[c-nsp] Interesting iBGP problem

[Stephen J. Wilcox]

ibgp next-hop-self OR redistribute connected in your igp

Steve

On Tue, 14 Sep 2004, Félix Izquierdo wrote:

> 1 min is the default bgp scan time for next-hop reachability checking. 
> It seems that the next-hop for the routes learned from border 1 is 
> unreachable. You must use next-hop-self in all the ibgp sessions 
> configured at the border routers.
> 
> 
> 
> Kevin wrote:
> 
> > 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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> > 
> > 
> 
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