User's Manual

This example shows how to prevent the specified interfaces from automatically interoperating with a connecting
switch that is not running MST:
switch# configure terminal
switch(config)# interface ethernet 1/4
switch(config-if)# spanning-tree mst simulate pvst disable
Specifying the Link Type
Rapid connectivity (802.1w standard) is established only on point-to-point links. By default, the link type is
controlled from the duplex mode of the interface. A full-duplex port is considered to have a point-to-point
connection; a half-duplex port is considered to have a shared connection.
If you have a half-duplex link physically connected point-to-point to a single port on a remote switch, you
can override the default setting on the link type and enable rapid transitions.
If you set the link to shared, STP reverts to 802.1D.
Procedure
PurposeCommand or Action
Enters configuration mode.switch# configure terminal
Step 1
Specifies the interface to configure, and enters interface
configuration mode.
switch(config)# interface type
slot/port
Step 2
Configures the link type to be either point to point or shared.
The system reads the default value from the switch
switch(config-if)# spanning-tree
link-type {auto | point-to-point |
shared}
Step 3
connection. Half-duplex links are shared and full-duplex
links are point to point. If the link type is shared, the STP
reverts to 802.1D. The default is auto, which sets the link
type based on the duplex setting of the interface.
This example shows how to configure the link type as point to point:
switch# configure terminal
switch (config)# interface ethernet 1/4
switch(config-if)# spanning-tree link-type point-to-point
Restarting the Protocol
An MST bridge can detect that a port is at the boundary of a region when it receives a legacy BPDU or an
MST BPDU that is associated with a different region. However, the STP protocol migration cannot determine
whether the legacy switch, which is a switch that runs only IEEE 802.1D, has been removed from the link
unless the legacy switch is the designated switch. Enter this command to restart the protocol negotiation (force
the renegotiation with neighboring switches) on the entire switch or on specified interfaces.
Cisco Nexus 3000 NX-OS Layer 2 Switching Configuration Guide, Release 5.0(3)U3(1)
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Configuring Multiple Spanning Tree
Specifying the Link Type