User Manual

Chapter 12: Spanning Tree and Rapid Spanning Tree Protocols
188 Section IV: Spanning Tree Protocols
5. Configure the STP parameters, described in Table 30, as needed.
Table 30. STP Parameters
Parameter Definition
Bridge Priority Specifies the priority number for the
bridge. This number is used in
determining the root bridge for STP. The
bridge with the lowest priority number is
selected as the root bridge. If two or more
bridges have the same priority value, the
bridge with the numerically lowest MAC
address becomes the root bridge. When a
root bridge goes off-line, the bridge with
the next priority number automatically
takes over as the root bridge. This
parameter can be from 0 (zero) to 61,440
in increments of 4096, with 0 being the
highest priority. For a list of the
increments, refer to Table 31 on
page 190.
Bridge Hello Time Specifies the time interval between
generating and sending configuration
messages by the bridge. This parameter
can be from 1 to 10 seconds. The default
is 2 seconds.
Bridge Forwarding Delay Specifies the waiting period in seconds
before a bridge changes to a new state,
for example, becomes the new root bridge
after the topology changes. If the bridge
transitions too soon, not all links may
have yet adapted to the change, resulting
in network loops. The range is 4 to 30
seconds. The default is 15 seconds.
Bridge Max Age Specifies the length of time after which
stored bridge protocol data units (BPDUs)
are deleted by the bridge. All bridges in a
bridged LAN use this aging time to test
the age of stored configuration messages
called bridge protocol data units (BPDUs).
For example, if you use the default value
20, all bridges delete current configuration
messages after 20 seconds. This
parameter can be from 6 to 40 seconds.