What is Bridge in Computer Network - Types, Uses, Functions & Differences

The bridge is a networking device in a computer network that is used to connect multiple LANs to a larger LAN. In computer networks, we have multiple networking devices such as bridges, hubs, routers, switches, etc, each device has its own specification and is used for a particular purpose. The bridge is a networking device that connects the larger LAN networks with the group of smaller LAN networks. 

In this article, we are going to discuss everything about the bridge including what exactly a bridge is, and the type of bridges we have in computer networks including transparent bridges, source routing bridges, and translational bridges, which will be followed by advantages and disadvantages of the bridge in networking. then how the bridge is different from the gateway and last we will look into the applications and functions of the bridge in the network. 

Bridge in Computer Network

A bridge in a computer network is a device used to connect multiple LANs together with a larger Local Area Network (LAN). The mechanism of network aggregation is known as bridging. The bridge is a physical or hardware device but operates at the OSI model's data link layer and is also known as a layer of two switches. 

The primary responsibility of a switch is to examine the incoming traffic and determine whether to filter or forward it. Basically, a bridge in computer networks is used to divide network connections into sections, now each section has a separate bandwidth and a separate collision domain. Here bridge is used to improve network performance. 

Types of Bridges 

There are three types of bridges in computer networks, which are as follows:

• Transparent Bridge: Transparent bridges are invisible to other devices on the network. This bridge doesn't reconfigure the network on the addition or deletion of any station. The prime function of the transparent bridge is to block or forward the data according to the MAC address. 
• Source Routing Bridge: Source routing bridges were developed and designed by IBM specifically for token ring networks. The frame's entire route is embedded with the data frames by the source station to perform the routing operation so that once the frame is forwarded it must follow a specific defined path/route. 
• Translational Bridge: Translational bridges convert the received data from one networking system to another. Or it is used to communicate or transmit data between two different types of networking systems. Like if we are sending data from a token ring to an Ethernet cable, the translational cable will be used to connect both the networking system and transmit data.  

Working of Bridges

Let's see the step-by-step working of the bridge in computer networks:

• Receiving Data: The bridge gets data packets (or frames) from both network segments A and B.
• Building a Table: It creates a table of MAC addresses by looking at where the data is coming from to know which device is on which segment.
• Filtering Data: If the data from network A is meant for a device also on network A, the bridge stops it from going further.
• Forwarding Data: If the data from network A is meant for a device on network B, the bridge sends it to the correct place on network B.
• Repeating for Both Sides: The bridge does the same thing for data coming from network B.

Models of Bridge in Computer Networks

There are two main models of bridging in computer network: Local bridging and remote bridging. Let us learn about them in detail.

• Local Bridging Local bridging connects LAN switches using local cables. This allows computers on the same Ethernet segment, whether they're connected to virtual hubs or physical LANs, to communicate freely. It's used when LANs within the same area need to talk to each other directly at the link layer.
• Remote Bridging Remote bridging connects two bridges over a Wide Area Network (WAN). This model is used when LANs are located in different geographical areas and need to communicate with each other at the link layer.

Uses of Bridge in Computer Network

• Bridges are used to increase the network capacity as they can integrate multiple LANs together. 
• On receiving a data frame, databases use the bridge to decide whether to accept or reject the data. 
• In the OSI model, it can be used to transmit the data to multiple nodes of the network.
• Used to broadcast the data even if the MAC address or destination address is unavailable.
• It forwards data packets despite faulty nodes. 
• The data packet can be forwarded or discarded by the bridge when the MAC address is available. 

Functions of Bridges in the Network 

• The bridge is used to divide LANs into multiple segments.
• To control the traffic in the network.
• It can interconnect two LANs with a similar protocols. 
• It can filter the data based on destination/MAC address. 

Advantages

• Bridges can be used as a network extension like they can connect two network topologies together. 
• It has a separate collision domain, which results in increased bandwidth. 
• It can create a buffer when different MAC protocols are there for different segments. 
• Highly reliable and maintainable. The network can be divided into multiple LAN segments. 
• Simple installation, no requirement of any extra hardware or software except the bridge itself. 
• Protocol transparency is higher as compared to other protocols. 

Disadvantages

• Expensive as compared to hubs and repeaters.
• Slow in speed. 
• Poor performance as additional processing is required to view the MAC address of the device on the network. 
• As the traffic received is in bulk or is broadcasted traffic, individual filtering of data is not possible. 
• During the broadcasting of data, the network has high broadcast traffic and broadcast storms can be formed. 

Conclusion

In computer networking, a bridge connects multiple network segments, allowing them to function as a single network. There are several types, including transparent, source-routing, and translation bridges, each serving different purposes. Bridges are used to improve network performance, reduce traffic, and extend the reach of networks. They function by filtering traffic and forwarding data based on MAC addresses. In essence, bridges help manage data flow in complex networks, ensuring efficient communication and connectivity between different network sections.