What are Bridges in Computer Networks? (Fully Explained)
Bridges serve the purpose of linking two subnetworks that utilize interchangeable protocols. They merge two LANs to create an extended LAN. The key distinction between a bridge and a repeater is that the bridge possesses a higher penetrating efficiency.
Functionality of Bridges
A bridge takes in all packets and amplifies them to the opposite side. These intelligent devices selectively allow certain packets to pass through. A bridge only forwards packets that are addressed from a node in one network to a node in the other network.
A bridge operates in the following manner:
- It receives all packets or frames from both LAN segments A and B.
- It constructs a table of addresses to identify which packets are sent from which LAN (or segment) to which other LAN.
- The bridge processes the packets, discarding those from LAN A that are directed to a computer on LAN A, while retransmitting packets from LAN A that are meant for a computer on LAN B to LAN B.
- The same method applies to packets from LAN B.
Types of Bridges
There are primarily two types of bridges:
1. Transparent Bridges
Also known as learning bridges, these bridges autonomously build their table of terminal addresses while connecting two LANs. They facilitate the source location in creating their table and are self-updating, functioning as plug-and-play devices.
2. Source Routing Bridge
This type of bridge indicates to the sending terminal where the frames should remain. It is utilized to avoid looping issues.
Applications of Bridges
The primary applications of bridges include:
- Dividing large, busy networks into smaller, interconnected networks to enhance performance.
- Expanding the physical size of a network.
- Connecting a LAN segment through a synchronous modem to another LAN segment located in a remote area.
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