During my time studying how the internet key exchange (IKE) phase1 process works I stumbled upon something that really hit home for me that makes it easy to remember what is needed during configuration, which is used to allow peers to negotiate security parameters to build a successful security association for the phase1 tunnel. It's simple, HAGLE.
In order to properly negotiate and agree on parameters your IKE policy needs the following:
H = hash
A = authentication
G = dh group
L = lifetime
E = encryption
HAGLE, HAGLE, HAGLE. Cheers!