Chapter 6 Configuring the System
Configuring STP
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Catalyst 2900 Series XL and Catalyst 3500 Series XL Software Configuration Guide
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Beginning in privileged EXEC mode, follow these steps to disable STP:
Accelerating Aging to Retain Connectivity
The default for aging dynamic addresses is 5 minutes. However, a reconfiguration
of the spanning tree can cause many station locations to change. Because these
stations could be unreachable for 5 minutes or more during a reconfiguration, the
address-aging time is accelerated so that station addresses can be dropped from
the address table and then relearned. The accelerated aging is the same as the
forward-delay parameter value when STP reconfigures.
Because each VLAN is a separate instance of STP, the switch accelerates aging
on a per-VLAN basis. A reconfiguration of STP on one VLAN can cause the
dynamic addresses learned on that VLAN to be subject to accelerated aging.
Dynamic addresses on other VLANs can be unaffected and remain subject to the
aging interval entered for the switch.
Configuring STP and UplinkFast in a Cascaded Cluster
STP uses default values that can be reduced when configuring Catalyst 2900 XL
and Catalyst 3500 XL switches in cascaded configurations. If an STP root switch
is part of a cluster that is one switch from a cascaded stack, you can customize
STP to reconverge more quickly after a switch failure.
Figure 6-5
shows modular
Catalyst 2900 XL and Catalyst 3500 XL switches in three cascaded clusters that
use the GigaStack GBIC.
Table 6-4
shows the default STP settings and those that
are acceptable for these configurations.
Command
Purpose
Step 1
configure terminal
Enter global configuration mode.
Step 2
no spanning-tree vlan stp-list
Disable STP on a VLAN.
Step 3
end
Return to privileged EXEC mode.
Step 4
show spanning-tree
Verify your entry.
