What is IPSEC consist of and what are their functions?

IPSEC is a combination of three primary protocols ESP(protocol 50), AH(protocol 51) and IKE(UDP 500)

Authentication: Authentication Header (AH) and Encapsulating Security Payload (ESP)

Integrity: Encapsulating Security Payload (ESP)

Confidentiality: Encapsulating Security Payload (ESP)

Bringing it all together: Internet key Exchange (IKE)