Strange network issue affecting Win2k only?

[AC439]

Hi,

We have three cisco switches on our network. Catalyst 4003 and two 2924. There is one FEC connecting between the 4003 and each of the 2924 switch. My servers (NT and w2k) are all connected to the 4003. I have clients connected to both the 4003 and 2924 switches. Clients (w2k and w98) on 4003 run fine. Win98 clients on 2924 run fine too. However, w2k professional clients on 2924 have very strange issue as follows :-

- On the w2k client, copying files from some particular server (w2k and NT, connected to 4003) is very slow. It takes about 60 seconds to copy a 5mb file. It may happens to other hosts as well but I only test on servers.

- If I connect to another server on the 4003 switch, speed is normal.

- My conclusion is a point to point switching issue?

- The issue is intermittent which happens about 50% of the time. If I reboot the PC, next time it may come up fine.

- If I move the client to connect directly to the 4003 switch, no problem at all.

- If I move a w2k client from the 4003 switch to the 2924 switch, I can reproduce the problem over 50% of the time.

- If I copy files from another computer located on the 2924 switch, speed is fine.

- It only affects w2k box. If I put a win98 box on the same data drop, it works perfectly fine.

- The 2924 switches were rebooted, same problem.

- tried manually set speed/duplex mode between w2k PC and the corresponding 2924 port, no go.

- Switched out all the patch cords, no go.

- Replace network card on the w2k PC, same problem.

- Search cisco site for win2k issues, can't find anything.

- Search Microsoft KB, no help, basically find one talks about speed/duplex mode etc...

- IOS is 11.2 on both switches. CatOS on 4003.

- Tried to fine out how to change 2924 from fragment free to store-and-forward but can't find any info. Wonder if it is possible.

- I checked the switch config, they are all on the same VLAN. In fact the config is very simple.

- Glad that I have majority w98 PCs on the 2924 switches.

I appreciate if anyone would throw me some ideas before I run netmon to see what traffic is like. (I am not good at netmon/sniffer so this is my last resort). Thanks.

AC %-(

 

[thekidcisco]

Hiya AC!

Okay, have you enabled portfast on the access-port that is going to this Win2k client? What settings are configured on the Win2k's NIC's per speed/duplex? Are there any errors on the interface to which the switch is connecting to? Have you tried different Win2k boxes - other laptops with Win2k etc? I work in an organisation that uses Win2k Prof extensively on desktops and we only use Cisco Catalyst switches, we have no problems at all. We run a mixture of XL series and CatOS.

If you have access to CCO try uprading one of the XL's see if the problem reoccurs (after you have tried all the above) and then take it from there...

rgds,
tkc

 

[AC439]

Hi Tkc,

I had checked everything you mentioned but no luck at all. The only thing I could not do is to upgrade IOS (since we are so cheap to use Cisco but without SmartNet contract). I guess something in w2k must have changed and my old IOS doesn't know how to handle it correctly.

One thing I did to further isolate the issue was to buy a cheap 8 ports Netgear 10/100 switch, downlink to one of the ports on my 4003 main switch and put the w2k pro clients there. Everything works fine. Problems seems to be at the 2924 switch.

Thanks,

- AC

 

[fastether]

Cisco recommends the following:" Disable Windows 2000 and Windows ME Power Management Functions. Windows 2000 & Windows ME employ a power management capability that can disable the NIC. When the NIC is disabled for power mangement, the NIC will drop link to the switch." --Cisco - Troubleshooting Cisco Catalyst Switches to Network Interface Cards, page 6.

 

[wybnormal]

If you sniff this, you *may* find that MS is having troubles with the sliding window of TCP. This seen many times with systems that started with a dial up connection and migrate to a LAN connection. Symptoms are a very slow connection and a trace shows 1 packet at a time instead of multiple large packets.

Now while you did not go from a dial up connection, there may be an issue with Win2K and the code level on the switch... maybe. A sniffer would be invaluable in this case.. Even the demo software would be enough to help.

MikeS "Diplomacy; the art of saying 'nice doggie' till you can find a rock" Wynn Catlin