Stewart I already replied to Sikhi explaining the concept of the SRLG used in this draft and the intent to make it even clearer.
IMO the scope of the draft is very clear from the draft itself as well as the numerous responses during the previous IETF and the mailing list. The issue below is *out of scope* of the draft and hence I have no plans on addressing it. I hope you don't insist on pushing out-of-scope topics down the throat of this draft :) Ahmed From: Stewart Bryant [mailto:[email protected]] Sent: Monday, August 07, 2017 12:48 PM To: Ahmed Bashandy (bashandy); Stewart Bryant; Sikhivahan Gundu; [email protected] Cc: [email protected]; [email protected] Subject: Re: I-D Action: draft-bashandy-rtgwg-segment-routing-ti-lfa-01.txt Your answer did not address the issue below, which is one of a class of issues related to SRLG. - Stewart On 07/08/2017 19:23, Ahmed Bashandy (bashandy) wrote: See my reply to Sikhi Thanks Ahmed On 8/7/2017 2:13 AM, Stewart Bryant wrote: On 07/08/2017 06:45, Sikhivahan Gundu wrote: By "ambiguity", I meant that backup calculation taking SRLG into account is based on speculated topology, whereas computation of post-convergence path, ie, SPF, is based on actual topology. This seems needs reconciling since in TI-LFA the backup is by definition the post-convergence path, with a single path-transition after link-failure as the intended outcome. Do I understand correctly that the draft prefers to relax that expectation for SRLG? Yes, that is a good point, in the event of an incomplete failure of an SRLG, there may not be congruence between the FRR path and the post convergence path. This certainly needs further study. * A--------//---------B | | | * | cost 2 C-------------------D | | | | cost 100 E-------------------F AB + CD in same SRLG TiLFA path is ACEFDB Post convergence path is ACDB In this case I think that the impact is just more SR hops in the repair path than might be needed without the SRLG, but we do need to be sure that there are no pathological cases in topologies that lack the proposed congruence, and as Sikhivahan notes this effect does need to be clarified in the text. - Stewart _______________________________________________ rtgwg mailing list [email protected]<mailto:[email protected]> https://www.ietf.org/mailman/listinfo/rtgwg
_______________________________________________ rtgwg mailing list [email protected] https://www.ietf.org/mailman/listinfo/rtgwg
