eBGP Session is boucing

From: Mushtaq A. Khan (mak.ccie2b@gmail.com)
Date: Wed Mar 01 2006 - 15:39:09 GMT-3


Hi Group,

I have an issue with eBGP session that continuously boucning between two
routers. I have a scenario where R1 is hub and R2 & R4 are spoke and all are
running EIGRP. I'm adv loopback 1.1.1.1 and loopback 4.4.4.4 from R1 and R4
respectively via EIGRP. R1 has ebgp peering with R4 and there is another
ebgp peering between R2 and R4. The requirement is also to adv loopback
1.1.1.1 and loopback 4.4.4.4 from R1 and R4 respectively via BGP. I am using
BGP backdoor to avoid recursive routing situation. What I'm noticing that
eBGP session between R1 and R4 is keep bouncing however there is no issue
between R2 and R4. Do you guys have any idea as to what is wrong here? Any
clue?

*Sep 23 04:45:18.706: %BGP-3-NOTIFICATION: received from neighbor
4.4.4.44/0 (hold time expired) 0 bytes
*Sep 23 04:45:18.706: %BGP-5-ADJCHANGE: neighbor 4.4.4.4 Down BGP
Notification received

Configurations details are given below:

                                           R2(AS23)
                                          /
                                         /
                             R1(AS1)
                                         \
                                          \
                                            R4 (AS4)

R1#sh run | beg router
router eigrp 100
 network 1.1.1.0 0.0.0.255
 network 172.10.0.0
 no auto-summary
 neighbor 172.10.124.4 Serial0/0
 neighbor 172.10.124.2 Serial0/0
!
router bgp 1
 no synchronization
 bgp log-neighbor-changes
 network 1.1.1.0 mask 255.255.255.0 backdoor
 neighbor 4.4.4.4 remote-as 4
 neighbor 4.4.4.4 ebgp-multihop 2
 neighbor 4.4.4.4 update-source Loopback1
 no auto-summary

R1#sh ip route 4.4.4.4 <--------------------- NOT sure why this is still
being learned via bgp even though I'm using BGP backdoor.
Routing entry for 4.4.4.0/24
  Known via "bgp 1", distance 20, metric 0
  Tag 4, type external
  Last update from 4.4.4.4 00:00:30 ago
  Routing Descriptor Blocks:
  * 4.4.4.4, from 4.4.4.4, 00:00:30 ago
      Route metric is 0, traffic share count is 1
      AS Hops 1
      Route tag 4

R4#sh run | beg router
router eigrp 100
 network 4.4.4.0 0.0.0.255
 network 172.10.0.0
 neighbor 172.10.124.1 Serial0/0
 no auto-summary
!
router bgp 4
 no synchronization
 bgp log-neighbor-changes
 network 4.4.4.0 mask 255.255.255.0 backdoor
 neighbor 1.1.1.1 remote-as 1
 neighbor 1.1.1.1 ebgp-multihop 2
 neighbor 1.1.1.1 update-source Loopback4
 neighbor 172.10.124.2 remote-as 23
 neighbor 172.10.124.2 ebgp-multihop 255
 no auto-summary
!

R4#sr 1.1.1.1
Routing entry for 1.1.1.0/24
  Known via "eigrp 100", distance 90, metric 2297856, type internal
  Redistributing via eigrp 100
  Last update from 172.10.124.1 on Serial0/0, 00:05:30 ago
  Routing Descriptor Blocks:
  * 172.10.124.1, from 172.10.124.1, 00:05:30 ago, via Serial0/0
      Route metric is 2297856, traffic share count is 1
      Total delay is 25000 microseconds, minimum bandwidth is 1544 Kbit
      Reliability 255/255, minimum MTU 1500 bytes
      Loading 1/255, Hops 1

Thanks,
Mushtaq



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