The Concept Behind the GRE Tunneling Protocol

GRE Tunneling Encapsulation is an advanced tunneling protocol developed by Cisco Systems, which enables routers to encapsulate an entire range of routing protocols within physical local area networks (LANs) or even point-to-Point links over an Ethernet network. Although similar in many ways to SSL/TLS, GRE is an independent protocol with its own advantages and disadvantages. This article provides a brief overview of the GRE and how it may be implemented on the network.

To understand why we need a GRE tunnel interface for our enterprise networking system, it is first necessary to understand how a typical organization uses VPN. When companies use VPN to protect their internal network, they typically utilize a private local network with a firewall within an external interface. Usually, the company has several internal sites that each have a private connection to the corporate network. Some companies also use virtual private LANs (VPLs) or workgroup interfaces within a private network to accomplish this goal.

The problem with these systems is that every time a third-party application requests a web page from a site in the internal network, the company must obtain an IP address from the VPN first. This process can be rather complicated when dealing with corporate networks that implement GRE tunneling. Most VPNs implement GRE by delegating traffic between multiple edge routers. Because of the need for IP addresses and the fact that the application doesn't know the identity of the source network, all traffic passes through the firewall and then the GRE tunnel interface.

With GRE tunnels, however, the IP address is only needed for the final connection between the internal network and the external application. The reason behind this is that traffic coming into a VPN will never leave the system. This prevents third-party applications from discovering the identity of the user and bypassing the security of the GRE tunnel. This is what makes the tunnel's ideal for businesses that wish to provide access without the need to configure numerous internal IP-based servers and network accessories.

One advantage that vpn has over other form of VPNs is the implementation of STUN and RASTC, or System Transfer Tracing and Traffic Control protocols. STUN is used to establish connections between two specific computers. RASTC is used to control the amount of information that flows through the network in a certain amount of time. An example of STUN would be a web browser that was trying to gain access to a website. On the other hand, RASTC is used with SCTP to establish a secure connection between computers so that two different network devices can establish a secure tunnel from one IP address to another.

Although STUN and RASTC are secure protocols, some companies choose to tunnel their traffic using another form of tunneling method known as BIND. BIND is actually short for Bordernel Entry Networking. In a nutshell, BIND is a routing protocol that is commonly used for exchanging sensitive data packets, such as credit card numbers, over an open network without requiring clients to authenticate themselves. Unlike STUN and RASTC, BIND does not require clients to authenticate themselves because the data packets are automatically exchanged between two trusted sources.

To begin, a client will connect to GRE via the internet. The client will then configure the necessary fields in the auto discovery settings of the GRE server. These include the e-mail address and the MAC address of the user to connect with. Once all these have been set, the client will send a header and the appropriate number of header updates. This is how a user will detect whether or not a connection to the target server has been established.

After this, the GRE traffic will be transferred into the GRE tunnels created by the router. This entire process can take a few seconds. Then, the packets will be transmitted across the network to the destination server. At the destination, the server will verify the integrity of the packets and if there are problems, it will close the connection. Since this is an efficient and reliable method, many organizations have switched from the older BIND methods to the GRE tunneling due to the increased reliability it provides.