Re: Protecting SR policy midpoints (draft-bashandy-rtgwg-segment-routing-ti-lfa)

I do not understand the question

Ahmed

On 11/23/2017 5:15 AM, Huzhibo wrote:
>
> Because the normal FRR can not protect the designated node of SR-TE, a 
> method is provided to perform the label POP action by the penultimate 
> hop of the specified node replacing the specified node and forward it 
> to the node corresponding to the next label. However, Here are some 
> questions we can discuss, if it is a loose path, SR-TE designated node 
> failure, the packet can not be forwarded to the penultimate hop of the 
> specified node.
>
> *? ??:*rtgwg [mailto:rtgwg-bounces@ietf.org] *? ? *Muthu Arul Mozhi 
> Perumal
> *? ???:*2017?11?23?21:04
> *???:*sasha@axerra.com
> *??:*rtgwg@ietf.org
> *??:*Re: Protecting SR policy midpoints 
> (draft-bashandy-rtgwg-segment-routing-ti-lfa)
>
> My understanding is that draft wants to provide a solution for the 
> problem where the active segment is a prefix/adjacency segment of the 
> neighbor and the neighbor fails. A solution to this is possible only 
> at a node that is enforcing the SR policy (consisting of the segment 
> list). For a transit node, its data plane would have to peek into the 
> label stack and determine the type of the segment/label following the 
> active segment and act accordingly, which is not inline with the SR 
> architecture which requires SR to work 'as is' on traditional MPLS 
> data plane
>
> Muthu
>
> On Wed, Nov 22, 2017 at 8:22 PM, Alexander Vainshtein 
> <vinesasha@yahoo.com <mailto:vinesasha@yahoo.com>> wrote:
>
>     Muthu and all,
>
>     I do not see how the draft in quesrion us related to "SR Policy".
>
>     From my POV its scope is a SR LSP comprised of multiple Node SIDs
>     within a single IGP domain, and it provides local fast protection
>     against failure of a node that terminates one of the segments
>     comprising this LSP. Pritection action is performed by the
>     penultimate node.
>
>     My 2c.
>
>     Sent from Yahoo Mail on Android
>     <https://overview.mail.yahoo.com/mobile/?.src=Android>
>
>         On Wed, Nov 22, 2017 at 3:27, Muthu Arul Mozhi Perumal
>
>         <muthu.arul@gmail.com <mailto:muthu.arul@gmail.com>> wrote:
>
>         Section 5.3 of draft-bashandy-rtgwg-segment-routing-ti-lfa
>         describes protecting SR policy midpoints against node failure
>         for the case where the active segment is the prefix or
>         adjacency segment of a neighbor.
>
>         I believe the steps described in the procedure is applicable
>         only for a node steering packets into the SR policy. This
>         could be an ingress PE steering IP packets into a SR-TE tunnel
>         or an intermediate node steering labeled packets received with
>         a BSID into a SR-TE tunnel identified by that BSID.
>
>         A transit node that has no idea about the SR policy itself is
>         not expected to perform the procedure described in that section.
>
>         Is my understanding correct?
>
>         Regards,
>
>         Muthu
>
>         _______________________________________________
>         rtgwg mailing list
>         rtgwg@ietf.org <mailto:rtgwg@ietf.org>
>         https://www.ietf.org/mailman/listinfo/rtgwg
>
>
>
> _______________________________________________
> rtgwg mailing list
> rtgwg@ietf.org
> https://www.ietf.org/mailman/listinfo/rtgwg