ZyXEL Communications ES-2108, User Manual, Page: 104 / 284

Chapter 11 Spanning Tree Protocol
ES-2108 Series User’s Guide
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Figure 49 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 50 MSTP Network Example
11.1.4.2 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
A
B
VLAN 1
VLAN 2
A
B
VLAN 1
VLAN 2