Notes On Multiple Spanning Tree Usage - Alaxala AX2200S Series Configuration Manual

19 Spanning Tree Protocol

19.9.4 Notes on Multiple Spanning Tree usage

(1) Notes on use with other functionality
For details, see 15.3 Compatibility between Layer 2 switch functionality and other
functionality.
(2) MST regions
The range of VLANs that can be handled by the Switch and other switches might differ. To
handle such switches as the same MST region, make sure that the corresponding VLANs
belong to MST instance 0.
(3) When time is required for topology convergence
When the events listed in the following table occur for CIST root bridges or MST instances,
the topology might take a long time to settle, during which time communication might stop
and MAC address tables might be cleared.
Table 19-16 Events occurring on root bridges
Event
Configuration
change
Additional
Information
330
Description
When the region name (1), revision
number (2), or correspondence
between instance number and VLAN
(3) is changed by configuration, and
the region is split or merged:
name
(1) command for the MST
configuration mode
revision
(2) command for the MST
configuration mode
instance
(3) command for the MST
configuration mode
When the bridge priority is reduced by
spanning-tree mst root
the
priority
command (a larger value is
currently set)
When the Switch is stopped
When all ports are down for the Switch
in a loop configuration, on the partner
switch connected to the switch (and
the Switch is no longer the root bridge
in the corresponding loop
configuration)
Root bridge type on
which the event occurs
CIST root bridge
Root bridge on MST
instance 0 (IST)
Root bridge on MST
instance 1 and those
subsequent
CIST root bridge
Root bridge on MST
instance 1 and those
subsequent
CIST root bridge
Root bridge on MST
instance 0 (IST)
Root bridge on MST
instance 1 and those
subsequent
CIST root bridge
Root bridge on MST
instance 0 (IST)
Root bridge on MST
instance 1 and those
subsequent
Affected
topology
CIST
CIST
Corresponding
MST instance
CIST
Corresponding
MST instance
CIST
CIST
Corresponding
MST instance
CIST
CIST
Corresponding
MST instance