Setting The Pvst+ Bridge Id Priority - Cisco WS-C6506 Software Manual

Chapter 7 Configuring Spanning Tree

Setting the PVST+ Bridge ID Priority

The bridge ID priority is the priority of a VLAN when the switch is in PVST+ mode.
When the switch is in PVST+ mode without MAC address reduction enabled, you can enter a bridge
priority value between 0–65535. The bridge priority value that you enter also becomes the VLAN bridge
ID priority for that VLAN.
When the switch is in PVST+ mode with MAC address reduction enabled, you can enter one of 16 bridge
priority values: 0, 4096, 8192, 12288, 16384, 20480, 24576, 28672, 32768, 36864, 40960, 45056, 49152,
53248, 57344, or 61440.
The bridge priority is combined with the system ID extension (that is, the ID of the VLAN) to create the
bridge ID priority for the VLAN.
To set the spanning-tree bridge priority for a VLAN, perform this task in privileged mode:
Task
Step 1 Set the PVST+ bridge ID priority for a VLAN. set spantree priority bridge_ID_priority [vlan]
Step 2 Verify the bridge ID priority.
This example shows how to set the PVST+ bridge ID priority when MAC address reduction is not
enabled (default):
Console> (enable) set spantree priority 30000 1
Spantree 1 bridge priority set to 30000.
Console> (enable) show spantree 1
VLAN 1
Spanning tree mode
Spanning tree type
Spanning tree enabled
Designated Root
Designated Root Priority
Designated Root Cost
Designated Root Port
Root Max Age
Bridge ID MAC ADDR
Bridge ID Priority
Bridge Max Age 20 sec
Port
------------------------ ---- ------------- --------- ---- -------- ----------
1/1
1/2
2/1
2/2
This example shows how to set the PVST+ bridge ID priority when MAC reduction is enabled:
Console> (enable) set spantree priority 32768 1
Spantree 1 bridge ID priority set to 32769
(bridge priority: 32768 + sys ID extension: 1)
Console> (enable) show spantree 1/1 1
VLAN 1
Spanning tree mode
Spanning tree type
Spanning tree enabled
OL-8978-04
PVST+
ieee
00-60-70-4c-70-00
16384
19
2/3
14 sec Hello Time 2 sec
00-d0-00-4c-18-00
30000
Hello Time 2 sec
Vlan Port-State
1 not-connected
1 not-connected
1 not-connected
1 not-connected
PVST+
ieee
Catalyst 6500 Series Switch Software Configuration Guide—Release 8.7
Configuring PVST+ on the Switch
Command
show spantree [vlan] [active]
Forward Delay 10 sec
Forward Delay 15 sec
Cost Prio Portfast Channel_id
4 32 disabled 0
4 32 disabled 0
100 32 disabled 0
100 32 disabled 0
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