Putting together a single, small network is relatively easy. Things really get complicated when you need to join multiple networks together. That’s where concepts like bridging come into play, and understanding the specific technology options available for this aspect of network design is essential to success.
To that end, you’ll find a simplified breakdown of bridges and switches below. It will help you see how devices can be leveraged to join networks and the trade-offs attached to those devices.
What Makes a Bridge?
In the world of networking, a bridge is a relatively simple device. It is designed for the specific purpose of connecting two local area networks (LANs) together. In order for a bridge to do this, both of those LANs have to be on the same protocol, and a common shared protocol is Ethernet. There are bridges that can connect other protocols as well, but Ethernet is one of the more common use cases. The bridge connects the two networks, and it then filters packets that come through it. It will either forward a packet to one LAN, or it will pass the packet to keep it on the other network. In short, there are two possibilities, and this brings up an important point.
The terms “bridge” and “switch” are often used interchangeably, and that’s because of how the bridge works. It is similar, in principle, to a circuit switch, routing a signal along one of two paths. It’s important to understand that a network switch is fundamentally different from a circuit switch, and that’s where a lot of the confusion happens.
A bridge is a simpler device as compared to a network switch, and while there is some overlap in their functionality, they serve different purposes.
The Essentials of a Network Switch
A switch is another device that determines the route that data can take through a network, but a switch is not designed for binary routing. A switch can route traffic to a number of destinations depending on how many ports are built into the device.
Despite the routing mechanisms, switches are simpler than true routers that can direct traffic for very large numbers of devices.
In general, switches operate on layer 2. There are some switches that provide functions on layer 3, and they are often called IP switches.
Considering the design, network switches can connect multiple LANs, but that is not the limit of their ability. They can also connect endpoint devices to a LAN, among other things.
When switches are connecting multiple LANs, that typically means that traffic will travel from one switch to another switch before traveling to any endpoint devices. Anytime a network has this setup — where traffic goes from a switch to a switch before moving on — it is called a hop.
Primary Differences Between the Two
While that covers the fundamentals of what the two devices are and how they work, it only begins to draw a direct comparison between them. To be more specific, there are two major differences in the operations of a switch and a bridge, and those can be found in their capacity and speed.
As mentioned before, bridges are designed for binary traffic direction. The signal either stays in the current LAN or gets routed to the other LAN. That makes them rather simple devices, and in many cases, they cost less than network switches, but binary routing is the defining feature.
Since network switches can handle more than two traffic destinations, they are necessarily more complicated. That may raise the price, but the value in higher priced devices (in this case) is increased capacities. Switches can handle anywhere from a handful to dozens of traffic destinations per device. That gives them the potential for much higher levels of cost-effectiveness, when they are used efficiently.
The capacity difference between the two devices comes with a trade-off. Switches handle a larger number of connections, and that means that more information has to be sorted in order to effectively route traffic through the switch. This process takes time, and it introduces latency.
On average, bridges experience far lower latency than switches. It ties back to the simplicity of one device over the necessary design complications of the other, but it’s worth noting. If a bridge will suffice for a network’s design, then it is the faster option between the two.
Additional Learning Center Resources
- Benefits of Cisco 9000 Series Switches
- Best Way to Connect Multiple Switches
- Should I upgrade from 3750X switch to the 3850 switch?
- Cisco Catalyst Switches Product Guide
- Basics of Network Switches
- What are the Differences between Cisco 3650 and 3750X Switches?
- What does 5G mean for my business network?
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