Cisco Catalyst 3550

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Catalyst 3550 Multilayer Switch Command Reference
OL-8566-01
Chapter 2 Catalyst 3550 Switch Cisco IOS Commands
spanning-tree vlan
spanning-tree vlan
Use the spanning-tree vlan global configuration command to configure spanning tree on a per-VLAN
basis. Use the no form of this command to return to the default setting.
spanning-tree vlan vlan-id {forward-time seconds | hello-time seconds | max-age seconds |
priority priority | {root {primary | secondary} [diameter net-diameter
[hello-time seconds]]}}
no spanning-tree vlan vlan-id [forward-time | hello-time | max-age | priority | root]
Syntax Description
Defaults Spanning tree is enabled on all VLANs.
The forward-delay time is 15 seconds.
The hello time is 2 seconds.
The max-age is 20 seconds.
The primary root switch priority is 24576.
The secondary root switch priority is 28672.
Command Modes Global configuration
vlan-id VLAN range associated with a spanning-tree instance. You can specify a
single VLAN identified by VLAN ID number, a range of VLANs separated
by a hyphen, or a series of VLANs separated by a comma. The range is 1
to
4094.
forward-time seconds Set the forward-delay time for the specified spanning-tree instance. The
forwarding time determines how long each of the listening and learning
states last before the interface begins forwarding. The range is 4 to 30
seconds.
hello-time seconds Set the interval between hello bridge protocol data units (BPDUs) sent by
the root switch configuration messages. The range is 1 to 10 seconds.
max-age seconds Set the interval between messages the spanning tree receives from the root
switch. If a switch does not receive a BPDU message from the root switch
within this interval, it recomputes the spanning-tree topology. The range is
6 to 40 seconds.
priority priority Set the switch priority for the specified spanning-tree instance. This setting
affects the likelihood that the switch is selected as the root switch. A lower
value increases the probability that the switch is selected as the root switch.
The range is 0 to 61440 in increments of 4096. Valid priority values are
4096, 8192, 12288, 16384, 20480, 24576, 28672, 32768, 36864, 40960,
45056, 49152, 53248, 57344, and 61440. All other values are rejected.
root primary Force this switch to be the root switch.
root secondary Set this switch to be the root switch should the primary root switch fail.
diameter net-diameter Set the maximum number of switches between any two end stations. The
range is 2 to 7.