Multiple Spanning Tree Protocol; Restrictions For Configuring Mstp; How To Configure Mst Protocol; Enabling Multiple Spanning Tree Protocol - Cisco NCS 4200 Series Configuration Manual

Lan switching

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Multiple Spanning Tree Protocol

The Multiple Spanning Tree Protocol (MSTP) is an STP variant that allows multiple and independent spanning

trees to be created over the same physical network. The parameters for each spanning tree can be configured

separately, so as to cause a different network devices to be selected as the root bridge or different paths to

be selected to form the loop-free topology. Consequently, a given physical interface can be blocked for some

of the spanning trees and unblocked for others.

Having set up multiple spanning trees, the set of VLANs in use can be partitioned among them; for example,

VLANs 1 - 100 can be assigned to spanning tree 1, VLANs 101 - 200 can be assigned to spanning tree 2,

VLANs 201 - 300 can be assigned to spanning tree 3, and so on. Since each spanning tree has a different

active topology with different active links, this has the effect of dividing the data traffic among the available

redundant links based on the VLAN - a form of load balancing.

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• RSTP is not supported. To support RSTP, all vlans are mapped to MSTI 0 when no instance is created

• PVSTP is not supported.

• Supports only 16 instances.

This section describes the procedure for configuring MSTP:

By default, MSTP is disabled on all interfaces. MSTP need not be enabled explicitly on each interfaces. By

turning the global configuration on, it is enabled on all interfaces.

Restrictions for configuring MSTP, page 33

How to Configure MST Protocol, page 33

for MSTP.

LAN Switching Configuration Guide, Cisco IOS XE Everest 16.6.1 (Cisco NCS 4200 Series)

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