Robert Craig
04/10/2008 6:03 PM
post6653
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Do you happen to know if this was after a high rate burst of packets? One
possibility is that either the tx or rx side ran out of buffers temporarily
with the result being a dropped packet. You can bump up the number of rx /
tx descriptors to get around that problem.
Robert.
-----Original Message-----
From: Mario Charest [mailto:mcharest@zinformatic.com]
Sent: Thursday, April 10, 2008 5:56 PM
To: general-networking
Subject: Re: Lost packet?
>
> We never ack the packet the PLC sends at line 5979 so it
> looks like we didn't get it or didn't like something about
> it (although the trace doesn't seem to say anything is wrong
> with it...). However the PLC should resend it either
> through a timeout or by being poked with our duplicate acks.
>
> -seanb
Wow, thanks Sean I appreciate this, I wasn't expecting an answer that fast
;-)
So it looks like the ACK never got transmitted or the packet 5979 was never
received. Gut feeling tells me the packet 5979 was lost in the driver,
which is why the ACK was not sent in the first place.
I'll see if I can move the PLC to a separate network card and one different
then Intel.
I'm not surprise the PLC doesn't handle this properly ;-(
_______________________________________________
General
http://community.qnx.com/sf/go/post6652
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Sean Boudreau(deleted)
04/11/2008 10:22 AM
post6674
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On Thu, Apr 10, 2008 at 05:56:12PM -0400, Mario Charest wrote:
> >
> > We never ack the packet the PLC sends at line 5979 so it
> > looks like we didn't get it or didn't like something about
> > it (although the trace doesn't seem to say anything is wrong
> > with it...). However the PLC should resend it either
> > through a timeout or by being poked with our duplicate acks.
> >
> > -seanb
>
> Wow, thanks Sean I appreciate this, I wasn't expecting an answer that fast ;-)
>
> So it looks like the ACK never got transmitted or the packet 5979 was never received. Gut feeling tells me the packet
5979 was lost in the driver, which is why the ACK was not sent in the first place.
>
> I'll see if I can move the PLC to a separate network card and one different then Intel.
>
> I'm not surprise the PLC doesn't handle this properly ;-(
We ack after packet 5979 but we ack the last bytes we received
which is previous to packet 5979. ie. we didn't get or didn't like
packet 5979. When the plc sees we're acking earlier bytes it
should re-send starting at where we're acking.
Regards,
-seanb
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