Subject: Re: Flow Label

From: Scott Bradner <[email-masked]>
Date: Thu, 27 Dec 2001 10:02:18 -0500 (EST)

> Nobody said they are. The issue is getting something minimal and
> unambiguous into the IPv6 spec before it's too late. 

if you want "something minimal" why should it imply anyting about QoS?

Tony's words talk about "packets requiring special handling" - I see
no reason to think that any router will ever want to look at a FL
for any QoS related reason  - there may be other reasons that routers
might want to look at FLs or there might be e2e reasons but I think it is
far too early to guess at uses 

if you want "something minimal" this would do:

   The 20-bit Flow Label field in the IPv6 header MAY be set by a
   source to uniquely label sets of packets. Nodes that do not support 
   the Flow Label field MUST set the field to zero when originating a 
   packet, and MUST ignore the field when receiving a packet. All routers 
   MUST pass the field on unchanged when forwarding a packet.

Scott
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From: Margaret Wasserman <[email-masked]>
Date: Thu, 27 Dec 2001 10:28:20 -0500

Are there any IPv6 router implementations that currently 
modify the flow label field in transit?

If not, I could live with the minimal change that Scott
has proposed below (in the nature of a "bug fix" to
RFC 2460).

>    MUST pass the field on unchanged when forwarding a packet.

I also agree that Appendix A should be removed (it is just wrong),
but we should NOT attempt to replace it with something that
is more right, given today's QoS mechanisms.

RFC 2460 shouldn't say anything else on this subject.  All other
information should be handled in separate specifications (and
WGs) including:

         - How flow label values are chosen
         - The meaning of flow label values
         - How flow labels are/aren't interpreted by
                 intermediate routers and/or end-nodes
         - How flow labels can/can't be used to 
                 identify a single flow

Does that work for everyone?

Again, does anyone know of any current implementations that this
would break?

Margaret

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From: "James Kempf" <[email-masked]>
Date: Thu, 27 Dec 2001 09:42:31 -0800

Margaret,

Given there seems to be so much contention around Tony's proposal,
I agree that Scott's minimal definition along with removal
of Appendix A is a viable alternative.

            jak