On 2017-02-18 Brian E Carpenter wrote: > On 18/02/2017 07:00, Stewart Bryant wrote: > > Ole > > > > Are you saying: > > > > A correct implementation of RFC2460 MUST NOT insert an EH at any point > > along the path other than at the packet source. > > > Or > > > > A correct implementation of RFC2460 MAY insert an EH at any point along > > the path. > > Ole doesn't, apparently, want to say either of those things. > > I want to say the first *as part of the promotion to Internet Standard* > because it was the clear and documented intent of the authors and WG > of RFC 1883, which became RFC 2460. (Documented in the ancient email I dug > out a while back.) And it has been assumed by subsequent work such > as PMTUD and IPsec/AH. For the benefit of those who find it inconvenient to dig into the 6man WG email archives, I've pasted the relevant part of that ancient email below. See https://mailarchive.ietf.org/arch/msg/ipv6/poEU0yz7m2qpx3EACsszktrOlpk for the full text of Brian's message. -------- Forwarded Message -------- Subject: (IPng 609) changes to Last Call'ed specs Date: Sun, 27 Aug 1995 20:59:26 PDT From: Steve Deering <deering@xxxxxxxxxxxxxx> To: ipng@xxxxxxxxxxxxxxxxxxx CC: deering@xxxxxxxxxxxxxx At the request of our ADs, I prepared the following list of agreed-upon changes and outstanding issues with the set of specs that underwent IETF-wide Last Call in June and July. Please let me know of any errors or omissions. Steve [ … ] =================================== The following suggestions in Charlie Lynn's formal response to the Last Call were rejected at the Stockholm meeting: - Add a bit to the Routing Header indicating whether or not it was inserted into the packet en-route, i.e., by a node other than the packet's originator. reasons for rejection: insertion of extension headers en-route breaks PMTU-discovery and can result in ICMP error messages being sent to non-guilty parties. The desired effect can be achieved, and those problems avoided, by using en-route encapsulation (with optional Routing Header) rather than header insertion. [ … ]