Operations Manual
25
Status.
The
Status
column basically shows whether the port participates,
or does not participate, in the transmission and/or reception of frames or,
more exactly, Bridge Protocol Data Units (
BPDUs)
which is defined as a data
unit transmitted as part of the STP algorithm. The exchange of BPDUs
allows bridges within a network to logically configure the network as a single
spanning tree.
The state of each port governs the processing of frames received from the
individual MAC entity associated with the port, the submission of frames to
the MAC entity for transmission, and the possible inclusion of the port in the
active topology of the bridged LAN.
Five possible states may be shown in the status column:
Enabled (
which
includes
Blocking, Listening, Learning, Forwarding) and
Disabled.
Enabled
indicates a port that is currently forwarding frames — a ready (but
not necessarily currently active) — port.
Blocking
indicates a port that is NOT PARTICIPATING in
forwarding packets thusly preventing the creation of multiple
topology paths. A port enters the blocking state because it has
received information that another bridge is the designated bridge for
the LAN to which the port is attached. Received packets are
discarded and packets are not submitted for transmission. Station
locations are not added to the database.
Listening
A port in this state is PREPARING TO PARTICIPATE
in packet transmission but is temporarily disabled to prevent
temporary loops. Learning is disabled since changes in the active
topology may lead to incorrect information when the active topology
becomes stable.
Received packets are discarded and packets are not submitted for
transmission. Station location information is not added to the
database.
Learning
indicates a port is PREPARING TO PARTICIPATE in
frame relay but it is temporarily disabled in order to prevent
temporary loops. Learning is enabled to allow information to be
acquired prior to frame relay in order to reduce the number of frames
unnecessarily relayed.
Received frames are discarded and frames are not submitted for
transmission. Station location information is added to the database.
Forwarding
indicates a port that is PARTICIPATING in packet
transmission. It is both forwarding and submitting packets. The
learning process incorporates station location information into the
filtering database.
Received BPDUs will be submitted for transmission. They will also be
processed as required by the STP algorithm.
Disabled
indicates a port that is NOT PARTICIPATING in packet
transmission. Nor is it participating in the operation of the STP algorithm and
protocol.
Received packets are discarded. Submitted packets are not forwarded for
transmission.
