In our office environment, our main switch is a Cisco Catalyst 2948, which has 48 ports (mrkitty, nodeid 7). We also have a number of Netgear GS108T switches, because they are cheap and manageable.
OpenNMS 1.11.90 reports that almost all of our devices are connected to one of those Netgear switches, (mrslave, nodeid 4). I've deleted the datalinkinterface table several times and discovery always shows that mrslave is the main switch instead of mrkitty.
I will attached the datalinkinterface table information as well as complete walks from mrkitty and mrslave.