Chapter
3: Web Management
Spanning Tree - CIST Ports
PoE Switch User Manual | 124
Path Cost
Controls the path cost incurred by the port. The Auto setting will set the path cost as
appropriate by the physical link speed, using the 802.1D recommended values. Using the
Specific setting, a user-defined value can be entered. The path cost is used when
establishing the active topology of the network. Lower path cost ports are chosen as
forwarding ports in favour of higher path cost ports. Valid values are in the range 1 to
200000000.
Priority
Controls the port priority. This can be used to control priority of ports having identical port cost.
(See above).
operEdge (state flag)
Operational flag describing whether the port is connecting directly to edge devices. (No
Bridges attached). Transition to the forwarding state is faster for edge ports (having operEdge
true) than for other ports. The value of this flag is based on AdminEdge and AutoEdge fields.
This flag is displayed as Edge in Monitor->Spanning Tree -> STP Detailed Bridge Status.
AdminEdge
Controls whether the operEdge flag should start as set or cleared. (The initial operEdge state
when a port is initialized).
AutoEdge
Controls whether the bridge should enable automatic edge detection on the bridge port. This
allows operEdge to be derived from whether BPDU's are received on the port or not.
Restricted Role
If enabled, causes the port not to be selected as Root Port for the CIST or any MSTI, even if it
has the best spanning tree priority vector. Such a port will be selected as an Alternate Port
after the Root Port has been selected. If set, it can cause lack of spanning tree connectivity. It
can be set by a network administrator to prevent bridges external to a core region of the
network influence the spanning tree active topology, possibly because those bridges are not
under the full control of the administrator. This feature is also known as Root Guard.
Restricted TCN
If enabled, causes the port not to propagate received topology change notifications and
topology changes to other ports. If set it can cause temporary loss of connectivity after
changes in a spanning tree's active topology as a result of persistently incorrect learned
station location information. It is set by a network administrator to prevent bridges external to
a core region of the network, causing address flushing in that region, possibly because those
bridges are not under the full control of the administrator or the physical link state of the
attached LANs transits frequently.
