GRE Tunneling is an Ethernet over Copper (IoC) technology that uses the physical layer as well as the logical layer for high-speed local area network (LAN) communication. Generic Routing Encapsulation (GRE) is a routing protocol developed by Cisco Systems, which essentially can encapsulate an incredibly wide spectrum of networking technology within very small point-to-point connections or multipoint links on an Ethernet network. This technology is quite capable of concealing all of the traffic that flows through any Ethernet device and is an ideal solution for many security applications. It is also highly useful for forwarding interactive traffic between different endpoints. In this article, we will discuss the basic operation and benefits of GRE tunneling.
A normal firewall in your organization can prevent your employees from accessing various resources or programs on your network; however, it is not enough to protect all of your traffic. Sometimes, a firewall is unable to block certain types of malicious traffic or if the traffic is under suspicious conditions. For instance, you might not be able to block some malicious programs but you can still deny certain resources. GRE tunneling can help you manage all of the traffic that is going to or leaving your company.
One great benefit of using a GRE tunnel is that it removes the physical barrier that surrounds your network. There are no more firewalls that need to be installed and taken down every time you want to upgrade your security measures. There is also no need to install expensive and complex network security devices that might not necessarily be deemed effective. All that is required is to configure the right application on the appropriate platform that supports the GRE protocol.
The concept behind a GRE tunnel is rather simple. The routers used for the process need to be configured with specialized IP addresses that are allocated to particular networks. Any packets that are sent and received will use this unique IP address. Once an IP packet is received on the receiving end, it is decoded and the destination network is mapped within the cloud service.
Usually, routers do not forward packets unless there is a reason why they have to. However, some of the newer dynamic routing protocols such as BGP, LSR, and OSP can cause problems when forwarding a packet. In many cases, BGP routers are not configured properly and packets can easily get lost. GRE tunnels take advantage of the fact that these IP packets can be forwarded regardless of the routing protocols being used.
Another benefit of a GRE tunnel is that it provides a cost-effective means of securing your network. A small payment can quickly pay for the hardware, software, and training needed to configure one of these IP-based tunnels. No dedicated resources are needed. This makes it a very affordable way to secure networks with little IT involvement. Many businesses and organizations are finding that an IP-based tunnel is more cost-effective than relying on expensive security solutions like firewalls.
Unlike standard BGP, EIGRP, or LSR, GRE tunnels do not have to deal with type-2 multipoint routing. These protocols do not send their packets in bulk, making them less susceptible to packet loss or delays. A GRE tunnel can forward its packets in only a few seconds and does not use up a huge portion of the bandwidth on a local Ethernet port. The smaller target IP address space that a GRE Tunnel provides is especially beneficial for small companies that need to secure isolated networks from the outside world. An Internet backbone provider can configure a GRE tunnel within seconds and route all of the packets it receives through this tunnel.
Traffic between a GRE-enabled client and an Internet backbone can be controlled by the administrator if he determines that it is necessary. The firewall in the GRE Tunnel can block certain types of packets and can limit the amount of data that is allowed through the tunnel. An IP-based firewall such as ICMP Firewall or the popular eBPF can be configured to allow the data that is allowed to enter the GRE Tunnel to be limited. GREs can also be implemented within a firewall in a simple manner to provide a layer of security without the need for a control plane or smart card. For more information about GRE technology and how to implement it within a business or other networking environment, contact a Cisco expert today.
