BGP Confederation Explained

Lessons Discussion
35

Infact I set up a similar lab and I don’t see any problem. I am able to ping between R1<<>>R8

R8#ping 1.1.1.1 source lo0
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 1.1.1.1, timeout is 2 seconds:
Packet sent with a source address of 8.8.8.8 
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 76/102/132 ms
R8#
R1#ping 8.8.8.8 source lo0

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 8.8.8.8, timeout is 2 seconds:
Packet sent with a source address of 1.1.1.1 
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 108/137/220 ms
R1#

And if I ping from the AS2 I am not able to ping.

R4#ping 8.8.8.8 source l0
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 8.8.8.8, timeout is 2 seconds:
Packet sent with a source address of 4.4.4.4 
.....
Success rate is 0 percent (0/5)
R4#

Its because R8 or R1 don’t have any return routes to R4.

R8#show ip route 4.4.4.4
% Network not in table
R8#

As soon as I advertize 4.4.4.4 in my IBGP , I am able to ping it.

R4#sh run | s bgp
router bgp 100
 no synchronization
 bgp log-neighbor-changes
 bgp confederation identifier 2
 bgp confederation peers 200 
 **network 4.4.4.4 mask 255.255.255.255  >>>>>>> Advertizing 4.4.4.4**
 neighbor 3.3.3.3 remote-as 100
 neighbor 3.3.3.3 update-source Loopback0
 neighbor 5.5.5.5 remote-as 200
 neighbor 5.5.5.5 ebgp-multihop 2
 neighbor 5.5.5.5 update-source Loopback0
 no auto-summary
R4#
R4#ping 8.8.8.8 source l0
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 8.8.8.8, timeout is 2 seconds:
Packet sent with a source address of 4.4.4.4 
!!!!!

So it has no relation to RIB failure or Confedaration or Route-reflector within Sub-AS. I assume you are not advertising the internal subnet of AS 2 in your BGP.

Hope this helps.

Thanks,
Madhu

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