Hi Stewart, Many thanks for your comments. Yes, we can add some text about the RX packet counters using the path segment. As RX packet counts for incoming labels are typically supported by most existing implementations, it is a natural choice. Other schemes e.g. using metadata after BOS of MPLS label stack for RX packet count may need new implementation.
Thanks, Rakesh On Wed, Jul 28, 2021 at 12:28 PM Stewart Bryant <stewart.bry...@gmail.com> wrote: > Hi Rakesh > > I can see why you would want to use a label in that application, but using > a label has a cost that should be more thoroughly discussed in the text and > compared to alternatives. > > What I see in the text is a reference to alt-marking, how are you > proposing to provide the alt pair? > > Thanks > > - Stewart > > > > On 28 Jul 2021, at 13:54, Rakesh Gandhi <rgandhi.i...@gmail.com> wrote: > > Hi Stewart, > > The SR-MPLS path segment (MPLS label) is used to count received packets on > a particular path on the egress node. This allows us to measure PM packet > loss on a given path. The (incoming) MPLS label as path segment has an > advantage of using existing implementations for RX packet count. > > Thanks, > Rakesh > > > > > > > > On Thu, Jul 22, 2021 at 10:06 AM Stewart Bryant <stewart.bry...@gmail.com> > wrote: > >> Once you find yourself needing to include path identifiers in an SR >> packet, I begin to wonder whether the segment routing design has gone off >> track. >> >> In MPLS we have the ability in both PCE and RSVP to lay out end to end >> paths in such a way that the forwarding label is the path identifier. If >> you recall the MPLS-TP approach you could deduce everything about the >> packet’s origin and path from the arrival label which was not PHPed. >> >> Assuming there are technical reasons why such a classic approach is not >> possible, I wonder why it is necessary to encode the path identifier within >> label stack itself with all of the constraints that imposes on the size and >> semantics of the identifier. >> >> An alternative approach is to look at the meta/ancillary data work that >> is going on in MPLS and carry the path identifier below the bottom of stack. >> >> At its most basic level this analogous to the approach to constructing a >> Pseudowires, with an outgoing label stack, a control word (which can be an >> extended control word carrying the path information) and then the payload. >> >> Such an approach would allow the packet designer to carry either the >> identity of the path, or the actual set of labels use to construct the >> path, or the reverse path or some combination of these. The latter two >> approaches are more dynamic than the approach proposed in this draft and >> more in keeping with the fundamental design philosophy of SR. >> >> - Stewart >> >> >> On 22 Jul 2021, at 14:02, James Guichard <james.n.guich...@futurewei.com> >> wrote: >> >> Dear WG: >> >> The WGLC for this document will be extended for a further 2 weeks ending >> August 4th 2021 so that feedback can be obtained from the WG. Other than >> the authors there has been little input so please respond on the mailing >> list with any comments etc. >> >> Thanks! >> >> Jim, Joel & Bruno >> >> *From:* James Guichard <james.n.guich...@futurewei.com> >> *Sent:* Wednesday, July 7, 2021 11:49 AM >> *To:* spring@ietf.org >> *Cc:* spring-cha...@ietf.org >> *Subject:* WGLC for >> https://datatracker.ietf.org/doc/draft-ietf-spring-mpls-path-segment/ >> >> Dear WG: >> >> This email starts a 2 week Working Group Last Call for >> draft-ietf-spring-mpls-path-segment [1]. >> >> Please read this document if you haven’t read the most recent version and >> send your comments to the SPRING WG list no later than July 21st 2021. >> >> If you are raising a point which you expect will be specifically debated >> on the mailing list, consider using a specific email/thread for this point. >> >> Lastly, if you are an author or contributor please response to indicate >> whether you know of any undisclosed IPR related to this document. >> >> Thanks! >> >> Jim, Joel & Bruno >> >> [1] https://datatracker.ietf.org/doc/draft-ietf-spring-mpls-path-segment/ >> <https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdatatracker.ietf.org%2Fdoc%2Fdraft-ietf-spring-mpls-path-segment%2F&data=04%7C01%7Cjames.n.guichard%40futurewei.com%7C4336eaaa34f543cc4c9e08d9415ebd06%7C0fee8ff2a3b240189c753a1d5591fedc%7C1%7C0%7C637612697462524718%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=v18Zntmw18jYiIXCNMDa7bYNQMZ90U29GVEkuPh5CjE%3D&reserved=0> >> >> >> >> >> _______________________________________________ >> spring mailing list >> spring@ietf.org >> https://www.ietf.org/mailman/listinfo/spring >> >> >> _______________________________________________ >> spring mailing list >> spring@ietf.org >> https://www.ietf.org/mailman/listinfo/spring >> > >
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