© 2006 Cisco Systems, Inc. All rights reserved. BCMSN v Implementing Spanning Tree Implementing MSTP

© 2006 Cisco Systems, Inc. All rights reserved. BCMSN v Multiple Spanning Tree Protocol Instance 1 maps to VLANs 1–500 Instance 2 maps to VLANs 501–1000

© 2006 Cisco Systems, Inc. All rights reserved. BCMSN v MST Regions MST configuration on each switch: Name Revision number VLAN association table

© 2006 Cisco Systems, Inc. All rights reserved. BCMSN v Extended System ID in Bridge ID Field

© 2006 Cisco Systems, Inc. All rights reserved. BCMSN v Interacting Between MST Regions and 802.1D

© 2006 Cisco Systems, Inc. All rights reserved. BCMSN v Configuring MSTP Switch(config)#spanning-tree mst configuration Enters MST configuration submode Switch(config-mst)#name name Sets the MST region name Switch(config-mst)#revision rev_num Sets the MST configuration revision number Switch(config-mst)#instance inst vlan range Maps the VLANs to an MST instance Switch(config-mst)#spanning-tree mst instance_number root primary|secondary Establishes primary and secondary roots for MST instance

© 2006 Cisco Systems, Inc. All rights reserved. BCMSN v Verifying MSTP Switch#show spanning-tree mst configuration Name [cisco] Revision 1 Instance Vlans mapped Switch#show spanning-tree mst configuration Displays MSTP configuration information

© 2006 Cisco Systems, Inc. All rights reserved. BCMSN v Verifying MSTP (Cont.) Switch#show spanning-tree mst 1 ###### MST01 vlans mapped: 1-10 Bridge address 00d0.00b priority (32768 sysid 1) Root this switch for MST01 Interface Role Sts Cost Prio.Nbr Status Fa4/4 Back BLK P2p Fa4/5 Desg FWD P2p Fa4/48 Boun FWD P2p Bound(STP) Switch#show spanning-tree mst instance_number Displays configuration information for a specific MSTP instance Switch#clear spanning-tree detected-protocols [interface interface-id] Forces renegotiation with neighboring switches during migration process

© 2006 Cisco Systems, Inc. All rights reserved. BCMSN v Summary MSTP reduces the encumbrance of PVST by allowing a single instance of spanning tree to run for multiple VLANs. An MST region is a group of MSTP switches that appears as a single virtual bridge to adjacent CST and MSTP regions. Extended system ID ensures that VLAN ID or MSTP instance can be carried in the Bridge ID field of a BPDU. An MSTP region requires an IST and an arbitrary number of MSTP instances as it connects to an 802.1Q network at the MST region border. MSTP is configured with a unique set of commands. MSTP implementation requires configuration and verification using specific configuration and show commands.

© 2006 Cisco Systems, Inc. All rights reserved. BCMSN v