! Data Link Layer

Layer 2 – The Data Link Layer

     Layer 2 of the OSI model provides the following functions:

          • Allows a device to access the network to send and receive messages

          • Offers a physical address so a device’s data can be sent on the network

          • Works with a device’s networking software when sending and receiving messages

          • Provides error-detection capability

     Common networking components that function at layer 2 include:

          • Network interface cards

          • Ethernet and Token Ring switches

          • Bridges

    NICs have a layer 2 or MAC address. A switch uses this address to filter and forward traffic, helping relieve congestion and collisions on a network segment.

      Bridges and switches function in a similar fashion; however, bridging is normally a software program on a CPU, while switches use Application-Specific Integrated Circuits (ASICs) to perform the task in dedicated hardware, which is much faster

 
ref: www.globalknowledge.com