Dell PowerConnect FCS624S Configuration Guide - Page 337

802.1s Multiple Spanning Tree Protocol 8 The no option moves a VLAN or VLAN group from its assigned MSTI back into the CIST. NOTE The system does not allow an MSTI without any VLANs mapped to it. Consequently, removing all VLANs from an MSTI, deletes the MSTI from the system. The CIST by contrast will exist regardless of whether or not any VLANs are assigned to it or not. Consequently, if all VLANs are moved out of a CIST, the CIST will still exist and functional. Configuring bridge priority for an MSTP instance Priority can be configured for a specified instance. To configure priority for an MSTP instance, use a command such as the following at the Global Configuration level. PowerConnect(config)#mstp instance 1 priority 8192 Syntax: [no] mstp instance priority The variable is the number for the instance of MSTP that you are configuring. You can set a priority to the instance that gives it forwarding preference over lower priority instances within a VLAN or on the switch. A higher number for the priority variable means a lower forwarding priority. Acceptable values are 0 - 61440 in increments of 4096. The default value is 32768. 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 forward-delay hello-time max-age max-hops The force-version parameter forces the bridge to send BPDUs in a specific format. You can specify one of the following 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 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 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 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. PowerConnect B-Series FCX Configuration Guide 295 53-1002266-01