From: Nick Shah (nshah@xxxxxxxxxxxxxx)
Date: Sun Jun 16 2002 - 08:54:05 GMT-3
Dude,
Here's a hint...
http://www.cisco.com/warp/customer/459/25.shtml
OSPF/BGP router - id :) (Check out my post a couple of weeks ago)
rgds
Nick
----- Original Message -----
From: Hunt Lee <ciscoforme3@yahoo.com.au>
To: <ccielab@groupstudy.com>
Sent: Sunday, June 16, 2002 9:05 PM
Subject: BGP w/ no synchronization
> Okay folks, starting off some late nite studying and just noticed
something
> weird. Got a Confederation setup like:
>
> 150.150.150.0/24---RTA ---RTB ---RTD---RTF
> | |
> RTC RTE
>
> RTA, B, C, D, & E are in a Confederation called AS 1, in which:-
>
> RTA is sub-AS 65530
> RTB & RTC are both in sub-AS 65531
> RTD & RTE are both in sub-AS 65532
>
> RTF is in AS 2
>
> RTB, C, D & E are running OSPF as IGP. And OSPF is being redistributed
into
> BGP at RTB.
>
> The network 150.150.150.0/24 is being advertised into BGP by BGP "network"
> command on RTA.
>
> Ok, here is the thing. The 150.150.150.0/24 network is being seen by RTA,
RTB,
> RTD, & RTF. I could ping 150.150.150.1 from these four routers. However,
it
> can't be seen by RTC & RTE (shown as follows). But when I put "no
> synchronization" on the middle four routers (RTB, RTC, RTD, & RTE), then
> everything becomes fine again... I thought since I used IGP (OSPF), and
if
> the router can see the EBGP Next-Hop (193.16.0.2) in their routing table,
then
> the synch. rule shouldn't apply anymore.
>
> Am I missing something here?
>
> RouterC#sh ip bgp
> BGP table version is 4, local router ID is 172.16.0.2
> Status codes: s suppressed, d damped, h history, * valid, > best, i -
internal
> Origin codes: i - IGP, e - EGP, ? - incomplete
>
> Network Next Hop Metric LocPrf Weight Path
> * i150.150.150.0/24 193.16.0.2 0 100 0 (65530) i
> <-----193.16.0.2 is the Serial int of RTA
>
> *>i172.16.0.0/30 172.16.0.1 0 100 0 ?
> * i172.16.0.12/30 172.16.0.18 30 100 0 ?
> *>i172.16.0.16/30 172.16.0.1 0 100 0 ?
> *>i193.16.0.0/30 172.16.0.1 0 100 0 ?
> * i193.16.0.8/30 172.16.0.18 0 100 0 (65532) i
> RouterC#sh 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
>
> 172.16.0.0/30 is subnetted, 3 subnets
> O 172.16.0.16 [110/128] via 172.16.0.1, 01:35:04, Serial1
> O 172.16.0.12 [110/192] via 172.16.0.1, 01:35:04, Serial1
> C 172.16.0.0 is directly connected, Serial1
> 193.16.0.0/30 is subnetted, 1 subnets
> O 193.16.0.0 [110/74] via 172.16.0.1, 01:35:04, Serial1
> RouterC#
> RouterC#ping 193.16.0.2
>
> Type escape sequence to abort.
> Sending 5, 100-byte ICMP Echos to 193.16.0.2, timeout is 2 seconds:
> !!!!!
> Success rate is 100 percent (5/5), round-trip min/avg/max = 28/32/36 ms
> RouterC#
>
>
> Thanks all!
>
> Hunt
>
> http://www.sold.com.au - SOLD.com.au
> - Find yourself a bargain!
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