ZyXEL XGS4700-48F User Guide - Page 153

MST Region, 1.5.3, MST Instance

Page 153 highlights

Chapter 13 Spanning Tree Protocol 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 63 MSTP Network Example A VLAN 1 VLAN 2 B 13.1.5.2 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 13.1.5.3 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. XGS4700-48F User's Guide 153

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Chapter 13 Spanning Tree Protocol
XGS4700-48F User’s Guide
153
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 63
MSTP Network Example
13.1.5.2
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
13.1.5.3
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.
A
B
VLAN 1
VLAN 2