3Com CoreBuilder 3500, Руководство по внедрению

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136 C
HAPTER
7: B
RIDGE
-W
IDE AND
B
RIDGE
P
ORT
P
ARAMETERS
Administering STP
Parameters
on Bridge Ports
You can enable, disable, or remove the Spanning Tree Protocol for one or
more ports on the system. This setting affects the operation of a port only
if the STP is enabled for the bridge. You can also set the following STP
port parameters:
■
Port path cost — The STP algorithm adds the path cost to the root
cost field in a configuration message that is received on this port. The
system uses this value to determine the path cost to the root through
this port. You can set this value individually on each port. The range is
1 through 65535.
A higher path cost value makes the LAN that is reached through the
port more likely to be low in the Spanning Tree topology. The lower
the LAN is in the topology, the less through traffic it carries. For this
reason, assign a high path cost to a LAN that has a lower bandwidth
or to one on which you want to minimize traffic.
■
Port priority — The STP port priority influences the choice of port
when the bridge has two ports connected to the same LAN, which
creates a loop. The port with the lowest port priority is selected by STP.
Port priority is a 1-octet value. The range for the port priority is 0x0
through 0xff hexadecimal. The default is
0x80
.