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Community Manager

Ask the Expert:Configuring and Troubleshooting MPLS Traffic Engineering

Read the bioWith Saurabh Chopra

Welcome to the Cisco Support Community Ask the Expert conversation. This is an opportunity to learn and ask questions MPLS Traffic Engineering can help to best utilize your network with Saurabh Chopra. MPLS TE brings explicit routing capabilities to MPLS networks and is very popular across Service Providers. Traffic Engineering can make best utilization of network  resources and avoid non-even load distribution by real-time monitoring traffic and traffic load on each network elements to dynamically tune traffic  management attributes, routing parameters and resources constraints. This event is a continuation of the Facebook Forum.

Remember to use the rating system to let Saurabh know if you have received an adequate response. 

Saurabh  might not be able to answer each question due to the volume expected during this event. Remember that you can continue the conversation on the Service Provider sub-community discussion forum shortly after the event.  This event lasts through January 25, 2013. Visit this forum often to view responses to your questions and the questions of other community members.

Rising star

Hello Saurabh,

Say I have tunnel from router A to B. Path: A---C---D--E--B.

If I change tunnel description on head end A then it is not reflected for rest of the nodes until I shutdown that tunnel.

Any idea what could be reason for this and is there any way I can change description of tunnel without any impact.

Actually we have around 400 nodes in network and we want to change description on all with visibility at intermediate nodes of these changes but since these changes are not reflecting in intermediate nodes this whole project is on hold.

Regards # Mahesh


Hi Mahesh,

Thanks for the question .

Please let me know which image you are using on the head end router .




Hi Saurabh,

Thanks !

We are running SRE4+Engg Fix image on all platform. This problem was also there in SRD3 as well.

Regards # Mahesh


Hi Mahesh,

I checked the debugs in SRD and SRE images , change in description doesnot trigger path messages with the new description.

Although with latest images like 151-1.S2 , i see the path messages are triggered ( with the session attribute containing new name )  the moment you change the description on tunnel which makes relevent changes on all the intermediate nodes.

WITH latest image:-

R1(config)#int t10

R1(config-if)#description saur2   >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>


*Jan 15 07:26:46.730: Outgoing PathTear:

*Jan 15 07:26:46.733:  SESSION_ATTRIBUTE    type 7 length 20:

*Jan 15 07:26:46.734:   Setup Prio: 7, Holding Prio: 7

*Jan 15 07:26:46.734:   Flags: (0x4) SE Style

*Jan 15 07:26:46.734:   Session Name: saur2 >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

*Jan 15 07:26:46.734:  SENDER_TEMPLATE      type 7 length 12:

*Jan 15 07:26:46.734:   Tun Sender:  LSP ID: 21

*Jan 15 07:26:46.734:  SENDER_TSPEC         type 2 length 36:

*Jan 15 07:26:46.734:   version=0, length in words=7

*Jan 15 07:26:46.734:   Token bucket fragment (service_id=1, length=6 words

*Jan 15 07:26:46.734:     parameter id=127, flags=0, parameter length=5

*Jan 15 07:26:46.734:     average rate=0 bytes/sec, burst depth=1000 bytes

*Jan 15 07:26:46.734:     peak rate   =0 bytes/sec

*Jan 15 07:26:46.734:     min unit=0 bytes, max pkt size=2147483647 bytes

*Jan 15 07:26:46.734:  ADSPEC               type 2 length 48:

*Jan 15 07:26:46.734:  version=0  length in words=10

*Jan 15 07:26:46.734:  General Parameters  break bit=0  service length=8

*Jan 15 07:26:46.734:                                         IS Hops:0

It seems that the latest images have that enhancement .




Hi Saurabh,

Thanks for your reply.

Nice to know that it is fixed in latest image.

Regards # mahesh

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