trouble with mismatched network

William J. Earl
Mon Oct 25 15:07:01 1999

Kirk Reiser writes:
 > Hi Folks:  I was wondering if someone might be able to give me a hand
 > with a network problem I am having.
 > I have a linux box acting as a server and gateway between a Windows
 > LAN and a Cisco 675 router to the internet through an adsl connection.
 > Although the LAN has 10/100 cards in all the boxes, the hub is a
 > 10-base-T 24 port hub.  What happens is when the linux box boots it
 > notices that the LAN is 10-base-T and drops into half duplex.  On the
 > other side it goes into full duplex to the router.  The problem I am
 > having is that none of the Windows boxes can transfer files larger
 > than about 10k to the linux box before timing out.  The linux box can
 > transfer files to the windows boxes no problem.
 > Does any one have any idea how I can make the network work smoothly.  I am
 > using NetGear FA310 TX cards in all of the systems and I am using
 > v0.91g of the tulip driver.  The chip is recognized as a Lite-On
 > 82c168.

      This sounds like the problem I was having, until I applied the
patch I sent out to the list a few months ago, based on a workaround
in the BSD driver for a 82c168 bug.  The part sometimes prefixes an
incoming packet with a lot of garbage, which leads to the packet
being dropped.  The workaround recovers the packet by deleting the
garbage.  If the patch is not in the latest driver, try applying the
patch.  (Find the patch in the archives.)

      Someone suggested turning off CPU-to-PCI write buffering in 
the BIOS setup.  This helped somewhat in my case.

      Also, if you get messages about "too much work at interrupt level",
you can add

    options tulip max_interrupt_work=75

This helped my situation.

      Lastly, if the interface goes catatonic on occasion, you can
have a script running all the time, testing that you can still ping
at least one other host (with a broadcast ping).  If the ping fails,
restart the interface.  With the other fixes, this no longer seems
necessary on my system.