Hi Joel, One small clarification.
Knowledge of the SRv6 SID block (either by configuration or using the new SRv6 block specified in draft-ietf-6man-sids as a default) is sufficient for an “observer node” to identify SRv6 traffic and potentially skip verifying the checksum. An SRv6 and C-SID aware “observer node” is indeed likely to require additional information to determine the ultimate destination address of such traffic, although how it will obtain that information may depend on its implementation. Thanks, Francois On 9 Apr 2024 at 00:34:43, Joel Halpern <j...@joelhalpern.com> wrote: > Note as an observer of this discussion: > > If we consider that the need for configuration of observer nodes is an > issue, I am pretty sure we need to remember that it is not just the SID > block that needs to be known. The compressed SID length and flavor also > need to be known. > > Yours, > > Joel > On 4/8/2024 2:36 PM, Robert Raszuk wrote: > > Hi Ketan, > > >> a) SR Source Node: the node originating the packet - it may have an SRH >> or may skip it (section 4.1) >> b) Transit Node: node doing IPv6 forwarding >> c) (Ultimate) Destination Node (from RFC8200): the final node to which >> the packet is destined >> > > All you said seems true valid, but the above three node categories do miss > a fourth one - randomly plugged sniffer, or any other way to selectively > capture subset of packets for troubleshooting. > > I do think this is a bit of an obstacle to require that before such an > analyzer is connected to process live or offline traffic captures it needs > to be configured with given's network's SRv6 dedicated locator(s) and/or > SID blocks. > > We clearly do not have such a requirement today for any other > transport protocol. > > Maybe this is a good topic for SRv6OPS WG ? I said maybe as there clearly > seems to be a group of folks who say do not care about SRv6 or CSIDs and > would like to continue using same operational tools for troubleshooting > bare IPv6 protocol. Well in the network where both are running in parallel > lacking a clear demux flag seems to make it a bit of a challenge ... > especially if any endpoints talking native SRv6 with uSIDs would also talk > native IPv6. > > Can you kindly share your perspective on this ? > > Cheers, > Robert > > > >> The CSID document in section 6.5 does not change or update the text in >> RFC8200 sec 8.1. It is simply stating what the "final destination" is going >> to be when CSID is used because RFC8200 does not talk about RHs in sec 8.1. >> RFC8754 covered this aspect by specifying that the last segment is the >> "final destination" but this needs to be specified when using C-SID (with >> or without SRH) and for all C-SID flavors/behaviors. >> >> I find the current text in section 6.5 to be necessary and sufficient for >> implementations that claim (or need to) support SR Source Node behavior for >> C-SIDs. >> >> The CSID document does not change any behavior at the Transit Node or for >> the (Ultimate) Destination Node. Therefore, the discussion of Transit Nodes >> is outside the scope of this document - just as it was outside the scope >> for RFC8754. >> >> Now, if some "Special Transit Node" wants to go beyond RFC8200 and do >> things like upper layer checksum validation enroute then they can refer to >> the same text in section 6.5 to first understand CSID processing and to do >> what is necessary for their packet processing enroute. This requires such >> "Special Transit Nodes" to be aware of first SRv6 and now C-SID - this is >> the same for any new packet encoding technology. >> >> It seems like we are putting the cart before the horse when raising >> concerns about existing implementations that are not SRv6 and C-SID aware >> of not being able to do their processing. Let us publish the C-SID document >> so implementers of those "Special Transit Nodes" (also being referred to as >> middleboxes on some threads) have a reference to upgrade for C-SID support. >> >> Finally, I’ve not heard of issues related to these "Special Transit >> Nodes" from operators that have deployed SRv6. That may be a good >> discussion to have (again outside the scope of this document and perhaps in >> srv6ops?) - so operators who have SRv6 deployment experience can share >> their learnings and best practices. >> >> Thanks, >> Ketan >> >> >> On Thu, Mar 28, 2024 at 5:34 PM Alvaro Retana <aretana.i...@gmail.com> >> wrote: >> >>> Section 6.5 of draft-ietf-spring-srv6-srh-compression describes the >>> behavior when an originating node inside an SRv6 domain creates a >>> packet with a C-SID as the final destination. This description differs >>> from the text in Section 8.1 of RFC8200. >>> >>> We plan to send the draft to the 6man WG for review and explicitly >>> highlight this difference. >>> >>> Please comment on the text in Section 6.5. Does anything need to be >>> added, deleted, changed, or clarified? >>> >>> We want to ask for feedback soon; please send comments on this topic >>> by April 5th. >>> >>> Thanks! >>> >>> Alvaro. >>> -- for spring-chairs >>> >>> _______________________________________________ >>> 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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