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Chapter 13 Spanning Tree Protocol

GS2200-8/24 User’s Guide

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13.10.1 MSTP Network Example

The following figure shows a network example where two VLANs are configured on the two

switches. If the switches are using STP or RSTP, the link for VLAN 2 will be blocked as STP and RSTP

allow only one link in the network and block the redundant link.

Figure 78 STP/RSTP Network Example

With MSTP, VLANs 1 and 2 are mapped to different spanning trees in the network. Thus traffic from

the two VLANs travel on different paths. The following figure shows the network example using

MSTP.

Figure 79 MSTP Network Example

13.10.2 MST Region

An MST region is a logical grouping of multiple network devices that appears as a single device to

the rest of the network. Each MSTP-enabled device can only belong to one MST region. When

BPDUs enter an MST region, external path cost (of paths outside this region) is increased by one.

Internal path cost (of paths within this region) is increased by one when BPDUs traverse the region.

VLAN 1

VLAN 2

VLAN 1

VLAN 2