Chapter 1 Rstp Configuration; Stp Overview; Function Of Stp; Implement Stp - Huawei Quidway S3000 Series Operation Manual

Operation Manual - STP
Quidway S3000 Series Ethernet Switches

Chapter 1 RSTP Configuration

1.1 STP Overview

1.1.1 Function of STP

Spanning Tree Protocol ( STP ) is applied in loop network to block some undesirable
redundant paths with certain algorithms and prune the network into a loop-free tree,
thereby avoiding the proliferation and infinite cycling of the packet in the loop network.

1.1.2 Implement STP

The fundamental of STP is that the switches exchange a special kind of protocol packet
(which is called configuration Bridge Protocol Data Units, or BPDU, in IEEE 802.1D) to
decide the topology of the network. The configuration BPDU contains the information
enough to ensure the switches to compute the spanning tree.
The configuration BPDU mainly contains the following information:
1) The root ID consisting of root priority and MAC address
2) The cost of the shortest path to the root
3) Designated switch ID consisting of designated switch priority and MAC address
4) Designated port ID consisting of port priority and port number
5) The age of the configuration BPDU: MessageAge
6) The maximum age of the configuration BPDU: MaxAge
7) Configuration BPDU interval: HelloTime
8) Forward delay of the port: ForwardDelay.
What are the designated switch and designated port?
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Chapter 1 RSTP Configuration