AHbis comments

[Black_David@emc.com]

Here are a couple of transport related comments on
draft-ietf-ipsec-rfc2402bis-03.txt .  These have no
effect on the specified processing - they're mostly
about updating the explanation and references.

Section 3.3.3.1.1.1 describes the TOS field in the IP
Header as mutable (that's correct) and says:

       TOS -- This field is excluded because some routers are known to
   change the value of this field, even though the IP specification
   does not consider TOS to be a mutable header field.

That's no longer correct.  The TOS field has now been
replaced by a 6 bit DS field (contains a Diffserv
codepoint) plus a 2 bit ECN field, and both are defined
to be mutable.  RFC 2780 and RFC 3168 should be cited
as the basis for this, and possibly also RFC 2474.  The 
same 6 bit DS + 2 bit ECN structure applies to the IPv6
(Traffic) Class field (section 3.3.3.1.2.1), which
has always been mutable, as the same RFCs specify it.

Thanks,
--David

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David L. Black, Senior Technologist
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