That being said, we are having an issue showing topology information. It seems that this stems from a problem retrieving the forwarding database from a Force10 switch. If I attempt to show the forwarding table, it is always empty.

It seems from the source code that you are retrieving as follows:
    node->CallSnmpEnumerate(_T(".1.3.6.1.2.1.17.4.3.1.1"), FDBHandler, fdb);
However, that is dot1dTpFdbAddress which seems to only contain the forwarding information for the default VLAN. For us, that OID is empty on those particular switches.
It seems like I am missing something.

According to the documentation that I have read, it seems that we need dot1qTpFdbPort (.1.3.6.1.2.1.17.7.1.2.2.1.2) to retrieve the full forwarding table for non-default VLANs. If I walk that part of the tree, I see values that appear to be correct for building the FDB.

On other switches that we have, such as 3Com, this behavior seems to be confirmed... The dot1dTpFdbTable contains a subset (or none) of the entries needed to complete the FDB, but the dot1qFdbTable seems to be more complete.

Am I missing something for how this should work?

Any thoughts on how we can get this topology mapping to work properly for us?

Thanks for your help!

-- Jared