Cisco Catalyst 4500 Series Command Reference Guide

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Catalyst 4500 Series Switch Cisco IOS Command Reference—Release IOS XE 3.4.0SG and IOS 15.1(2)SG)
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Chapter 2 Cisco IOS Commands for the Catalyst 4500 Series Switches
spanning-tree mst root
spanning-tree mst root
To designate the primary root, secondary root, bridge priority, and timer value for an instance, use the
spanning-tree mst root command. To return to the default settings, use the no form of this command.
spanning-tree mst instance-id root {primary | secondary} | {priority prio} [diameter dia
[hello-time hello]]
no spanning-tree mst root
Syntax Description
Defaults Bridge priority is 32768.
Command Modes Global configuration mode
Command History
Usage Guidelines The bridge priority can be set in increments of 4096 only. When you set the priority, valid values are 0,
4096, 8192, 12288, 16384, 20480, 24576, 28672, 32768, 36864, 40960, 45056, 49152, 53248, 57344,
and 61440.
You can set the priority to 0 to make the switch root.
The spanning-tree root secondary bridge priority value is 16384.
The diameter dia and hello-time hello options are available for instance 0 only.
If you do not specify the hello_time value, the value is calculated from the network diameter.
instance-id Instance identification number; valid values are from 1 to 15.
root Configures switch as the root switch.
primary Sets a high enough priority (low value) to make the bridge root of the spanning-tree
instance.
secondary Designates this switch as a secondary root if the primary root fails.
priority prio Sets the bridge priority; see the “Usage Guidelines” section for valid values and
additional information.
diameter dia (Optional) Sets the timer values for the bridge based on the network diameter; valid
values are from 2 to 7.
hello-time hello (Optional) Specifies the duration between the generation of configuration messages
by the root switch.
Release Modification
12.1(12c)EW Support for this command was introduced on the Catalyst 4500 series switch..

Cisco Catalyst 4500 Series Specifications

General

Series	Catalyst 4500 Series
Category	Switch
Layer Support	Layer 2, Layer 3
Form Factor	Modular chassis
Stackable	No
Chassis Slots	3, 6, 7, 10
Power Supply Options	AC, DC
Redundancy	Power supply, Supervisor engine
Network Management	Cisco IOS Software CLI, SNMP, Cisco Prime Infrastructure
Features	Security, QoS
Port Density	Up to 384 ports per chassis
Security Features	802.1X, ACLs, DHCP Snooping, Dynamic ARP Inspection, IP Source Guard
Supervisor Engine	8-E