Set The Port Characteristics - Symbol ES3000 Manual

5-8 ES3000 Advanced Concept Guide

5.5.3 Set the Port Characteristics

To speed the convergence of the spanning tree configuration or to push the spanning tree algorithm
to make certain choices, the different ports characteristics can be tuned. The characteristics to be
tuned are:
• Priority: An integer between 0 and 240. When choosing between two paths, the spanning
tree algorithm will choose the path through the port with the higher priority (lower numeric
value). Set the priority to a lower number to increase the likelihood that the port will be used.
Defaults to 128.
• Path Cost: An integer between 1 and 200000000. This number represents the cost of
spending a packet through this port. A higher value means that the port link is a slower
speed. By default 10BaseT links have a cost of 2000000, 100BaseT links have a cost of
200000 and Gigabit links have a cost of 20000. If two port have the same priority, the
spanning tree algorithm will cost the port with the lower cost.
• STP Status: Determines whether spanning tree protocols can work on this port. Spanning
tree operations are disabled for the switch as a whole, setting this flag to Enabled will not
turn on spanning tree protocols for this port along. However, setting this flag to Disabled will
disable spanning tree protocols for this port, even if spanning tree protocols are enabled for
the switch as a whole. Disabling a STP operations on individual ports should be done with
caution, as the potential for loops and subsequent broadcast storms is significant.
• Admin/OperEdge: Indicates that the port connects to a device on the edge of the network,
e.g., a workstation or an access port. If the port is connected to an edge unit and if this is
set to True, the RSTP spanning tree algorithm will converge more quickly on a spanning tree.
Defaults to False.
• Admin/OperPtoP: Indicates that the port connects to another switch. This variable may be
set to Auto, True, or False and defaults to Auto. If it is set to Auto, the switch itself will
determine a True or False value to use. If the port connects to another switch and the used
value is True, then the RSTP spanning tree algorithm can more quickly reconfigure after a
topology change. Unless the autodetection is failing, this is usually best left at Auto.
Priority, Path Cost, and STP Status are set using the CIST Basic Port Configuration screen (Spanning
Tree > MSTP Config. > CIST Basic Port Config). OperEdge and OperPtoP are set using the CIST
Advanced Port Configuration screen (Spanning Tree > MSTP Config. > CIST Advanced Port Config.).
In either case, these parameters are set using the same port configuration interface used elsewhere.
That is, use the checkboxes at the top of the screen to select the ports which will be changed, select
checkbox to the left of the variable that is to be modified, set the variable's value using the pull-down
menus, then click on the Apply button. The port list will redisplay with the new variable values.