EtherChannel protocol allow ports with similar characteristics to form an Bundle through dynamic negotiation(LACP and PAgP) or Forceful enforcement (ON) with connected network devices.
While configuring EtherChannel across devices (Switches/Routers), 2 most widely used negotiation protocols are PAgP and LACP. While PAgP is Cisco proprietary, LACP is Open standard and supported by most of vendors.
In order to configure EtherChannel through PAgP , Auto and Desirable are the keywords used while LACP uses Active and Passive modes.Infact the multicast address used by both Negotiation modes are dissimilar – PAgP uses “01-00-0C-CC-CC-CC” and LACP uses “01-80-c2-00-00-02”
A detailed comparison between both negotiation modes is enlisted in the below table –