Installation guide

Configuring the Switch

3-176

The following interface attributes can be configured:

• Spanning Tree – Enables/disables STA on this interface. (Default: Enabled).

• BPDU Flooding - Enables/disables the flooding of BPDUs to other ports when

global spanning tree is disabled (page 3-168) or when spanning tree is disabled on

a specific port. When flooding is enabled, BPDUs are flooded to all other ports on

the switch or to all other ports within the receiving port’s native VLAN as specified

by the Spanning Tree BPDU Flooding attribute (page 3-168).

This attribute can only be configured through the command line interface (see the

spanning-tree port-bpdu-flooding command on page 4-232)

• Priority – Defines the priority used for this port in the Spanning Tree Protocol. If

the path cost for all ports on a switch are the same, the port with the highest priority

(i.e., lowest value) will be configured as an active link in the Spanning Tree. This

makes a port with higher priority less likely to be blocked if the Spanning Tree

Protocol is detecting network loops. Where more than one port is assigned the

highest priority, the port with lowest numeric identifier will be enabled.

- Default: 128

- Range: 0-240, in steps of 16

• Admin Path Cost – This parameter is used by the STA to determine the best path

between devices. Therefore, lower values should be assigned to ports attached to

faster media, and higher values assigned to ports with slower media. (Path cost

takes precedence over port priority.)

(Range: 0 for auto-configuration, 1-65535 for the short path cost method

1-200,000,000 for the long path cost method)

By default, the system automatically detects the speed and duplex mode used on

each port, and configures the path cost according to the values shown below. Path

cost “0” is used to indicate auto-configuration mode. When the short path cost

method is selected and the default path cost recommended by the IEEE 8021w

standard exceeds 65,535, the default is set to 65,535.

15. Refer to “Configuring Global Settings” on page 3-168 for information on setting the path

cost method.

Table 3-12 Recommended STA Path Cost Range

Port Type IEEE 802.1D-1998 IEEE 802.1w-2001

Ethernet 50-600 200,000-20,000,000

Fast Ethernet 10-60 20,000-2,000,000

Gigabit Ethernet 3-10 2,000-200,000