Portfast、uplinkfast、backbonefast

 

实验目的

分别配置stp的三个增强功能，观察配置前后端口启动时间的变化

实验拓扑

 

配置要点

1、sw2#sho run

interface FastEthernet0/48

 switchport mode dynamic desirable

 spanning-tree portfast

2、sw1#sh run   (接入层 全局模式)

spanning-tree uplinkfast

 

3、S1#sho run   (所有交换机 全局模式)

spanning-tree backbonefast

S2#sho run

spanning-tree backbonefast

S3#sho run

spanning-tree backbonefast

实验验证

1、portfast

在配置stp portfast功能之前，开启交换机的端口后，通过debug可看到，端口状态由disable—listening—learning—forwarding

S1#debug spanning-tree events

Spanning Tree event debugging is on

S1#

*Mar  1 00:16:09.091: %LINK-3-UPDOWN: Interface FastEthernet0/48, changed state to up

*Mar  1 00:16:10.091: set portid: VLAN0001 Fa0/48: new port id 8030

*Mar  1 00:16:10.095: STP: VLAN0001 Fa0/48 -> listening

*Mar  1 00:16:10.095: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/48, changed state to up

*Mar  1 00:16:25.095: STP: VLAN0001 Fa0/48 -> learning

*Mar  1 00:16:40.095: STP: VLAN0001 sent Topology Change Notice on Fa0/20

*Mar  1 00:16:40.095: STP: VLAN0001 Fa0/48 -> forwarding

 

在fa0/29端口开启portfast后，可看到该端口直接进入转发状态

S1(config)#int fa0/48

S1(config-if)#no shut

S1(config-if)#

*Mar  1 00:23:54.167: %LINK-3-UPDOWN: Interface FastEthernet0/48, changed state to up

*Mar  1 00:23:56.715: set portid: VLAN0001 Fa0/48: new port id 8030

*Mar  1 00:23:56.719: STP: VLAN0001 Fa0/48 ->jump to forwarding from blocking

*Mar  1 00:23:57.719: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/48, changed state to up

 

2、uplinkfast

在接入层交换机上配置uplinkfast之前，shut S1 fa0/20，通过debug观察S1的fa0/24接口

S1#debug spanning-tree events

Spanning Tree event debugging is on

S1#

*Mar  1 00:46:36.939: STP: VLAN0001 new root port Fa0/24, cost 38

*Mar  1 00:46:36.939: STP: VLAN0001 Fa0/24 -> listening

*Mar  1 00:46:37.939: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/20, changed state to down

*Mar  1 00:46:38.939: STP: VLAN0001 sent Topology Change Notice on Fa0/24

*Mar  1 00:46:38.947: %LINK-3-UPDOWN: Interface FastEthernet0/20, changed state to down

*Mar  1 00:46:51.939: STP: VLAN0001 Fa0/24 -> learning

*Mar  1 00:47:06.939: STP: VLAN0001 sent Topology Change Notice on Fa0/24

*Mar  1 00:47:06.939: STP: VLAN0001 Fa0/24 -> forwarding

 

通过show spanning-tree vlan 1 可发现fa0/24已经成为根端口

S1#sho spanning-tree vlan 1

Fa0/13              Desg FWD 3100      128.13   Shr

Fa0/14              Desg FWD 3100      128.14   Shr

Fa0/24              Root FWD 3019      128.24   P2p

Fa0/48              Desg FWD 3019      128.48   P2p Edge

 

当故障恢复后，可发现fa0/20又恢复到root port状态，而fa0/24也恢复到Altn状态

S1#sho spanning-tree vlan 1

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

Fa0/14              Desg FWD 100       128.14   Shr

Fa0/20              Root FWD 19        128.20   P2p

Fa0/24              Altn BLK 19        128.24   P2p

Fa0/48              Desg FWD 19        128.48   P2p Edge

 

开启接入层交换机的uplinkfast功能，仍通过debug查看端口状态变化S1(config)#spanning-tree uplinkfast

S1#debug spanning-tree events

Spanning Tree event debugging is on

S1#

*Mar  1 01:04:26.599: STP: VLAN0001 new root port Fa0/24, cost 3038

*Mar  1 01:04:26.599: %SPANTREE_FAST-7-PORT_FWD_UPLINK: VLAN0001 FastEthernet0/24 moved to Forwarding (UplinkFast).

*Mar  1 01:04:27.599: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/20, changed state to down

*Mar  1 01:04:28.599: STP: VLAN0001 sent Topology Change Notice on Fa0/24

*Mar  1 01:04:28.607: %LINK-3-UPDOWN: Interface FastEthernet0/20, changed state to down

 

此时查看端口角色的变化：

S3#sho spanning-tree

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

Fa0/21              Desg FWD 19        128.21   P2p

S1#sho spanning-tree

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

Fa0/13              Desg FWD 3100      128.13   Shr

Fa0/14              Desg FWD 3100      128.14   Shr

Fa0/24              Root FWD 3019      128.24   P2p

Fa0/48              Desg FWD 3019      128.48   P2p Edge

恢复故障后，

*Mar  1 01:13:00.875: %LINK-3-UPDOWN: Interface FastEthernet0/20, changed state to up

*Mar  1 01:13:01.875: set portid: VLAN0001 Fa0/20: new port id 8014

*Mar  1 01:13:01.879: STP: VLAN0001 Fa0/20 -> listening

*Mar  1 01:13:01.995: STP: VLAN0001 Fa0/20: root port delay timer active

*Mar  1 01:13:01.995: STP: VLAN0001 Fa0/20 -> blocking

*Mar  1 01:13:02.879: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/20, changed state to up

S1#

*Mar  1 01:13:36.995: STP: VLAN0001 new root port Fa0/20, cost 3019

*Mar  1 01:13:36.995: STP: VLAN0001 Fa0/24 -> blocking (uplinkfast)

*Mar  1 01:13:36.995: %SPANTREE_FAST-7-PORT_FWD_UPLINK: VLAN0001 FastEthernet0/20 moved to Forwarding (UplinkFast).

*Mar  1 01:13:36.995: STP: VLAN0001 sent Topology Change Notice on Fa0/20

所有端口角色都恢复到原状态

 

3、backbonefast

开启该功能之前，关闭S3 fa0/21，观察S1 fa0/24状态变化：

S1(config)#

*Mar  1 01:52:35.039: STP: VLAN0001 heard root 32769-000e.d 786.1a 80 on Fa0/24

*Mar  1 01:52:36.867: STP: VLAN0001 heard root 32769-000e.d 786.1a 80 on Fa0/24

*Mar  1 01:52:38.867: STP: VLAN0001 heard root 32769-000e.d 786.1a 80 on Fa0/24

*Mar  1 01:52:40.867: STP: VLAN0001 heard root 32769-000e.d 786.1a 80 on Fa0/24

*Mar  1 01:52:42.867: STP: VLAN0001 heard root 32769-000e.d 786.1a 80 on Fa0/24

*Mar  1 01:52:44.867: STP: VLAN0001 heard root 32769-000e.d 786.1a 80 on Fa0/24

*Mar  1 01:52:46.867: STP: VLAN0001 heard root 32769-000e.d 786.1a 80 on Fa0/24

*Mar  1 01:52:48.867: STP: VLAN0001 heard root 32769-000e.d 786.1a 80 on Fa0/24

*Mar  1 01:52:50.867: STP: VLAN0001 heard root 32769-000e.d 786.1a 80 on Fa0/24

*Mar  1 01:52:52.867: STP: VLAN0001 heard root 32769-000e.d 786.1a 80 on Fa0/24     -----MAX-AGE ???

*Mar  1 01:52:53.043: STP: VLAN0001 Fa0/24 -> listening

*Mar  1 01:52:54.043: STP: VLAN0001 Topology Change rcvd on Fa0/24

*Mar  1 01:52:54.043: STP: VLAN0001 sent Topology Change Notice on Fa0/20

*Mar  1 01:53:08.043: STP: VLAN0001 Fa0/24 -> learning

*Mar  1 01:53:23.043: STP: VLAN0001 sent Topology Change Notice on Fa0/20

*Mar  1 01:53:23.043: STP: VLAN0001 Fa0/24 -> forwarding

 

开启backbonefast,再次观察:发现直接跳过block状态

S1(config)#spanning-tree backbonefast

S2(config)#spanning-tree backbonefast

S3(config)#spanning-tree backbonefast

S1#   

*Mar  1 02:03:55.447: STP: VLAN0001 heard root 32769-000e.d 786.1a 80 on Fa0/24

*Mar  1 02:03:55.503: STP: VLAN0001 Fa0/24 -> listening

*Mar  1 02:03:56.055: STP: VLAN0001 Topology Change rcvd on Fa0/24

*Mar  1 02:03:56.055: STP: VLAN0001 sent Topology Change Notice on Fa0/20

*Mar  1 02:04:10.503: STP: VLAN0001 Fa0/24 -> learning

*Mar  1 02:04:25.503: STP: VLAN0001 sent Topology Change Notice on Fa0/20

*Mar  1 02:04:25.503: STP: VLAN0001 Fa0/24 -> forwarding

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