nanog mailing list archives
Re: Great Suggestion for the DNS problem...?
From: Laird Popkin <laird () pando com>
Date: Tue, 29 Jul 2008 12:25:32 -0400
We mainly use UDP for tracker announces, and only use TCP when we have to, and can confirm that the server spends far more time on the TCP setup/teardown than on computing the tracker response.
- LP On Jul 29, 2008, at 12:21 PM, Mikael Abrahamsson wrote:
On Tue, 29 Jul 2008, Steven M. Bellovin wrote:In this situation, UDP uses one query packet and one reply. TCP uses 3 to set up the connection, a query, a reply, and three to tear down theconnection. *Plus* the name server will have to keep state for every client, plus TIMEWAIT state, etc. (Exercise left to TCP geek readers: how few packets can you do this in? For example -- send thequery with the SYN+ACK, send client FIN with the query, send server FINwith the answer? Bonus points for not leaving the server's side in TIMEWAIT. Exercise for implementers: how sane can your stack be if you're going to support that?)The bittorrent tracker guys seem to run into problems at around 30kk tracker requests per second (TCP), and they say it's mostly setup/ teardown (sy usage in vmstat), the tracker hash lookup doesn't take that much.They're trying to move to UDP, currently their workload is approx 5% UDP.I guess TCP DNS workload would be similar in characteristics. -- Mikael Abrahamsson email: swmike () swm pp se
Current thread:
- Re: Great Suggestion for the DNS problem...?, (continued)
- Re: Great Suggestion for the DNS problem...? Colin Alston (Jul 28)
- RE: Great Suggestion for the DNS problem...? Tomas L. Byrnes (Jul 28)
- Re: Great Suggestion for the DNS problem...? Jay R. Ashworth (Jul 28)
- Re: Great Suggestion for the DNS problem...? Colin Alston (Jul 28)
- Re: Great Suggestion for the DNS problem...? Tony Finch (Jul 29)
- Re: Great Suggestion for the DNS problem...? Colin Alston (Jul 29)
- Re: Great Suggestion for the DNS problem...? Laurence F. Sheldon, Jr. (Jul 29)
- Re: Great Suggestion for the DNS problem...? Steven M. Bellovin (Jul 29)
- Re: Great Suggestion for the DNS problem...? Mohacsi Janos (Jul 29)
- Re: Great Suggestion for the DNS problem...? Mikael Abrahamsson (Jul 29)
- Re: Great Suggestion for the DNS problem...? Laird Popkin (Jul 29)
- RE: Great Suggestion for the DNS problem...? Tomas L. Byrnes (Jul 28)
- Re: Great Suggestion for the DNS problem...? Colin Alston (Jul 28)
- Re: Great Suggestion for the DNS problem...? Michael Smith (Jul 28)
- Re: Great Suggestion for the DNS problem...? Matt F (Jul 28)
- Re: Great Suggestion for the DNS problem...? Randy Bush (Jul 29)
- Re: Great Suggestion for the DNS problem...? Florian Weimer (Jul 29)