[c-nsp] MPLS TE Fast Re-route

[Yan Filyurin]

When you say backup path for patch-protection, are you talking about path protection?  I've never done path protection, but it is slightly slower than FRR with link or node protection to converge, but  from what I understand it is alternative to FRR that does link and node and the path gets set up in advance, so bandwidth has to be reserved, but then again you don't have to reserve too much bandwidth, as the path is backup and its reservation should not interfere in the rservation of other primary paths. 

As far as MPLS link and node and protection where FRR comes in, same thing happens.  The path gets set up in advance and you can protect multiple links with one backup path in case of link and node protection and if you do MPLS TE mesh groups (of which I only read about and see in the lab) you can have relatively easy configuration, but possibly too much troubleshooting.  So, the path is set up in advance and you can either set this up to protect until the primary tunnel fixes itself through another path, or in some cases when you don't want it happen you can keep it going on the backup path until the primary tunnel fixes itself by another path going back up.  So to answer your question, the path is built, and "show mpls tra fa da" (too lazy to type it up) should show you the info for the backup path.  At least that is how I remember it, os the path is built and ready for failure. 

But I think you know all that anyway.  I've only read about this, but there is a concept of using backup tunnel bandwidth protection where you can say how much bandwidth of all primary tunnels it is protecting can go on it. OPNET if you have access to it (and it is too expensive for most people to use it) is good about calculating just how to best plan for various outages and what happens when various outages in a TE environment happen. 

Yan




________________________________
From: Charlie Greenaway <Charlie.Greenaway at btinet.bt.com>
To: cisco-nsp at puck.nether.net
Sent: Monday, September 14, 2009 7:25:36 PM
Subject: [c-nsp] MPLS TE Fast Re-route

Hi,

I have a question on MPLS TE and Fast Re-Route.

I have a test network and I want to check that the behaviour I am seeing is correct.

When you set-up an backup path for patch-protection, it would seem that RSVP sends signalling messages down the backup path to reserve the bandwidth.  However, it does not seem to build an LSP and assign labels to it until the primary path breaks.  Is this correct?  Has anyone got any advice on using MPLS FRR?

Thanks,

Charlie G



Charlie Greenaway - CCIE#11226 (Security/R&S)

Solutions Architect | BT iNet | 
Email: charlie.greenaway at btinet.bt.com | Web: www.btinet.bt.com 



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