[c-nsp] Interesting iBGP problem

Kevin kevin at honeycomb.net
Tue Sep 14 00:15:53 EDT 2004


I have two 7500 routers, border1 and border2, border1 currently has a
GiGE to a backbone router, border2 will soon have an ds3 to another
providor. I have a GIGe connection between the routers.
Border2 has a brand new default config. Basically what I can tell is
happening is that when I configure iBGP between the two routers, border2
will insert all the ebgp routes from border1 into the routing table and
then about 1min later it'll remove all the routes out of the routing
table. Then after another minute the routes are back. Has anyone seen
this before? I checked to see if bgp was flapping, and it was'nt. I
checked for interface errors, their was'nt any.
I am running 12.3(8)T3 on these routers. Below are the bgp configs.


Kevin,


Border1:
router bgp 25720
 bgp log-neighbor-changes
 bgp bestpath compare-routerid
 neighbor 192.168.1.2 remote-as 25720
 neighbor 192.168.1.2 update-source Loopback0
 neighbor 207.67.87.49 remote-as 4323
 neighbor 207.67.87.49 description TWtelecom
 neighbor 207.67.87.49 version 4
 !
 address-family ipv4
 neighbor 192.168.1.2 activate
 neighbor 207.67.87.49 activate
 neighbor 207.67.87.49 next-hop-self
 neighbor 207.67.87.49 remove-private-as
 neighbor 207.67.87.49 soft-reconfiguration inbound
 neighbor 207.67.87.49 distribute-list BGP_Advertisment out
 neighbor 207.67.87.49 route-map tw-in in
 no auto-summary
 no synchronization
 network 199.199.208.0 mask 255.255.248.0
 aggregate-address 199.199.208.0 255.255.248.0 summary-only
 exit-address-family

Border2:

router bgp 25720
 no synchronization
 bgp log-neighbor-changes
 neighbor 192.168.1.1 remote-as 25720
 neighbor 192.168.1.1 update-source Loopback0
 no auto-summary







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