Cisco Nexus 5000 Series Switch CLI Software Configuration Guide, NX-OS 4.0(1a)N1 (OL-16597-01, January 2009)

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Cisco Nexus 5000 Series Switch CLI Software Configuration Guide
OL-16597-01
Chapter 9 Configuring MST
Configuring MST
This example shows how to set the MST interface port priority for MSTI 3 on Ethernet port 3/1 to 64:
switch# configure terminal
switch(config)# interface ethernet 3/1
switch(config-if)# spanning-tree mst 3 port-priority 64
You can only apply this command to a physical Ethernet interface.
Configuring the Port Cost
The MST path cost default value is derived from the media speed of an interface. If a loop occurs, MST
uses the cost when selecting an interface to put in the forwarding state. You can assign lower cost values
to interfaces that you want selected first and higher cost to interfaces values that you want selected last.
If all interfaces have the same cost value, MST puts the interface with the lowest interface number in the
forwarding state and blocks the other interfaces.
Note MST uses the long pathcost calculation method.
To configure the port cost, perform this task:
Step 2
switch(config)# interface {{type
slot/port} | {port-channel number}}
Specifies an interface to configure, and enters
interface configuration mode.
Step 3
switch(config-if)# spanning-tree mst
instance-id port-priority priority
Configures the port priority as follows:
• For instance-id, you can specify a single MSTI, a
range of MSTIs separated by a hyphen, or a series
of MSTIs separated by a comma. The range is
from 1 to 4094.
• For priority, the range is 0 to 224 in increments of
32. The default is 128. A lower number indicates
a higher priority.
The priority values are 0, 32, 64, 96, 128, 160, 192,
and 224. The system rejects all other values.
Command Purpose
Command Purpose
Step 1
switch# configure terminal
Enters configuration mode.