Stride Industrial Ethernet Switches User Manual 2nd Ed. Rev. B
Chapter 3 - Managed Switch Software Monitoring
Name: The user configured name of the port.
Status: The configured state of the port in the STP protocol (included or excluded). An
included port is part of the managed network. An excluded port will not be used as part
of the managed network. For example, a single uplink from a managed network of factory
devices to a business network would be configured to be excluded from STP use. A pair of
ports configured for Real-Time Ring should be excluded from Spanning Tree.
State: The STP/RSTP state of the port:
STP:
• Blocking = A port in this state does not participate in frame relay (pass frames received to other
locations). Once a port is in this state, it prevents frame duplication caused by multiple paths in an
active topology.
• Listening = A port in this state is about to participate in frame relay, but is not involved in any
relay of frames (no frames will be forwarded). The reason for not entering frame relay immediately
is to ensure that there are no temporary loops introduced when the network topology is changing.
During this state, the switch will disable all learning states on its ports to prevent the race
conditions when ports are changing roles and the forwarding process will discard all frames and not
submit any frames for transmission. Meanwhile BPDUs (Configuration Messages - Bridge Protocol
Data Units) can still be received and forwarded to keep the algorithm running.
• Learning = A port in this state is about to participate in frame relay, but it is not involved in any
relay of frames. Frame relays are not performed to prevent the creation of temporary loops during
the active topology of a changing bridged LAN. In addition, the forwarding process will discard all
frames and not submit any frames for transmission. The reason for enabling learning is to acquire
information prior to any frame relay activities. Information gathered will be used and placed in the
filtering database (MAC table) to reduce the number of frames being unnecessarily relayed.
• Forwarding = A port in the forwarding state is currently participating in frame relay. BPDUs
will include the forwarding port in the computation of the active topology. BPDUs received are
processed according to the Spanning Tree algorithm and transmitted based on the hello time or
BPDU information received.
RSTP:
• Discarding = In this state, station location information is not added to the Filtering Database
(MAC table) because any changes in port role will make the Filtering Database information
inaccurate.
• Learning = In this state, information is being added to the Filtering Database under the assumption
that the port role is not changing. Gathering information before frame relay (forwarding state) will
reduce the number of frames sent out when entering the forwarding state.
• Forwarding = Frames will be forwarded to and from the particular port that is in the forwarding
state. In addition, during the forwarding state, the learning process is still incorporating station
information into the Filtering database.
Cost: The cost of using this port to reach other parts of the managed network. The cost
is used in calculating the best path from the switch to the root bridge. The lower the cost,
the more likely that the path will be used. See the configuration section for Spanning Tree
settings for more detail.
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