Ping from Router E like: ping 1.1.1.1 sour 5.5.5.5
HTH,
John
*** Please rate all useful posts ***
01-21-2014 07:01 AM
I forgot to mention. All the loopback addreses are configured on each router and it has posted with network command under BGP.
thank you
Chamara
01-21-2014 07:06 AM
you means Do I have to configure all connection IPs with network command? if it is like that how can I configure this kind of scenario with ISPs?
thank you for all helps
Chamara
01-21-2014 07:47 AM
Hi Chamara,
John is right.
you means Do I have to configure all connection IPs with network command? if it is like that how can I configure this kind of scenario with ISPs?
Well you don't have to since you don't care about advertising the internal 10.X.X.X that are used only for neighbor definition and p2p connections with other routers, right?
The only reason that you think you have a problem is because your routers do not know about other than connected 10.X.X.X networks and that's why the ping/traceroute fails. If you would do it as John suggests, you will find no problems in the setup. If you intended the other routers to know about 10.X.X.X network as well then do so via static or dynamic routing but that is not necessary if you want just the loopbacks (and other networks specified in bgp through the network command as well) to communicate with each other.
Best regards,
Jan
01-21-2014 06:06 PM
Hi Jan and john ,
both of you are correct since the Router A doesnt know where is Router E because as you said it doesnt have any way to know it.
On the packet tracer the "ping
thank you for remembering me the root cause.
further I have added connected Networks to BGP and advertised. But Ping takes very loang time than it should. but it works. What will be the issue?
thank you again for everybody.
Kind regards
Chamara
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