auto是被动，desireable是主动
acive是主动，passive是被动，不同厂商建议配置ON
SW1(config)#int range f0/1-2
SW1(config-if-range)#channel-group ?
<1-6> Channel group number
SW1(config-if-range)#channel-group 1
% Incomplete command.
SW1(config-if-range)#channel-group ?
<1-6> Channel group number
SW1(config-if-range)#channel-group 1 mo
SW1(config-if-range)#channel-group 1 mode ?
active Enable LACP unconditionally
auto Enable PAgP only if a PAgP device is detected
desirable Enable PAgP unconditionally
on Enable Etherchannel only
passive Enable LACP only if a LACP device is detected
SW1(config-if-range)#channel-group 1 mode on
SW1(config-if-range)#
Creating a port-channel interface Port-channel 1
%LINK-5-CHANGED: Interface Port-channel 1, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface Port-channel 1, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/1, changed state to down
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/1, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/2, changed state to down
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/2, changed state to up
SW2(config-if-range)#channel-group 1 mode on
SW2(config-if-range)#
Creating a port-channel interface Port-channel 1
%LINK-5-CHANGED: Interface Port-channel 1, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface Port-channel 1, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/1, changed state to down
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/1, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/2, changed state to down
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/2, changed state to up
SW1#show etherchannel summary
原文：http://blog.51cto.com/433266/2113371