What is a Network Bridge?

In computer networks, Bridge is a hardware or software system that connects different parts of a network operating in an Intranet at layer 2 of the OSI model.

What is a Network Bridge?

What is Bridge in Computer Network, How Does It Work?

The main role of bridges is to connect LAN (Local Area Network) networks, but they are not usually used to connect all networks together.

They can be used to connect an Intranet to the Internet or to connect a subnet to another subnet depending on their usage. It also works by using the table of MAC addresses detected in each segment it is connected to.

Bridge originally refers to a device described in the IEEE 802.1D standard.

When there is a large amount of traffic on a local area network, packets can collide with each other and slow down network traffic as it reduces network efficiency.

Packets can conflict because a lot of traffic is routed between all computers on the network. To reduce this ratio, a LAN can be divided into two or more networks.

Network traffic in each segment remains only within its own LAN, so collisions are reduced and performance is increased since the traffic does not have to travel through all computers on the network. In short, bridges are used to connect LANs together.

Each data packet on an Intranet can contain more information than an IP address and also contains addressing information required for network architecture such as Ethernet.

Bridges check this information from the external network and send the packet to the full address on a LAN and query a learning table containing the addresses of all nodes in the network. If a bridge discovers a packet belongs to its LAN, it keeps the packet on the LAN.

If the bridge detects that the destination computer is on another LAN, it sends the packet and updates the learning table continuously while monitoring and routing the traffic.

Bridges also connect LANs in a number of different ways. For example, they can connect LANs over ISDN lines using traditional phone lines and modems, and over direct cable connections or using serial connections.

In addition, CSU/DSU units are used to connect bridges to telephone lines using remote conductivity. Bridges and routers are sometimes combined into a single product called BRouter.

A BRouter device performs the tasks of bridges and routers. So if the data needs to be sent only to a specific network or another LAN in the subnet, it sends the data based on the Ethernet packet.

If the destination is on another network, it acts as a router task that examines IP packets and routes data according to the IP address.

In short, network bridges connect two or more networks or WAN networks that are physically close to each other.


  1. It is generally a cheap network device in terms of price.
  2. It separates the network segments and thus prevents collision.
  3. It does not need an advanced configuration.
  4. It provides access control and network management.
  5. Spanning Tree Protocol can be used to prevent loops.


  1. Broadcasts do not have a limit.
  2. It is not useful in very large networks.
  3. There are processing times for submitted data.
  4. It causes a Loop in a network environment that is divided into multiple LANs.

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