I have three WS-C2960X-48FPD-L with FlexStack+ modules. Prior to stacking, I assigned an IP address to the master switch fastethernet0. My router has a single gbe connection that was connected to a third party switch which in turn fed the master. I then setup two more switches giving them different IP addresses and could reach all three. Next, I installed the stack modules. The second and third switch management ports went dark and the two latter IP addresses were no longer accessible but the entire stack was reachable via the command switch IP. If I unplugged fastethernet0, the link would be picked up by another switch and I could still reach the master switch IP address. So far, so good. Then, I moved the router connection from the third party switch to an access port on one of the C2960x switches. This simple change made the stack IP address unreachable. I had planned to migrate everything to the stack and retire the third party switch, but need to have remote access. So, this comes down to two questions:
1) why did I lose connectivity? Is this a a spanning tree problem? How could it be if fastethernet0 is a layer3 interface?
2) if I can't use fastethernet0, how can I configure a management IP for the stack? Can I put it onto the appropriate vlan with a vlan interface?
