Message-ID: <454799F3.1020609@tls.msk.ru>
Date: Tue, 31 Oct 2006 21:46:11 +0300
From: Michael Tokarev <mjt@tls.msk.ru>
Organization: Telecom Service, JSC
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To: Peter Hicks <peter.hicks@poggs.co.uk>
CC: linux-kernel@vger.kernel.org
Subject: Re: Thousands of interfaces
References: <20061031092550.GA8201@tufnell.london.poggs.net>
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Peter Hicks wrote:
> All,
> 
> I have a dual 3GHz Xeon machine with a 2.4.21 kernel and thousands (15k+) of
> ipip tunnel interfaces.  These are being used to tunnel traffic from remote
> routers, over a private network, and handed off to a third party.
[]
> Is there a userspace program which would handle this application better than
> using interfaces?

Not that it may be suitable for your case because of various reasons (including
but not limited to your use of specific - IPIP - type of tunnels, interoperability
issues), but take a look at the tinc principles -- http://www.tinc-vpn.org/ .  They
use single interface (based on tun driver) and a single select-loop-based userspace
program.  Initially you configure routing to route ALL your peer's traffic to this
interface, and next tincd takes care of {dis,re}appearing peers, shortest pathes,
{un}reachability of certain networks and so on.

I don't know whenever their implementation scales up to 15K+ peers any better than
current in-kernel implementation, but I think it's easier to deal with this stuff
in userspace anyway.  And the principles which are in the base of tinc are very..
interesting and are unique (as far as I know) to it, making this solution ideal for
certain setups.

/mjt
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