변군이글루

STP 선발 기준

1단계 : 누가 더 작은 Root BID를 가졌는가?

2단계 : 루트 브리지까지의 Path Cost 값은 누가 더 작은가?

3단계 : 누구의 BID(Sender BID)가 더 낮은가?

4단계 : 누구의 포트 ID가 더 낮은가?

 < Switch C Bridge ID Priority  변경 >

Switch#show spanning-tree

VLAN0001

  Spanning tree enabled protocol ieee

  Root ID    Priority    32769

             Address     0000.0C16.E477

             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    32769  (priority 32768 sys-id-ext 1)

             Address     00E0.F753.5C28

             Aging Time 300

Interface        Role Sts Cost      Prio.Nbr Type

---------------- ---- --- --------- -------- --------------------------------

Fa0/1            Altn BLK 19        128.3    Shr

Fa0/2            Root FWD 19        128.3    Shr

Switch(config)#spanning-tree vlan 1 priority 100//할당된 범위 안에서 선택 가능

% Bridge Priority must be in increments of 4096.

% Allowed values are:

  0     4096  8192  12288 16384 20480 24576 28672

  32768 36864 40960 45056 49152 53248 57344 61440

Switch(config)#spanning-tree vlan 1 priority 4096

Switch#show spanning-tree

VLAN0001

  Spanning tree enabled protocol ieee

  Root ID    Priority    4097

             Address     00E0.F753.5C28

             This bridge is the root

             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    4097  (priority 4096 sys-id-ext 1)

             Address     00E0.F753.5C28

             Aging Time 300

Interface        Role Sts Cost      Prio.Nbr Type

---------------- ---- --- --------- -------- --------------------------------

Fa0/1            Desg LSN 19        128.3    Shr

Fa0/2            Desg FWD 19        128.3    Shr