05-18-2024 02:16 AM
Hi,
I built a small lab with 5 routers. On some routers I have distributed the loopback addresses on the network.
R1:
router bgp 100
bgp log-neighbor-changes
neighbor 10.1.1.2 remote-as 200
neighbor 10.1.2.2 remote-as 300
R1#show ip route
B 4.4.4.4 [20/0] via 10.1.1.2, 00:01:24
6.0.0.0/32 is subnetted, 1 subnets
B 6.6.6.6 [20/0] via 10.1.2.2, 00:01:24
R2:
router bgp 200
bgp router-id 2.2.2.2
bgp log-neighbor-changes
neighbor 10.1.1.1 remote-as 100
neighbor 10.24.1.2 remote-as 400
R3:
router bgp 300
bgp log-neighbor-changes
neighbor 10.1.2.1 remote-as 100
neighbor 10.36.1.2 remote-as 400
R4:
router bgp 400
bgp router-id 4.4.4.4
bgp log-neighbor-changes
network 4.4.4.4 mask 255.255.255.255
neighbor 10.24.1.1 remote-as 200
R6:
router bgp 400
bgp log-neighbor-changes
network 6.6.6.6 mask 255.255.255.255
neighbor 10.25.1.1 remote-as 400
neighbor 10.36.1.1 remote-as 300
But I can not ping the loopback adresses.
Can you help me?
Thanks.
05-18-2024 02:38 AM - edited 05-18-2024 08:21 AM
This not work' R1 know LO of R4/R6
But are R4/R6 dont know any IP from R1 ?
So the R1 use ip unknown from R4/R6 and hence the ping drop
Simple solution is redistrubte connect in all router.
MHM
05-18-2024 08:16 AM
Hello,
While R1 has the route to the 6.6.6.6 address the R6 router doesn't have any way to get back to R1. You need to advertise a network from R1 into the BGP domain to get propagated to R6. Then when you issue a ping make sure you ping with a source address of the loopback as that's all that's reachable to the BGP peers.
-David
05-19-2024 01:52 AM
Hello
Assumption is your bgp peering is via directly attached interfaces?
Aslo it looks like you have incomplete ibgp peering in AS400, R4-R6 requires ibgp peering between each other so the bgp reachability information pertaining to a next hop is updated so each AS400 ebep/ibgp rtr will advetise itself as a nexthop for bgp preifxes external to AS400
R4
neigbour <r6> next-hop-self
R6
neigbour <r4> next-hop-self
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