Date: Thu, 01 Aug 2013 11:59:13 +0800 From: Julian Elischer <julian@freebsd.org> To: freebsd-hackers@freebsd.org Subject: Re: Stacking lots of IP's on a single box - any 'gotchas'? Message-ID: <51F9DD11.1020606@freebsd.org> In-Reply-To: <20130731202722.GA11852@night.db.net> References: <34C668004A0D654205D0516B@Mail-PC.tdx.co.uk> <CAE-mSOJZ4OwpPhjmkJwEOjuHXGjtH5LHLJ%2B92qexjQs6EgPM-g@mail.gmail.com> <20130731202722.GA11852@night.db.net>
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On 8/1/13 4:27 AM, Diane Bruce wrote: > On Wed, Jul 31, 2013 at 11:47:02PM +0400, Sergey Kandaurov wrote: >> On 31 July 2013 13:37, Karl Pielorz <kpielorz_lst@tdx.co.uk> wrote: >>> Hi, >>> >>> We've got a number of boxes we'd like to consolidate - this could mean >>> upward of 1,500 IP's on a single box (9.1 amd64). >>> >>> Last time we did anything like this we hit at issue at around 900 (ntpd >>> 'binds' by default to all available IP's - I think we had a workaround for >>> that). >>> >> This is because select() has a limit on FD_SETSIZE (1024). >> If it tries to select > 1024 fds, bad things could happen. >> Newer ntpd (not in base) has a feature to bind only to the specific >> interface; this was used to run ntpd on boxes with > 1200 IPs on 1 i/face. > I can tell you from experience that FreeBSD has no problems at all selecting > on more than 1024 fds. In fact, this is what I would suggest you do. > Your limit then is going to be the number of anonymous ports on each > IP. Figure 32000 or so to be conservative that's more than what you need. Once again. I ask: Why do you want to do this? if you just want to respond to a small number of ports on multiple addresses there are easier ways to do this with a single socket. > > >>> But is there any hard limit we're likely to encounter putting so many IP's >>> on a single machine? - Are there any limits that would likely need tuning to >>> support that many IP's? >>> >> Unlikely, besides those unrelated things like ntpd+select() et.al. >> >> -- >> wbr, >> pluknet > - Diane
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