Multiple Spanning Tree Protocol Groups - Nortel business policy switch 2000 User Manual

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Multiple Spanning Tree Protocol groups

BPS 2000 switches support the Spanning Tree Protocol (STP) as defined in IEEE
802.1D. As defined in the IEEE 802.1D standard, the Spanning Tree Protocol
detects and eliminates logical loops in a bridged or switched network. When
multiple paths exist, the spanning tree algorithm configures the network so that a
bridge or switch uses only the most efficient path. If that path fails, the protocol
automatically reconfigures the network to make another path become active, thus
sustaining network operations.
Starting with software version 1.2, the BPS 2000 supports multiple spanning tree
groups (STGs). The BPS 2000 supports a maximum of 8 STGs, either all in one
standalone switch or across a stack consisting of only BPS 2000 switches (Pure
BPS 2000 Stack mode). Multiple STGs provide multiple data paths, which can be
used for load-balancing and redundancy. You enable load balancing between two
BPS 2000 switches using multiple STGs by configuring each path with a different
VLAN and then assigning each VLAN to a separate STG. Each STG is
independent. Each STG sends its own Bridge Protocol Data Units (BPDUs), and
each STG must be independently configured.
To use more that one STG, ensure that the Stack Operational Mode is set to Pure
BPS 2000 Stack mode. To view and set the Stack Operational Mode, refer to
Chapter 3, Using Web-based Management for the Business Policy Switch 2000
Software Version 2.0, or Reference for the Business Policy Switch 2000 Command
Line Interface Software Version 2.0.You have only the single default STG
available if you are in Hybrid Stack mode, which is for running mixed stacks.
The STG, or bridge group, forms a loop-free topology that includes one or more
virtual LANs (VLANs). With software version 1.2, the BPS 2000 supports
multiple instances (8) of STGs running simultaneously.
As noted in "Increased VLANs," the BPS 2000 with software version 1.2 supports
a maximum of 256 VLANs. With a maximum of 8 STGs, on average, each STG
will have 32 VLANs.
Using the Business Policy Switch 2000 Version 2.0