Explanation:
The LACP is Link Aggregation Control Protocol. LACP is an open protocol, published under the 802.3ad.
The modes of LACP are active, passive or on. The side configured as “passive” will waiting the other side that should an Active for the Etherchannel to be established.
PAgP is Port-Aggregation Protocol. It is Cisco proprietary protocol. The mode are On, Desirable or Auto.
Desirable Auto will establish an EtherChannel.
An example of how to configure an Etherchannel:
SwitchFormula1>enable
SwitchFormula1#configure terminal
SwitchFormula1(config)# interface range f0/5 -14
SwitchFormula1(config-if-range)# channel-group 13 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