From: Joseph Brunner (joe@affirmedsystems.com)
Date: Mon Sep 24 2007 - 21:49:56 ART
John, I have tried to go through this config; and draw it out in my head.
"Show ip interface brief" and "show ip bgp summary" in the future would also
be helpful to us to provide more assistance ;)
Here is how I normally go about solving these issues in my lab...
Do some "debug ip icmp" + "term mon" on the routers send and receiving the
pings, lets see what's failing. Debug ip packet <ACL> also helps, again with
term mon turned on, or "logging console" if you are directly connected.
The next hop is automatically reset to the outgoing interface for EBGP (or
if the update-source is set, it will use that interface). I suspect a broken
igp underlying your perhaps working bgp config.
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of John
Sent: Monday, September 24, 2007 9:19 PM
To: John; ccielab@groupstudy.com
Subject: Re: IWE BGP
error R2 not R1 is connected to R5 via EBGP
----- Original Message -----
From: "John" <jgarrison1@austin.rr.com>
To: <ccielab@groupstudy.com>
Sent: Monday, September 24, 2007 7:03 PM
Subject: IWE BGP
> This is killing me I've set up this same lab a number of times. It
> appears
> that the BGP and routing tables are correct at all routers.R1 R2 R3 are in
> AS2
> R4 is in AS3 and R5 is in AS1. From R4 I cannot ping R3 or R5's
> ethernet/vlan(155.1.37.0, 155.1.5.0), but from R3 I can ping R4 and R5's
> ethernet/vlan here is the relevant info for R4
> Network Next Hop Metric LocPrf Weight Path
> *> 155.1.5.0/24 155.1.146.1 0 2 1 i
> *> 155.1.37.0/24 155.1.146.1 0 2 i
> *> 204.12.1.0 0.0.0.0 0 32768 i
> Rack1R4#sh ip route
> C 204.12.1.0/24 is directly connected, FastEthernet0/1
> 155.1.0.0/24 is subnetted, 3 subnets
> C 155.1.146.0 is directly connected, FastEthernet0/0
> B 155.1.5.0 [20/0] via 155.1.146.1, 00:37:13
> B 155.1.37.0 [20/0] via 155.1.146.1, 00:37:13
> Rack1R4#sh ip bgp 155.1.5.0
> BGP routing table entry for 155.1.5.0/24, version 2
> Paths: (1 available, best #1, table Default-IP-Routing-Table)
> Not advertised to any peer
> 2 1
> 155.1.146.1 from 155.1.146.1 (155.1.146.1)
> Origin IGP, localpref 100, valid, external, best
> Rack1R4#sh ip bgp 155.1.37.0
> BGP routing table entry for 155.1.37.0/24, version 3
> Paths: (1 available, best #1, table Default-IP-Routing-Table)
> Not advertised to any peer
> 2
> 155.1.146.1 from 155.1.146.1 (155.1.146.1)
> Origin IGP, localpref 100, valid, external, best
>
> Heres where it gets weird R4 is connected to R1 via EBGP and from R1 I can
> ping R3 and R4's ethernet /vlan(155.1.37.0, 204.12.1.0), but not
> R5's(155.1.5.0). From R1 I cannot reach 155.1.0.0 which is connecting R1
> to
> R5 via EBGP, but I can reach 155.1.23.0 which connects R3 to R2 via IBGP
> and
> EIGRP heres R1's relevant info
> Network Next Hop Metric LocPrf Weight Path
> *>i155.1.5.0/24 155.1.23.2 0 100 0 1 i
> *>i155.1.37.0/24 155.1.13.3 0 100 0 i
> *> 204.12.1.0 155.1.146.4 0 0 3 i
> Rack1R1#sh ip route
> Codes: C - connected, S - static, 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
> i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS
> level-2
> ia - IS-IS inter area, * - candidate default, U - per-user static
> route
> o - ODR, P - periodic downloaded static route
>
> Gateway of last resort is not set
>
> B 204.12.1.0/24 [20/0] via 155.1.146.4, 00:53:17
> 155.1.0.0/24 is subnetted, 5 subnets
> C 155.1.146.0 is directly connected, FastEthernet0/0
> D 155.1.23.0 [90/2681856] via 155.1.13.3, 01:37:10, Serial2/1
> C 155.1.13.0 is directly connected, Serial2/1
> B 155.1.5.0 [200/0] via 155.1.23.2, 00:54:49
> B 155.1.37.0 [200/0] via 155.1.13.3, 01:30:38
> Rack1R1#sh ip bgp 155.1.5.0
> BGP routing table entry for 155.1.5.0/24, version 6
> Paths: (1 available, best #1, table Default-IP-Routing-Table)
> Advertised to update-groups:
> 1
> 1
> 155.1.23.2 (metric 2681856) from 155.1.23.2 (155.1.23.2)
> Origin IGP, metric 0, localpref 100, valid, internal, best
>
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