Spanning Tree Help

[gskatz]

I need to to configure STP to act a specific way and have not done this before. The design and need is as follows:

I have 2 6509s(A&B) and 2 4506s(C&D) configured in a loop. And need to force B to be the root bridge and block traffic between A&B. Also, traffic must exit the loop where it entered. For argument sakes lets say D is where traffic originates. This is also where the internet connection is linked to.

There is a link from B to C.

A--X------------B

| |

| |

| |

D---------------C

From my under standing I need to set UDLD for the direction and spanning-tree guard to set the root bridge. How is this done?

Thanks

Greg

[rais]

For root, make the priority for B to be zero.

For blocking A-B, increase the cost of port on A.

Hope this helps.