iii
Configuring port isolation ································································· 72
Assigning a port to an isolation group ··························································································· 72
Displaying and maintaining port isolation ······················································································· 72
Port isolation configuration example ····························································································· 73
Network requirements ········································································································ 73
Configuration procedure ····································································································· 73
Verifying the configuration ··································································································· 73
Configuring spanning tree protocols ··················································· 75
STP ······································································································································ 75
STP protocol frames ·········································································································· 75
Basic concepts in STP ········································································································ 77
Calculation process of the STP algorithm ··············································································· 78
RSTP ···································································································································· 84
RSTP protocol frames ········································································································ 84
Basic concepts in RSTP ····································································································· 84
How RSTP works ·············································································································· 85
RSTP BPDU processing ····································································································· 85
PVST ···································································································································· 86
PVST protocol frames ········································································································ 86
Basic concepts in PVST ······································································································ 87
How PVST works ·············································································································· 87
MSTP ···································································································································· 87
MSTP features ·················································································································· 87
MSTP protocol frames ········································································································ 87
MSTP basic concepts ········································································································· 89
How MSTP works ·············································································································· 92
MSTP implementation on devices ························································································· 93
Rapid transition mechanism ································································································· 93
Protocols and standards ············································································································ 95
Spanning tree configuration task lists ··························································································· 96
STP configuration task list ··································································································· 96
RSTP configuration task list ································································································· 97
PVST configuration task list ································································································· 97
MSTP configuration task list ································································································ 98
Setting the spanning tree mode ··································································································· 99
Configuring an MST region ········································································································ 99
Configuring the root bridge or a secondary root bridge ··································································· 100
Configuring the device as the root bridge of a specific spanning tree ·········································· 101
Configuring the device as a secondary root bridge of a specific spanning tree ······························ 101
Configuring the device priority ··································································································· 101
Configuring the maximum hops of an MST region ········································································· 102
Configuring the network diameter of a switched network································································· 102
Setting spanning tree timers ····································································································· 103
Configuration restrictions and guidelines ·············································································· 103
Configuration procedure ··································································································· 103
Setting the timeout factor ········································································································· 104
Configuring the BPDU transmission rate ····················································································· 104
Configuring edge ports ············································································································ 105
Configuration restrictions and guidelines ·············································································· 105
Configuration procedure ··································································································· 105
Configuring path costs of ports ·································································································· 105
Specifying a standard for the device to use when it calculates the default path cost ······················· 106
Configuring path costs of ports ··························································································· 108
Configuration example ······································································································ 108
Configuring the port priority ······································································································ 109
Configuring the port link type ···································································································· 109
Configuration restrictions and guidelines ·············································································· 109
Configuration procedure ··································································································· 110
Configuring the mode a port uses to recognize and send MSTP frames ············································· 110
Enabling outputting port state transition information ······································································· 111