Re: [DNSOP] A possible late addition to draft-ietf-dnsop-5966bis

Paul Vixie <> Sun, 08 November 2015 00:39 UTC

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From: Paul Vixie <>
Date: Sat, 07 Nov 2015 16:39:43 -0800
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Cc: Paul Hoffman <>
Subject: Re: [DNSOP] A possible late addition to draft-ietf-dnsop-5966bis
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On Saturday, November 07, 2015 03:55:36 PM Paul Hoffman wrote:
> Greetings. draft-stenberg-httpbis-tcp covers TCP considerations for
> HTTP. During the discussion of draft-ietf-dnsop-5966bis, we often said
> "HTTP servers handle lots of TCP just fine", and this draft describes
> how. Are there things in here that we don't cover that we should?

to the extent that tuning the number of file descriptors and tcp protocol 
control blocks is important, yes. to the extent that kernels who hash their 
tcpcb's vs. using simple linked lists will do better at demuxing, yes. to the 
extent that servers who use kevent will do better than those who use poll or 
select, yes.

however, the basic persistence negotiation in modern http are the same as what 
5966-bis covers, and so would be duplicative here.

if we're seriously willing to reconsider any of that logic, i'd like us to 
address the connection ecosystem with phase changes. that is, a server whose 
connection pool fills beyond some threshold might first advise its client pool 
that the clients should avoid persistence, and give those clients a chance to 
gracefully shut down their connections as a way to indirectly manage the 
server's resources. only when the connection pool gets into its "red zone" 
should the server start initiating connection closes.

i considered this to be a stretch for the current draft and its schedule, and 
so i wasn't going to bring it up. but if we're bringing up other stuff, we 
should talk about this too.

> It's a
> -00, and will probably not be published for real for quite some time,
> but maybe an Informative reference to the draft in
> draft-ietf-dnsop-5966bis would be useful to some readers.

an informative reference sounds best.

P. Vixie