HP BL e-Class Avoiding Trouble

Spanning Tree Protocol

Avoiding Trouble

Below are some tips for avoiding trouble.

Know Where the Root is Located

Although the STP can elect a root bridge, a well-designed network will have an identifiable root for each VLAN. Careful setup of the STP parameters will lead to the selection of this best interconnect switch as the root for each VLAN. Redundant links can then be built into the network. STP is well suited to maintaining connectivity in the event of a device failure or removal, but is poorly suited to designing networks.

Know Which Links are Redundant

Organize the redundant links and tune the port cost parameter of STP to force those ports to be in the blocking state.

For each VLAN, know which ports should be blocking in a stable network. A network diagram that shows each physical loop in the network and the ports that break each loop is extremely helpful.

Minimize the Number of Ports in the Blocking State

A single blocking port transitioning to the forwarding state at an inappropriate time can cause a large part of a network to fail. Limiting the number of blocked ports helps to limit the risk of an inappropriate transition.

Figure D-9: Example 1: A common network design

HP ProLiant BL e-Class C-GbE Interconnect Switch User Guide D-13