Re: [Isis-wg] Conflicting MS entries

"Aissaoui, Mustapha (Mustapha)" <mustapha.aissaoui@alcatel-lucent.com> Fri, 19 June 2015 18:18 UTC

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From: "Aissaoui, Mustapha (Mustapha)" <mustapha.aissaoui@alcatel-lucent.com>
To: "stephane.litkowski@orange.com" <stephane.litkowski@orange.com>, "DECRAENE Bruno IMT/OLN" <bruno.decraene@orange.com>
Thread-Topic: Conflicting MS entries
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Date: Fri, 19 Jun 2015 18:18:40 +0000
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Cc: "spring@ietf.org" <spring@ietf.org>, "isis-wg@ietf.org list" <isis-wg@ietf.org>, "Stefano Previdi \(sprevidi\)" <sprevidi@cisco.com>
Subject: Re: [Isis-wg] Conflicting MS entries
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Hi Stephane and Bruno,
I do not think programming multiple SIDs makes sense. While there are multiple MS prefix sub-TLVs, there is only single active route for the prefix with potentially ECMP next-hops which was resolved from a received IP reachability TLV.

I agree that selecting one of the entries is preferable to dropping traffic. We could come up with selection criteria but the reality is that there no way for the router to check if any of the MS entries is legitimate or not. As a result, I would think that once an entry is selected based on the criteria and programmed, we should not be changing it unless the MS entry is withdrawn.

Mustapha.

> -----Original Message-----
> From: spring [mailto:spring-bounces@ietf.org] On Behalf Of
> stephane.litkowski@orange.com
> Sent: Friday, June 19, 2015 5:17 AM
> To: DECRAENE Bruno IMT/OLN; Stefano Previdi (sprevidi)
> Cc: spring@ietf.org; isis-wg@ietf.org list
> Subject: Re: [spring] Conflicting MS entries
> 
> Even if choosing any IP to MPLS entry does not break anything, I'm not sure this is
> a good idea from an operational point of view to let it undeterministic.
> 
> 
> -----Original Message-----
> From: spring [mailto:spring-bounces@ietf.org] On Behalf Of
> bruno.decraene@orange.com
> Sent: Thursday, June 18, 2015 09:29
> To: LITKOWSKI Stephane SCE/IBNF; Stefano Previdi (sprevidi)
> Cc: spring@ietf.org; isis-wg@ietf.org list
> Subject: Re: [spring] Conflicting MS entries
> 
> Hi St├ęphane,
> 
> > From: stephane.litkowski@orange.com> Sent: Thursday, June 18, 2015
> > 9:23 AM
> >
> > Hi Bruno,
> >
> > "	 1) I don't really the issue. From a forwarding standpoint, looks like
> > we can simply program multiple SIDs in the FIB."
> >
> > [SLI] What about the IP to MPLS entry ?
> 
> [Bruno] If transit LSRs install all SIDs, an ingress may use any SID, no? Local
> decision.
> 
> Bruno
> 
> 
> 
> ____________________________________________________________________