[ECOS] Re: ARP-related problem

Grant Edwards grant.b.edwards@gmail.com
Sun Jan 27 21:40:00 GMT 2013


On 2013-01-25, Grant Edwards <grant.b.edwards@gmail.com> wrote:

> I've been examining Ethernet traces from a customer site where there
> appear to be problems associated with the eCos ARP table entry
> timeouts.

It seems this is a known problem with a known fix, so I thought I
would follow-up just for the record...

Bernd Edlinger has kindly pointed me to a patch he submitted that
among other things fixes the periodic packet loss due to ARP entry
timeouts:

  http://bugs.ecos.sourceware.org/show_bug.cgi?id=1001656

It would be interesting to have a chat with whoever decided that
letting the entry expire every 20 minutes [and thus potentially
discarding tx packets] was the right thing to do.

While it's obvious that discarding eCos's tx packets is part of the
design of the BSD ARP subsystem, what I haven't figured out is why the
TCP connection doesn't recover.  The smart money is betting on
Microsft as the culprit: one end of the TCP/IP connection is Windows
7, and the customer claims they never had the problem when using XP.

How long as TCP/IP been around?  It seems nothing is so old and well
understood that it can't be screwed up by Microsoft...

--
Grant

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