Allied Telesis AT-S63 - Manual (Page 168)

Chapter 14: STP and RSTP
168 Section II: Advanced Features
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 5.
Bridge Hello Time
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
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
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.
In selecting a value for maximum age, the following rules must be
observed:
MaxAge must be greater than (2 x (HelloTime + 1))
Table 5. Bridge Priority Value Increments
Increment
Bridge
Priority
Increment
Bridge
Priority
0 0 8 32768
1 4096 9 36864
2 8192 10 40960
3 12288 11 45056
4 16384 12 49152
5 20480 13 53248
6 24576 14 57344
7 28672 15 61440