[c-nsp] MPLS LDP Neighbourship Flapping

Sat Nov 12 11:47:34 EST 2005

If it's a targeted peer then the router its peering with could be many
hops and many flaky links away.

So, If a ping to the neighbor fails around the same time that the
neighbor disappears you know that ldp is working fine and is just
telling you about flakiness along an intermediate link.

Now you have an underlying link problem to solve.  So do a traceroute or
something to figure out what hops are in between and start looking for
messages from ospf or is-is or regular ldp sessions that would clue you
in about a flaky link.  Don't forget, LDP is a very good indicator of
link healthiness, your local ldp neighbor will go away very very quickly
if there is a problem.

If you don't see any intermediate link problems, no ping fails, no ldp
neighbor loss, no link down, no ospf or is-is, then the problem is on
the router (high cpu, some bug) or with the LDP implementation.  I have
the previous version in a lab environment with targeted LDP and I
haven't experienced any targeted ldp neighbor loss that wasn't caused by
my downing an interface.  

-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net
[mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Atiqur Rahman
Mohammed
Sent: Saturday, November 12, 2005 9:03 AM
To: Aamer Akhter (aakhter)
Cc: cisco-nsp
Subject: Re: [c-nsp] MPLS LDP Neighbourship Flapping

hi Aamer
This is a targetted peer.
The Cisco IOS 12.2(18)SXF is being used.
 I will provide the output of debug command requested and as well as
show
tech later.

 On 11/12/05, Aamer Akhter (aakhter) <aakhter at cisco.com> wrote:
>
> Atiqur,
>
> Is this a targetted peer (usually l2vpn or TE) or a basic peer
(directly
> connected)?
>
> You may want to get the output from the following debugs. Be sure to
apply
> the peer acl so that you only get debugs from this particular peer.
>
> debug mpls ldp messages received all peer-acl <acl>
> debug mpls ldp messages sent all peer-acl <acl>
> debug mpls ldp session io all peer-acl <acl>
>
> Which version of IOS are you running? Be aware that the show-tech
didn't
> seem to get sent...
>
> --
> Aamer Akhter / aa at cisco.com
> NSITE - cisco Systems
>
> > -----Original Message-----
> > From: cisco-nsp-bounces at puck.nether.net
> > [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of
> > Atiqur Rahman Mohammed
> > Sent: Saturday, November 12, 2005 6:13 AM
> > To: cisco-nsp
> > Subject: [c-nsp] MPLS LDP Neighbourship Flapping
> >
> > Can anyone help resolving this issue.
> > Please find topology diagram of my network attached.
> > The issue is that LDP neigbhourship between MCCTY1LOC1B001C76001 and
> > MCCTY2LOC1B001C76001is flapping. I continuosly get these message.
> > C76001#
> > *Nov 12 15:06:17.654: %LDP-5-NBRCHG: LDP Neighbor
> > 192.168.71.165:0
<http://192.168.71.165:0><http://192.168.71.165:0/>is
> DOWN
> > *Nov 12 15:07:53.516: %LDP-5-NBRCHG: LDP Neighbor
> > 192.168.71.165:0
<http://192.168.71.165:0><http://192.168.71.165:0/>is
> UP
> > *Nov 12 15:10:53.476: %LDP-5-NBRCHG: LDP Neighbor
> > 192.168.71.165:0
<http://192.168.71.165:0><http://192.168.71.165:0/>is
> DOWN
> > *Output of the show mpls ldp neighbour command from
> > MCCTY1LOC1B001C76001*
> > **
> > Peer LDP Ident: 192.168.71.164:0 <http://192.168.71.164:0> <
> http://192.168.71.164:0/>;
> > Local LDP
> > Ident 192.168.71.161:0 <http://192.168.71.161:0> <
> http://192.168.71.161:0/>
> > TCP connection: 192.168.71.164.11170 - 192.168.71.161.646
> > State: Oper; Msgs sent/rcvd: 1680/1683; Downstream
> > Up time: 23:44:50
> > LDP discovery sources:
> > Targeted Hello 192.168.71.161 <http://192.168.71.161> <
> http://192.168.71.161/> ->
> > 192.168.71.164 <http://192.168.71.164><http://192.168.71.164/>,
> > active, passive
> > GE-WAN2/4, Src IP addr: 192.168.71.22 <http://192.168.71.22> <
> http://192.168.71.22/>
> > Addresses bound to peer LDP Ident:
> > 192.168.71.164 <http://192.168.71.164> <http://192.168.71.164/>
> 192.168.72.3 <http://192.168.72.3>
> > <http://192.168.72.3/>
> > 192.168.49.130 <http://192.168.49.130> <http://192.168.49.130/>
> > 192.168.71.189 <http://192.168.71.189><http://192.168.71.189/>
> > 192.168.71.22 <http://192.168.71.22> <http://192.168.71.22/>
> > Peer LDP Ident: 192.168.71.163:0 <http://192.168.71.163:0> <
> http://192.168.71.163:0/>;
> > Local LDP Ident
> > 192.168.71.161:0 <http://192.168.71.161:0>
<http://192.168.71.161:0/>
> > TCP connection: 192.168.71.163.11192 - 192.168.71.161.646
> > State: Oper; Msgs sent/rcvd: 1677/1678; Downstream
> > Up time: 23:44:47
> > LDP discovery sources:
> > Targeted Hello 192.168.71.161 <http://192.168.71.161> <
> http://192.168.71.161/> ->
> > 192.168.71.163 <http://192.168.71.163><http://192.168.71.163/>,
> > active, passive
> > Addresses bound to peer LDP Ident:
> > 192.168.71.163 <http://192.168.71.163> <http://192.168.71.163/>
5.5.5.2<http://5.5.5.2><
> http://5.5.5.2/>
> > 3.3.3.1 <http://3.3.3.1><http://3.3.3.1/>
> > 192.168.71.9 <http://192.168.71.9> <http://192.168.71.9/>
> > 192.168.49.33 <http://192.168.49.33> <http://192.168.49.33/>
> > Peer LDP Ident: 192.168.71.168:0 <http://192.168.71.168:0> <
> http://192.168.71.168:0/>;
> > Local LDP Ident
> > 192.168.71.161:0 <http://192.168.71.161:0>
<http://192.168.71.161:0/>
> > TCP connection: 192.168.71.168.11120 - 192.168.71.161.646
> > State: Oper; Msgs sent/rcvd: 1680/1678; Downstream
> > Up time: 23:44:46
> > LDP discovery sources:
> > Targeted Hello 192.168.71.161 <http://192.168.71.161> <
> http://192.168.71.161/> ->
> > 192.168.71.168 <http://192.168.71.168><http://192.168.71.168/>,
> > active, passive
> > Addresses bound to peer LDP Ident:
> > 192.168.71.168 <http://192.168.71.168> <http://192.168.71.168/>
> > 192.168.71.18 <http://192.168.71.18><http://192.168.71.18/>
> > Peer LDP Ident: 192.168.71.167:0 <http://192.168.71.167:0> <
> http://192.168.71.167:0/>;
> > Local LDP Ident
> > 192.168.71.161:0 <http://192.168.71.161:0>
<http://192.168.71.161:0/>
> > TCP connection: 192.168.71.167.11059 - 192.168.71.161.646
> > State: Oper; Msgs sent/rcvd: 1680/1686; Downstream
> > Up time: 23:45:10
> > LDP discovery sources:
> > Targeted Hello 192.168.71.161 <http://192.168.71.161> <
> http://192.168.71.161/> ->
> > 192.168.71.167 <http://192.168.71.167><http://192.168.71.167/>,
> > active, passive
> > Addresses bound to peer LDP Ident:
> > 192.168.71.167 <http://192.168.71.167> <http://192.168.71.167/>
> > 192.168.71.37 <http://192.168.71.37><http://192.168.71.37/>
> > 5.5.5.6 <http://5.5.5.6> <http://5.5.5.6/> 3.3.3.2 <http://3.3.3.2>
<
> http://3.3.3.2/>
> > Peer LDP Ident: 192.168.71.165:0 <http://192.168.71.165:0> <
> http://192.168.71.165:0/>;
> > Local LDP Ident
> > 192.168.71.161:0 <http://192.168.71.161:0>
<http://192.168.71.161:0/>
> > TCP connection: 192.168.71.165.28858 - 192.168.71.161.646
> > State: Oper; Msgs sent/rcvd: 59/2; Downstream
> > Up time: 00:01:08
> > LDP discovery sources:
> > Targeted Hello 192.168.71.161 <http://192.168.71.161> <
> http://192.168.71.161/> ->
> > 192.168.71.165 <http://192.168.71.165><http://192.168.71.165/>,
> > active, passive
> > I am also attaching the output of show tech-support from
> > MCCTY1LOC1B001C76001 and MCCTY2OC1B001C76001
> > gards
> > Atiqur Rahman
> > Infocomm Technology Cente
> > Reliance Infocomm
> > Mobile: 09324621784
> > _______________________________________________
> > cisco-nsp mailing list cisco-nsp at puck.nether.net
> > https://puck.nether.net/mailman/listinfo/cisco-nsp
> > archive at http://puck.nether.net/pipermail/cisco-nsp/
> >
>

--
Regards,
Atiqur Rahman
Infocomm Technology Cente
Reliance Infocomm
Mobile: 09324621784
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