ZyXEL Communications XGS-4728F Switch User Manual


 
Chapter 11 Spanning Tree Protocol
XGS-4728F User’s Guide
110
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.
Figure 46 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.
A
B
VLAN 1
VLAN 2