Reference Guide

Per-VLAN Spanning Tree Plus (PVST+) | 711
Figure 39-4. Display the PVST+ Forwarding Topology
Modifying Global PVST+ Parameters
The root bridge sets the values for forward-delay, and hello-time and overwrites the values set on other
PVST+ bridges.
• Forward-delay is the amount of time an interface waits in the Listening State and the Learning State
before it transitions to the Forwarding State.
• Hello-time is the time interval in which the bridge sends Bridge Protocol Data Units (BPDUs).
• Max-age is the length of time the bridge maintains configuration information before it refreshes that
information by recomputing the PVST+ topology.
To change PVST+ parameters, use the following commands on the root bridge:
Task Command Syntax Command Mode
Change the forward-delay parameter.
• VLAN range: 1 to 4094.
• Forward-delay range (in seconds): 4 to 30. Default: 15
seconds.
vlan vlan-range
forward-delay value
PROTOCOL PVST
Change the hello-time parameter.
Note: With large configurations (especially those with more
ports) Dell Networking recommends that you increase the
hello-time.
VLAN range: 1 to 4094.
Hello-time range (in seconds): 1 to 10. Default: 2 seconds
vlan vlan-range
hello-time value
PROTOCOL PVST
Dell(conf)#do show spanning-tree pvst vlan 100
VLAN 100
Root Identifier has priority 4096, Address 0001.e80d.b6d6
Root Bridge hello time 2, max age 20, forward delay 15
Bridge Identifier has priority 4096, Address 0001.e80d.b6d6
Configured hello time 2, max age 20, forward delay 15
We are the root of VLAN 100
Current root has priority 4096, Address 0001.e80d.b6d6
Number of topology changes 5, last change occurred 00:34:37 ago on Te 1/32
Port 375 (TenGigabitEthernet 1/22) is designated Forwarding
Port path cost 20000, Port priority 128, Port Identifier 128.375
Designated root has priority 4096, address 0001.e80d.b6:d6
Designated bridge has priority 4096, address 0001.e80d.b6:d6
Designated port id is 128.375 , designated path cost 0
Number of transitions to forwarding state 2
BPDU sent 1159, received 632
The port is not in the Edge port mode
Port 385 (TenGigabitEthernet 1/32) is designated Forwarding
Port path cost 20000, Port priority 128, Port Identifier 128.385
Designated root has priority 4096, address 0001.e80d.b6:d6
Designated bridge has priority 4096, address 0001.e80d.b6:d6
Designated port id is 128.385 , designated path cost 0