Hi Greg, Just one nit ...
> that reporting on-path telemetry can be done over the management plane Just for clarity I did not mean to report on mgmt plane. Just like MPLS networks were using IP data plane so here SRv6 networks are using IPv6 data plane. So I would actually prefer not to use mgmt plane for reporting OAM but regular data plane. Best, R. On Fri, Feb 9, 2024 at 12:37 AM Greg Mirsky <gregimir...@gmail.com> wrote: > Hi Robert, > thank you for your clarification. I agree with you that reporting on-path > telemetry can be done over the management plane. I don't see any issues > with using C-SID specific to use of a two-way active measurement protocol > like STAMP. > > Regards, > Greg > > On Thu, Feb 8, 2024 at 1:45 PM Robert Raszuk <rob...@raszuk.net> wrote: > >> Greg, >> >> The doubt here is not about test path which truley you are correct to be >> useful MUST follow data plane of real user traffic, but node on the path >> simply reporting the error or reporting the measurements to the collector. >> Hence those packets can be just IPv6 (modulo some VPN where we would need >> to identify such VPN within the payload of the reply). >> >> Do you see any issue with STAMP packets in networks using C-SIDs ? If so >> can you kindly describe it in detail ? >> >> Many thx, >> R. >> >> >> >> >> >> >> >> >> >> On Thu, Feb 8, 2024 at 10:30 PM Greg Mirsky <gregimir...@gmail.com> >> wrote: >> >>> Hi Robert, >>> could you clarify "can be used"? Is it MAY, SHOULD or MUST? >>> If we use an active performance measurement protocol, e.g., STAMP, then >>> it is expected that the path of the reflected STAMP test packet traverses >>> the same set of nodes and links as the original STAMP test packet. Thus, >>> the Session-Reflector must use encapsulation that ensures the path >>> coroutedness for the reflected test packet, e.g., C-SIDs. >>> >>> Regards, >>> Greg >>> >>> On Wed, Feb 7, 2024 at 4:14 AM Robert Raszuk <rob...@raszuk.net> wrote: >>> >>>> Hi, >>>> >>>> Actually for OAM responses in vast majority of cases vanilla IPv6 >>>> packets can be used. >>>> >>>> Kind regards, >>>> R. >>>> >>>> On Wed, Feb 7, 2024, 10:58 Mark Smith <markzzzsm...@gmail.com> wrote: >>>> >>>>> >>>>> >>>>> On Wed, 7 Feb 2024, 20:08 Robert Raszuk, <rob...@raszuk.net> wrote: >>>>> >>>>>> Hi Mark, >>>>>> >>>>>> > however UDP and ICMPv6 would be for OAM per RFC 9269 >>>>>> >>>>>> I do agree if we are talking about no SRH containing packets. >>>>>> >>>>> >>>>> I think it would also occur with an SRH if a middlebox is ignoring the >>>>> SRH EH (e.g. unaware of how to handle it, or ignoring some or all IPv6 >>>>> EHs) >>>>> and validating the pseudo-header checksum when the packet's current DA >>>>> isn't the final one, which of course it may not be if the packet is >>>>> somewhere where in flight between the origin SA and the final DA. >>>>> >>>>> For a middlebox to validate the L4 pseudo header checksum somewhere >>>>> during flight, it would have to determine the final DA for the calculation >>>>> by digging it out of the SRH rather than using the packet's current DA. >>>>> >>>>> Without an SRH the middlebox would have to process the C-SIDs in the >>>>> packet's DA field until it could identify the final DA before then >>>>> performing the L4 pseudo-header calculation and validation. >>>>> >>>>> The would be conditional on the SRv6 payload being TCP, UDP or ICMPv6 >>>>> and the middlebox being SRv6 aware (i.e. understand SRH when present) and >>>>> SR configured to identify C-SID DAs (SRH'less). >>>>> >>>>> So I don't really see how including an SRH in OAM packets solves the >>>>> problem unless the middlebox is SRv6 aware. >>>>> >>>>> And this is precisely why I said "vast majority of packets" not "all >>>>>> packets" >>>>>> >>>>> >>>>>> Glad that you nailed it on the list. >>>>>> >>>>>> Cheers, >>>>>> R. >>>>>> >>>>>> PS. What Ron suggests is too big of a hammer. Instead I see no reason >>>>>> why OAM packets should not contain SRH and resolve the nit that way. >>>>>> >>>>>> >>>>>> >>>>>> On Wed, Feb 7, 2024 at 5:44 AM Mark Smith <markzzzsm...@gmail.com> >>>>>> wrote: >>>>>> >>>>>>> >>>>>>> >>>>>>> On Tue, 6 Feb 2024, 03:17 Robert Raszuk, <rob...@raszuk.net> wrote: >>>>>>> >>>>>>>> Hi Ron, >>>>>>>> >>>>>>>> Is there a problem ? >>>>>>>> >>>>>>>> If I read RFC8200 L4 checksum is computed by the packet *originator >>>>>>>> and validated by the packet's ultimate receiver. * >>>>>>>> >>>>>>>> In all SPRING work to the best of my knowledge the vast majority of >>>>>>>> packets are only encapsulated by transit nodes. >>>>>>>> >>>>>>> >>>>>>> >>>>>>> If the payload of the SRv6 packet is another IP packet or layer 2 >>>>>>> frame e.g. Ethernet, common for L2 and L3 VPNs, then the layer 4 >>>>>>> checksum >>>>>>> issue probably wouldn't occur, because those protocols don't include the >>>>>>> IPv6 pseudo-header fields in their checksum calculations if they even >>>>>>> have >>>>>>> a checksum at all - RFC 2473 IPin IPv6 doesn't, and in GRE it is >>>>>>> optional. >>>>>>> >>>>>>> However, if SRv6 was used to to directly carry an upper layer >>>>>>> transport layer protocol PDU like UDP, TCP or ICMPv6, then that's when >>>>>>> the >>>>>>> checksum/middlebox issue arises, because they do include the IPv6 >>>>>>> pseudo-header in their checksum, which would therefore include the SRv6 >>>>>>> SA >>>>>>> and DAs. >>>>>>> >>>>>>> Not sure if TCP would be commonly carried directly in an SRv6 >>>>>>> packet, however UDP and ICMPv6 would be for OAM per RFC 9269. >>>>>>> >>>>>>> So your SRv6 L2 or L3 VPN might be able to carry customer traffic >>>>>>> successfully through a middle box, however you may not be able to SRv6 >>>>>>> traceroute or ping across it successfully, or have ICMPv6 error >>>>>>> successfully sent between SRv6 nodes. >>>>>>> >>>>>>> Regards, >>>>>>> Mark. >>>>>>> >>>>>>> >>>>>>>> Is there any formal mandate in any of the RFCs that an >>>>>>>> encapsulating node must mangle the inner packet's L4 checksum ? I don't >>>>>>>> think so but stand open to get my understanding corrected. >>>>>>>> >>>>>>>> Cheers, >>>>>>>> Robert >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> On Mon, Feb 5, 2024 at 5:04 PM Ron Bonica <rbonica= >>>>>>>> 40juniper....@dmarc.ietf.org> wrote: >>>>>>>> >>>>>>>>> Folks, >>>>>>>>> >>>>>>>>> Has anyone proposed a solution to the L4 checksum problem that >>>>>>>>> Andrew talks about? >>>>>>>>> >>>>>>>>> Ron >>>>>>>>> >>>>>>>>> Juniper Business Use Only >>>>>>>>> ------------------------------ >>>>>>>>> *From:* spring <spring-boun...@ietf.org> on behalf of Andrew >>>>>>>>> Alston - IETF <andrew-ietf=40liquid.t...@dmarc.ietf.org> >>>>>>>>> *Sent:* Monday, February 5, 2024 5:21 AM >>>>>>>>> *To:* spring@ietf.org <spring@ietf.org> >>>>>>>>> *Subject:* [spring] draft-ietf-spring-srv6-srh-compression >>>>>>>>> >>>>>>>>> >>>>>>>>> [External Email. Be cautious of content] >>>>>>>>> >>>>>>>>> Hi All, >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> (In capacity as a contributor and wearing no other hats) >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> At this point I cannot support progression of this document until >>>>>>>>> the issues around the L4 Checksum have been resolved. It’s been >>>>>>>>> clearly >>>>>>>>> stated in other emails on the list that in certain circumstances the >>>>>>>>> behavior described in this document break the L4 checksum as defined >>>>>>>>> in >>>>>>>>> RFC8200. This requires an update to RFC8200 to fix it – and I’m not >>>>>>>>> sure >>>>>>>>> that spring can update 8200 absent the consent of 6man, which I’m not >>>>>>>>> sure >>>>>>>>> has been asked for, nor am I sure that a spring document can update >>>>>>>>> something like 8200 in an area so fundamental as the checksum without >>>>>>>>> a >>>>>>>>> -BIS, which would have to be done via 6man. The L4 checksum issue >>>>>>>>> though >>>>>>>>> is real – and it cannot simply be ignored. >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> I also have deep concerns that the compression document creates >>>>>>>>> something that (in a similar way to SRv6) creates something that is >>>>>>>>> completely non-conformant with RFC4291. There are multiple >>>>>>>>> references to >>>>>>>>> this in draft-6man-sids, and should draft-6man-sids become an RFC I >>>>>>>>> would >>>>>>>>> argue that it should probably be a normative reference in this >>>>>>>>> document – >>>>>>>>> on the logic that this document relies on similar RFC4291 violations >>>>>>>>> that >>>>>>>>> srv6 itself does (and for the record, just because SRv6 itself >>>>>>>>> violates >>>>>>>>> RFC4291 as is clearly documented in draft-6man-sids – does not make it >>>>>>>>> acceptable to do so in yet another draft without clear and >>>>>>>>> unambiguously >>>>>>>>> stating the deviations and ideally updating RFC4291 to allow for said >>>>>>>>> deviations) >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> I believe these two issues alone are sufficient that to pass this >>>>>>>>> document would create still further tensions about the relationship >>>>>>>>> between >>>>>>>>> SRv6 and IPv6 and lead to confusion. As such – I believe these >>>>>>>>> issues need >>>>>>>>> to be adequately dealt with – and the solutions to them need to be >>>>>>>>> approved >>>>>>>>> by 6man as the working group that holds responsibility for ipv6 >>>>>>>>> maintenance. >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> Thanks >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> Andrew Alston >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> Internal All Employees >>>>>>>>> _______________________________________________ >>>>>>>>> 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 >>>>>>>> >>>>>>> _______________________________________________ >>>> spring mailing list >>>> spring@ietf.org >>>> https://www.ietf.org/mailman/listinfo/spring >>>> >>>
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