Cisco WS-C2960-24TC-S Software Guide - Page 340

Specifying the MST Region Configuration and Enabling MSTP

Page 340 highlights

Configuring MSTP Features Chapter 16 Configuring MSTP • Partitioning the network into a large number of regions is not recommended. However, if this situation is unavoidable, we recommend that you partition the switched LAN into smaller LANs interconnected by routers or non-Layer 2 devices. • For configuration guidelines about UplinkFast and BackboneFast, see the "Optional Spanning-Tree Configuration Guidelines" section on page 17-10. Specifying the MST Region Configuration and Enabling MSTP For two or more switches to be in the same MST region, they must have the same VLAN-to-instance mapping, the same configuration revision number, and the same name. A region can have one member or multiple members with the same MST configuration; each member must be capable of processing RSTP BPDUs. There is no limit to the number of MST regions in a network, but each region can only support up to 65 spanning-tree instances. You can assign a VLAN to only one spanning-tree instance at a time. Beginning in privileged EXEC mode, follow these steps to specify the MST region configuration and enable MSTP. This procedure is required. Step 1 Step 2 Step 3 Command configure terminal spanning-tree mst configuration instance instance-id vlan vlan-range Step 4 name name Step 5 Step 6 Step 7 Step 8 revision version show pending exit spanning-tree mode mst Purpose Enter global configuration mode. Enter MST configuration mode. Map VLANs to an MST instance. • For instance-id, the range is 0 to 4094. • For vlan vlan-range, the range is 1 to 4094. When you map VLANs to an MST instance, the mapping is incremental, and the VLANs specified in the command are added to or removed from the VLANs that were previously mapped. To specify a VLAN range, use a hyphen; for example, instance 1 vlan 1-63 maps VLANs 1 through 63 to MST instance 1. To specify a VLAN series, use a comma; for example, instance 1 vlan 10, 20, 30 maps VLANs 10, 20, and 30 to MST instance 1. Specify the configuration name. The name string has a maximum length of 32 characters and is case sensitive. Specify the configuration revision number. The range is 0 to 65535. Verify your configuration by displaying the pending configuration. Apply all changes, and return to global configuration mode. Enable MSTP. RSTP is also enabled. Caution Changing spanning-tree modes can disrupt traffic because all spanning-tree instances are stopped for the previous mode and restarted in the new mode. You cannot run both MSTP and PVST+ or both MSTP and rapid PVST+ at the same time. 16-16 Catalyst 2960 Switch Software Configuration Guide OL-8603-04

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16-16
Catalyst 2960 Switch Software Configuration Guide
OL-8603-04
Chapter 16
Configuring MSTP
Configuring MSTP Features
Partitioning the network into a large number of regions is not recommended. However, if this
situation is unavoidable, we recommend that you partition the switched LAN into smaller LANs
interconnected by routers or non-Layer 2 devices.
For configuration guidelines about UplinkFast and BackboneFast, see the
“Optional Spanning-Tree
Configuration Guidelines” section on page 17-10
.
Specifying the MST Region Configuration and Enabling MSTP
For two or more switches to be in the same MST region, they must have the same VLAN-to-instance
mapping, the same configuration revision number, and the same name.
A region can have one member or multiple members with the same MST configuration; each member
must be capable of processing RSTP BPDUs. There is no limit to the number of MST regions in a
network, but each region can only support up to 65 spanning-tree instances. You can assign a VLAN to
only one spanning-tree instance at a time.
Beginning in privileged EXEC mode, follow these steps to specify the MST region configuration and
enable MSTP. This procedure is required.
Command
Purpose
Step 1
configure terminal
Enter global configuration mode.
Step 2
spanning-tree mst configuration
Enter MST configuration mode.
Step 3
instance
instance-id
vlan
vlan-range
Map VLANs to an MST instance.
For
instance-id
, the range is 0 to 4094.
For
vlan
vlan-range
, the range is 1 to 4094.
When you map VLANs to an MST instance, the mapping is
incremental, and the VLANs specified in the command are added to
or removed from the VLANs that were previously mapped.
To specify a VLAN range, use a hyphen; for example,
instance 1 vlan
1-63
maps VLANs 1 through 63 to MST instance 1.
To specify a VLAN series, use a comma; for example,
instance 1 vlan 10,
20, 30
maps VLANs 10, 20, and 30 to MST instance 1.
Step 4
name
name
Specify the configuration name. The
name
string has a maximum length
of 32 characters and is case sensitive.
Step 5
revision
version
Specify the configuration revision number. The range is 0 to 65535.
Step 6
show pending
Verify your configuration by displaying the pending configuration.
Step 7
exit
Apply all changes, and return to global configuration mode.
Step 8
spanning-tree mode mst
Enable MSTP. RSTP is also enabled.
Caution
Changing spanning-tree modes can disrupt traffic because all
spanning-tree instances are stopped for the previous mode and
restarted in the new mode.
You cannot run both MSTP and PVST+ or both MSTP and rapid PVST+
at the same time.