Re: [mpls] ahRE: draft-bashandy-mpls-ldp-bgp-frr-00 motivation

I totally agree with your point as if the P router is not directly connected to the protected PE, the solution doesn't bring any improvement compared to PIC Edge.
The solution as a value for a repairing P connnected to the PE and so detecting the failure immediately.
If the repairing P is remote to the failure, we are no more in a FRR case ... And I think this should be prevented ...

-----Message d'origine-----
De : Jeff Tantsura [mailto:jeff.tantsura@ericsson.com] 
Envoyé : mardi 27 mars 2012 10:44
À : LITKOWSKI Stephane DTF/DERX
Cc : Ilya Varlashkin; IETF MPLS
Objet : Re: [mpls] ahRE: draft-bashandy-mpls-ldp-bgp-frr-00 motivation

Hi,

The switchover AFTER the failure has been detected in both cases is:
Prefix independent - ie no RIB->FIB interactions Sub 100ms for reasonable number of primary/backup pairs

So the real issue here is reliable and fast failure notification!

As for this draft - if the repairing P router is not directly connected to the primary PE it is subject to the same limitations and would initiate switchover on either multihop BFD down or IGP convergence.
Even though it is presumably closer to the failure than ingress PE and could react faster IMHO the complexity introduced is rather significant compared to the gain.

Regards,
Jeff

On Mar 27, 2012, at 10:21 AM, "stephane.litkowski@orange.com" <stephane.litkowski@orange.com> wrote:

> Ilya,
> 
> The best current available mechanism is BGP PIC Edge that relay on IGP convergence to detect that remote PE is no longer reachable : PIC Edge result mainly depends on how fast your IGP is converging (sub sec or more).
> 
> Ahmed solution is an FRR solution so doesn't rely on convergence. As soon as a P router detects that the link to the protected PE fails, it will switch (using pre-programmed backup NHLFE), so there you are in FRR numbers ... 50msec - 100msec depending of implementation ...
> 
> Clearly the solution is today complex, and I hope it could be a bit 
> simplified :)
> 
> Regards,
> 
> Stephane
> 
> 
> -----Message d'origine-----
> De : mpls-bounces@ietf.org [mailto:mpls-bounces@ietf.org] De la part 
> de Ilya Varlashkin Envoyé : mardi 27 mars 2012 10:08 À : IETF MPLS 
> Objet : [mpls] draft-bashandy-mpls-ldp-bgp-frr-00 motivation
> 
> Ahmed, Kamran,
> 
> as first expressed at the mic during MPLS session, I'd like to ask you for a clarification of the motivation behind the draft. You say that this draft will provide faster switch-over/fail-over time compare to anything already existing today. Do you have some numbers for comparison?
> 
> /iLya
> 
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