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Re: [tsvwg] Alternative version of the UDP FRAG option

Gorry Fairhurst <gorry@erg.abdn.ac.uk> Wed, 20 March 2019 15:09 UTC

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Date: Wed, 20 Mar 2019 15:09:29 +0000
From: Gorry Fairhurst <gorry@erg.abdn.ac.uk>
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To: Joe Touch <touch@strayalpha.com>
CC: Tom Herbert <tom@herbertland.com>, tsvwg <tsvwg@ietf.org>
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Subject: Re: [tsvwg] Alternative version of the UDP FRAG option
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On 20/03/2019, 14:58, Joe Touch wrote:
>
>> On Mar 20, 2019, at 7:34 AM, Tom Herbert<tom@herbertland.com>  wrote:
>>
>> On Wed, Mar 20, 2019 at 3:25 PM Joe Touch<touch@strayalpha.com>  wrote:
>>>
>>>
>>> On Mar 19, 2019, at 1:37 PM, Tom Herbert<tom@herbertland.com>  wrote:
>>>
>>> Gorry,
>>>
>>> Suppose we create a compression option whereby UDP payload is compressed and decompressed at the receiver.
>>>
>>>
>>> See the rules in Section 7 - which are there specifically to avoid this sort of tangle.
>>>
>>  From section 7:
>>
>>>> At the sender, new options MUST NOT modify UDP packet content
>>    anywhere except within their option field; areas that need to remain
>>    unmodified include the IP header, IP options, the UDP body, the UDP
>>    option area (i.e., other options), and the post-option area.
>>
>> So that would seem to mean we'll never be able to add any interesting
>> options like the payload compression I described.
> Yes, but for a very specific reason.
>
> If you do, you then have to decide on what content every other option would operate - pre-compression or post. I suspect you’d say pre, but if more than one option does that, you’re dead.
>
> Joe
I'm not so sure we can "never" do this - but I agree we should choose 
not to do this now. UDP-Options already provides lots of functions. I'm 
very keen on getting some things well defined and implemented and then 
thinking - rather than just trying to design for every possibility.

Gorry

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