Quick Reference Guide

PowerConnect B-Series TI24X Configuration Guide 193
53-1002269-02
Chapter
8
Configuring Metro Features
Topology groups
A topology group is a named set of VLANs that share a Layer 2 topology. Topology groups simplify
configuration and enhance scalability of Layer 2 protocols by allowing you to run a single instance
of a Layer 2 protocol on multiple VLANs.
You can use topology groups with the following Layer 2 protocols:
• STP
• MRP
• VSRP
• 802.1W
Topology groups simplify Layer 2 configuration and provide scalability by enabling you to use the
same instance of a Layer 2 protocol for multiple VLANs. For example, if a device is deployed in a
Metro network and provides forwarding for two MRP rings that each contain 128 VLANs, you can
configure a topology group for each ring. If a link failure in a ring causes a topology change, the
change is applied to all the VLANs in the ring topology group. Without topology groups, you would
need to configure a separate ring for each VLAN.
NOTE
If you plan to use a configuration saved under an earlier software release and the configuration
contains STP groups, the CLI converts the STP groups into topology groups when you save the
configuration. For backward compatibility, you can still use the STP group commands. However, the
CLI converts the commands into the topology group syntax. Likewise, the show stp-group command
displays STP topology groups.
Master VLAN and member VLANs
Each topology group contains a master VLAN and can contain one or more member VLANs and
VLAN groups:
• Master VLAN – The master VLAN contains the configuration information for the Layer 2
protocol. For example, if you plan to use the topology group for MRP, the topology group master
VLAN contains the ring configuration information.
• Member VLANs – The member VLANs are additional VLANs that share ports with the master
VLAN. The Layer 2 protocol settings for the ports in the master VLAN apply to the same ports in
the member VLANs. A change to the master VLAN Layer 2 protocol configuration or Layer 2
topology affects all the member VLANs. Member VLANs do not independently run a Layer 2
protocol.
• Member VLAN groups – A VLAN group is a named set of VLANs. The VLANs within a VLAN
group have the same ports and use the same values for other VLAN parameters.