We have an IBM Netfinity server with two network cards. One network connection changes from 100MBs to 10MBs. Is this normal?

Question

We have an IBM Netfinity server with two network cards running SQL Server. We notice that when we right-click on the network connection icons (lower right on the screen), that one runs at 100Mbs all the time, and the other starts at 100MBs, but eventually settles down to 10Mbs. Is this normal?

Answer

No, this is not normal. Most likely, the network cards you have are set to auto-negotiate their speed with the switch port they are connected to. Some network cards, or the switches they attach to, cannot auto-negotiate correctly. One result of this is that the speed indicated by the network connection icon may incorrect, or change from time to time.

To avoid this problem, and the reduced network performance that can result from this, you must manually configure your network cards for the appropriate speed (such as 100Mbs), along with manually configuring the appropriate duplex setting for the network cards.