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2012-02-07 20:41:17
注意，Access 2交换机是运行CatOS操作系统的。在这台交换机上必须先禁止原来PVST+模式下的BackboneFast特性，然后再把生成树模式从PVST+迁移到Rapid-PVST+模式，最后清除交换机上原来PVST+模式的Uplinkfast特性。
Access 2> (enable) set spantree backbonefast disable !--禁止PVST+模式下的BackboneFast特性
Backbonefast disabled for all VLANs.
Access 2> (enable) set spantree mode rapid-pvst+ !--把生成树模式从PVTS+迁移到Rapid-PVST+模式
PVST+ database cleaned up.
Spantree mode set to RAPID-PVST+.
Access 2> (enable) clear spantree uplinkfast !--清除原来PVST+模式下的UplinkFast特性配置，使交换机上端口所有的端口
!--开销、交换机优先级设置恢复到默认设置
This command will cause all portcosts, portvlancosts, and the
bridge priority on all vlans to be set to default.
Do you want to continue (y/n) [n]? y
VLANs 1-4094 bridge priority set to 32768.
The port cost of all bridge ports set to default value.
The portvlancost of all bridge ports set to default value.
uplinkfast all-protocols field set to off.
uplinkfast disabled for bridge.
迁移后，查看Access 2交换机上的生成树配置。
Access 1#show spanning-tree summary
Switch is in rapid-pvst mode
Root bridge for: none
Extended system ID is enabled
Portfast Default is disabled
PortFast BPDU Guard Default is enabled
Portfast BPDU Filter Default is disabled
Loopguard Default is disabled
EtherChannel misconfig guard is enabled
UplinkFast is disabled
BackboneFast is enabled but inactive in rapid-pvst mode
Configured Pathcost method used is short
Name Blocking Listening Learning Forwarding STP Active
---------------------- -------- --------- -------- ---------- ----------
VLAN0010 1 0 0 1 2
VLAN0020 1 0 0 1 2
---------------------- -------- --------- -------- ---------- ----------
2 vlans 2 0 0 2 4
【注意】在启用了BackboneFast特性时，CatOS系统不允许你改变到Rapid-PVST+生成树模式，你必须在迁移前禁止BackboneFast特性。而UplinkFast特性在生成树模式迁移前后的改变与IOS系统中生成树模式迁移前后的UplinkFast特性改变一样。
