Description Of Pvst; Using Pvst+ To Balance Load; Pvst+ For Access Ports - Alaxala AX2200S Series Configuration Manual

19.3 Description of PVST+

PVST+ builds a tree for each VLAN. These trees can be used for load balancing. In
addition, access ports can be used to connect with switches running on Single Spanning
Tree.

19.3.1 Using PVST+ to balance load

When Single Spanning Tree is used in a network that has redundant paths between
switches, such as Switch A and Switch B in the figure below, access from each terminal to
the server is concentrated on port 1 between Switches A and B. In this case, PVST+ can be
used to set up multiple VLANs that have different topologies in order to create redundant
paths, which would allow the load to be distributed. The figure below shows an example of
load balancing by port priority.
In this example, the port priority for VLAN 100 is set higher for port 0/1 than port 0/2,
whereas the port priority for VLAN 200 is set higher for port 0/2 than port 0/1, allowing
access from each terminal to the server to be load-balanced for each VLAN.
Figure 19-6 Using PVST+ to balance loads

19.3.2 PVST+ for access ports

(1) Description
A network can be built using switches that use Single Spanning Tree or switches that
support Single Spanning Tree functionality for one tree (abbreviated hereafter simply as
Single Spanning Tree) and PVST+. Switches running with Single Spanning Tree are used
as edge switches, and Switches are used as core switches. This kind of network
19 Spanning Tree Protocol
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