3Com 9100 manual Initialization, Traffic flowing through Bridge B

Overview of the Spanning Tree Protocol 89

If the link through Bridge C fails, as shown in Figure 15, the STP system reconfigures the network so that traffic from segment 2 flows through Bridge B.

Figure 15 Traffic flowing through Bridge B

How STP Works STP has the following three stages of operation:

■Initialization

■Stabilization

■Reconfiguration

Initialization

Initially, the STP system requires the following before it can configure the network:

■All bridges exchange information by way of Bridge Protocol Data Units (BPDUs), which are transmitted in packets with a known multicast address

■To determine a single root bridge as a result of BPDU exchange

The Root Bridge is selected on the basis of it having the lowest Bridge Identifier value. This value is a combination of the unique MAC address of the bridge and a priority component defined for the bridge.