Hi Shraddha, Many thanks for your comments! Please see my reply inline.
Thanks, Cheng From: Shraddha Hegde [mailto:[email protected]] Sent: Monday, December 7, 2020 5:18 PM To: [email protected] Cc: [email protected] Subject: Comments on draft-li-rtgwg-enhanced-ti-lfa Authors, Few comments below. 1. Abstract TI-LFA backup path computation is always to the destination so it is less likely that a Node that cannot be bypassed gets skipped due to TI-LFA. The node that must be visited might get skipped due to node protection procedures that require Next label lookup. I suggest to update the abstract as below [Cheng] Great! Many thanks! “ Topology Independent Loop-free Alternate Fast Re-route (TI-LFA) aims at providing protection of node and adjacency segments within the Segment Routing (SR) framework. A key aspect of TI-LFA is the FRR path selection approach establishing protection over the expected post-convergence paths from the point of local repair.Node protection procedures for adjacency SIDs and immediate nexthop prefix-sids require the next label lookup bypassing the immediate node. The SIDs in the label stack may represent service instructions which Should not be bypassed. This draft describes a mechanism to advertise SIDs that cannot be bypassed” 2.Introduction “traffic engineer” Change to Traffic Engineering” [Cheng] Ack 3.Overview of Enhanced TI-LFA When the SR-TE path is being built, the node-sids/service sids Used to build the path MUST use SIDs with no-bypass flag set. The TI-LFA repair-list building procedure need not change. It will continue to use SIDs with N bit set. When the SR-Te label stack is built with “no bypass” SIDs, The PLR will drop the traffic and not do any node protection procedure for the The “no-bypass” SIDs [Cheng] Yes， Ack. 4. Do we really need a “no bypass” flag for adj-sids? We have the B flag which can be used [Cheng] Good question. Does the B flag in End.X equal to No-bypass flag? When an End.X SID has a back-up SID, then what is the back-up SID? Another End.X SID originated by the same node? Or another Node SID of the node pointed by the End.X SID? We may need to make this clear. 5. no-bypass flag in SRH It is not clear why this is require. The NB flag in SRV6 SIDs isn’t good enough? Also the NB flag is generally applicable to a specific SID And should not be a global packet level flag. [Cheng] Personally, the NB flag in SID is good enough for me, while a flag in SRH is an optional choice as well, and it is an very easy solution. We may need this, because flag in the SID CAN NOT work if the TI-LFA computation is based on locator/prefix instead of SIDs. Rgds Shraddha Juniper Business Use Only
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