[j-nsp] Fwd: Quick way to Shift MPLS traffic away from an interface

[Adam Vitkovsky]

Hello Tim,

> tim tiriche
> Sent: 21 May 2015 04:02
> 
> Hello,
> 
> What is the quick way to shift LSP traffic from an interface after
> increasing the igp metric?
>
If you have configured loose EROs (hops) in your LSPs and you have also used "optimize-timer" (as unfortunately Juniper does not have a reoptimize timer enabled by default) the LSPs should reoptimize automatically after a period of time configured.

 
> question:
> 
> - What command can I use to find all lsp traversing the iface and a good
> way to clear them? I am assuming I would need to run clear mpls
> optimize-aggressive on the lsp's on that particular router only? Is my
> understanding correct?
> 
I think you can use "show mpls lsp" to list the active RSVP LSPs traversing the box.

But how to trigger LSP reoptimization from a mid-point router that is a good question indeed.
Since the LSPs are signalled from the head-end router they can be rerouted only by the head-end router.
Saying that you have to force the mid-point router to send a RSVP PathErr msg towards the head-end router, 
the head-end router should then perform the LSP reoptimization 
As Ivan proposed breaking the RSVP session is the obvious choice 
-but preferably you'd want to do the reoptimization in a make before break fashion (though if you don't have the LSPs configured as adaptive it doesn't matter)
-anyways I really don't know if it's possible to trigger reoptimization from a mid-point router when you are not using BW reservations.
 


> - Is it a good idea to turn on optimize-aggressive?
If you are using RSVP LSPs just for pure MPLS forwarding and not for BW reservations or you're not using SRLGs then you can reduce the CSPF to just comparing IGP metric.
 
> 
> Any best practices or pointers would be appreciated!
I think that good practice would be "optimize-timer" so that paths are optimized automatically (e.g. once a day) and to use adaptive LSPs to enable make before break.


addam
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