FCC1 failing on large packet PINGS, while FCC2 is successful

Scott Wood scottwood at freescale.com
Tue Sep 30 00:43:13 EST 2008

embedded wrote:
> We've found a way to get ping to fail all of the time by increasing
> the size of the ping messages.  When we use the max in Windows of
> 65500, every ping to the first FCC1 Ethernet is dropped.  However,
> when we ping with a size of 65500 to the second FCC2 Ethernet
> everything is fine and all echos are successful.
> In windows:
> ping -l 64000  -t
> It definitely seems to be a problem with the mpc, but I'm not sure
> where to look.  Board? KErnel? boot loader?  The two Ethernet devices
> should be configured identically, and looking through the kernel code,
> it seems that there aren't any preferred treatment differences.  Could
> the problem be in the bit-banging mdio control, or should I look
> within fs_enet?  We've got this reproducing on all of our boards and
> it could also reside in the board setup...
> Does anyone with experience on the ep8248 and/or mpc8272 family,
> fs_enet-* code have any ideas where I should look next?

It looks very similar to what I was seeing on ep8248 -- the first 
ethernet port would fail when attempting to receive back-to-back 
packets.  I didn't look into it too closely since I thought it was 
probably a board issue (I had only one, and the firmware never generated 
any traffic that resulted in back-to-back receives).

I'd be very interested if you ever figure out what's wrong.


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