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
To configure the maximum hop count, perform this task:
This example shows how to set the maximum hops to 40:
switch# configure terminal
switch(config)# spanning-tree mst max-hops 40
Configuring PVST Simulation Globally
You can block this automatic feature either globally or per port. You can enter the global command, and
change the PVST simulation setting for the entire switch while you are in interface command mode.
To configure PVST simulation, perform this task:
This example shows how to prevent the switch from automatically interoperating with a connecting
switch that is running Rapid PVST+:
switch# configure terminal
switch(config)# no spanning-tree mst simulate pvst global
Configuring PVST Simulation Per Port
Note PVST simulation is enabled by default; all interfaces on the switch interoperate between MST and Rapid
PVST+.
MST interoperates seamlessly with Rapid PVST+. However, to prevent an accidental connection to a
switch that does not run MST as the default STP mode, you may want to disable this automatic feature.
If you disable PVST simulation, the MST-enabled port moves to the blocking state once it detects it is
connected to a Rapid PVST+-enabled port. This port remains in the inconsistent state until the port stops
receiving BPDUs, and then the port resumes the normal STP transition process.
Command Purpose
Step 1
switch# configure terminal
Enters configuration mode.
Step 2
switch(config)# spanning-tree mst
max-hops hop-count
Specifies the number of hops in a region before the
BPDU is discarded, and the information held for a
port is aged. For hop-count, the range is from 1 to 255,
and the default value is 20 hops.
Command Purpose
Step 1
switch# configure terminal
Enters configuration mode.
Step 2
switch(config)# no spanning-tree mst
simulate pvst global
Disables all interfaces on the switch from
automatically interoperating with connected switch
that is running in Rapid PVST+ mode. The default for
this is enabled; that is, by default, all interfaces on the
switch operate seamlessly between Rapid PVST+ and
MST.