Technical data

BLADE OS 5.1 Application Guide
82
 Chapter 5: Spanning Tree Group BMD00136, November 2009
MSTP Configuration Guidelines
This section provides important information about configuring Multiple Spanning Tree Groups:
 When MSTP is turned on, the switch automatically moves all VLANs to the CIST.
When MSTP is turned off, the switch moves all VLANs from the CIST to STG 1.
 When enabling MSTP, Region Name must be configured, and a default version number of one
is configured automatically. Each bridge in the region must have the same name, version
number, and VLAN mapping.
Figure 12 shows how multiple Spanning Trees can provide redundancy without wasting any uplink
ports. In this example, the server ports are split between two separate VLANs. Both VLANs belong
to two different Multiple Spanning Tree (MSTP) groups. The Spanning Tree priority values are
configured so that each routing switch is the root for a different MSTP instance. All of the uplinks
are active, with each uplink port backing up the other.
Figure 12 Implementing Multiple Spanning Tree Groups
Server 1
VLAN 2
Server 2
VLAN 2
Server 3
VLAN 1
Server 4
VLAN 1
Server 5
VLAN 1
Enterprise
Routing Switch
Enterprise
Routing Switch
Blocking VLAN 1
Passing VLAN 2
Passing VLAN 1
Blocking VLAN 2
(MSTP Group 1 root)
(MSTP Group 2 root)