12-16-2006 12:32 PM - edited 03-03-2019 03:04 PM
I have a lab setup for learning BGP. I'm trying to understand why I cannot ping the loopback interface of router c from router b.
Three routers.
Router A -
Lo0:10.252.1.1/32
S0:192.168.27.1/30
S1:192.168.27.5/30
S2:192.168.27.9/30
router bgp 65000
no synchronization
bgp log-neighbor-changes
network 10.252.1.1 mask 255.255.255.255
neighbor 192.168.27.2 remote-as 65001
neighbor 192.168.27.6 remote-as 65003
neighbor 192.168.27.10 remote-as 65002
Router B:
Lo0:10.252.1.5
S0:192.168.27.2
router bgp 65001
no synchronization
bgp log-neighbor-changes
network 10.252.1.5 mask 255.255.255.255
neighbor 192.168.27.1 remote-as 65000
Router C
Lo0:10.252.1.9
S0:192.168.27.10
router bgp 65002
no synchronization
bgp log-neighbor-changes
network 10.252.1.9 mask 255.255.255.255
neighbor 192.168.27.9 remote-as 65000
12-16-2006 01:20 PM
What do the routing tables on B & C show ?
Have you tried doing an extended ping with the source of the ping as the loopback address of router B. You are not advertising the p2p 192.168.27.x networks - is there a route on C for B's 192.168.27.0/30 network ? If not and the ping goes out with a source of 192.168.27.2 then C does not how to get back.
HTH
12-16-2006 01:42 PM
Thanks for the help. I tried doing an extended ping with src as the loopback and that didn't work. Unless I was doing it wrong. I did however advertise the wan networks and that worked. Thanks for the help.
12-16-2006 01:32 PM
Hello,
If you send an ping from router C it will have as source address 192.168.27.9. This address is unknown for router B. Try an extended ping to router B with source address loopback0 on router C. This should get an reply.
regards
Rogier
12-16-2006 01:45 PM
Thanks for the help. I tried that and it didn't work. Not sure why.
12-16-2006 01:52 PM
My bad. Using extended ping with the source as the Loopback ip address does work. Thanks
12-17-2006 11:11 PM
Hi,
Just give no auto-summary on all 3 routers and see.
rgrds,
hardik
12-18-2006 12:01 PM
I think since the routers are advertising only their loopback addresses, RouterB doesn't know hot to get to RouterC's Serial interface therefore the next hope is unreachable (it has to use Router C's serial address to get to the loopback interface. on RouterA you should add next-hop self command for the neigbors. if you use that, the router will have valid next hop address
on router A:
neighbor 192.168.27.2 next-hop-self
neighbor 192.168.27.10 next-hop-self
should fix
cheers
Tayfun
12-18-2006 11:41 PM
Hello,
This is not correct. Using next-hop-self is for use between IBGP peers not EBGP peers as is the case here.
Regards
Rogier
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