Operation Manual – MSTPH3C S7500 Series Ethernet Switches Chapter 1 MSTP Configuration1-14II. Configuration example# Configure the current switch to operate in the STP-compatible mode. system-view[H3C] stp mode stp1.2.6 MST Region Maximum Hops ConfigurationThe maximum hop values configured on the region roots in an MST region limit the sizeof the MST region.A configuration BPDU contains a field that maintains the remaining hops of theconfiguration BPDU. And a switch discards the configuration BPDUs whose remaininghops are 0. After a configuration BPDU reaches a root bridge of an MSTI in an MSTregion, the value of the remaining hops field in the configuration BPDU is decreased by1 every time the configuration BPDU passes a switch. Such a mechanism disables theswitches beyond the maximum hops from participating in spanning tree generation,and thus limits the size of an MST region.With such a mechanism, the maximum hops configured on the switch operating as theroot bridge of the CIST or an MSTI in an MST region becomes the network diameter ofthe spanning tree, which limits the size of the spanning tree in the current MST region.The switches that are not root bridges in the MST region adopt the maximum hopssettings of their root bridges.I. Configuration procedureFollow these steps to configure the maximum hops for an MST region:To do ... Use thecommand ... RemarksEnter system view system-view —Configure the maximumhops for the MST region stp max-hops hopsRequiredBy default, the maximum hopsof an MST region are 20.Note that only the maximum hops settings on the switches operating as region rootscan limit the size of the MST region.II. Configuration example# Configure the maximum hops of the MST region to be 30 (assuming that the currentswitch operates as the region root). system-view[H3C] stp max-hops 30
