HP Cisco Nexus 5000 Cisco Nexus 5000 Series Switch CLI Software Configuration - Page 163

Chapter 9 Configuring MST Information About MST Send feedback to [email protected] Note We do not recommend that you partition the network into a large number of regions. MST BPDUs Each region has only one MST BPDU, and that BPDU carries an M-record for each MSTI within the region (see Figure 9-1). Only the IST sends BPDUs for the MST region; all M-records are encapsulated in that one BPDU that the IST sends (see "IST, CIST, and CST Overview" section on page 9-4 for more information on IST). Because the MST BPDU carries information for all instances, the number of BPDUs that need to be processed to support MSTIs is significantly reduced. Figure 9-1 MST BPDU with M-Records for MSTIs Protocol information for the IST Protocol information for the MSTI present on the port (M-records) 182778 MST Configuration Information The MST configuration that must be identical on all switches within a single MST region is configured by the user. You can configure the following three parameters of the MST configuration: • Name-32-character string, null padded and null terminated, identifying the MST region • Revision number-Unsigned 16-bit number that identifies the revision of the current MST configuration Note You must set the revision number when required as part of the MST configuration. The revision number is not incremented automatically each time that the MST configuration is committed. • MST configuration table-4096-element table that associates each of the potential 4094 VLANs supported to a given instance with the first (0) and last element (4095) set to 0. The value of element number X represents the instance to which VLAN X is mapped. Caution When you change the VLAN-to-MSTI mapping, the system restarts MST. OL-16597-01 Cisco Nexus 5000 Series Switch CLI Software Configuration Guide 9-3