Brocade Communications Systems Brocate Ethernet Access Switch 6910 - Manual (Page 392)

342 Brocade 6910 Ethernet Access Switch Configuration Guide
53-1002581-01
Spanning Tree Commands
18
Default Setting
20
Command Mode
MST Configuration
Command Usage
An MSTI region is treated as a single node by the STP and RSTP protocols. Therefore, the message
age for BPDUs inside an MSTI region is never changed. However, each spanning tree instance
within a region, and the internal spanning tree (IST) that connects these instances use a hop count
to specify the maximum number of bridges that will propagate a BPDU. Each bridge decrements
the hop count by one before passing on the BPDU. When the hop count reaches zero, the message
is dropped.
Example
Console(config-mstp)#max-hops 30
Console(config-mstp)#
mst priority
This command configures the priority of a spanning tree instance. Use the no form to restore the
default.
Syntax
mst instance-id priority priority
no mst instance-id priority
instance-id - Instance identifier of the spanning tree. (Range: 0-4094)
priority - Priority of the a spanning tree instance.
(Range: 0-61440 in steps of 4096; Options: 0, 4096, 8192, 12288, 16384, 20480,
24576, 28672, 32768, 36864, 40960, 45056, 49152, 53248, 57344, 61440)
Default Setting
32768
Command Mode
MST Configuration
Command Usage
• MST priority is used in selecting the root bridge and alternate bridge of the specified instance.
The device with the highest priority (i.e., lowest numerical value) becomes the MSTI root
device. However, if all devices have the same priority, the device with the lowest MAC address
will then become the root device.
• You can set this switch to act as the MSTI root device by specifying a priority of 0, or as the
MSTI alternate device by specifying a priority of 16384.
Example
Console(config-mstp)#mst 1 priority 4096
Console(config-mstp)#