the set interface service-gre and set interface service-ipsec commands are only available on the Cisco CRS router – Sets interface instances when IKE IPSec-SAs negotiates for traffic that is remote. The calculation of the Diffie-Hellman key (also known as the exponential key chord) is based on the Hellman diffy mathematical groups (DH). A security gateway supports these DH groups during both phases of IKE. The IETF ipsecme working group has standardized a number of extensions to modernize the IKEv2 protocol and better adapt it to high-volume production environments. These extensions include: IKE consists of two phases. In Phase 1, IKE creates an authenticated and secure channel between the two IKE-Peers. This is done using the key convention protocol Diffie Hellman. IKE supports multiple authentication methods as part of the Phase 1 exchange. . .