Specifying The Link Type To Ensure Rapid Transitions; Designating The Neighbor Type - Cisco ME 3400 Software Configuration Manual

Chapter 15 Configuring MSTP

Specifying the Link Type to Ensure Rapid Transitions

If you connect an STP port to another STP port through a point-to-point link and the local port becomes
a designated port, the RSTP negotiates a rapid transition with the other port by using the
proposal-agreement handshake to ensure a loop-free topology as described in the
section on page
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 running MSTP, you can override the default setting of the link type and enable rapid
transitions to the forwarding state.
Beginning in privileged EXEC mode, follow these steps to override the default link-type setting. This
procedure is optional.
Command
Step 1 configure terminal
Step 2 interface interface-id
Step 3 spanning-tree link-type point-to-point
Step 4 end
Step 5
show spanning-tree mst interface interface-id
Step 6
copy running-config startup-config
To return the port to its default setting, use the no spanning-tree link-type interface configuration
command.

Designating the Neighbor Type

A topology could contain both prestandard and IEEE 802.1s standard compliant devices. By default,
ports can automatically detect prestandard devices, but they can still receive both standard and
prestandard BPDUs. When there is a mismatch between a device and its neighbor, only the CIST runs
on the interface.
OL-9639-07
15-10.
Purpose
Enter global configuration mode.
Specify an interface to configure, and enter interface
configuration mode. Valid interfaces include physical NNIs or
ENIs with spanning tree enabled, VLANs, and NNI or ENI port
channels. The VLAN ID range is 1 to 4094. The port-channel
range is 1 to 48.
Note
Specify that the link type of a port is point-to-point.
Return to privileged EXEC mode.
Verify your entries.
(Optional) Save your entries in the configuration file.
Cisco ME 3400 Ethernet Access Switch Software Configuration Guide
If a physical interface is a UNI, before attempting to
configure MST port priority, you must enter the
port-type nni interface configuration command or
configure the port as an ENI and enable spanning tree on
the port. See "Enabling Spanning Tree on an ENI"
section on page 14-13.
If the interface is a VLAN, only ports with spanning tree
enabled in the VLAN will run spanning tree.
If the interface is a port channel, all members of the port
channel must be NNIs or ENIs with spanning tree
enabled.
Configuring MSTP Features
"Rapid Convergence"
15-25