[BCMSN]试验9 配置Spanning-tree根桥和根路径开销

SW1配置

sw1(config)#int f0/11
sw1(config-if)#sw mo tr
sw1(config-if)#no sh

sw1(config-if)#int f0/12
sw1(config-if)#sw mo tr
sw1(config-if)#no sh

sw1(config-if)#^Z
sw1#sh sp

VLAN1 is executing the ieee compatible Spanning Tree protocol
  Bridge Identifier has priority 32768, address ccd1.9160.0000
  Configured hello time 2, max age 20, forward delay 15
  We are the root of the spanning tree
  Topology change flag set, detected flag set
  Number of topology changes 1 last change occurred 00:00:24 ago
          from FastEthernet0/11
  Times:  hold 1, topology change 35, notification 2
          hello 2, max age 20, forward delay 15
  Timers: hello 1, topology change 25, notification 0, aging 0

Port 12 (FastEthernet0/11) of VLAN1 is forwarding
   Port path cost 19, Port priority 128, Port Identifier 128.12.
   Designated root has priority 32768, address ccd1.9160.0000
   Designated bridge has priority 32768, address ccd1.9160.0000
   Designated port id is 128.12, designated path cost 0
   Timers: message age 0, forward delay 0, hold 0
   Number of transitions to forwarding state: 1
   BPDU: sent 54, received 0

Port 13 (FastEthernet0/12) of VLAN1 is forwarding
   Port path cost 19, Port priority 128, Port Identifier 128.13.
   Designated root has priority 32768, address ccd1.9160.0000
   Designated bridge has priority 32768, address ccd1.9160.0000
   Designated port id is 128.13, designated path cost 0
   Timers: message age 0, forward delay 0, hold 0
   Number of transitions to forwarding state: 1
   BPDU: sent 41, received 1

sw1#sh sp bri

VLAN1 

  Spanning tree enabled protocol ieee
  Root ID    Priority    32768
             Address     ccd1.9160.0000
             This bridge is the root
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    32768
             Address     ccd1.9160.0000
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec
             Aging Time 0 

Interface                                   Designated
Name                 Port ID Prio Cost  Sts Cost  Bridge ID            Port ID
――――――�C ――- ―- ―�C ― ―�C ――――――�C ――-
FastEthernet0/11     128.12   128    19 FWD     0 32768 ccd1.9160.0000 128.12
FastEthernet0/12     128.13   128    19 FWD     0 32768 ccd1.9160.0000 128.13

sw1#sh sp int f0/11 

Port 12 (FastEthernet0/11) of VLAN1 is forwarding
   Port path cost 19, Port priority 128, Port Identifier 128.12.
   Designated root has priority 32768, address ccd1.9160.0000
   Designated bridge has priority 32768, address ccd1.9160.0000
   Designated port id is 128.12, designated path cost 0
   Timers: message age 0, forward delay 0, hold 0
   Number of transitions to forwarding state: 1
   BPDU: sent 188, received 0

sw1#sh sp int f0/12 

Port 13 (FastEthernet0/12) of VLAN1 is forwarding
   Port path cost 19, Port priority 128, Port Identifier 128.13.
   Designated root has priority 32768, address ccd1.9160.0000
   Designated bridge has priority 32768, address ccd1.9160.0000
   Designated port id is 128.13, designated path cost 0
   Timers: message age 0, forward delay 0, hold 0
   Number of transitions to forwarding state: 1
   BPDU: sent 192, received 8

SW2配置

sw2(config)#int f0/11
sw2(config-if)#sw mo tr
sw2(config-if)#no sh
sw2(config-if)#int f0/12
sw2(config-if)#sw mo tr
sw2(config-if)#no sh

sw2#sh sp

VLAN1 is executing the ieee compatible Spanning Tree protocol
  Bridge Identifier has priority 32768, address ccd2.9268.0000
  Configured hello time 2, max age 20, forward delay 15
  Current root has priority 32768, address ccd1.9160.0000
  Root port is 12 (FastEthernet0/11), cost of root path is 19
  Topology change flag not set, detected flag not set
  Number of topology changes 0 last change occurred 00:03:22 ago
  Times:  hold 1, topology change 35, notification 2
          hello 2, max age 20, forward delay 15
  Timers: hello 0, topology change 0, notification 0, aging 0

Port 12 (FastEthernet0/11) of VLAN1 is forwarding
   Port path cost 19, Port priority 128, Port Identifier 128.12.
   Designated root has priority 32768, address ccd1.9160.0000
   Designated bridge has priority 32768, address ccd1.9160.0000
   Designated port id is 128.12, designated path cost 0
   Timers: message age 2, forward delay 0, hold 0
   Number of transitions to forwarding state: 1
   BPDU: sent 0, received 101

Port 13 (FastEthernet0/12) of VLAN1 is blocking
   Port path cost 19, Port priority 128, Port Identifier 128.13.
   Designated root has priority 32768, address ccd1.9160.0000
   Designated bridge has priority 32768, address ccd1.9160.0000
   Designated port id is 128.13, designated path cost 0
   Timers: message age 15, forward delay 0, hold 0
   Number of transitions to forwarding state: 0
   BPDU: sent 18, received 9

sw2#sh sp bri

VLAN1
  Spanning tree enabled protocol ieee
  Root ID    Priority    32768
             Address     ccd1.9160.0000
             Cost        19
             Port        12 (FastEthernet0/11)
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    32768
             Address     ccd2.9268.0000
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec
             Aging Time 0 

Interface                                   Designated
Name                 Port ID Prio Cost  Sts Cost  Bridge ID            Port ID
――――――�C ――- ―- ―�C ― ―�C ――――――�C ――-
FastEthernet0/11     128.12   128    19 FWD     0 32768 ccd1.9160.0000 128.12
FastEthernet0/12     128.13   128    19 BLK     0 32768 ccd1.9160.0000 128.13

sw2#sh sp int f0/11 

Port 12 (FastEthernet0/11) of VLAN1 is forwarding
   Port path cost 19, Port priority 128, Port Identifier 128.12.
   Designated root has priority 32768, address ccd1.9160.0000
   Designated bridge has priority 32768, address ccd1.9160.0000
   Designated port id is 128.12, designated path cost 0
   Timers: message age 2, forward delay 0, hold 0
   Number of transitions to forwarding state: 1
   BPDU: sent 0, received 107

sw2#sh sp int f0/12 

Port 13 (FastEthernet0/12) of VLAN1 is blocking
   Port path cost 19, Port priority 128, Port Identifier 128.13.
   Designated root has priority 32768, address ccd1.9160.0000
   Designated bridge has priority 32768, address ccd1.9160.0000
   Designated port id is 128.13, designated path cost 0
   Timers: message age 8, forward delay 0, hold 0
   Number of transitions to forwarding state: 0
   BPDU: sent 20, received 10

sw2#debug spanning-tree events

sw2#config t 

*Mar  1 00:33:51.387: STP: VLAN1 Fa0/12 -> listening
*Mar  1 00:33:53.387: STP: VLAN1 Fa0/12 -> blocking
sw2(config)#int f0/11
sw2(config-if)#spanning-tree cost 100
sw2(config-if)#
*Mar  1 00:34:09.743: STP: VLAN1 new root port Fa0/12, cost 19
*Mar  1 00:34:09.747: STP: VLAN1 sent Topology Change Notice on Fa0/12
*Mar  1 00:34:09.807: STP: VLAN1 Fa0/11 -> blocking
*Mar  1 00:34:09.839: STP: VLAN1 Fa0/12 -> listening
sw2(config-if)#
*Mar  1 00:34:24.855: STP: VLAN1 Fa0/12 -> learning
sw2(config-if)#
*Mar  1 00:34:30.827: STP: VLAN1 new root port Fa0/11, cost 100
*Mar  1 00:34:30.871: STP: VLAN1 Fa0/11 -> listening
sw2(config-if)#
*Mar  1 00:34:33.359: STP: VLAN1 new root port Fa0/12, cost 19
*Mar  1 00:34:33.415: STP: VLAN1 Fa0/11 -> blocking
sw2(config-if)#
*Mar  1 00:34:39.879: STP: VLAN1 Fa0/12 -> forwarding
sw2(config-if)#
*Mar  1 00:34:53.415: STP: VLAN1 new root port Fa0/11, cost 100
*Mar  1 00:34:53.447: STP: VLAN1 Fa0/11 -> listening
sw2(config-if)#
*Mar  1 00:34:55.343: STP: VLAN1 new root port Fa0/12, cost 19
*Mar  1 00:34:55.399: STP: VLAN1 Fa0/11 -> blocking
sw2(config-if)#
*Mar  1 00:35:15.399: STP: VLAN1 new root port Fa0/11, cost 100
*Mar  1 00:35:15.415: STP: VLAN1 Fa0/11 -> listening
sw2(config-if)#
*Mar  1 00:35:17.359: STP: VLAN1 new root port Fa0/12, cost 19
*Mar  1 00:35:17.415: STP: VLAN1 Fa0/11 -> blocking
sw2(config-if)#
*Mar  1 00:35:37.415: STP: VLAN1 new root port Fa0/11, cost 100
*Mar  1 00:35:37.463: STP: VLAN1 Fa0/11 -> listening
sw2(config-if)#
*Mar  1 00:35:39.359: STP: VLAN1 new root port Fa0/12, cost 19
*Mar  1 00:35:39.387: STP: VLAN1 Fa0/11 -> blocking
sw2(config-if)#