Allied Telesis AT-8100L/8POE, User Manual

Page: 146 / 330

Chapter 12: Spanning Tree Protocols on the Switch
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Note
If you try to select MSTP from the menu, a message will appear
indicating that MSTP can only be set via the Command Line
Interface and will not allow the selection. To set the protocol to
MSTP, and for more information on MSTP, see
Section VII:
Spanning Tree Protocols in the AT-8100 Series Version 2.2.5.0
Management Software Command Line Interface User’s Guide and
refer to the STP, RSTP and MSTP Protocols , and MSTP
Commands chapters.

Status — Enable or disable the spanning tree protocol on the
switch. By default, the spanning tree protocol is enabled.

Bridge Priority — Assign the switch a bridge priority number. The
device that has the lowest priority number in the spanning tree
domain becomes the root bridge. You can use the priority number
to influence which switch becomes the root bridge. If two or more
devices have the same priority value, the device with the
numerically lowest MAC address becomes the root bridge.
The actual range is 0 to 61440, in increments of 4096, for a total of
16 increments, shown in Table 2. You specify the increment of the
value, from 0 to 15. The default is 32768, which is increment 8.
Note
Set the hello time, forward delay, and max-age fields according to
the following formulas, as specified in IEEE Standard 802.1d:
max-age <= 2 x (forward time - 1.0 second)
max-age => 2 x (hello time + 1.0 second)
Table 2. STP 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