Margaret Wasserman wrote: > > I have a few comments/questions on the general flow label topic. > They are not specific to draft-rajahalame-ipv6-flow-label-00.txt, > but they do apply to this proposal, as well as others. > > I've hesitated to raise this issue for fear of being publicly > stoned, but... > > It seems to me that an IPv6-specific location within the IPv6 > header may not be the right place for a flow label. > > I am not an expert in label switching technologies, but the ones > that I do know (VLAN, MPLS) put the label after the link layer > header and before the IP header (conceptually at layer 2-1/2). > This allows the flow label to be located, and used for switching, > without the need to process the layer 3 header at all. This > allows the same label switching technology to work in current > IPv4 and mixed-protocol networks.
Exactly. But that is not the kind of flow label that we have in IPv6. It isn't used for or intended for MPLS style label-swapping. It's different. > > Since we may not have large IPv6-only networks for some time, a > flow label within the IPv6 header seems, to me, fundamentally > less useful than a flow label that can be appended before any > layer 3 header (IPv4, IPv6, ??). But it is a different animal entirely; a separate discussion; not an IPv6 discussion. And isn't it exactly what MPLS has already defined? > > Are there reasons for preferring to put a flow label inside the > IPv6 header? Is this being done on the advice of folks who are > standardizing label switching technologies? > No, because it has nothing to do with label switching. It's much more to do with QOS than routing. We know how to use the draft-rajahalme- label for Intserv and Diffserv, but it may well have other QOS usage as well. It's end2end property is vital for that and completely different from the swappable MPLS-type label. Brian -------------------------------------------------------------------- IETF IPng Working Group Mailing List IPng Home Page: http://playground.sun.com/ipng FTP archive: ftp://playground.sun.com/pub/ipng Direct all administrative requests to [EMAIL PROTECTED] --------------------------------------------------------------------
