What is the GRE protocol and how does it work?

by | Oct 8, 2019 | CCNA, CCNP, CompTIA, Encryption, End Point Protection, Exclusive Articles, Network Security, VPN

GRE Protocol

What is the GRE protocol?

Generic Routing Encapsulation (GRE) protocol is a tunneling protocol that can encapsulate a number of OSI layer 3 protocols. This protocol can be used for point-to-point links, where two endpoints communicate with each other, and for point-to-multipoint links, where one node can transmit data to many nodes.

GRE protocol is developed by Cisco Systems and it is often used with IPSec or PPTP to create a VPN. But why do we need the GRE protocol in a VPN? How does the GRE protocol work? And how is the GRE IPSec tunnel different from a tunnel created in IPSec VPN? Let’s try to understand that.


In this article, we will discuss:

  • What is the GRE protocol?

  • How does the GRE protocol work?

  • Where is the GRE protocol used?

  • How is the GRE IPSec tunnel different from a tunnel created in IPSec VPN?

  • What are the security considerations of the GRE protocol?

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Amrita Mitra

Author

Ms. Amrita Mitra is an author, who has authored the books “Cryptography And Public Key Infrastructure“, “Web Application Vulnerabilities And Prevention“, “A Guide To Cyber Security” and “Phishing: Detection, Analysis And Prevention“. She is also the founder of Asigosec Technologies, the company that owns The Security Buddy.

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