Product

• Brisque 3.0.38 Update CD2
• Brisque 4.0
• Brisque Serve 4.021
• Timna 3.1.8.6

Platform

Brisque 3.0.38

• E30 - Victory
• 43P-140 Tiger1
• 43P-150 Tiger2
• F50 - Wildcat (2 and 4 CPUs)

Brisque 4.0:

• E30 - Victory
• 43P-140 Tiger 1
• 43P-150 Tiger 2
• F50 - Wildcat (2 and 4 CPUs)
• 44P-170 Hammerhead
• 6F1 Condor (2, 4, and 6 CPUs)

Operating system

IBM AIX 4.2.1 or IBM AIX 4.3.3 

Symptoms

There is a slow transmit rate or communications completely stop on AIX machines with 100BT boards set to Full duplex.

Cause

Incorrectly configured auto-negotiation.

One of the most common causes of performance issues on 10/100Mb Ethernet links is when one port on the link is operating at half duplex while the other port is operating at full duplex. This occasionally happens when the auto-negotiation process doesn't result in both link partners having the same configuration. It also happens when users reconfigure one side of a link and forget to reconfigure the other side.

Solution

Both sides of a link should have auto-negotiate on, or both sides should have it off. Our current recommendation is to leave auto-negotiate on.

Use auto-negotiate as the default. Only, if there are problems, should the card and switch be set to a specific mode.

If auto-negotiate is not used, you should change the settings on both the switch port and the NIC (as the speed, and not the duplex mode, is negotiated). 

If you cannot change the settings on the switch (because you don’t know how, don't have the password, and so forth) the only safe option is to set the switch port to 100BaseT HALF duplex, as this is what the switch defaults to when auto-negotiating.

Important: You must test both the Tx and Rx speed, as there have been cases (ice blue G3) where copying from the Brisque was very fast, but copying to it was very slow.

Technical contact(s)

Lev Weissman

Submitted by

Benito DelMonico

Date submitted

22 May 2002