On Tue, May 5, 2015 at 11:47 AM, Templin, Fred L <fred.l.temp...@boeing.com> wrote: > Hi Joe, > >> -----Original Message----- >> From: Joe Touch [mailto:to...@isi.edu] >> Sent: Tuesday, May 05, 2015 11:26 AM >> To: Templin, Fred L; Xuxiaohu; Donald Eastlake; tr...@ietf.org >> Cc: nvo3@ietf.org; int-a...@ietf.org; s...@ietf.org >> Subject: Re: [trill] Fwd: Mail regarding draft-ietf-trill-over-ip >> >> >> >> On 5/5/2015 11:04 AM, Templin, Fred L wrote: >> > Hi Joe, >> > >> >> -----Original Message----- >> >> From: Joe Touch [mailto:to...@isi.edu] >> >> Sent: Tuesday, May 05, 2015 10:54 AM >> >> To: Templin, Fred L; Xuxiaohu; Donald Eastlake; tr...@ietf.org >> >> Cc: nvo3@ietf.org; int-a...@ietf.org; s...@ietf.org >> >> Subject: Re: [trill] Fwd: Mail regarding draft-ietf-trill-over-ip >> >> >> >> >> >> >> >> On 5/5/2015 9:39 AM, Templin, Fred L wrote: >> >>> Hi Joe, >> >> .. >> >>>> IP in UDP adds only port numbers and an Internet checksum. >> >>>> >> >>>> That doesn't address fragmentation; if outer fragmentation is assumed, >> >>>> IPv4 needs to be rate-limited to avoid ID collisions and the Internet >> >>>> checksum is insufficient to correct those collisions. >> >>> >> >>> Right - that is why we have GUE. But, when these functions are not >> >>> needed GUE can perform header compression and the result looks >> >>> exactly like IP in UDP. >> >> >> >> That seems impossible. >> > >> > Not impossible - Tom Herbert provided the solution: >> > >> > http://www.ietf.org/mail-archive/web/int-area/current/msg04593.html >> >> That is allocating bits (or bit patterns) from the IP header. >> >> The solution provided - to check for 0x01 - is incorrect. IP can have >> versions that include 0x10 and 0x11. > > The version field in both IPv4 and IPv6 have that bit set to 1. If GUE > then deems that bit to indicate "direct IP encapsulation, then there > is no need for a GUE header of length greater than 0. > > You may say that future IP protocol versions might not have that bit > set in the version field. But, the version bits for IPv4 and IPv6 will > never change (by definition) and we do not see a new IP protocol > version replacing IPv4 or IPv6 on the near-term horizon. > > Even if a new IP protocol version emerged with the "direct IP > encapsulation" bit set to 0, that version can still be accommodated > by GUE. It's just that direct encapsulation cannot be used and a > non-zero-length GUE header is needed. > Or just define a simple version translation as part of encapsulation. So for IPv8:
0x1000->0x0101 on encapsulation 0x0101->0x1000 on decapsualtion > Thanks - Fred > fred.l.temp...@boeing.com > >> The only solution would be to say that if the first three bits were 0, >> then it's not an IP packet - but that would require reassigning 0x0000 >> and 0x0001 for GUE purposes. >> >> Although that's possible, I don't see why we would allocate IP versions >> to GUE message types. >> >> Joe > > _______________________________________________ > trill mailing list > tr...@ietf.org > https://www.ietf.org/mailman/listinfo/trill _______________________________________________ nvo3 mailing list nvo3@ietf.org https://www.ietf.org/mailman/listinfo/nvo3
