Allied Telesis AT-S39 - Manual (Page 108)

Section II: Local and Telnet Management
108
2. Adjust the bridge STP settings as needed. The parameters are
described below.
1 - Bridge Priority
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. The range is
0 (zero) to 65,535, with 0 being the highest priority.
2 - Bridge Hello Time
The time interval in seconds between generating and sending
configuration messages by the bridge. The range is 1 to 10
seconds. The default is 2 seconds.
3 - Bridge Forwarding
The waiting period 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.
4 - Bridge Max Age
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 20, all bridges delete current configuration
messages after 20 seconds. The range is 6 to 40 seconds. The
default is 20 seconds.
In selecting a value for maximum age, the following must be
observed:
MaxAge must be greater than (2 x (HelloTime + 1)).
MaxAge must be less than (2 x (ForwardingDelay - 1)).
Note
The aging time for BPDUs is different from the aging time used by
the MAC address table.
5 - Bridge Identifier
The MAC address of the switch. This parameter cannot be
changed.