Subject: [Tsvwg] Comment on ECN Tunnel draft

From: [email-masked]
Date: Mon, 17 Nov 2008 16:57:36 -0500

I've read (fairly quickly) the -01 version of the latest ECN
Tunnel draft (draft-ietf-tsvwg-ecn-tunnel-01.txt).  This version
is significantly improved over some earlier versions of the draft
that I've looked at.

I do have a comment:  I would like to see clear specification of
allowed vs. prohibited changes to the ECN field at intermediate
nodes, with rationale explained  for why the prohibited changes
are prohibited.

A useful view of the reason why this draft is needed is that a
number of transitions that were effectively "Don't Care" for the
basic end-to-end ECN functionality have become important for PCN
and similar functionality.  This is a reason why the design
assumptions should be set down, probably as a transition table,
so that what is intended to be allowed vs. prohibited is clear.

Thanks,
--David
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David L. Black, Distinguished Engineer
EMC Corporation, 176 South St., Hopkinton, MA  01748
+1 (508) 293-7953             FAX: +1 (508) 293-7786
[email-masked]        Mobile: +1 (978) 394-7754
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