Multiple Instance Spanning-Tree Operation

Overview

Overview

MSTP Features

802.1s Spanning Tree

Default

Menu

CLI

Web

Protocol

 

 

 

 

 

 

 

 

 

Viewing the MSTP Status

n/a

page 5-40

and Configuration

 

 

 

 

Enable/Disable MSTP and

Disabled

page 5-19

Configure Global

 

 

 

 

Parameters

 

 

 

 

Configuring Basic Port

admin-edge-port: No-disabled

page 5-23

Connectivity Parameters

auto-edge-port: Yes-enabled

 

and

 

 

bpdu-filter: No-disabled

 

following

 

 

 

 

 

 

bpdu-protection: No-disabled

 

 

 

 

mcheck: Yes

 

 

 

 

hello-time: 2

 

 

 

 

path-cost: auto

 

 

 

 

point-to-point MAC: Force-True

 

 

 

 

priority: 128 (multiplier: 8)

 

 

 

 

root-guard: No-disabled

 

 

 

 

tcn-guard: No-disabled

 

 

 

 

loop-protection: Send disable

 

 

 

Configuring MSTP Instance

instance (MSTPI): none

page 5-32

Parameters

priority: 32768 (multiplier: 8)

 

 

 

Configuring MSTP Instance

Auto

page 5-35

Per-Port Parameters

 

 

 

 

Enabling/Disabling MSTP

Disabled

page 5-38

Spanning Tree Operation

 

 

 

 

Enabling an Entire MST

n/a

page 5-38

Region at Once

 

 

 

 

 

 

 

 

 

Without spanning tree, having more than one active path between a pair of nodes causes loops in the network, which can result in duplication of mes- sages, leading to a “broadcast storm” that can bring down the network.

Multiple-Instance spanning tree operation (802.1s) ensures that only one active path exists between any two nodes in a spanning-treeinstance. A spanning-tree instance comprises a unique set of VLANs, and belongs to a specific spanning-treeregion. A region can comprise multiple spanning-tree instances (each with a different set of VLANs), and allows one active path among regions in a network. Applying VLAN tagging to the ports in a multiple-

5-2