Subject: RE: [ipfix] STCP as a default transport not

From: "Carter Bullard" <[email-masked]>
Date: Thu, 9 Oct 2003 15:28:51 -0400

You know, I've read RFC 2309 about 10 times now, and nowhere does
it say that you shouldn't use UDP.  I think RFC 3497, section 9
does a good job with congestion control and UDP.  Is the A Mankin
on the author list of 3497 related to Allison Mankin?

Carter

> -----Original Message-----
> From: majordomo listserver
> [mailto:[email-masked]] On Behalf Of Randy Bush
> Sent: Thursday, October 09, 2003 2:15 PM
> To: MEYER,JEFFREY D (HP-Cupertino,ex1)
> Cc: [email-masked]
> Subject: RE: [ipfix] STCP as a default transport not
>
>
> > I'm sorry, perhaps I missed the well reasoned argument against the
> > use of UDP on point to point connections?
> >
> > Could you direct me to that.
>
http://ipfx.doit.wisc.edu/list/ipfix/archive/

and you may want to review RFC 2309, particularly section 4

randy

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---

From: "Carter Bullard" <[email-masked]>
Date: Thu, 9 Oct 2003 15:37:40 -0400

And my recollection on the mailing list, and if anyone is
interested, the brief discussion started on Oct 04, 2001,
was everyone was pretty much amazed that the charter only
mentioned TCP or SCTP, and everyone kept asking why not UDP?
There was no consensus, just simple dictation from above.

Did anyone very really hear an IESG member say that UDP
is verboten?  There have been a number of RFC's out in
2003 that use UDP.  What's the real story here?

Carter

randy

---

From: Nevil Brownlee <[email-masked]>
Date: Fri, 10 Oct 2003 10:52:44 +1300

> 2003 that use UDP.  What's the real story here?

You're right about that date.  The story is that a year or so before
before the IPFIX WG got started the IAB were discussing congestion
management.  That discussion moved to at least one IESG open plenary
(I'm sure I was there, but I can't remember which meeting), and the
consensus from that was that "new standards-track protocols MUST be
congestion-aware."  That was written up and published as RFC 2309,
which is a very good document about congestion management.

The IPFIX charter says IPFIX must "run over IETF approved congestion-aware
transport protocol .." and lists TCP and SCTP as examples.

UDP on its own is not congestion-aware, we spent more time than I care
to remember thrashing that on the mailing list two years ago, let's please
not go down that rat-hole again.

However, as you pointed out, RTP/UDP is OK, because the RTP part of it
provides a limit on a session's data rate.  That's fine for streaming
audio and video, but IPFIX traffic may well be a lot burstier than that,
so I think you need to consider carefully if you're proposing RTP/UDF
as an IPFIX transport protocol.

For the IPFIX WG, the position is that the protocol draft has sections
in it to describe how SCTP and TCP can be used to carry IPFIX, and we're
happy to add sections for any other congestion-aware transport.
We need people to write text for those sections, now!

The WG issue which we opened at the Vienna meeting was "what should we
specify as a *default* transport for IPFIX?"
We need clear, *technical* arguments for each of the likely protocols,
so as to reach WG consensus on this real soon now.

Cheers, Nevil

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From: Randy Bush <[email-masked]>
Date: Sat, 11 Oct 2003 06:49:15 -0700

> specify as a *default* transport for IPFIX?"

i suggest it be phrased as "mandatory to implement," so you can be sure
it is there.

if one knows *for sure* one is in special circumstances, e.g. on a local
wire, one might use optional transports.

but the congestion-friendly transport is mandatory to implement and the
default.

randy

---

From: Stewart Bryant <[email-masked]>
Date: Mon, 13 Oct 2003 08:03:25 +0100

> wire, one might use optional transports.

Some text of the form TTL SHOULD be set to one might help.

Stewart