Multiple Stp - ZyXEL Communications XGS3700-48 User Manual

In the following example, there are two RSTP instances (MRSTP1 and MRSTP2) on switch A.
Figure 86 MRSTP Network Example
To set up MRSTP, activate MRSTP on the Switch and specify which port(s) belong to which spanning
tree.
Note: Each port can belong to one STP tree only.

11.1.5 Multiple STP

Multiple Spanning Tree Protocol (IEEE 802.1s) is backwards compatible with STP/RSTP and
addresses the limitations of existing spanning tree protocols (STP and RSTP) in networks to include
the following features:
• One Common and Internal Spanning Tree (CIST) that represents the entire network's
connectivity.
• Grouping of multiple bridges (or switching devices) into regions that appear as one single bridge
on the network.
• A VLAN can be mapped to a specific Multiple Spanning Tree Instance (MSTI). MSTI allows
multiple VLANs to use the same spanning tree.
• Load-balancing is possible as traffic from different VLANs can use distinct paths in a region.
11.1.5.1 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.
Chapter 11 Spanning Tree Protocol
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