Re: RFC3697 [Re: [RRG] FLOWv6: IPv6 Flow Label to control DFZ forwarding]

[Robin Whittle <rw@firstpr.com.au>]

Hi Brian,

Thanks very much for researching this.

Were you or any other RRG people involved in the creation of the
Flow Label?  I see you were a co-author of:

  http://tools.ietf.org/html/rfc3697

You wrote, in part:

> You will find that the bounding semantics of the flow label
> are quite well defined in 3697. The history is that there was
> a very clear consensus in the IPv6 WG that the semantics
> should be defined strictly end to end between hosts; use as
> a routing handle was explicitly set aside.

OK.

> I can't assert that there is no use of the flow label, since
> it has consenting-host semantics. On the other hand, no use cases
> have been documented to RFC level since RFC 3697 came out,
> and I've never seen any statistics or traces indicating
> non-zero flow labels. The flow-aware router people planned
> to use it at one stage, but that is now caught up in ITU-T
> process following on ITU-T Y.2121 (see
> draft-adams-tsvwg-flow-signalling-codepoint-00). I don't
> know for sure if they still plan to use the flow label.

http://tools.ietf.org/html/draft-adams-tsvwg-flow-signalling-codepoint-00
(2008-06-24)

It is high-level discussion of a flow-related control packet,
implicitly one for IPv6. There is no specific mention of the Flow
Label, but I assume they are planning to use it.

Although IPv6 is not widely used, I think it has been extremely well
researched for all manner of networking enhancements.

If the Flow Label has been there from the start, and in 14 years has
yet to find a substantial use, maybe these bits could be renamed and
used for a different purpose with something like FLOWv6, if this
proves to be a markedly better approach to scalable routing than the
alternatives.

With something like FLOWv6, there would be nothing to stop the Flow
Label being used for any purpose in private networks.  However it
would be ugly to do this and not have it work if the packet went
through, or anywhere near, the DFZ.

  - Robin

--
to unsubscribe send a message to rrg-request@psg.com with the
word 'unsubscribe' in a single line as the message text body.
archive: <http://psg.com/lists/rrg/> & ftp://psg.com/pub/lists/rrg