From: KRATTIGER Lukas (Lukas.KRATTIGER@nextiraone.ch)
Date: Sun Feb 17 2008 - 06:38:02 ARST
Hi Christian
Did you try to use the bgp ttl-security ?
1. trace to the destination "trace ip 10.1.1.4"
2. count the number of hops , for example 2
3. add this to your bgp config "neighbor 10.1.1.4 ttl-security hops 2"
4. see if the session comes up
http://www.cisco.com/en/US/products/sw/iosswrel/ps5207/products_feature_guide09186a008020b982.html
Regards
-Lukas
________________________________
From: nobody@groupstudy.com on behalf of Cristian Ionescu
Sent: Fri 15.02.2008 14:22
To: Dan C
Cc: Cisco certification
Subject: Re: BGP - Connection refused by remote host
You r right but ei x.x.x.x update-source loopback 0 does not solve the
problem......
u can try it and see it is not working...
Dan C wrote:
> Hi Cristian,
>
> Having another look at the output it looks like the TCP is bound to
> your loopback address instead of the interface address. Adding nei
> x.x.x.x update-source loopback 0 may solve this issue
>
> Cheers, Dan
>
> On Fri, Feb 15, 2008 at 6:50 PM, Cristian Ionescu
> <cristian.ionescu@omnilogic.ro <mailto:cristian.ionescu@omnilogic.ro>>
> wrote:
>
> 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 <http://54.1.1.254 <http://54.1.1.254/> > open
> active, local address 150.1.6.6 <http://150.1.6.6 <http://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
> <http://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 <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 <http://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 <http://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>
> <mailto: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 <http://150.1.6.6/> > <http://150.1.6.6 <http://150.1.6.6/> >
> 255.255.255.0 <http://255.255.255.0 <http://255.255.255.0/> >
> > <http://255.255.255.0 <http://255.255.255.0/> >
> > !
> > interface Serial0/0/0
> > ip address 54.1.1.6 <http://54.1.1.6 <http://54.1.1.6/> > <http://54.1.1.6 <http://54.1.1.6/> >
> 255.255.255.0 <http://255.255.255.0 <http://255.255.255.0/> >
> > <http://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 <http://54.1.1.254/> > <http://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 <http://54.1.1.254/> >
> > <http://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 <http://54.1.1.254/> >
> <http://54.1.1.254 <http://54.1.1.254/> > open
> > active, local address 54.1.1.6 <http://54.1.1.6 <http://54.1.1.6/> >
> <http://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 <http://54.1.1.254:179/> >
> > <http://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 <http://54.1.1.254/> >
> > <http://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 <http://54.1.1.254/> >
> <http://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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