A bridge is a networking device that connects multiple network segments, making them function as a single network. Its main purpose is to filter and forward traffic based on MAC addresses, thus reducing network traffic and creating a more organized and efficient network. Let’s explore its key aspects:

Function:

  • Filtering: By checking the MAC address of the data packet, a bridge determines if the data should be allowed to pass through or if it should be discarded.
  • Forwarding: If a data packet’s destination MAC address resides on another network segment, the bridge forwards the packet to that segment.
  • Isolating Collision Domains: Bridges reduce network collisions by separating collision domains while still allowing communication between them.

Types:

  • Transparent Bridges: These are self-learning bridges. They automatically build a table of MAC addresses by observing the source addresses of incoming packets.
  • Source Route Bridges: Used primarily in Token Ring networks. They rely on the source station to determine the route a particular frame should take through the network.
  • Translational Bridges: Connect two networks with different frame formats, such as Ethernet and Token Ring.

Benefits:

  • Network Segmentation: Breaks larger networks into smaller segments, reducing traffic and collisions on each segment.
  • Adaptability: Modern bridges can automatically learn and update their MAC address table.
  • Connectivity: Bridges can connect networks with different physical layer protocols.

Limitations:

  • Broadcast Traffic: Bridges still forward broadcast traffic, which can result in unnecessary data being sent across the network. This limitation is addressed by switches and routers.
  • Latency: Introducing a bridge can sometimes add a small amount of latency as it processes frames.

Spanning Tree Protocol (STP):

  • To prevent loops in bridged networks, which can result in broadcast storms and other network issues, the Spanning Tree Protocol is used. STP dynamically disables certain network paths, ensuring there’s only one active path between two network nodes.

Conclusion:
A bridge plays a crucial role in enhancing network efficiency and organization by connecting multiple segments and ensuring only necessary traffic passes between them. However, with the advent of switches, which operate at a more granular level (individual ports), the traditional use of bridges has declined in modern networks.