This sounds exactly like a problem we (and our customers) have seen
here.  One of our guys coded-up a fix.  I'm attaching it as a diff
against the fec.c that shipped with the 2.4.2_hhl20 kernel (i.e. HardHat
2.0 from MontaVista).  I've included 10 lines of context in either
direction to help you place it in your own fec.c version.

I didn't code this myself, so don't blame me if it causes problems! :-)

John

NBLIST@sbcglobal.net wrote:
>
> Hello all,
>
> I am using the fec on the MPC855T on my custom board.
> I seem to be having some weird ethernet configuration
> problems. My eth0 interface comes up only the first
> time. If I "ifconfig down" the eth0 and bring it back
> up by doing "ifconfig up", the eth0 interface shows up
> fine. But ethernet doesnt work anymore. After a couple
> of minutes, I get "tx buffer full" error messages. But
> it always works the first time I boot the linux kernel
> and bring up etho using ifconfig.
>
> What's going on here? Any ideas, clues, tips????
>
> Thank you,
> NB
>

--
John W. Linville
LVL7 Systems, Inc.