Re: Last Call: 'A Lightweight UDP Transfer Protocol for the the Internet Registry Information Service' to Proposed Standard (draft-ietf-crisp-iris-lwz)

On Wed, 16 Aug 2006, Harald Alvestrand wrote:

> Andrew Newton wrote:
>>> 3 - Why is LWZ limited to UDP, desperately trying to solve
>>>     various size issues with delated XML and other tricks ?
>> 
>> TCP is handled by XPC and BEEP.  But for very short and quick answers (and 
>> lots of them, such as domain availability checks) UDP is better.  Don't 
>> know what you mean by tricks, but the deflation is optional.
> my congestion control alarm went off.
>
> after reviewing the document, it's still ringing.
>
> There's nothing in the document that says "if you want to send 4000 requests, 
> and 70 out of the first 100 get lost, you should slow down your sending rate 
> to that server".
>
> The word "retransmit" does not occur in the document.
> The word "packet loss" does not occur in the document.
> The word "congestion" does not occur in the document.

Session control is why we have TCP.

Tell us where 'retransmit', 'packet loss' and 'congestion' appear in DNS,
DHCP or some other UDP-based protocol documents and I'm sure author of
this spec will be happy to put something similar in his document.

> 4000-byte UDP packets will have 3x the drop rate of 1500-byte UDP packets.

This is general UDP issue specifically due to currently deployed 
network equipment. It need not be mentioned in every UDP-based
protocol spec especially since its operations issue.

> So  retransmissions are more likely than with DNS over the same wire.
> I can't envision an implementation of this that wouldn't retransmit.
> So guidance is needed.
>
> Using UDP is fine, but I regard this specification as incomplete.
>
>                      Harald

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