User manual

C HAPTER 5 | Monitoring the Switch
Displaying Information on the Spanning Tree
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◆ Internal Root Cost – The Regional Root Path Cost. For the Regional
Root Bridge this is zero. For all other CIST instances in the same MSTP
region, it is the sum of the Internal Port Path Costs on the least cost
path to the Internal Root Bridge. (This parameter only applies to the
CIST instance.)
◆ Topology Change Count – The number of times the Spanning Tree
has been reconfigured (during a one-second interval).
CIST Ports & Aggregations State
◆ Port – Port Identifier.
◆ Port ID – The port identifier as used by the RSTP protocol. This
consists of the priority part and the logical port index of the bridge 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 an alternate or backup port that may provide
connectivity if other bridges, bridge ports, or LANs fail or are removed.
◆ State – Displays the current state of this port in the Spanning Tree:
■
Blocking – Port receives STA configuration messages, but does not
forward packets.
■
Learning – Port has transmitted configuration messages for an
interval set by the Forward Delay parameter without receiving
contradictory information. Port address table is cleared, and the
port begins learning addresses.
■
Forwarding – Port forwards packets, and continues learning
addresses.
◆ Path Cost – The contribution of this port to the path cost of paths
towards the spanning tree root which include this port. This will either
be a value computed from the Auto setting, or any explicitly configured
value.
◆ Edge – The current RSTP port (operational) Edge Flag. An Edge Port is
a switch port to which no bridges are attached. The flag may be
automatically computed or explicitly configured. Each Edge Port
transitions directly to the Forwarding Port State, since there is no
possibility of it participating in a loop.
◆ Point-to-Point – Indicates a connection to exactly one other bridge.
The flag may be automatically computed or explicitly configured. The
point-to-point properties of a port affect how fast it can transition RSTP
states.
◆ Uptime – The time since the bridge port was last initialized.