Chapter 13 Spanning Tree Protocol
XS1920 Series User’s Guide
140
Figure 97
MSTP Network Example
13.7.2 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.
Devices that belong to the same MST region are configured to have the same MSTP configuration
identification settings. These include the following parameters:
• Name of the MST region
• Revision level as the unique number for the MST region
• VLAN-to-MST Instance mapping
13.7.3 MST Instance
An MST Instance (MSTI) is a spanning tree instance. VLANs can be configured to run on a specific
MSTI. Each created MSTI is identified by a unique number (known as an MST ID) known internally
to a region. Thus an MSTI does not span across MST regions.
The following figure shows an example where there are two MST regions. Regions 1 and 2 have 2
spanning tree instances.
A
B
VLAN 1
VLAN 2
Summary of Contents for XS1920 Series
Page 18: ...18 PART I User s Guide ...
Page 32: ...32 PART II Technical Reference ...
Page 177: ...Chapter 21 Classifier XS1920 Series User s Guide 177 Figure 122 Classifier Example EXAMPLE ...
Page 408: ...Appendix C IPv6 XS1920 Series User s Guide 408 ...
Page 412: ...Appendix D Legal Information XS1920 Series User s Guide 412 Environmental Product Declaration ...