Using gigabit NIC and switch with 100Mbps clients doesn't work

[David Trask]

"Scott Ledyard" <scott at redboot.biz> writes:
>Thanks Gavin for your suggestions. It took me a while to work through
>your list.
>-I had been using a cat5e cable. Swapped it out with others, but same
>result.
>-/sbin/ifconfig was normal. /var/log/syslog had nothing much.
>/var/log/messages had one line that indicated a successful request for
>NFS services, but nothing else. 
>-pinging showed no problems
>-Installed Ethereal (wireshark?) on server and sniffed during the
>thinclient boot. DHCP fine and a bunch (100+) of NFS packets back and
>forth. Not equipped to understand them, but nothing Ethereal marked as
>errors. 
>-I installed a new 6.10 Ubuntu workstation, connected @ gigabit to
>Edubuntu 6.10 server (it's the DHCP server) and set up a Samba share (I'm
>more familiar with samba.) I could successfully tranfer a large file. 
>-I setup NFS share on server and when I mounted it on the workstation it
>never came back to the command prompt (using the gigabit switch.)
>Rebooted all and tried with 100Mbps switch. Again, it took over 60
>seconds for the client command prompt to return, but the NFS did work and
>I was able to transfer the same 2MB file in a few seconds. 
>You may recall that I could swap switches during the thinclient boot
>(from gigabit to 100) and it would continue, so I tried the same thing
>using this workstation. Rebooted all and mounted NFS share while using
>the 100Mbps switch. Then, switched to the gigabit switch and tried the
>file transfer. It worked just as well! (FWIW, I sniffed both transfers.
>There were some TCP windowing errors in both that I would consider
>normal, but only the gigabit transfer had packet out-of-order TCP
>errors.) 
>So, my tenative conclusion is the client/server cannot establish a NFS
>share while the gigabit switch is in place, but it can employ one when it
>has  already been established. Not much good when you have to boot a
>thinclient.  
>Does this information help? Any suggestions?
>Thanks, Scott

Is it a managed switch?  Are you able to turn off "spanning tree"....I've
found that spanning tree on some switches can interfere in this case.  
Just something to try....

David N. Trask
Technology Teacher/Director
Vassalboro Community School
dtrask at vcsvikings.org
(207)923-3100