ZyXEL Communications MES3500 Series, Руководство пользователя

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Chapter 13 Spanning Tree Protocol
MES3500 Series User’s Guide
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In the following example, there are two RSTP instances ( MRSTP 1 and MRSTP2 ) on switch A .
Figure 56
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.
13.1.5 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.
13.1.5.1 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.