RSTP Bridge ID Configuration

BCE

Rapid Spanning Tree Protocol (RSTP) is an extension of the Spanning Tree Protocol (STP) that is used to provide rapid convergence in a switched network. RSTP uses a bridge ID to determine the root bridge and the designated ports in the network.

The bridge ID is a unique identifier that consists of three elements: priority, MAC address, and extended system ID. The combination of these elements determines the bridge ID and helps RSTP select the root bridge.

The three elements that contribute to the bridge ID when configuring RSTP are:

A. Designated MAC Address: The MAC address of the bridge is used as part of the bridge ID. This address must be unique within the network.

B. Priority: The priority value is a configurable parameter that is used to determine the root bridge. The bridge with the lowest priority value is selected as the root bridge. The default priority value is 32768, and it can be configured to a value between 0 and 65535.

C. Extended System ID: The extended system ID is an optional 2-byte field that is used to differentiate between multiple bridges with the same priority and MAC address. It is used when the priority and MAC address alone are not sufficient to uniquely identify a bridge.

D. Root ID: The root ID is the bridge ID of the root bridge in the network. It is used by all the other bridges to calculate their own path cost to the root bridge.

E. Bridge Address: The bridge address is the MAC address of the bridge. It is used in the calculation of the path cost to the root bridge.

In summary, the designated MAC address, priority, and extended system ID are the three elements that contribute to the bridge ID when configuring RSTP. These elements are used by RSTP to select the root bridge and determine the designated ports in the network.