ADTRAN 1000R Series spanning-tree path-cost <value>

Command Reference Guide ATM Sub-Interfa c e Config Command Set

spanning-tree path-cost <value>

Use the spanning tree path-cost command to assign a cost to a bridge group that is used when co mputin g

the spanning-tree root path. To return to the default path-cost value, use the no form of this command.

Syntax Description

<value> Assigns number to the bridge interface to be used as the path cost in spanning

calculations (valid range: 0 to 65,535).

Default Values

By default, the path-cost value is set to 19.

Applicable Platforms

This command applies to the NetVanta 300, 1000R, 3000, and 4000 Series units.

Command History

Release 1.1 Command was introduced.

Release 8.1 ATM sub-interface was added.

Functional Notes

The specified value is inversely proportional to the likelihood the bridge interface will be chosen as the root

path. Set the p ath-cost value lower to increase the chance the interface will be the root. To obtain the most

accurate spanning tree calculations, develop a system for determining path costs for links and apply it to all

bridged interfaces.

Usage Examples

The following example assigns a p ath cost of 100 for bridge group 17 on an ATM sub-interface:

(config)#interface atm 1.1

(config-atm 1.1)#spanning-tree path-cost 10 0

Technology Review

S p anning-tree protocol provides a way to preven t loopback or p arallel pa ths in bridged networ ks. Using the

priority values and path costs assigned to each bridging interface, the spanning-tree protocol determines

the root path and identifies whether to block or allow other paths.