I have two 4000 switches currently are configured as a root bridge for 10 vlans. VLAN 100,200,6,106 etc. I will be connecting a 6509 switch with 2 Port Channels (4 physical ports) to (2) 4000 switches as Layer II trunks, and will also configure the above VLANs in 6509. 6509 will act as an internim switch for couple of months since we are in process of redesigning our data center. How do I make sure that 6509 doesn't become a root bridge for the above VLANs to avoid spanning tree loop. As far as I am concerned, the 6509 will not become a root bridge if the priority for the above VLANs are lower on 4000 switches.
What do I need to configure on Port channel ports to make (1) port channel connecting to 4000 (A) switch as a forwarding path, and the other Port Channel connecting to 4000(B) switch as a backup path.