PAgP cannot be enabled on cross−stack EtherChannels while LACP is supported on cross−stack EtherChannels from Cisco IOS Software Release 12.2(25)SEC and later.
Interfaces with the on mode configuration do not exchange PAgP or LACP packets.
These EtherChannel modes are supported on cross−stack EtherChannel:
active Places an interface into an active negotiation state, in which the interface starts negotiations with other interfaces by sending LACP packets.
passive Places an interface into a passive negotiation state, in which the interface responds to LACP packets that the interface receives, but does not start LACP packet negotiation. This setting minimizes the transmission of LACP packets.
on Forces the interface into an EtherChannel without PAgP or LACP. With the on mode, a usable
EtherChannel exists only when an interface group in the on mode has a connection to another
interface group in the on mode.
on mode command
3750switchstackA(config)#interface range gigabitethernet 1/0/4 − 5
3750switchstackA(config−if−range)#channel−group 1 mode on
3750switchstackA(config−if−range)#switchport trunk encapsulation dot1q
3750switchstackA(config−if−range)#switchport mode trunk
跑了Pagp會警告
With PAgP enabled, all ports in the Channel should belong to the same switch
Command rejected (Port−channel1, Gi2/0/3): Invalid etherchnl mode
LACP mode (active-active)
3750switchstackA(config)#interface range gigabitethernet 1/0/4 − 5
3750switchstackA(config−if−range)#channel−group 1 mode active
3750switchstackA(config−if−range)#switchport trunk encapsulation dot1q
3750switchstackA(config−if−range)#switchport mode trunk
驗證
3750switchstackA#show interfaces port−channel 1
3750switchstackA#show etherchannel summary
注意spanning tree
