HP 7000 dl Router manual Spanning-tree path-cost value

SROS Command Line Interface Reference Guide Frame Relay Sub-Interface Config Command Set

spanning-tree path-cost <value>

Use the bridge-grouppath-costcommand to assign a cost to a bridge group that is used when computing the spanning-tree root path. To return to the default path-cost value, use the no form of this command.

Syntax Description

<value>	Number assigned to the bridge interface to be used as the path cost in spanning
	calculations (valid range: 0 to 65535)

Default Values

<value> 19

Command Modes

(config-interface)#	Interface Configuration Mode
	Valid interfaces include: Ethernet (eth 0/1), virtual PPP interfaces (ppp 1), and
	virtual Frame Relay interfaces (fr 1).

Functional Notes

The specified value is inversely proportional to the likelihood the bridge interface will be chosen as the root path. Set the path-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-fr1.16)#spanning-tree path-cost 100

Technology Review

Spanning-tree protocol provides a way to prevent loopback or parallel paths in bridged networks. 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.

5991-2114 © Copyright 2005 Hewlett-Packard Development Company, L.P. 642