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C
ONFIGURING THE
•
Port Role – Roles are assigned according to whether the port is part
of the active topology connecting the bridge to the root bridge (i.e.,
root port), connecting a LAN through the bridge to the root bridge
(i.e., designated port), or is the MSTI regional root (i.e., master port);
or is an alternate or backup port that may provide connectivity if
other bridges, bridge ports, or LANs fail or are removed. The role is
set to disabled (i.e., disabled port) if a port has no role within the
spanning tree.
Alternate port receives more
useful BPDUs from another
bridge and is therefore not
selected as the designated
port.
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.
•
External 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.)
3-128
S
WITCH
R
A
x
R
A
D
x
Backup port receives more
useful BPDUs from the same
bridge and is therefore not
selected as the designated
port.
R
D
B
R: Root Port
A: Alternate Port
D: Designated Port
B: Backup Port
R
B
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