Performance/lockup issues with FreeBSD as a router

[Peter Kieser]

Hello guys,

I'm not quite sure if this is the right list to address this to, as it's partly
a performance problem and partly otherwise.

I have a FreeBSD machine acting as a router (doing approx. 15-25Mbit/s of
traffic (lot's of small packets, about 45,000 pps)), however I'm currently
running into issues where one, or both of the NICs will stop transmitting
traffic. When I go onto the machine, and try to ping something I get "No buffer
space available"

The nics are if_dc, this is a stock FreeBSD 5.4-RELEASE installation (no
firewall or anything):

Here's my /etc/sysctl.conf:

net.inet.ip.rtexpire=1800
net.inet.ip.rtminexpire=1800
kern.maxfiles=32768
kern.maxfilesperproc=32768
kern.ipc.somaxconn=32767
net.inet.tcp.sendspace=256000
net.inet.tcp.recvspace=256000
kern.ipc.maxsockbuf=2097152
net.inet.ip.fastforwarding=1
net.inet.tcp.rfc1323=1
net.link.ether.inet.max_age=600
net.inet.tcp.msl=7500
net.inet.ip.fw.dyn_udp_lifetime=10
net.inet.ip.fw.dyn_buckets=1024

And here's my /boot/loader.conf:

kern.ipc.maxsockets="163840"
kern.maxusers="2048"

Is there anythign I'm overlooking that would be causing the machine to lockup
like this?

--Peter