SMC Networks TigerSwitch 1000, Management Manual

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S
PANNING
T
REE
A
LGORITHM
C
ONFIGURATION
3-123
Trunk Member – Indicates if a port is a member of a trunk.
(STA Port Information only)
These additional parameters are only displayed for the CLI:
•
Admin status – Shows if this interface is enabled.
• Path cost – The path cost for the IST. This parameter is used by the
STA to determine the best path between devices. Therefore, lower
values should be assigned to ports attached to faster media, and higher
values assigned to ports with slower media. (Path cost takes
precedence over port priority.)
• Priority – Defines the priority used for this 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 (i.e., lowest value) will be 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 the lowest numeric identifier will be
enabled.
Alternate port receives more
useful BPDUs from another
bridge and is therefore not
selected as the designated
port.
x
R: Root Port
A: Alternate Port
D: Designated Port
B: Backup Port
R R
A D B
Backup port receives more
useful BPDUs from the same
bridge and is therefore not
selected as the designated
port.
x
R R
A D B