11-15
Catalyst 2950 Desktop Switch Software Configuration Guide
78-14982-01
Chapter 11 Configuring STP Configuring Spanning-Tree Features
Beginning in privileged EXEC mode, follow these steps to configure a switch to become the secondary
root for the specified VLAN:
To return the switch to its default setting, use the no spanning-tree vlan vlan-id root global
configurati on comm a nd.

Configuring the Port Priority

If a loop occurs, spanning tree uses the port priority when selecting an interface to put into the
forwarding state. You can assign hi gher prio rity values (lower numer ical values) to interfa ces that you
want selected first and lower priority values (higher numerical values) that you want selected last. If all
interf aces ha ve t he same prio rity v alue, spanni ng tree p uts the interf ace wi th the lo west inte rface n umber
in th e for war ding st ate an d b lock s t he ot her in ter faces.
Cisco IO S uses the port priority v alue whe n the interfa ce is conf igur ed as an access port and us es VLAN
port priority values when the interface is con figured as a trunk port.
Beginning in privileged EXEC mode, follow these steps to configure the port priority of an interfa ce:
Command Purpose
Step 1 configure terminal Enter g lob al c onfigura tion m ode .
Step 2 spanning-tree vlan vlan-id root secondary
[diameter net-diameter [hello-time
seconds]]
Configure a switc h to becom e the seconda ry root for the speci fied
VLAN.
•For vlan-id, the range is 1 to 4 094 when th e E I is insta lled an d 1
to 1005 when the SI is installed. Do not enter leading zeros.
•(Optio na l) For diameter net-diameter, specify the maximum
number of swit ches bet ween any t wo en d sta tions. T he r ange is
2 to 7.
•(Optio na l) For hello-time seconds, specify the interval in
seconds be tween th e genera tion of co nfiguration messages by
the root sw itch. The rang e is 1 to 10 seco nds; the default is 2
seconds.
Use the sam e network dia meter and hello-t ime values that you used
when configuring the primary root switch. See the “Configuring the
Root Switch” section on pa ge 11-1 2.
Step 3 end Return to pr ivileged EX EC m ode.
Step 4 show spanning-tree detail Verify your entries.
Step 5 copy running-config startup-config (Optional) Save your entries in the configuration file.
Command Purpose
Step 1 configure terminal Enter glo bal co nfigur ati on mo de.
Step 2 interface interface-id En ter int erfac e c onfigura tion m ode , a nd specif y a n
interface to configure.
Valid in terfaces in clude physi cal int erfaces and
port-channel logical interfaces (port-channel
port-channel-number).