Cisco switch and NICS

[six3077]

alright,
I have a few nics that are listed here

http://www.cisco.com/warp/public/473/46.html

mainly focused on the 3com 3COM 3C5905C (and the on board version).
As simple as possible.
These machines are plugged into a 2948G switch which goes to a 6500.
Now after setting the ports to auto neg, I had some major errors,so I set both the cards and the ports to full/100.
I'm still getting a vast range of errors with different nics, but mainly for this one, I get Align, FCS and runt errors.
Thats all I want to concentrate on for now.
Any ideas with what settings or cfg's will work for this type of card? I noticed that on the above link, it states
'For more details, refer to Cisco bug ID CSCdt68700 ( registered customers only) .'
also, the nic drivers are fully updated.
any ideas or suggestions would be appreciated.

thanks

 

[eurobadger]

Hi


Here is what the bug report gets you if you are logged in:


Under normal traffic conditions, a 100 Megabit, Full-duplex connection between
any Cisco Catalyst Switch and a 3Com 3C905C will result in Layer 2 errors. The
Catalyst Switch will report these Layer 2 errors as FCS, Alignment and Runt
Packets.

Troubleshoot this issue by reviewing the below guidelines and documentation.

1. Verify that both the 3Com 3C905C and Catalyst Switch are both set for
auto-negotiate or both are manually set for 100 MB, Full-Duplex. A duplex
mismatch will cause a higher rate of Layer 2 (physical) layer errored frames.

2. Load the lastest 3Com 3C905C driver available from

http://www.3com.com

3. Load the diagnostic utility available with the lastest 3Com 3C905C driver.
update.exe /diag)

4. Connect 2 test workstations with 3Com 3C905Cs back-to-back using a crossover
cable.

5. Test Connectivity initiating a large file transfer between the workstations
and noting the following counters with the 3Com Diag Utility. This test, the
back-to-back between the PCs with 3C905C(s), will give a benchmark for performance and physical layer errors.

According to the 3Com documentation, the details of the following counters are
significant:

Receive Overruns: Receive Overrun is the number of lost packets that cannot be
stored in the receive buffer because the PC's buffer is already full.

Carrier Sense Lost: Carrier Sense Lost is the number of packets transmitted
with a carrier sense loss. This normally occurs as a result of collisions.

Transmit Underrun: Transmit underrun is the number of times a packets was
transmitted without adequate data by the NIC.

In respective the Catalyst Switch Counters, a packet transferred that results in
the Carrier Sense Lost or Transmit Underrun incrementing on the 3Com NIC will
cause at least one of the following counters to increase on the Switch:
Alignment, FCS, CRC, Input Errors, Receive Errors, and/or Runts.

Noting the errors and performance back-to-back between 2 PCs with the 3C905C
NIC will give a minimum baseline for the number of errors reported by the switch
and a generally baseline for performance.

6. Repeat step 5 with the PCs connected to the switch and baseline the number
of errors to the errors recorded in Step 5. Expect a higher number of errors
when the workstation is connected to the network as there will be higher load of
traffic including multicast, unicast-flood, and broadcast traffic.

Note: It has been noted that increasing CPU/BUS Speed on the workstation
increases the number of Transmit Underrun packets recorded on the NIC and Runt
Packets on the Catalyst Switches.

In conclusion, this issue is not a Switch specific issue nor an issue with
compatability. Please contact 3Com Tech Support for resolution.



EB

 

[baddos]

You could try turning off flow control on the nic.

 

[TimRegester]

3Com Knowledgebase has a solution see knowledgebase article 3KB2813

This solution explains a solution to this issue for the cat 2950. The issue lies in a mismatch between the nway negotiation process between the PHYs on the nic and the switch. I would guess one is breaking the NWay 802.1z rules and sending malformed FLPs

You will need the latest 3Com drivers for the nic.

The knowledgebase article explains all at

http://knowledgebase.3com.com/