What is Bridge?
Bridge operates in both the physical layer and the data link layer of the OSI model.
Bridges can divide a large network in to smaller segments. Bridge connects one local area network to another local area network and uses the same protocol. The Bridge looks each and every message and passes it to the other interconnected network. They can also relay frames between two originally separate LANs.It reduces the traffic between two LANs.Bridge can also provide security through this partitioning or traffic.
A Bridge operates at the data link layer, giving it access to the physical address of all stations connected to it. When a frame enters in a Bridge, it not only regenerates the signal but checks the address of the destination and forward the new copy only to the segment to which the address belong. It checks the incoming traffic and decides whether it is to be forwarded or discard. In Bridge network there is no relationship between host addresses and their locations, the message are sent to each and every address in the network and the only intended host accepts the message.
Bridges have same function as Switches and also operate at layer 2.Some time Switches are known as multiport bridges because Switches has more ports than bridges.
Bridge are more complex than hub and repeaters. Becauses Bridge works on the data link layer of the OSI model, this processes the information of each frame it receives. Bridges uses two methods to resolve the local area network segments. First one is Transparent Bridging that uses the forwarding database to send frame across the network. Bridges uses this method known as Adaptive Bridges. The second one is Source Route Bridging that uses two frame types to find the route to the destination network-Single Route frame that manage the network traffic and set the destination and All-Routes frame are used to find the route to destination. Bridges broadcast the All-Route frame to all network segments.
Bridging and Routing both perform the data control task but uses different method. Bridges works on data link layer of the OSI model and uses MAC address while Routers works on network layer of the OSI model and uses the IP address.
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