Core router bakeoff?

Adam Rothschild writes:

While we're on this topic, what's a good v.35 card for the PC?
Specifically, one that works nicely with FreeBSD?

I'm looking for same to T1/E1 speed. But I need to have it work
as a normal device and not via a specially supplied driver, or
else the driver must be a source patch to the kernel. Linux
would be preferred in my case, since I already know how to work
with it's internals. A channelized T1 over T3 would also be of
interest (same requirements of being able to work the source code
still apply).