Re: Thousands of interfaces

[Michael Tokarev <mjt@tls.msk.ru>]

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