Hi Eric,
I believe that this draft should be withdrawn. Initially, the draft had the
following goals:
1.
To correct an oversight in RFC 4884.
2.
To rescue the ICMP Extended Echo Request/Reply from misuse.
While the first goal is laudable, it isn't worth the effort. Generally
speaking, a variable length data structure should include a length attribute.
If it doesn't, its length must be inferred. While various techniques allow us
to infer length, each technique introduces its unique drawbacks.
As Ketan points out, the second goal is not attainable. Currently, ICMP
implementations infer extension structure length by subtracting the extension
structure offset from the total length of the ICMP message. This works, so long
as the extension structure is the last item in the ICMP message.
Some years ago, RFC 8335 implementations added information to the ICMP Extended
Echo Request/Reply messages. Rather than encoding this information in the
extension structure, they encoded it after the extension structure. So, in the
Extended Echo Request/Reply messages, we can no longer infer the extension
structure length using the old technique. We must assume that in ICMP Extended
Echo Request/Reply messages, the extension structure contains exactly one
object. So, its length can be calculated by adding the extension header length
to the length of the one and only object.
We would not have had this problem if the Extended Echo Request/Reply had a
length attribute on day one. However, it's too late to rescue the ICMP Extended
Echo Request/Reply messages by adding one. The only way to maintain backwards
compatibility with legacy PROBE implementations is to limit the number of
objects that the extension structure can carry in the Extended Echo
Request/Reply.
Ron
Juniper Business Use Only
________________________________
From: Eric Vyncke (evyncke) <[email protected]>
Sent: Friday, October 17, 2025 4:48 AM
To: [email protected] <[email protected]>
Cc: Ron Bonica <[email protected]>; [email protected]
<[email protected]>; xiao.min2 <[email protected]>; Tal Mizrahi
<[email protected]>; Gorry Fairhurst <[email protected]>; Ketan
Talaulikar <[email protected]>
Subject: Status of draft-ietf-intarea-icmp-exten-hdr-len-02
[External Email. Be cautious of content]
Dear authors, dear intarea WG,
It seems that this I-D has reached a dead-end based on all email discussions
after the IESG evaluation and the blocking DISCUSS ballot by Gorry and Ketan
(in cc).
I sincerely think that this I-D should be removed and not published anymore,
especially in the light of draft-ietf-intarea-rfc8335bis, which is in WG Last
Call.
What do you and the intarea WG think about this removal ?
Regards
-éric (after discussion with the intarea WG chairs)
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