Network Bridge Device in Computer Networks

In the world of computer networks, efficient data flow and seamless communication across devices are vital. One device that plays a crucial role in managing this data flow is the network bridge.

In this guide, we have explained the network bridge device and its purpose. You will also learn the steps for its configuration and troubleshooting.

If you are interested in learning more about such networking devices and their configuration, check out our online IT infrastructure courses.

What is a Bridge in Networking? 

A network bridge is a device used to connect two or more network segments, allowing devices on different segments to communicate. Operating at the data link layer (Layer 2) of the OSI model, a bridge works by filtering and forwarding data packets between network segments based on MAC addresses.

A network bridge can intelligently decide whether to pass a packet to another segment or drop it based on its MAC address. A bridge learns which devices are in which segment by keeping a table of MAC addresses, known as a forwarding table.

Network bridging is explained as a bridge that helps to control the flow of data across segments, preventing congestion and ensuring that data is forwarded only to the correct destination.

Read our article on Routing table

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What is a LAN Bridge? 

A LAN bridge is a specific type of bridge used in Local Area Networks (LANs) to connect multiple LAN segments.  It is a tool that allows different parts of a LAN to work together more effectively.

For instance, in a large office, multiple floors may have their separate LANs, but a LAN bridge allows devices across different floors to communicate seamlessly without overwhelming any single segment with traffic. 

Check out our article on Privatre VLAN and Configuration

What is the Purpose of a Network Bridge? 

The primary purpose of a bridge for networking is to reduce congestion, segment the network, and improve data transfer efficiency. The main uses include: 

● By dividing a large network into smaller segments, a bridge helps prevent traffic from becoming congested. 

● A bridge can connect different types of networks, such as Ethernet and Wi-Fi, allowing them to communicate. 

● A bridge reduces collisions by isolating network segments. 

● Bridges also play a role in network security, as they limit the traffic that is forwarded between segments, ensuring that data is only shared with the appropriate devices. 

Also, read our article on Wireless Communication

Types of Bridges in Networking 

There are 4 types of bridges in a computer network:

Network Bridge vs Switch vs Router 

Network Bridge: A network bridge connects two or more network segments at the data link layer (Layer 2). It filters traffic based on MAC addresses and forwards data between segments to reduce congestion. Bridges are primarily used to divide a large network into smaller, manageable segments. 

Switch: A switch is similar to a bridge but more advanced. It operates at Layer 2 and connects multiple devices within a single network. Unlike a bridge, which connects two segments, a switch manages traffic between many devices, reducing collisions and improving network efficiency. Switches often have more ports than bridges. 

Router: A router operates at Layer 3 (network layer) and connects different networks, such as local networks, to the internet. It routes data based on IP addresses and is responsible for directing traffic between different network segments or even entirely separate networks. 

Advantages of a Network Bridge 

A network bridge is a valuable tool for optimizing performance, reducing congestion, and connecting different network segments. The following are its advantages 

1. Divides a large network into smaller segments, reducing congestion. 

2. Isolates collision domains, improving network efficiency. 

3. Optimizes bandwidth usage by separating traffic across segments. 

4. Devices communicate without knowing a bridge is present. 

5. Filters traffic based on MAC addresses, enhancing security. 

Disadvantages of a Network Bridge 

It has limitations in scalability, performance in large networks, and traffic management. They are further explained below 

1. Not ideal for large networks; can become a bottleneck. 

2. Can introduce latency in high-traffic environments. 

3. Only filters based on MAC addresses, not IP addresses. 

4. Poor configuration may cause loops and outages. 

5. Managing a bridge can be challenging in large setups. 

How to Configure a Network Bridge 

Configuring a network bridge involves setting up a device to connect two separate sub-networks (sub-LANs). While the steps can differ depending on the system you are using, this guide will focus on setting up a bridge on a Linux machine. Windows users will follow similar procedures with slight variations in terminology. 

1. Evaluate the Network Interfaces 

First, open a terminal and use the commands ifconfig or ip link to display the available network interfaces on your system. These are the interfaces that will be part of the bridge. 

2. Install Bridge Utilities (if necessary) 

You may need to install bridge utilities. On Debian-based systems, you can do this with: 

3. Modify the Network Configuration 

Next, update your network configuration file. For Debian-based systems, you typically edit the /etc/network/interfaces file using a text editor such as nano or vim. Add the following configuration: 

Make sure to replace eth0, eth1, and br0 with the correct interface names for your setup. 

4. Restart the Networking Service 

Once you’ve updated the configuration, restart the networking service to apply the changes. On Debian-based systems, use: 

or 

This should cover the basic steps to get your network bridge working. 

Troubleshooting a Network Bridge 

If your network bridge isn't functioning correctly, here are some troubleshooting steps to help resolve common issues: 

1. Ensure that the bridge is properly connected to the router or switch on both sides. Test the Ethernet cables by replacing them with new ones to rule out any issues with the cables themselves. 

2. Revisit the network configuration file and ensure there are no mistakes or typos. Double-check that the interfaces are correctly set up. 

3. Make sure there are no duplicate IP addresses within the bridged segments. Duplicate IPs can create network conflicts and disrupt communication. 

4. Restart Devices 

5. Use a tool like Wireshark to observe the network traffic. This can help you identify any unusual behavior in the data packets or routing, indicating issues with the bridge. 

Conclusion 

In summary, a network bridge is a crucial element in modern networking, particularly for connecting and managing data flow across different network segments.

By segmenting traffic and reducing congestion, bridging networks allow organizations to maintain efficient, scalable networks that can handle increased demands without compromising performance. 

From LAN bridges that help organize local networks to multiport bridges for complex infrastructures, bridges provide a powerful means of managing network traffic and optimizing communication across devices.