Advanced Traffic Management Guide K/KA/KB.15.15

Configuring loop protection...................................................................................................104
Enabling loop protection in port mode................................................................................105
Enabling loop protection in VLAN mode.............................................................................106
Changing modes for loop protection..................................................................................106
Viewing loop protection status in port mode........................................................................106
Viewing loop protection status in VLAN mode......................................................................106
STP loop guard................................................................................................................107
Troubleshooting an MSTP configuration...................................................................................110
Viewing the change history of root bridges..........................................................................111
Enabling traps and Viewing trap configuration.....................................................................113
Viewing debug counters for all MST instances......................................................................113
Viewing debug counters for one MST instance ....................................................................114
Viewing debug counters for ports in an MST instance...........................................................115
Field descriptions in MSTP debug command output...............................................................116
Troubleshooting MSTP operation........................................................................................119
About MSTP.........................................................................................................................119
Overview........................................................................................................................119
MSTP structure.................................................................................................................120
How MSTP operates.........................................................................................................121
802.1s Multiple Spanning Tree Protocol (MSTP)....................................................................121
MST regions...............................................................................................................122
How separate instances affect MSTP..............................................................................122
Regions, legacy STP and RSTP switches, and the Common Spanning Tree (CST)..................124
MSTP operation with 802.1Q VLANs.............................................................................124
Types of Multiple Spanning Tree Instances...........................................................................125
Operating rules...............................................................................................................125
Operating notes for the VLAN configuration enhancement....................................................126
MSTP compatibility with RSTP or STP..................................................................................127
About BPDU protection.....................................................................................................127
PVST protection and filtering..............................................................................................128
PVST protection...........................................................................................................128
PVST filtering..............................................................................................................129
Loop protection................................................................................................................129
Operating notes..............................................................................................................130
4 Rapid per-VLAN spanning tree (RPVST+) operation.....................................131
Overview............................................................................................................................131
Configuring RPVST+ at a glance.............................................................................................131
Configuring RPVST+..............................................................................................................131
Selecting RPVST+ as the spanning tree mode.......................................................................131
Configuring global spanning tree.......................................................................................132
Configuring per-VLAN spanning tree..................................................................................132
Configuring per-port per-VLAN spanning tree......................................................................133
Configuring per-port spanning tree.....................................................................................134
Enabling or disabling RPVST+ spanning tree.......................................................................135
Configuring BPDU filtering.....................................................................................................136
Viewing BPDU filtering..........................................................................................................137
Configuring and managing BPDU protection............................................................................137
Viewing BPDU protection status..........................................................................................139
Re-enabling a port blocked by BPDU protection...................................................................139
Allowing traffic on VLAN ID (PVID) mismatched links.................................................................139
Configuring STP loop guard...................................................................................................140
Viewing RPVST+ statistics and configuration.............................................................................143
Viewing RPVST+ global statistics........................................................................................143
Viewing global and VLAN spanning tree status...............................................................143
6 Contents