Confidentiality between two communicators is achieved by using the appropriate encryption method. While sending the data it will be encrypted within sending node and decrypted in receiving node. Encryption will also protect the traffic between the two nodes from eavesdropping to some extent. We have to be specific about what will be encrypted to use it in networks effectively.
Starting with the Link Layer Encryption:
Link Layer Encryption has been available for some time and is used by bulk encryptors which encrypts all traffic on a given link. Packets are encrypted when they leave a node and decrypted when they enter a node. Each link will typically use a separate key to encrypt all traffic. The effectiveness of link-layer encryption depends on the relative security of nodes in the path. Link-layer encryption provides delay and expense so in this case, we use satellite links, because of their vulnerability to eavesdropping. In this case, the satellite service provider will take responsibility for providing encryption between any two earth stations.
Moving towards Application Layer Encryption:
In application layer encryption, end-to-end security is provided at the user level by encrypting applications at client workstations and server hosts. For necessity, encryption will be as close as source and decryption as close to as a destination.
Now let's move towards last but not least Network layer Security:
Network Layer Encryption may be applied to sections of the network rather than end-to-end encryption, in this scenario network layer packets are encapsulated within IP packets. A major advantage of Network Layer Encryption is that it is normally not concerned with the detail of the transmitting medium. It is generally transparent to the user so the user may be unaware of security breaches. As with the link-layer encryption, delays associated with encryption and decryption are to be kept at an acceptable level, Hardware-based devices should be used in carrying out these time taking processes.
In order to provide better standards of security, we have to use security services like authentication, integrity, and access control in IP networks.
This is how I supposed as a Network Engineer to provide better security between two communications.