On Tue, May 5, 2015 at 11:26 AM, Joe Touch <to...@isi.edu> wrote: > > > 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. > It is correct as we defined it-- this is a solution to support direct encapsulation of only IPv4 and IPv6. This optimizes encapsulation those two IP protocols, and does not effect encapsulation of other protocols (including new versions of IP) using the GUE and header and protocol field. Whether this optimization is worth it is a fair question, but if this obviates the need for a separate port number in UDP-IP maybe it would be.
> 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. > We're not proposing that at all. > 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
