Tuning kernel for mpd

[Andrew P.]

I've googled for a few days - and I couldn't get any
clear info on the subj. I've never had to recompile or
tune kernel before, when I only had to deal with 20-
30 PPPoE clients.

Now I need to implement a solution that will support
up to 3000 PPPoE/PPTP clients in the long run, and
I've already got problems when trying to create only
200 ng interfaces.

I'm running latest mpd4 from ports on FreeBSD 6.0
i386 box. Whenever I try to create more than 200
bundles I get this:

Dec 16 16:06:00 gw mpd: [Bhq] ppp node is "mpd99407-Bhq"
Dec 16 16:06:00 gw mpd: [Bhq] using interface ng199
Dec 16 16:06:00 gw mpd: [Bhr] ppp node is "mpd99407-Bhr"
Dec 16 16:06:00 gw mpd: [Bhr] using interface ng200
Dec 16 16:06:00 gw mpd: [Bhs] ppp node is "mpd99407-Bhs"
Dec 16 16:06:00 gw mpd: mpd: pipe: Too many open files in system
Dec 16 16:06:00 gw mpd: mpd: fatal error, exiting

I also sometimes get this under different circumstances:

Dec 13 17:27:04 gw mpd: [bptp1] created 128 interfaces, that's too many!
Dec 13 17:27:04 gw mpd: [bptp1] can't create interface "ng301"
Dec 13 17:27:04 gw mpd: [bptp1] netgraph initialization failed

There are different sysctl tunables in examples
scattered all around mpd-users mailing list - but
there's no description whatsoever. Can someone
share his experience on this?

Thanks,
Andrew P.