[vortex] Framing error problem

[Alan Chandler]

I am re-submitting the following message - because it accidentally got 
deleted.  Since submitting it, I am getting a handle on the problem.  
By putting an ethernet switch in the circuit between the ethernet card 
and the modem, I can see that the modem is operating at 10Mb/sec 
whereas the vortex card has autonegotiated itself to 100Mb/sec.

Why it should not negotiate the correct rate I don't know.

Anyway here was the message I previously submitted ...

---------------------------------------------------------------------


I have a strange problem that I would like some advice on.  I would have
liked to have scanned your archives first, but for some reason every
attempt to access them seems to give an error message from your web
server. I have therefore subscribed to this list, and this is my first
post to it.


I have a linux desktop connected via a lan (100Mb via an Edimax Fast
Ethernet Switch) inside my home to another linux box acting as
firewall/router/nat gateway to my isp.  This gateway has two ethernet
cards (both 3cSOHO100-Tx Hurricane) in, one onto the lan and the other
connected via a point to point link to a Motorola SB3100 cable modem
and thence onward to my ISP. It is a Celeron 1.7Ghz running linux
2.6.18 (Debian Etch).

I have been having a throughput problem downloading videos from youtube
to my desktop - where at best I was getting approximately 7KBytes/sec.
Anyway in the last few days I discovered that if I download from my
gateway itself I achieve 80KBytes/sec - so I set out to discover what
is wrong.

What appears to be happening is that I get framing errors on the packets
being received from the WAN.  So, much so that it appears to be about
5% of packets when I am forwarding stuff through the gateway.

If I do the download directly from the gateway machine I do not get any
framing errors at all.  It is almost as though I am getting framing
errors caused by transmission of packets through the other Ethernet
card.

I get no errors of any sort on my LAN ethernet interface an no
transmission errors on either interface.

I am not sure where to go from here.  It may be a problem with these
Ethernet cards - I have had them a few years now.  It maybe a problem
with the cable modem - I is about 5 years old.  But I don't know how to
go about figuring out what it might be and whether I should ask my ISP
to examine the cable modem.

What concerns me the most is how can I get framing errors on the WAN
interface when I am forwarding packets, and not when I am receiving
them directly.

Any ideas?
-- 
Alan Chandler
http://www.chandlerfamily.org.uk