This was on a ProctorLabs pod, 109, to be specific. I was working IPExpert Vol3, Lab9 at the time. The actual scenario occurs between R1 and BB1 with RIP as the IGP. I know that R9 is running 12.4(3), but I didn't check R7, R1, or the BB1 routers. I did reboot, several times, and they all come up the same way. And, I've rebooted both sides, even though the side with ebgp-multihop sees everything fine.
I'll try it again on Dynagen this AM and see if there's any difference. On Thu, Jul 9, 2009 at 9:01 PM, Bryan Bartik<[email protected]> wrote: > 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 > _______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com
