Bridges have a very specific function in computer networking. While most organizations will likely employ switches and routers for similar tasks, bridges are very good at one particular sort of task. They can still be found in hundreds, if not thousands, of business networks around the world.
If you’ve been curious as to what a bridge is, then you’re in the right place. Today’s guide will go over the three specific types of bridges in computer networking, what they are used for, and some other details on how they function within a network.
Casual home users will likely never encounter a bridge in their lives. It has no place in the modern home unless your modern home has dozens to hundreds of residents.
What is a Bridge?
A bridge is a device that hooks into a local area network to connect subnetworks. A subnetwork, simply put, is a segment of the local area network, like an office floor for example. In the early days of computer networking, bridges were ubiquitous as they were an easy way to interconnect devices.
They still have a place today, as you can imagine. Most networking personnel will know the ins and outs of configuring one, and it makes connecting multiple segments a breeze. It has largely been replaced by the router or the switch in most contexts for business networks.
It never really had a place in small offices or home networks. For a home network, you’d likely just aim to get a wireless repeater or run longer lengths of cable to connect devices.
How Does it Work?
Bridges use the second layer of the OSI model, the data-link layer, to establish connectivity between devices. More savvy users will know this is the level where MAC addresses are utilized, over something like IP addresses.
Once connected, a bridge acts as a combined or aggregate network, rather than function as multiple individual segments. As such, users will be sharing bandwidth, but also get the ability to share resources.
Now, these days you likely aren’t using local messaging clients, but bridges would allow for in-office messaging years ago.
Bridges bear quite a bit of resemblance to routers or switches, you’ll find they both have a plethora of ethernet jacks for cabling. To set up a bridge, you could connect all your cables to the jack, and then run the output jack of the bridge to a switch or hub to establish the aggregate network.
Once connected, the bridge creates a routing table of sorts, similar to a router. Both devices share quite a few similarities in that they will automatically configure the traffic flow from the network to prevent packet collisions and network congestion.
The Purpose of a Bridge for Networking
A bridge is meant to extend and connect subnetworks, as previously stated. You would typically deploy bridges in an enterprise scenario where you have central resources meant for all workstations. When left as single segments, clients can’t access the resources.
However, if you deploy bridges to connect all the segments to create an aggregate local area network, all users have access to resources. It also helps to provide other means of connectivity, like providing external internet access to all devices connected.
Transparent Bridges
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Transparent bridges are one of the more common types of bridges in computer networking. Chances are if you are encountering a bridge in a business environment.
It functions by watching network traffic to pool and record all MAC addresses on the network segment. After looking at the flow of network traffic, the transparent bridge functions in a similar fashion to a routing table. It will take data and automatically makes it flow to its intended location.
Transparent bridges can also be utilized with other networking devices to have extended functionality. You will typically encounter these in ethernet-based local area networks, where hardware cabling is the primary means of creating a connection.
Use Cases
You would configure a transparent bridge if you’re after a bridge that is super simple to set up. It doesn’t require a very in-depth configuration, and you could very easily have IT personnel install one after skimming the manual.
It isn’t ideal for wireless connections, so you’ll want to choose a different device for strengthening wireless network segments.
Source Routing Bridges
Source routing bridges are the next step up from a transparent bridge. As the name suggests, it functions very similarly to a traditional router. Most home users will have routers in their homes, but the actual function is a combination of switch and router.
Source bridges allow for finer control over the flow of network traffic, and utilize headers to configure traffic for its intended destination. They also scale quite well, so you can implement multiple source routing bridges in a local area network to establish an extended aggregate connection.
Traffic is filtered through source routing bridges, so they are far more secure than a transparent bridge. As such, if you’re wanting to make your local area network bulletproof, this is the bridge to choose.
They are a specialty bridge in computer networking and reward technical know-how with the ability to shape network traffic.
Use Cases
Source routing bridges are intentionally implemented devices. What this means if your network architect is going to intentionally use these in a network to help shape and control the flow of traffic.
They are complex devices and require far more technical know-how to get up and running. Given their complexity, they may not be supported by all networking devices used in an enterprise environment.
If you are tailor-making your network and looking to make thoughtful choices to have granular control, then you will choose a source routing bridge. If you’re looking to just have the network up and running in no time, a transparent bridge might be a more ideal choice.
Translational Bridges
Translational bridges are a unique sort of bridge in computer networking. They don’t have a steady place in computer networking, but they do serve a vital purpose.
Before the days of standardization, computer networks could vary from location to location. These configurations, also known as topologies, weren’t uniform by any measure.
What a translational bridge ultimately does is provide a means to connect two or more disparate networks. The topology isn’t important, but rather the function of the bridge itself. It is able to translate, as the name suggests, traffic between segments to bolster a network’s overall functionality.
Use Cases
Translational bridges are deployed to connect two different network topologies to one another. They have no standardization, so some are going to be more capable than others.
These aren’t common devices to encounter in any enterprise environment in the modern era. Network topologies have largely been standardized in 2023.
If you by some chance want to create a token ring and star topology, then a translational bridge will help to connect those network segments.
Bridge Models
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Bridges can function in different environments for connectivity purposes. Now, it doesn’t matter so much the types of bridges in computer networking you choose, but rather the overall intent of the design of the network. There are two core models to keep in mind when thinking about computer networking.
Local Bridges
A local bridge is as its sounds and is meant to connect devices within the same physical location. Cabling might not perhaps for every single device to be connected to a single router. Bridges in the same physical location can allow for a network segment to join the wider local area network.
These are the most typical sort of bridge uses and are common in business networks where bridges are still used.
Remote Bridges
A remote bridge is used when two or more segments are meant to connect, but are separated by location. A connection is created using the wide area network, or the internet, to create a simulated local area network.
These aren’t super common, but you still might find them in use for campus area networks or metropolitan area networks.
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