Re: [tsvwg] Comments on recent UDP options work

"C. M. Heard" <> Tue, 19 February 2019 05:45 UTC

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From: "C. M. Heard" <>
Date: Mon, 18 Feb 2019 21:45:33 -0800
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Subject: Re: [tsvwg] Comments on recent UDP options work
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On Sun, Nov 25, 2018 at 12:33 PM C. M. Heard <> wrote:
> The attraction that I see for FRAG as a UDP-Option is that it offers
> incremental deployability in the important case of DNS (and probably in
> some other cases as well). Its use can be negotiated on a
> transaction-by-transaction basis. The negotiation signal from a client
> that supports it (use of a null FRAG option in a request) will be ignored
> by a legacy server. And an upgraded server will not use the option unless
> the client negotiates it. So, upgraded client can talk to a legacy server,
> and a legacy client can talk to an upgraded server, without the
> need to introduce any extra protocol exchanges.

I see that dnsop recently declined to adopt the ATR (Additional Truncated
Response) draft as a fix for paths on which IP fragmentation does not work.
and related messages. The problem remains unsolved. One of the respondents
said "i would prefer to embrace fragmentation and fix it," which would be
ideal if it is possible; but barring that, the best proposal that I have
seen UDP fragmentation along the lines described in the udp-options draft.

Mike Heard