Users Guide

• Change the hello-time parameter.
PROTOCOL PVST mode
vlan hello-time
NOTE: With large configurations (especially those configurations with more ports), Dell Networking
recommends increasing the hello-time.
The range is from 1 to 10.
The default is 2 seconds.
• Change the max-age parameter.
PROTOCOL PVST mode
vlan max-age
The range is from 6 to 40.
The default is 20 seconds.
The values for global PVST+ parameters are given in the output of the show spanning-tree pvst
command.
Modifying Interface PVST+ Parameters
You can adjust two interface parameters (port cost and port priority) to increase or decrease the probability
that a port becomes a forwarding port.
• Port cost — a value that is based on the interface type. The greater the port cost, the less likely the port
is selected to be a forwarding port.
• Port priority — influences the likelihood that a port is selected to be a forwarding port in case that
several ports have the same port cost.
The following tables lists the default values for port cost by interface.
Table 54. Default Values for Port Cost
Port Cost Default Value
100-Mb/s Ethernet interfaces 200000
1-Gigabit Ethernet interfaces 20000
10-Gigabit Ethernet interfaces 2000
25-Gigabit Ethernet interfaces 1700
40-Gigabit Ethernet interfaces 1400
50-Gigabit Ethernet interfaces 1200
100-Gigabit Ethernet interfaces 200
Port Channel with 100 Mb/s Ethernet interfaces 180000
Per-VLAN Spanning Tree Plus (PVST+) 738