Cisco WS-C2950SX-48-SI Configuration Manual page 138

Configuring a Root Switch
To speed up convergence, use nondefault parameters values that are permitted by the IEEE 802.1D
standard. Nondefault parameters set for a reconvergence of 14 seconds are as follows:
Parameter
Network Diameter (dia)
Hello Time
Forward Delay Timer
Maximum Age Timer
You can set these parameters on the Catalyst 4500 series switches without modifying the switches.
Note You can set switch ports for improved convergence in PortFast mode. This setting affects only the
transition from disable (link down) to enable (link up), moving the port immediately to the forwarding
state. If a port in PortFast mode begins blocking, then it goes through listening and learning before
reaching the forwarding state.
To configure the spanning tree bridge to improve convergence, perform this task in privileged mode:
Task
Step 1
Configure the Hello time for a VLAN or
MISTP instance.
Step 2 Verify the configuration.
Step 3
Configure the forward delay time for a
VLAN or MISTP instance.
Step 4
Verify the configuration.
Step 5
Configure the maximum aging time for a
VLAN or MISTP instance.
Step 6
Verify the configuration.
This example shows how to configure the spanning tree Hello Time, Forward Delay Timer, and
Maximum Age Timer to 2, 4, and 6 seconds:
Console> (enable) set spantree hello 2 100
Spantree 100 hello time set to 7 seconds.
Console> (enable)
Console> (enable) set spantree fwddelay 4 100
Spantree 100 forward delay set to 21 seconds.
Console> (enable)
Console> (enable) set spantree maxage 6 100
Spantree 100 max aging time set to 36 seconds.
Console> (enable)
Catalyst 4500 Series, Catalyst 2948G, Catalyst 2980G Switches Software Configuration Guide
7-42
Time
2 hops
2 sec
4 sec
6 sec
Command
set spantree hello interval [vlan] mistp-instance
[instances]
show spantree [vlan | mistp-instance instances]
set spantree fwddelay delay [vlan] mistp-instance
[instances]
show spantree [mod/port] mistp-instance [instances]
[active]
set spantree maxage agingtime [vlans] mistp-instance
instances
show spantree [mod/port] mistp-instance [instances]
[active]
—
Release 8.1
Chapter 7 Configuring Spanning Tree
78-15486-01