A Bridge is a device that can join two LANs. However, a bridge can also divide an overloaded network into separate networks, reducing the traffic on each segment and making each network more efficient. A bridge can link unlike physical media such as twisted-pair and coaxial Ethernet. It can also link unlike network segments such as Ethernet and Token Ring.

They are also referred to as Media Access Control layer bridges. A Media Access Control layer bridge:

  • Checks the source and destination address of each packet.
  • Creates a routing table.
  • Forwards packets.
Note: A routing table stores the addresses and all the other information necessary to route information from one network to another.

If the destination address is not listed in the routing table, the bridge forwards the packets to all segments.

Multiple bridges can be used to combine several small networks into one large network. A bridge can be installed internally or externally. Bridges are faster than routers because routers perform complex functions on each packet.

The following are the differences between bridges and routers:

  • The bridge only recognizes the addresses of network cards in its own segment. Routers recognize network addresses.
  • A bridge can only recognize one path between networks. A router can search among multiple active paths and determine the best path.
  • The router only works with routable protocols.