Joe, > -----Original Message----- > From: Int-area [mailto:[email protected]] On Behalf Of Templin, Fred L > Sent: Tuesday, May 23, 2017 11:49 AM > To: Joe Touch <[email protected]>; [email protected] > Subject: Re: [Int-area] IPv6 fragmentation for IPv4 > > Hi Joe, > > > -----Original Message----- > > From: Joe Touch [mailto:[email protected]] > > Sent: Tuesday, May 23, 2017 11:01 AM > > To: Templin, Fred L <[email protected]>; [email protected] > > Subject: Re: IPv6 fragmentation for IPv4 > > > > Hi, Fred (et al.), > > > > On 5/23/2017 9:17 AM, Templin, Fred L wrote: > > > Joe, I wanted to run an idea by you. We all know that IPv4 fragmentation > > > has > > > problems because of the 16-bit ID field. So, why not insert an IPv6 > > > Fragment > > > Header between the IPv4 header and the upper layer protocol data, then > > > use IPv6-style fragmentation instead of IPv4 fragmentation? > > > > IPv4 fragmentation has several impediments: > > - small ID field > > - lack of a reassembly checksum > > - lack of a fixed-location flow ID > > > > Using IPv6-Frag as the next header solves only the first of these. The > > last is significant - putting a new header would defeat IPv4 flow ECMP > > even for the first fragment. > > ECMP gateways could be updated to look at the ULP headers > following the IPv6 Frag header in the first fragment. > > > IPv6 includes a flow field that serves this > > purpose. > > How does it work for plain-old IPv4 fragmentation? I would think > that ECMP gateways would look at the IP ID and try to associate > the fragments so they all get equal ECMP treatment, i.e., the > same as for vanilla IPv4.
Here's another think - since the IPv6 Frag Header already has a 32-bit IP ID that we are using for fragmentation, and since we are asking the IPv4 header to set DF=1, the 16-bit IP ID field in the IPv4 header is available for use as a flow field - right? Thanks - Fred > Thanks - Fred > [email protected] > > > Joe > > _______________________________________________ > Int-area mailing list > [email protected] > https://www.ietf.org/mailman/listinfo/int-area _______________________________________________ Int-area mailing list [email protected] https://www.ietf.org/mailman/listinfo/int-area
