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Contents
Spanning tree protocol overview ·························································· 1
About STP ································································································································ 1
STP protocol frames ············································································································ 1
Basic concepts in STP ·········································································································· 3
Calculation process of the STP algorithm ················································································· 4
Example of STP calculation ··································································································· 5
The configuration BPDU forwarding mechanism of STP ······························································ 9
STP timers ························································································································· 9
About RSTP ··························································································································· 10
RSTP protocol frames ········································································································ 10
Basic concepts in RSTP ····································································································· 10
How RSTP works ·············································································································· 11
RSTP BPDU processing ····································································································· 11
About PVST ···························································································································· 12
PVST protocol frames ········································································································ 12
How PVST works ·············································································································· 13
About MSTP ··························································································································· 13
MSTP features ·················································································································· 13
MSTP protocol frames ········································································································ 13
Basic concepts in MSTP ····································································································· 15
How MSTP works ·············································································································· 18
MSTP implementation on devices ························································································· 19
Rapid transition mechanism ······································································································· 19
Edge port rapid transition ···································································································· 19
Root port rapid transition ····································································································· 20
P/A transition ···················································································································· 20
Protocols and standards ············································································································ 21
Configuring spanning tree protocols ··················································· 23
Restrictions and guidelines: spanning tree protocol configuration ······················································· 23
Restrictions: Compatibility with other features ·········································································· 23
Restrictions: Interface configuration ······················································································· 23
Spanning tree protocol tasks at a glance ······················································································· 24
STP tasks at a glance ········································································································ 24
RSTP tasks at a glance ······································································································ 25
PVST tasks at a glance ······································································································ 26
MSTP tasks at a glance ······································································································ 27
Setting the spanning tree mode ··································································································· 28
Configuring an MST region ········································································································ 29
Configuring the root bridge or a secondary root bridge ····································································· 30
Restrictions and guidelines ·································································································· 30
Configuring the device as the root bridge of a spanning tree ······················································· 30
Configuring the device as a secondary root bridge of a spanning tree ··········································· 30
Configuring the device priority ····································································································· 31
Configuring the maximum hops of an MST region ··········································································· 31
Configuring the network diameter of a switched network··································································· 32
Setting spanning tree timers ······································································································· 32
Setting the timeout factor ··········································································································· 34
Configuring the BPDU transmission rate ······················································································· 34
Configuring edge ports ·············································································································· 35
Configuring path costs of ports ···································································································· 35
About path cost ················································································································· 35
Specifying a standard for the default path cost calculation ·························································· 35
Configuring path costs of ports ····························································································· 38
Configuring the port priority ········································································································ 39
Configuring the port link type ······································································································ 39
Configuring the mode a port uses to recognize and send MSTP frames ··············································· 40