Hi authors, This is an interesting work, thanks for the draft and the rtgwg presentation.
1) Regarding node protection, have you considered/evaluated the use of the algorithm proposed in TI-LFA (draft-francois-segment-routing-ti-lfa)? Namely: computing the backup path with a (C)SPF (without the protected node), and enforcing this explicit path using multiple segments/labels? Clearly, using TI-LFA in the absence of Segment Routing (more precisely the absence of adjacency segments/labels), 100% coverage is not possible. But this is also not possible with draft-psarkar. It's a priori not clear to me if the coverage would be increased or decreased. On the pro side, the use of multiple segments increases the coverage by allowing reaching more Q nodes. On the con side, the additional constraints added during the computation (namely enforcing the post convergence path (only)) decreases the coverage as this specific path may require an adjacency segment to cross a high metric link. Evaluating this option would probably be interesting (in term of coverage, control plane computation, label stack depth, routing optimality, number of T-LDP sessions). 2) On a related note, a possible heuristic for draft-psarkar to pick a node protecting PQ, would be to pick the PQ on the post convergence SPF (as per above/TI-LFA). That's simple, computationally not expensive (one SPF), and reduce the set of Candidate Node-Protecting PQ to a single element at most (not considering ECMP, to simply). If the set has one node, a node protecting PQ node has been found (on the optimal path, as a free property). If the set is empty, you may choose to fall back on draft-psarkar (picking a subset of PQ using heuristic and running SPF on those PQ). Thanks, Regards, Bruno From: rtgwg [mailto:[email protected]] On Behalf Of Alvaro Retana (aretana) Sent: Friday, March 14, 2014 6:02 AM To: [email protected] Cc: [email protected] Subject: WG Adoption Call for draft-psarkar-rtgwg-rlfa-node-protection Hi! During the meeting in London the authors asked for the WG to adopt this draft. This message officially starts the call for adoption for draft-psarkar-rtgwg-rlfa-node-protection. Please indicate your position about adopting it by end-of-day on March 28, 2014. http://tools.ietf.org/html/draft-psarkar-rtgwg-rlfa-node-protection Thanks! Alvaro. _________________________________________________________________________________________________________________________ Ce message et ses pieces jointes peuvent contenir des informations confidentielles ou privilegiees et ne doivent donc pas etre diffuses, exploites ou copies sans autorisation. Si vous avez recu ce message par erreur, veuillez le signaler a l'expediteur et le detruire ainsi que les pieces jointes. Les messages electroniques etant susceptibles d'alteration, Orange decline toute responsabilite si ce message a ete altere, deforme ou falsifie. Merci. This message and its attachments may contain confidential or privileged information that may be protected by law; they should not be distributed, used or copied without authorisation. If you have received this email in error, please notify the sender and delete this message and its attachments. As emails may be altered, Orange is not liable for messages that have been modified, changed or falsified. Thank you.
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