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Chapter 3 General Management of the Switch 3-125
3.4.6 Managing Interfaces for Spanning Tree Algorithm
You can configure RSTP attributes for specific interfaces, including port priority,
path cost, link type, and edge port. You can use a different priority or path cost for
ports of same media type to indicate the preferred path, link type to indicate a point-
to-point connection or shared-media connection, and edge port to indicate if the
connected device can support fast forwarding.
3.4.6.1 Displaying the Current Interface Settings for STA
When viewing STA interface settings through the web interface or CLI, the following
parameters are displayed:
■ Port – The interface (ports only, no aggregated links or members of aggregated
links). Up-link ports NETP0 to NETP7 or down-link ports SNP0 to SNP15.
■ STA Status – The current state of the port within the Spanning Tree:
■ Discarding – The port receives STA configuration messages, but does not
forward packets.
■ Learning – The port has transmitted configuration messages for an interval set
by the Forward Delay parameter without receiving contradictory information.
The port address table is cleared and the port begins learning addresses.
■ Forwarding – The port forwards packets and continues learning addresses.
■
Priority – The priority used for the port in the Spanning Tree Algorithm. If the
path cost for all ports on a switch is the same, the port with the highest priority
(lowest value) is configured as an active link in the Spanning Tree. This makes a
port with higher priority less likely to be blocked if the Spanning Tree Algorithm
is detecting network loops. Where more than one port is assigned the highest
priority, the port with lowest numeric identifier is enabled.
■
Path Cost – This parameter is used by the STA to determine the best path between
devices. Therefore, assign lower values to ports attached to faster media and
higher values to ports with slower media. (Path cost takes precedence over port
priority.)
■
Designated Cost – The cost for a packet to travel from the port to the root in the
current Spanning Tree configuration. The slower the media, the higher the cost.
■
Designated Bridge – The priority and MAC address of the device through which
this port must communicate to reach the root of the Spanning Tree.
■
Designated Port – The priority and number of the port on the designated bridging
device through which the switch must communicate with the root of the Spanning
Tree.