Hmmmm. Is this real lab or dynagen? Have you rebooted? What version of code? I just set up two routers back to back and I do not get this behavior. For kicks, can you disable all other connections (only leave the connected interfaces enabled) and we can try and narrow it down?
On Thu, Jul 9, 2009 at 7:37 PM, jmangawang <[email protected]> wrote: > Yeah, it started flapping not long after I posted the first message. > So, I stopped advertising the loop0 interface, and created a totally > new Loop2 interface assigning them IPs of 7.7.7.7/32 and 9.9.9.9/32 > for each respective router. > > Unfortunately, I'm still getting the same issue, and there's no > flapping this time around. Here's R9's config: > > R9(config-router)#do sh ip bgp > BGP table version is 4, local router ID is 50.51.0.9 > Status codes: s suppressed, d damped, h history, * valid, > best, i - > internal, > r RIB-failure, S Stale > Origin codes: i - IGP, e - EGP, ? - incomplete > > Network Next Hop Metric LocPrf Weight Path > * 7.7.7.7/32 50.51.0.7 0 0 9 i > *> 9.9.9.9/32 0.0.0.0 0 32768 i > > R9(config-router)#do sh run | s bgp > router bgp 7 > no synchronization > bgp log-neighbor-changes > network 9.9.9.9 mask 255.255.255.255 > neighbor 50.51.0.7 remote-as 9 > neighbor 50.51.0.7 ttl-security hops 2 > neighbor 50.51.0.7 update-source Loopback0 > no auto-summary > R9(config-router)#do sh ip bgp > BGP table version is 4, local router ID is 50.51.0.9 > Status codes: s suppressed, d damped, h history, * valid, > best, i - > internal, > r RIB-failure, S Stale > Origin codes: i - IGP, e - EGP, ? - incomplete > > Network Next Hop Metric LocPrf Weight Path > * 7.7.7.7/32 50.51.0.7 0 0 9 i > *> 9.9.9.9/32 0.0.0.0 0 32768 i > > R9(config-router)#do sh ip bgp 7.7.7.7/32 > BGP routing table entry for 7.7.7.7/32, version 0 > Paths: (1 available, no best path) > Not advertised to any peer > 9 > 50.51.0.7 (inaccessible) from 50.51.0.7 (50.51.0.7) > Origin IGP, metric 0, localpref 100, valid, external > > R7, which is set up with ebgp-multihop, sees both routes with best paths. > > I finally was able to get it show up properly if I enabled the > 'neighbor 50.51.0.7 disable-connected-check' option. > > R9(config-router)#do sh ip bgp 7.7.7.7/32 > BGP routing table entry for 7.7.7.7/32, version 3 > Paths: (1 available, best #1, table Default-IP-Routing-Table) > Flag: 0x820 > Not advertised to any peer > 9 > 50.51.0.7 (metric 2) from 50.51.0.7 (50.51.0.7) > Origin IGP, metric 0, localpref 100, valid, external, best > > But I couldn't figure out from the description of this option if it > broke the ttl-security check. Thoughts? > > On Thu, Jul 9, 2009 at 8:12 PM, Bryan Bartik<[email protected]> wrote: > > Try "debug ip routing". Are you getting recursion errors? It looks like > you > > are advertising the loopbacks in BGP which will cause the peers to learn > the > > loopback via the loopback. This will cause recursion and removal of the > > route from the BGP table and route table. Then the OSPF route is chosen, > BGP > > comes up and the whole process starts agaon. > > > > Don't advertise the loopback in BGP unless required or alter the > > administrative distances so OSPF is preferred over BGP. > > > -- Bryan Bartik CCIE #23707 (R&S), CCNP Sr. Support Engineer - IPexpert, Inc. URL: http://www.IPexpert.com
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