Subject: RE: I-D ACTION:draft-ietf-ipngwg-icmp-v3-01.txt

From: "Mohit Talwar" <[email-masked]>
Date: Wed, 8 Aug 2001 10:02:08 -0700

Hi All,

I believe there is something amiss from the current draft.  To quote
Brian...

[Quote]
Section 2.1 says "The type field indicates the type of the message.  Its
value determines the format of the remaining data".

Section 2.4 point (a) says "If an ICMPv6 error message of unknown type
is received, it MUST be passed to the upper layer".

Section 2.4 point (d) says "In those cases where the internet-layer
protocol is required to pass an ICMPv6 error message to the upper-layer
process, the upper-layer protocol type is extracted from the original
packet (contained in the body of the ICMPv6 error message) and used to
select the appropriate upper-layer process to handle the error.

The problem here is that since the format of the remaining data is type
dependent, and we have an unknown error type, then we don't know how to
find the original packet header in the remaining data section in order
to extract the upper-layer protocol type.  And we need to be able to do
that if we're going to meet the requirements of section 2.4.

It is the case that all defined error types have a 32 bit type-specific
field, so treating all known errors the same way is possible today.
It's the handling of unknown error types that causes the problem.
[\Quote]

Perhaps, if it is not considered too restrictive, we should enforce that
all ICMPv6 error messages consist of the base ICMPv6 header followed by
"32 bits of type-specific data", (followed by as much of the offending
packet as will fit without making the error packet exceed 1280 bytes.

Thanx,
Mohit.

PS Also, there is a typo in sections 2.4, e.4 and 2.4, e.5.  These
should refer to e.3, not e.2.

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] 
Sent: Tuesday, July 24, 2001 3:29 AM
Cc: [email-masked]
Subject: I-D ACTION:draft-ietf-ipngwg-icmp-v3-01.txt

A New Internet-Draft is available from the on-line Internet-Drafts
directories. This draft is a work item of the IPNG Working Group of the
IETF.

	Title		: Internet Control Message Protocol (ICMPv6)for
the 
                          Internet Protocol Version 6 (IPv6)
Specification
	Author(s)	: A. Conta, S. Deering
	Filename	: draft-ietf-ipngwg-icmp-v3-01.txt
	Pages		: 20
	Date		: 23-Jul-01
	
This document specifies a set of Internet Control Message Protocol
(ICMP) messages for use with version 6 of the Internet Protocol (IPv6).

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http://www.ietf.org/internet-drafts/draft-ietf-ipngwg-icmp-v3-01.txt

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From: JINMEI Tatuya / 神明達哉<[email-masked]>
Date: Mon, 13 Aug 2001 05:02:17 +0900

>>>>> On Wed, 8 Aug 2001 10:02:08 -0700, 
>>>>> "Mohit Talwar" <[email-masked]> said:

> packet as will fit without making the error packet exceed 1280 bytes.

I agree.  At least the spec should be more clear about the format of
the unknown error messages.

					JINMEI, Tatuya
					Communication Platform Lab.
					Corporate R&D Center, Toshiba Corp.
					[email-masked]
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