Bridges operate at Layer 2, the data link layer, of the OSI reference model and are not required to examine upper-layer information. Therefore, a bridge eliminates unnecessary traffic and minimizes the chances of collisions occurring on a network by dividing it into segments and filtering traffic based on the station or MAC address.
Bridges filter network traffic by only looking at the MAC address. Therefore they can rapidly forward traffic representing any network-layer protocol. Because bridges only took at MAC addresses, they are not concerned with protocols. Consequently, bridges are only concerned with passing packets, or not passing packets based on their destination MAC addresses. The following are the important properties of bridges:
In other language,
Bridges do not promiscuously copy traffic to all ports, as hubs do, but learn which MAC addresses are reachable through specific ports. Once the bridge associates a port and an address, it will send traffic for that address only to that port. Bridges do send broadcasts to all ports except the one on which the broadcast was received.
Bridges learn the association of ports and addresses by examining the source address of frames that it sees on various ports. Once a frame arrives through a port, its source address is stored and the bridge assumes that MAC address is associated with that port. The first time that a previously unknown destination address is seen, the bridge will forward the frame to all ports other than the one on which the frame arrived.
Bridges filter network traffic by only looking at the MAC address. Therefore they can rapidly forward traffic representing any network-layer protocol. Because bridges only took at MAC addresses, they are not concerned with protocols. Consequently, bridges are only concerned with passing packets, or not passing packets based on their destination MAC addresses. The following are the important properties of bridges:
In other language,
Bridges do not promiscuously copy traffic to all ports, as hubs do, but learn which MAC addresses are reachable through specific ports. Once the bridge associates a port and an address, it will send traffic for that address only to that port. Bridges do send broadcasts to all ports except the one on which the broadcast was received.
Bridges learn the association of ports and addresses by examining the source address of frames that it sees on various ports. Once a frame arrives through a port, its source address is stored and the bridge assumes that MAC address is associated with that port. The first time that a previously unknown destination address is seen, the bridge will forward the frame to all ports other than the one on which the frame arrived.
- They are more intelligent than hubs-that is, they can analyze incoming packets and forward (or drop) them based on addressing information.
- They collect and pass packets between two network segments.
- They control broadcasts to the network.
- They maintain address tables.
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