Switch and Bridge Diferences and Working

Switch and Bridge

Switches and Bridges are pretty similar, both operate at the Data Link layer (just above Physical) and both can filter data so that only the appropriate segment or host receives a transmission. Both filter packets based on the physical address (AKA MAC - Media Access Control - address) of the sender/receiver although newer switches sometimes include the capabilities of a router and can forward data based on IP address (operating at the Network Layer) and are referred to as IP Switches or Multi Layer Switches.

Often the desired results could be achieved using either a switch or a bridge but *in general* bridges are used to extend the distance capabilities of the network because bridge can connect only two networks/ LANs/ hosts, means bridge has only two ports. While switch can connect more than two networks/ LANs/ Hosts because switch has more than two ports., and switches are used to primarily for their filtering capabilities to create multiple, smaller virtual LAN's out of one large LAN for easier management/administration (V-Lan's). Further details about both of them are given below;

The Switch

A switch is a layer 2 network device that forwards frames using MAC addresses in the header of frames. It improves network performance by segmenting the network and creating separate collision domains on each port so reducing competition for bandwidth.

In a switch, frame forwarding is handled by specialized hardware called "Application Specific Integrated Circuit" (ASIC). A switch dynamically builds and maintains a Content-Addressable Memory (CAM) table, holding all of the necessary MAC information for each port.

The Bridge

            Bridge is a layer 2 device used to connect different network types or networks of the same type. Packets having destination address on the same network segment are dropped. Bridges use "Store and Forward" method to inspect the whole packet. As a common thought, bridge introduces 20 to 30 % latency. Generally, a bridge has only two ports and divides a collision domain into two parts.