From: Huan Pham (huan.pham@valuenet.com.au)
Date: Fri Feb 15 2008 - 04:10:16 ARST
Hi Cristian,
The remote BGP peer does not accept your BGP connection. Most likely the
Backbone setup BGP using loopback address. I do not know the best debug
commands to effectively trouble-shoot this type of issue, but one thing you
can use is to turn on "debug ip packet detail" or just limit it to bgp
packet only using ACL to see where the source and destination IP for the BGP
session defined on the BB router.
access-list 100 permit tcp any any eq bgp
access-list 100 permit tcp any eq bgp any
debug ip packet 100
Cheers,
Huan
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Cristian Ionescu
Sent: Thursday, 14 February 2008 11:40 PM
To: Cisco certification
Subject: BGP - Connection refused by remote host
Hi GS
I have a strange situation with a "simple" BGP peering session.
I have 2 router connected over FR in different AS-es and i want to
establish a peering session between them. Let's say i do not know the
config of BB.
AS100 - - - - - AS54
R6 <----------> BB
The config of R6 is:
R6#
interface Loopback0
ip address 150.1.6.6 255.255.255.0
!
interface Serial0/0/0
ip address 54.1.1.6 255.255.255.0
!
router bgp 100
no synchronization
bgp log-neighbor-changes
neighbor 54.1.1.254 remote-as 54
no auto-summary
!
BB is directly connected and the peer address is 54.1.1.254 (i have ping
to this address)
I get the following debug output:
*Feb 14 11:33:31.259: BGP: 54.1.1.254 open active, local address 54.1.1.6
TCB45114344 created
*Feb 14 11:46:32.839: TCB45114344 setting property TCP_WINDOW_SIZE (0)
4511D1C8
*Feb 14 11:46:32.839: TCB45114344 setting property TCP_MD5KEY (5) 0
*Feb 14 11:46:32.839: TCB45114344 setting property TCP_TOS (11) 4511D1A8
*Feb 14 11:46:32.839: TCB45114344 setting property TCP_OUT_TTL (24)
46B25A2A
*Feb 14 11:46:32.839: TCP: Random local port generated 53511
*Feb 14 11:46:32.839: TCB45114344 bound to 54.1.1.6.53511
*Feb 14 11:46:32.839: TCP: sending SYN, seq 664141347, ack 0
*Feb 14 11:46:32.839: TCP0: Connection to 54.1.1.254:179, advertising
MSS 1460
*Feb 14 11:46:32.839: TCP0: state was CLOSED -> SYNSENT [53511 ->
54.1.1.254(179)]
*Feb 14 11:46:32.839: TCP0: state was SYNSENT -> CLOSED [53511 ->
54.1.1.254(179)]
*Feb 14 11:46:32.839: TCP0: bad seg from 54.1.1.254 -- closing
connection: port 53511 seq 0 ack 664141348 rcvnxt 0 rcvwnd 0 len 0
*Feb 14 11:46:32.843: TCP0: connection closed - remote sent RST
*Feb 14 11:46:32.843: TCB 0x45114344 destroyed
*Feb 14 11:33:31.259: BGP: 54.1.1.254 open failed: Connection refused by
remote host, open active delayed 29499ms (32000ms max, 28% jitter)
Can u please tell me where is the problem? What is the cause of this
kind of error message?
Regards
Cristian Ionescu
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