Bridges

Bridges are devices that operate at Layer 2 of the OSI reference model.
That is why they are widely referred to as Data Link Layer devices.
They serve a simple purpose:
They analyze incoming frames make forwarding decisions based on information contained in the frames and forward the frames toward the destination.
Local and remote bridges connect LAN segments in specific areas.
A bridge consists of a computer unit two or more network interface cards connecting two types of networks.
For example one interface card might connect to an Ethernet system while the second connects to a token ring system.
These two systems speak entirely different data languages and require the bridge to translate the node address supplied by one network into an address that is recognized by the others.
The bridge uses special software that accepts data from the sending network and translates it to the language other network.
A bridge therefore extends the maximum distance of network just like a repeater.

However it can also be used to segment the network to reduce network congestion.
A vast congested network can be divided into separate segments using a bridge.
Each of these segments hence will experience far lower levels of traffic loads.
This is because the bridge passes the signal only from one segment to another if needed.
Traffic between devices on the same segment also called intrasegment traffic will not affect the other segments.
A bridge works efficiently if the traffic between devices on different segments is kept minimal.
There is a business principal called the 80:20 principal this should be followed here as well.
According to this rule a well-designed network should keep 80 % of the traffic on the same segment.
Whereas it will let the remaining 20% of traffic needing to pass to another segment.
They need to ensure clients and their associated servers are placed on the same segment whenever possible.