Re: BGP - Connection refused by remote host

From: Cristian Ionescu (cristian.ionescu@omnilogic.ro)
Date: Fri Feb 15 2008 - 05:50:50 ARST


Hi and thanks for all answers.

1. The config on FR on R6 is straight forward...nothing special. I have
ping to BB even with source Loop0

2. I have tried to peer using a different update source (the loop 0) and
i have the same output:
*Feb 14 11:33:31.259: BGP: 54.1.1.254 open active, local address 150.1.6.6
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 150.1.6.6.53511
*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)

3. The other end has for sure BGP configured

4. There is no ACL on R6

I will try to hardcoded the router id and do debug ip packet detail to
see the output....

Regards
Cristian Ionescu

Dan C wrote:
> Hi Cristian,
>
> Looking at : *Feb 14 11:46:32.839: TCP0: bad seg from 54.1.1.254
> <http://54.1.1.254/> -- closing
> connection: port 53511 seq 0 ack 664141348 rcvnxt 0 rcvwnd 0 len 0
>
> rcvnxt 0 rcvwnd 0 len 0 ----- your peer ( bb router ) is not aware of
> the tcp connection.
>
> Few solutions may address this issue:
>
> Ping peer bb router using your loopback ip address, if ok, try hard
> code the bgp router-id to the loopback.
> If not create a new loopback int and use that ip address as bgp
> router-id.
>
> Check for any MTU mismatch using extended ping sweeping between 1400
> 1500 size
>
> Any ACL on R6 ?
>
> Cheers, Dan
>
> On Thu, Feb 14, 2008 at 11:40 PM, Cristian Ionescu
> <cristian.ionescu@omnilogic.ro <mailto:cristian.ionescu@omnilogic.ro>>
> wrote:
>
> 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 <http://150.1.6.6> 255.255.255.0
> <http://255.255.255.0>
> !
> interface Serial0/0/0
> ip address 54.1.1.6 <http://54.1.1.6> 255.255.255.0
> <http://255.255.255.0>
> !
> router bgp 100
> no synchronization
> bgp log-neighbor-changes
> neighbor 54.1.1.254 <http://54.1.1.254> remote-as 54
> no auto-summary
> !
>
>
> BB is directly connected and the peer address is 54.1.1.254
> <http://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 <http://54.1.1.254> open
> active, local address 54.1.1.6 <http://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
> <http://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
> <http://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 <http://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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