From: Vijay Venkatesh (vijay.venkatesh@xxxxxxx)
Date: Thu Aug 10 2000 - 00:21:29 GMT-3
WHich ones are your loopbacks ? A diagram will help. A route to either
loopback needs to be known via IGP first. BGP will show connected
state and hence the flapped route. If RIp is the IGP then the loopbacks
should only be known to RIP. Then you can use the update-source
loop 0.
Vijay.
Scott wrote:
>
> Hello
>
> I was trying to connect two AS with a EBGP multihop command between two
> loopbacks and it looks like I am getting a some type of routing loop. The BGP
> routes are put in the routing table and removed every 60 seconds (see
> attached). I have IP connectivity via RIP and the connection is showing as
> established. Any suggestions? Thanks
>
> Scotty
>
> router2#show ip route
> Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
> D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
> N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
> E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
> i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate
> default
> U - per-user static route, o - ODR
>
> Gateway of last resort is not set
>
> 138.6.0.0/24 is subnetted, 2 subnets
> B 138.6.5.0 [200/0] via 172.16.35.5, 00:09:52
> B 138.6.1.0 [200/0] via 172.16.35.5, 00:09:52
> 4.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
> B 4.4.4.0/24 [20/0] via 4.4.4.4, 00:00:36
> R 4.0.0.0/8 [120/11] via 172.16.24.4, 00:00:27, Serial1
> 172.16.0.0/24 is subnetted, 5 subnets
> O IA 172.16.35.0 [110/74] via 172.16.23.3, 00:10:44, Ethernet0
> C 172.16.24.0 is directly connected, Serial1
> C 172.16.23.0 is directly connected, Ethernet0
> C 172.16.12.0 is directly connected, Serial0
> C 172.16.2.0 is directly connected, Loopback0
> router2#ping 4.4.4.4
>
> Type escape sequence to abort.
> Sending 5, 100-byte ICMP Echos to 4.4.4.4, timeout is 2 seconds:
> .....
> Success rate is 0 percent (0/5)
> router2#
> 05:08:12: BGP: no valid path for 4.4.4.0/24
> 05:08:12: BGP: nettable_walker 4.4.4.0/24 no best path
> 05:08:12: BGP: 4.4.4.4 computing updates, neighbor version 15, table version
> 16,
> starting at 0.0.0.0
> 05:08:12: BGP: 4.4.4.4 update run completed, ran for 0ms, neighbor version 15
,
> s
> tart version 16, throttled to 16, check point net 0.0.0.0
> 05:08:12: BGP: 172.16.23.1 computing updates, neighbor version 15, table
> version
> 16, starting at 0.0.0.0
> 05:08:12: BGP: 172.16.23.1 send UPDATE 4.4.4.0/24 -- unreachable
> 05:08:12: BGP: 172.16.23.1 1 updates enqueued (average=27, maximum=27)
> 05:08:12: BGP: 172.16.23.1 update run completed, ran for 8ms, neighbor versio
n
> 1
> 5, start version 16, throttled to 16, check point net 0.0.0.0
> 05:08:12: BGP: 172.16.23.3 computing updates, neighbor version 15, table
> version
>
> !
> interface Loopback0
> ip address 172.16.2.2 255.255.255.0
> no ip directed-broadcast
> !
> !
> interface Serial1
> ip address 172.16.24.2 255.255.255.0
> no ip directed-broadcast
> clockrate 64000
> !
> interface BRI0
> no ip address
> no ip directed-broadcast
> shutdown
> !
> router ospf 3
> network 172.16.23.0 0.0.0.255 area 3
> !
> router rip
> version 2
> network 172.16.0.0
> default-information originate
> !
> router bgp 3
> no synchronization
> network 172.16.2.0 mask 255.255.255.0
> neighbor 4.4.4.4 remote-as 4
> neighbor 4.4.4.4 ebgp-multihop 5
> neighbor 4.4.4.4 update-source Loopback0
> neighbor 4.4.4.4 distribute-list 2 out
> neighbor 172.16.23.1 remote-as 3
> neighbor 172.16.23.3 remote-as 3
> !
>
> Router 1
> !
> interface Loopback0
> ip address 4.4.4.4 255.255.255.0
> no ip directed-broadcast
> !
> interface Loopback1
> ip address 215.6.10.1 255.255.255.0
> no ip directed-broadcast
> !
> interface Loopback2
> ip address 215.6.11.1 255.255.255.0
> no ip directed-broadcast
> !
> interface Loopback5
> no ip address
> no ip directed-broadcast
> !
> interface Ethernet0
> no ip address
> no ip directed-broadcast
> appletalk cable-range 600-600 600.5
> appletalk zone biteme
> appletalk protocol eigrp
> bridge-group 1
> !
> interface Serial0
> ip address 172.16.24.4 255.255.255.0
> no ip directed-broadcast
> no ip mroute-cache
> no fair-queue
> !
> interface Serial1
> ip address 172.16.10.10 255.255.255.252
> no ip directed-broadcast
> bridge-group 1
> !
> interface BRI0
> no ip address
> no ip directed-broadcast
> shutdown
> !
> router rip
> version 2
> offset-list 1 out 10
> network 4.0.0.0
> network 172.16.0.0
> !
> router bgp 4
> no synchronization
> network 4.4.4.0 mask 255.255.255.0
> neighbor 172.16.2.2 remote-as 3
> neighbor 172.16.2.2 ebgp-multihop 5
> neighbor 172.16.2.2 update-source Loopback0
>
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