GRE is a tunnelling protocol designed by Cisco that facilitates a secure tunnel for transmitting packets through a public network by encapsulating packets. In other words, it creates a point-to-point connection.

Examples of Generic Routing Encapsulation

History of Generic Routing Encapsulation

Cisco Systems designed the GRE protocol in 1994 to simplify the connection between different networks. Initially, it was stated in RFC 1701 and RFC 1702, describing how to encapsulate various protocols. Later, RFC 2784 streamlined the GRE’s header structure and made it more effective.

RFC 2890 includes optional fields such as checksum, key, and sequence number in the GRE header. Today, GRE is widespread and has many use cases, such as mobility protocols, multicast routing, and VPNs.

Benefits of Generic Routing Encapsulation

Drawbacks of Generic Routing Encapsulation 

Generic Routing Encapsulation Use Cases

Examples of how GRE is used include: