If we were to run a contest for the most deceptively simple question in the networking world, “How do you interconnect two networks?” would be one of the most likely winners. It’s a very common problem: Companies with multiple sites, as well as companies with a single site but multiple buildings or located in remote areas, frequently have to solve it.
You’d think the answer is obvious – you run a cable between them – but that’s not always an option. Today we’re going to talk about the other option: wireless bridges.
What Is a Wireless Bridge and Why Do You Need One?
A wireless bridge is a solution (specifically, a set of devices) that allows you to connect two networks, or more accurately two network segments, over a wireless channel – sort of like a bridge, if you will, hence the name. Wireless bridges can be used to interconnect networks such as those in buildings on the same campus, in shipping and manufacturing sites in neighbouring districts or nearby towns, offices across the street from one another and so on. You may also find a wireless bridge referred to as a WiFi bridge.
Wireless bridges use radio (RF) signals in the microwave (MW) or optical/laser (free space optics – FSO) links to interconnect two access points. They use antennae – usually highly directional antennae – to send and receive wireless signals on one side and connect to regular IP networks on the other side. This way, two IP networks can be connected through a wireless link.
Since they transmit and receive signals through air using antennae or optical receptors, wireless bridges are sometimes referred to as free-to-air (FTA) bridges. And, since communication over a wireless bridge is always done between two transceivers (as opposed to one emitter that broadcasts a signal to any receiver that is willing to “listen”), these wireless links are point-to-point links.
How Are Wireless Bridges Useful?
Why go through all that trouble?
The most common answer is that you need a physical link, which rules out a VPN connection, and a wired link isn’t possible, either. In some areas of London, for example, high-performance leased lines can be prohibitively expensive. In other locations, leased lines may simply be unavailable.
Deploying and maintaining your own long-distance wired infrastructure is also expensive and sometimes outright impossible for technical reasons. It may also require various approvals from public authorities. In short, sometimes, a wireless bridge is the only feasible option.
In other cases, a wireless bridge may simply turn out to be the better option, for technical, performance or security reasons, price or legal constraints, business goals, or maintenance capacity constraints.
Some of the most common reasons for deploying wireless bridges include:
- Leased lines are too expensive or not available, and you cannot use a VPN for bandwidth, latency, or security/compliance reasons
- A fast network connection is simply not available at one of the two endpoints (in other words, there’s no line to lease and no Internet connection), and a wired link cannot be deployed
- Electrical interference (e.g. from industrial equipment) makes Ethernet connections impossible, and long-distance fibre links cannot be installed or are too expensive
- A wired link can be deployed, but not quickly enough, or you don’t expect to use it for long enough to be worth the initial effort.
- Wired links cannot be deployed for technical and/or legal reasons: one of the involved parties can’t or won’t approve deployment, cables have to be deployed over difficult or inaccessible terrain, buried in busy urban areas, etc.
What is a Bridge in a Network?
A bridge in a network is a fundamental networking device that operates at the data link layer of the OSI model, commonly referred to as Layer 2. Its primary function is to interconnect multiple local area networks (LANs) or segments to enable communication between them. Bridges work by examining the destination media access control (MAC) addresses of the data packets they receive. When a bridge receives a data packet, it analyses the MAC address and determines the appropriate path for forwarding the packet to its intended destination. By doing so, bridges can effectively filter and control the flow of network traffic, thereby improving network efficiency and reducing unnecessary data transmission. Overall, bridges play a crucial role in enhancing network performance by breaking down larger network domains into smaller segments to reduce collisions and congestion.
So, what is a bridge in a network? In addition to their ability to interconnect LAN segments, bridges also contribute to the overall security of a network. As they operate at the data link layer, they can create separate collision domains for each connected segment, effectively isolating network traffic. This isolation prevents data collisions from affecting other segments, thereby enhancing network stability and security. Although bridges have been largely superseded by more advanced networking devices such as switches and routers, they still find application in certain scenarios. For instance, in bridging two different types of LAN technologies or extending the reach of a network, bridges can be deployed. Despite their limitations compared to modern network devices, bridges remain an essential part of network history, playing a pivotal role in shaping the evolution of networking technologies.
