What Is A Network Bridge? - ITU Online

What Is a Network Bridge?

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Definition: Network Bridge

A network bridge is a network device that connects multiple network segments at the data link layer (Layer 2) of the OSI model. Its primary function is to filter traffic, either forwarding or blocking data packets based on the MAC addresses of the devices connected on either side of the bridge. This process helps in managing the traffic flow within a network by reducing collision domains and segmenting traffic to improve overall efficiency.

Understanding Network Bridges

Network bridges serve an essential role in extending and segmenting networks without the need for routing, thus maintaining performance and organizational simplicity in network design. They are particularly useful in situations where a network needs to be expanded without significant changes to the existing infrastructure.

Key Features and Benefits

Traffic Management

By examining the MAC addresses in incoming data packets, a bridge can determine whether the packet should be forwarded or blocked, effectively reducing unnecessary traffic on network segments.

Increased Network Size

Bridges can extend the size of a network by connecting multiple network segments, allowing for greater reach and coverage without degrading the performance due to excessive traffic.

Improved Performance

Network bridges reduce the number of broadcast domains within a network which decreases the overall network traffic and increases the performance.

Simple Network Management

Bridges do not require an IP address to perform their operations, making network configuration and management simpler compared to routers.

Types of Network Bridges

Transparent Bridges

These are the most common type of bridges that learn the network’s topology by analyzing incoming frames and determining how to forward traffic based on MAC addresses.

Learning Bridges

A subset of transparent bridges, learning bridges build a table of MAC addresses as they receive frames, determining the segment on which a MAC address is located and thus reducing future traffic by not forwarding unnecessary traffic to other segments.

Remote Bridges

These connect local area networks (LANs) over greater distances, often used to connect two geographically separated networks into a single larger network.

How Network Bridges Work

A network bridge reads the MAC address contained in the header of a data packet, consulting its internal MAC address table to decide whether to forward or discard the packet. If the destination MAC address is on a different segment, the bridge forwards the packet to that segment; if the destination is on the same segment, it blocks the packet to avoid duplication.

Frequently Asked Questions Related to Network Bridge

What Is the Main Purpose of a Network Bridge?

The main purpose of a network bridge is to connect multiple network segments at the data link layer, managing the flow of data to ensure that only necessary traffic is passed through to different parts of the network.

How Does a Network Bridge Differ from a Network Router?

A network bridge operates at the data link layer and primarily manages traffic using MAC addresses without concerning itself with network protocols. In contrast, a router operates at the network layer and directs traffic based on IP addresses, making decisions using more complex routing protocols.

Can a Network Bridge Improve Network Performance?

Yes, a network bridge can improve performance by reducing the number of collision domains within a network and effectively managing the traffic flow, which minimizes unnecessary data transmissions and optimizes network efficiency.

Is It Possible to Connect Different Types of Networks with a Bridge?

Generally, a network bridge is used to connect network segments within the same network type, such as Ethernet. Connecting different types of networks typically requires more sophisticated functions, like those provided by routers or gateways.

What Are the Limitations of Using Network Bridges?

Network bridges cannot read or filter data based on IP addresses since they operate at the data link layer. They also do not manage the traffic based on network policies or protocols, which can limit their usefulness in complex network setups requiring advanced routing capabilities.

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