Hi Lucy, > -----Original Message----- > From: Lucy yong [mailto:[email protected]] > Sent: Tuesday, April 28, 2015 2:51 PM > To: Joe Touch; Templin, Fred L; Tom Herbert > Cc: [email protected] > Subject: RE: [Int-area] Why combine IP-in-UDP with GUE? > > Joe and Fred, > > If a packet/payload is IP protocol, it is fine to check the first nibble of > it to determine IPv4 or IPv6. > > But we don't adopt this encoding into another protocol and identify IP (v4 or > v6) from it, i.e., the compression mechanism.
Then, you miss the opportunity to have the best of both worlds in a single packaging. Call it GUE or something else, but there is no reason to split it into two docs and miss out on a useful header compression. Thanks - Fred [email protected] > Lucy > > -----Original Message----- > From: Joe Touch [mailto:[email protected]] > Sent: Tuesday, April 28, 2015 3:14 PM > To: Lucy yong; Templin, Fred L; Tom Herbert > Cc: [email protected] > Subject: Re: [Int-area] Why combine IP-in-UDP with GUE? > > > >> [Lucy] since GUE aims to encapsulation for a payload, it needs a > > payload field. > > If GUE encapsulates only IPv4 and IPv6, it would need no payload type field. > > If GUE encapsulates other payloads as well as IPv4 and IPv6, then it needs a > payload type field. However, one type should be "IP". > > There is no reason for having the GUE header differentiate between > payload=IPv4 and payload=IPv6. The IP version is addressed by the version > field of the IP header. If GUE encapsulates both type of IP > the same way (and it should), it should NOT differentiate between them in its > (GUE) header. > > > You suggest that making exception for IPv4 and IPv6, i.e. > > using first nibble to determine. I am not sure when the first nibble > > indicate IPv4, does it mean Fred's compression case or GUE header with > > IPv4 payload. > > In this case, you would want a way to differentiate between the following UDP > payloads: > > - IP payload (IPv4 or IPv6) > - compressed IPv4 or IPv6 payload > - GUE payload > which could have IPv4 or IPv6 inside > > If these are the first thing after the UDP header, then the UDP header is the > only way to differentiate - that's what we use destination > transport port numbers for. > > However, once you say "it's IP", then the IP payload - whether inside UDP > directly (IP-in-UDP), inside GUE inside UDP, or inside a > compression header inside UDP, then the IP payload ought to indicate what > type of IP it is. > > The point is simple: > > IP is a protocol that has versions > > We should treat it as such, not treat every individual version of IP as a > separate encapsulation. > > Joe > > > > > > Lucy > > > > Joe > > _______________________________________________ Int-area mailing list [email protected] https://www.ietf.org/mailman/listinfo/int-area
