What is a One-Armed Router?

A one-armed router is the name for a router that routes traffic between one or more virtual local area networks (LAN). These routers work basically the same way as a normal router; they take in information and send it out to the correct location. In the case of a one-armed router, the networks that they route between are on the same physical network. Virtual LANs, and the routers that connect them, are primarily used as a security device.

Standard routers take in information from one network and send it out into another. If everything is working as it should, each piece of data on a network has an intended destination. Routers read that information and send it to the proper machine. By doing this, they keep the amount of traffic on the network lower than if every piece of information simply went to every device.

A standard LAN connects multiple devices together into a single network. While connected together, the devices are able to share information quicker and easier than when they are on separate networks. Their direct connectivity bypasses several network security procedures, since the information’s beginning and end are both within the network.

Virtual networks are designed to encourage or discourage that connectivity. Some virtual LANs are based on software systems. These networks may consist of devices all around the world that all act as though they are on the same network. These types of virtual LANs are the less common type. The usual virtual LAN consists of multiple networks operating in the same physical space. Even though information is going over the same wires, the LANs are considered different, and there is no direct communication.

A one-armed router is used to connect these virtual systems. This router has a single network interface controller that every connected virtual network recognizes. This single controller is the focal point for each network. Since it is recognized as the router for each system, the information that it takes in may go to any connected network.

These routers are typically installed outside of the main data path. A one-armed router connects multiple virtual networks, but doesn’t operate as the primary routing source for the physical network. These routers direct traffic between the virtual LANs, which takes pressure off the primary router and speeds up the network.

The primary reason to use a virtual LAN is security. Multiple departments inside an office, or several offices inside a building, may share a network system without sharing data. This keeps data more secure and compartmentalizes information. Using a one-armed router within this system will still keep some of the LANs separate, such as two business that operate in the same floor of a building, but also allow others to connect with one another, such as a sales and marketing department.