Quick Reference Guide

166 PowerConnect B-Series TI24X Configuration Guide
53-1002269-02
802.1s Multiple Spanning Tree Protocol
6
Setting the MSTP global parameters
MSTP has many of the options available in RSTP as well as some unique options. To configure
MSTP Global parameters for all instances on a switch.
PowerConnect(config)#mstp force-version 0 forward-delay 10 hello-time 4 max-age
12 max-hops 9
Syntax: [no] mstp force-version <mode-number> forward-delay <value> hello-time <value>
max-age <value> max-hops <value>
The force-version parameter forces the bridge to send BPDUs in a specific format. You can specify
one of the following <mode-number> values:
• 0 – The STP compatibility mode. Only STP BPDUs will be sent. This is equivalent to single STP.
• 2 – The RSTP compatibility mode. Only RSTP BPDUS will be sent. This is equivalent to single
STP.
• 3 – MSTP mode. In this default mode, only MSTP BPDUS will be sent.
The forward-delay <value> specifies how long a port waits before it forwards an RST BPDU after a
topology change. This can be a value from 4 – 30 seconds. The default is 15 seconds.
The hello-time <value> parameter specifies the interval between two hello packets. The parameter
can have a value from 1 – 10 seconds. The default is 2 seconds.
The max-age <value> parameter specifies the amount of time the device waits to receive a hello
packet before it initiates a topology change. You can specify a value from 6 – 40 seconds, where
the value adheres to the following formula.
max age equal to or greater than 2 x (hello-time + 1) AND max age equal to or greater than 2 x
(forward-delay – 1)
The default max-age is 20 seconds.
The max-hops <value> parameter specifies the maximum hop count. You can specify a value from
1 – 40 hops. The default value is 20 hops.
Setting ports to be operational edge ports
You can define specific ports as edge ports for the region in which they are configured to connect to
devices (such as a host) that are not running STP, RSTP, or MSTP. If a port is connected to an end
device such as a PC, the port can be configured as an edge port. To configure ports as operational
edge ports enter a command such as the following.
PowerConnect(config)#mstp admin-edge-port ethernet 1
Syntax: [no] mstp admin-edge-port ethernet <portnum>
The <portnum> parameter specifies a port or range of ports as edge ports in the instance in which
they are configured.
Setting automatic operational edge ports
You can configure a Layer 3 switch to automatically set a port as an operational edge port if the
port does not receive any BPDUs since link-up. If the port receives a BPDU later, it is automatically
reset to become an operational non-edge port. This feature is set globally to apply to all ports on a
router where it is configured. This feature is configured as shown in the following.
PowerConnect(config)#mstp edge-port-auto-detect