iii
STP protocol packets ············································································································································· 50
Basic concepts in STP············································································································································ 51
Calculation process of the STP algorithm ··········································································································· 52
RSTP ················································································································································································· 57
MSTP················································································································································································ 57
STP and RSTP limitations
······································································································································· 57
MSTP features ························································································································································ 57
MSTP basic concepts ············································································································································ 58
How MSTP works ·················································································································································· 61
Implementation of MSTP on devices···················································································································· 62
Protocols and standards ················································································································································ 62
Spanning tree configuration task list ···························································································································· 62
Configuration restrictions and guidelines ··········································································································· 62
STP configuration task list ····································································································································· 63
RSTP configuration task list ··································································································································· 63
MSTP configuration task list ································································································································· 64
Setting the spanning tree mode ···································································································································· 66
Configuring an MST region ·········································································································································· 66
Configuring the root bridge or a secondary root bridge ·························································································· 67
Configuration restrictions and guidelines ··········································································································· 67
Configuring the current device as the root bridge of a specific spanning tree ·············································· 68
Configuring the current device as a secondary root bridge of a specific spanning tree ······························ 68
Configuring the device priority ····································································································································· 68
Configuring the maximum hops of an MST region ···································································································· 69
Configuring the network diameter of a switched network························································································· 69
Configuring spanning tree timers ································································································································· 70
Configuration restrictions and guidelines ··········································································································· 70
Configuration procedure ······································································································································ 70
Configuring the timeout factor ······································································································································ 71
Configuring the maximum port rate ····························································································································· 71
Configuring edge ports ················································································································································· 72
Configuration restrictions and guidelines ··········································································································· 72
Configuration procedure ······································································································································ 72
Configuring path costs of ports ···································································································································· 73
Specifying a standard for the device to use when it calculates the default path cost ··································· 73
Configuring path costs of ports···························································································································· 74
Configuration example ········································································································································· 75
Configuring the port priority ········································································································································· 75
Configuring the port link type ······································································································································· 76
Configuration restrictions and guidelines ··········································································································· 76
Configuration procedure ······································································································································ 76
Configuring the mode a port uses to recognize or send MSTP packets ·································································· 76
Enabling outputting port state transition information·································································································· 77
Enabling the spanning tree feature ······························································································································ 77
Performing mCheck························································································································································ 78
Performing mCheck globally ································································································································ 78
Performing mCheck in interface view ················································································································· 78
Configuring Digest Snooping ······································································································································· 79
Configuration restrictions and guidelines ··········································································································· 79
Configuration procedure ······································································································································ 79
Digest Snooping configuration example············································································································· 80
Configuring No Agreement Check ······························································································································ 81
Configuration prerequisites ·································································································································· 82
Configuration procedure ······································································································································ 82