1-37stp root secondarySyntaxstp [ instance instance-id ] root secondary [ bridge-diameter bridgenum [ hello-timecenti-seconds ] ]undo stp [ instance instance-id ] rootViewSystem viewParametersinstance-id: MSTI ID ranging from 0 to 16. The value of 0 refers to the CIST.bridgenum: Network diameter of the specified spanning tree. This argument ranges from 2 to 7 anddefaults to 7.centi-seconds: Hello time in centiseconds of the specified spanning tree. This argument ranges from100 to 1,000 and defaults to 200.DescriptionUse the stp root secondary command to configure the current switch as a secondary root bridge of aspecified MSTI.Use the undo stp root command to cancel the current configuration.By default, a switch does not operate as a secondary root bridge.If you do not specify the instance-id argument, the two commands apply to only the CIST.You can configure one or more secondary root bridges for an MSTI. If the switch operating as the rootbridge fails or is turned off, the secondary root bridge with the least MAC address becomes the rootbridge.You can specify the network diameter and the hello time of the switch when you are configuring it as asecondary root bridge. The switch will then figure out the other two time parameters: forward delay andmax age. If the instance-id argument is specified to 0 in this command, the current switch is configuredas the secondary root bridge of the CIST. You can configure only one root bridge for an MSTI but youcan configure one or more secondary root bridges for an MSTI.Once a switch is configured as the root bridge or a secondary root bridge, its priority cannot be modified.Examples# Configure the current switch as a secondary root bridge of MSTI 4, setting the network diameter of theswitched network to 5 and the hello time of the current switch to 300 centiseconds. system-viewSystem View: return to User View with Ctrl+Z.[Sysname] stp instance 4 root secondary bridge-diameter 5 hello-time 300
