Subject: Flow label/QoS clarification

From: Nathan Lutchansky <[email-masked]>
Date: Mon, 14 May 2001 20:20:57 -0400 (EDT)

Hello everyone,

I'm in the process of updating my IPv6 Primer, per the recommendations of
the helpful people who sent me comments back in February, and I'm having
some trouble finding basic information about QoS in IPv6.

My understanding so far is that IPv6 has this opaque flow-label field in
packet headers that should be used to implement QoS, but so far there has
been no consensus as to how it should be used effectively.  Appendix A of
RFC 2460 states that sensitive flows should be allocated a flow label in a
pseudorandom and uniform fashion, but beyond that, no information is given
on how labelling could provide varying levels of service.

I gather that the original intent of this field is to allow protocols like
RSVP to distinguish between flows easily, to enable clients to reserve
levels of service without having to use IPv4 tricks of looking into the
transport and session headers.  There are several expired drafts
(draft-schmid-rsvp-fl-01, draft-berson-rsvp-ipv6-fl-00) that attempt to
specify RSVP filters based on the flow label field, but they all seem to
have expired.

There was some discussion at the March meeting (which I wasn't able to
attend) about use of the flow label, but it seems from the minutes that no
conclusions were reached, and no real progress was made.

Am I missing something, or do I have an accurate idea of where QoS in IPv6
is at right now?  Unless somebody corrects me, the discussion of QoS in my
primer will essentially be a paraphrasing of this email.  -Nathan

-- 
+-------------------+---------------------+------------------------+
| Nathan Lutchansky | [email-masked] |  Lithium Technologies  |
+------------------------------------------------------------------+
|  I dread success.  To have succeeded is to have finished one's   |
|  business on earth...  I like a state of continual becoming,     |
|  with a goal in front and not behind. - George Bernard Shaw      |
+------------------------------------------------------------------+

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