This is the review for this draft and replaces the one I incorrectly submitted a few days ago. I have submitted a third party IPR disclosure relative to this draft, there is clearly an overlap with the IPR disclosed against RFC5715, and SR. There may of course now be other IPR. Subject to resolving the above, we should adopt the draft since SR can clearly be used to provide two stage loop-free convergence. ====== This document provides a mechanism leveraging Segment Routing to ensure loop-freeness during the IGP reconvergence process following a link-state change event. SB> Whilst technically that is a completely correct statement many readers SB> will interpret that statement as the provision of link protection SB> when you provide this service for link and node failure and SB> presumable for metric change. We use Figure 1 to illustrate the mechanism. In this scenario, all the IGP link metrics are 1, excepted R3-R4 whose metric is 100. We consider the traffic from S to D. SB> There needs to be a note of the symmetry properties of the links. ========= Stage 2: After C elapses, R installs the normal post-convergence FIB entry for D, i.e. without any additional segments inserted that ensure the loop-free property. SB> The timers can usefully be advertised rather than configured SB> (draft-bryant-rtgwg-param-sync) ========== 5. Security Considerations The behavior described in this document is internal functionality to a router that result in the ability to explicitly steer traffic over the post convergence path after a remote topology change in a manner that guarantees loop freeness. As such no additional security risk is introduced by using the mechanisms proposed in this document. SB> I don't think that there are zero increased risks. For example SB> the extended convergence delay and the presence SB> of routers without this feature magnifies the impact SB> of a link flap attack