Bridge in Computer Network

In computer networking, various devices are used to connect computers and allow smooth data sharing. These devices ensure that data is sent and received quickly and securely. One such important device is a bridge in computer network. It connects different segments of a network and controls the flow of data between them. It plays a key role in improving network performance and keeping it organized. In this blog, we will explore what a bridge in computer network, how it works, and the various types used in computer networks.

Table of Contents

• What is a Bridge in Computer Network?
• Types of Bridges in Computer Networks
• Functions of a Bridge in Computer Network
• Working of a Bridge in Computer Network
• Advantages and Disadvantages of a Bridge in Computer Network
• Bridge vs Repeater vs Switch in Computer Network
• Performance Impact of a Bridge in Computer Network
• Practical Use Cases of Bridge in Computer Network
• Common Problems with a Bridge in a Computer Network
• Best Practices for Using a Bridge in a Computer Network
• Conclusion

What is a Bridge in Computer Network?

A bridge in a computer network is a device that operates at the data link layer (Layer 2) and connects two or more network segments. A bridge makes the network larger and more efficient, as the bridge forwards the data through the part of the network where it is needed. Think of a bridge as a traffic police officer at a road junction. Similar to a traffic police officer who only allows the right vehicles through in the right direction, a bridge only allows “useful” data to pass and discards the unwanted data.

Example: If there are two small LANs (Local Area Networks) in an office, a bridge can connect them and make them appear as if they are one big LAN. It would be easier for computers on both sides to exchange and share information.

Types of Bridges in Computer Networks

Bridges can be categorized into multiple kinds based on their function and the types of data and features they support. Here are the most common types of bridges:

1. Transparent Bridge

This is the most widely used type in local area networks (LANs). It works automatically in the background, so the users do not need to set anything up.

Key Features:

• Automatically learns MAC addresses from incoming data packets
• Uses a MAC address table to decide whether to forward or block packets
• Devices connected to it are not aware of the bridge, as it operates silently without affecting their communication.

Example: A transparent bridge is used to connect two departments of a small office for managing the flow of data without setting it manually.

2. Translational Bridge

This bridge is used to connect two networks that have different types of technological implementations. For example, one network may communicate using Ethernet while the other network may use Token Ring.

Key features:

• Converts the format of data from one type of network to another.
• Provides a means of communicating with two different networks operating on different protocols.

Example: If the marketing team uses Ethernet and the accounting department uses older network systems, a translational bridge can assist in sharing information.

3. Remote Bridge

Remote bridges connect networks over long distances using a wide area network (WAN) or the Internet.

Key Features:

• Functions as a bridge over a long distance.
• Frequently use telephone lines or leased lines.
• Create a LAN over a geographic area.

Example: If a company has offices in two different cities, a remote bridge can connect their LANs to access files and applications from either location.

4. Multiport Bridge

As the name suggests, a multiport bridge has more than two ports and can connect many segments of a network simultaneously.

Key Features:

• Works like a basic version of a network switch.
• Manages traffic from many sources and many different destinations.
• Helps reduce collisions and improve overall data flow efficiency

Example: In a school where different labs and departments are connected, a multiport bridge could manage the data traffic occurring between them effortlessly.

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Functions of a Bridge in Computer Network

Let’s explore the main functions of a bridge:

1. Connects Two Networks

A bridge connects two different networks, or a segment of a network, to allow them to function as one. This is particularly useful in an office, school, or building when different departments or floors utilize different networks. For example, a bridge would make it possible to link multiple floors or departments together to share data, making it seem like they were all on the same network.

2. Filter Traffic

It ensures that only the intended destination receives the data packets by blocking or forwarding packets based on their destination address. By filtering traffic, the bridge helps to keep unnecessary data from traveling across the network. Consequently, only the correct information reaches the desired destination, which makes the overall system more efficient. 

3. Reduces Network Traffic

A bridge only sends data where it is needed. Bridges minimize unwanted traffic, making the network much faster. Less traffic means a lower chance of collisions (where data crashes into each other), leading to improved speeds and performance of the network as a whole.

4. Expands the size of the network

Bridges provide the ability to further expand a network by adding more devices or computers. Instead of one large network that has an overhead of information, bridges break it up into smaller sections that are still connected together.

5. Learns the MAC Address

A bridge maintains a table of MAC addresses (unique ID of a device) so it can remember where to send the information in the future. Over time, a bridge learns and creates an actual “map” of where each device is located, thus making decisions to send data faster and smarter.

Working of a Bridge in Computer Network

Let’s look at the working of a bridge in a computer network in a step-by-step manner:

Step 1: Receives Data Packets

When a device sends a data packet, the bridge captures it before it reaches its destination. This means that the bridge can verify the data and determine what to do with it. It is the “checkpoint” for all network traffic.

Step 2: Read the MAC Address

It reads the source and destination MAC addresses in each packet. The MAC address is a unique ID each device on the network has. By looking at the MAC addresses, the bridge knows who sent the data and who should receive it. This process is important in case any of the data, even if just a packet, is sent to the wrong device.

Step 3: Decide Where to Send

If the destination is on another segment, the bridge sends the packet. If it is on the same segment as the source, it does not send it. In this manner, the bridge is not wasting bandwidth on sending data where it does not need to be sent. The bridge takes care to ensure that the data travels only to the right side of the network, just like a green light directs drivers to move forward.

Step 4: Learns and Updates

The bridge continues to learn which devices are located on which side and updates its MAC address table to make better decisions later on. Each time a new device transmits or receives data, the bridge will update its memory. This kind of intelligent learning will allow the bridge to make decisions faster and with greater accuracy in the future. 

Advantages and Disadvantages of a Bridge in Computer Network

Bridges in computer networks offer both advantages and disadvantages, depending on the size, type, and needs of the network. Let’s explore the main advantages and disadvantages of using a bridge in a computer network.

Advantages of a Bridge in Computer Network

Let’s look at some advantages of bridges in computer networks:

1. Lowers Network Traffic: A bridge forwards data only when needed, as this prevents excessive traffic and improves network performance.
2. Increases Network Efficiency: When you split the network into segments, every segment is alone and will receive very few or no collisions, making the movement of data efficient.
3. Expand the Network: A bridge can allow you to connect two or more small networks, allowing you to expand your network with ease.
4. Learns Automatically: It builds a MAC address table on its own so that it can forward data efficiently with no additional configuration required.
5. Inexpensive: For small networks, bridges are a low-cost option for managing traffic and providing control.

Disadvantages of a Bridge in Computer Network

Let’s look at some disadvantages of using a bridge in a computer network:

1. Slower Than Switching: Bridges have a slower throughput compared to switches, especially as the network scales up.
2. Cannnot Handle Heavy Loads: If the network is large or has a lot of traffic, bridges may not perform very well, but they do not include advanced traffic management functionality.
3. Limited to LANs: Bridges can be deployed for local area networks (LANs) and are not applicable for other network types like wide area networks (WANs).
4. No Advanced Security: Bridges do not deliver security functionality on par with routers or firewalls.
5. One Collision Domain per Port: Some bridges forward broadcast traffic across segments, causing shared collision domains. This can increase collisions and affect network performance.

Bridge vs Repeater vs Switch in Computer Network

Performance Impact of a Bridge in Computer Network

In some cases, bridges can enhance network performance, but in others, delays can arise owing to the size of the network and the amount of traffic.

Positive Impact:

• Filters data and minimizes unnecessary traffic.
• Minimizes the likelihood of a data collision.
• It will be used efficiently to communicate between segments.

Negative Impact:

• Can introduce a delay in the delivery of data as a result of the filtering and learning process.
• In a larger or high-capacity network, it can become a bottleneck.
• They are not practical for networks operating with a high data plane speed or with many devices connected to the network.

Practical Use Cases of Bridge in Computer Network

Here are examples of real-world situations in which using a bridge can be useful:

• Connecting Two LANs in an Office: When two departments use different LANs, a bridge may be used between them so the users can share files and printers.
• Segmenting a Large Network: If one LAN has too much data being shared, a bridge can be used to segment it into two parts, thus reducing congestion.
• Interfacing Different Types of Devices: If you have old and new devices interfacing together, a bridge can help in communication if they have similar data link protocols.
• Improving Efficiency on Small Networks: For homes and small business environments, bridges can help to improve network efficiency by providing interconnection without the expense of adding more network equipment.

Common Problems with a Bridge in a Computer Network

While bridges can be useful, they can have some difficulties. The types of difficulties identified below typically occur based on how the bridge is implemented and operated. 

1. Network Delay: A small amount of time is involved in a bridge filtering and forwarding data, delaying data transfer. Slow delivery is common in busy network environments and can affect performance.

2. Scalability: Bridges are a better choice when small networks are implemented. In a large or high-traffic network, bridges become challenged and may slow down or delay service. Bridges are not designed to accommodate a large number of devices.

3. No advanced features: Bridges do not have advanced features or capabilities available with switches or routers. Switches offer Quality of Service (QoS), routers handle Layer 3/IP routing, and bridges provide minimal security.

4. Difficult to troubleshoot: If anything goes wrong in the network, it may be difficult to trace the issue as bridges work quickly and without visibility.

5. Looping Issues: If not connected properly, bridges can create a network loop if you connect multiple bridges. A network loop will create a broadcast storm and slow a network unless the loop prevention is properly configured (possibly using the Spanning Tree Protocol).

Best Practices for Using a Bridge in a Computer Network

Follow these guidelines to maximize the benefits of a bridge in your network:

1. Use in Small to Medium Networks: Bridges are intended to be used for home networks, small businesses, schools, or departments with little traffic.

2. Do Not Overload: Do not connect too many devices via a single bridge, as this can slow down if overloaded.

3. Place Bridges Strategically: Bridges should be placed where two different network segments intersect, such as between different departments or floors.

4. Compatible Devices: Make sure that the devices on either side of the bridge use the same protocols and formats.

5. Avoid Loops: If more than one bridge is used, make sure the network is properly configured or does not form a network loop by using loop-prevention protocols.

Conclusion

A bridge in a computer network is a smart device that connects different parts of a network and controls how data flows between them. It uses MAC addresses to filter traffic and only forwards what is needed, like a traffic officer guiding vehicles. Bridges are useful in small or medium networks where better speed and less traffic are needed. They help devices talk to each other easily and make the network faster and more organized. But they may not work well in large or high-speed networks. Using a bridge the right way can make your network more reliable and efficient.

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