Sorry, I should have clarified, the four IP addresses given are the storage NICs in the server that is running the iSCSI initiator.  Having four NICs, two connected per volume, is overkill for a 2GB SAN but has made performance tracking and troubleshooting much easier, since I can easily see how much bandwidth is going to each of the two volumes.

I just did a test.  I created a third volume on the SAN.  I was able to connect the two un-used NICs to that new volume.

However, I still can't connect those two NICs to any of the original two volumes.  

In the iSCSI initiator, I select Logon to target, check the box for enabling multipathing, then in the dropdown for Source IP, I can pick any of the four cards, and it seems to work but a few seconds later the SAN seems to over-ride that selection and goes back to 224 and 234.

No ESX here.  This is simply a physical Windows Server box with a bunch of network cards in it.

I updated the SAN to the latest firmware just a couple months ago.  It had been working fine in this configuration until a few days ago.

Firmware version 5.2.6 with the Dell MPIO module installed on the Windows server.

Like I said, I know that four NICs isn't necessary on the 2GB SAN, but it is extremely useful when tuning performance.  I have our busiest SQL databases in these two volumes, and it is important for me to be able to see how much bandwidth each volume/database is consuming, separately.

Thanks, Don.  I appreciate the replies.