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

Command Reference Guide Frame Relay Sub-Interface 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 a path cost value for spanning calculations to the bridge interface (valid

range: 0 to 65,535).

Default Values

Be default, the path-cost value is set at 19.

Applicable Platforms

This command applies to the NetVanta 1000R, 3000, 4000, and 5000 and Total Access 900 Series units.

Command History

Release 1.1 Command was introduced.

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 path cost of 100 for bridge group 17 on a Frame Relay sub-interface:

(config)#interface frame-relay 1.16

(config-fr 1.16)#spanning-tree path-cost 100

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.