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Link Layer of the Internet protocol suite (TCP/IP)

Last Edit: 10/01/17

The link layer, sometimes referred to as the physical layer or data link layer, is the lowest layer of the four layer Internet protocol suite. The Internet protocol suite uses data packets to communicate between hosts: data packets are small blocks of data.

The link layer of the Internet protocol suite has no responsibility for transporting data packets across computer networks The link layer is only responsible for transporting data between hosts that are physically connected on the same network link.

Listed below are link layer protocols found in the Internet protocol suite:

  1. Address Resolution Protocol (ARP)
  2. Media Access Control (MAC)
    1. Digital Subscriber Line
    2. Ethernet
    3. Fiber Distributed Data Interface (FDDI)
    4. Integrated Services for Digital Network (ISDN)
  3. Layer 2 Tunneling Protocol (L2TP)
  4. Neighbor Discovery Protocol (NDP)
  5. Open Shortest Path First (OSPF)
  6. Point-to-Point Protocol (PPP)
  7. Reverse Address Resolution Protocol (RARP)

The Internet protocol suite (TCP/IP) was developed to work upon any computer hardware that supports packet switching. The Internet protocol suite does not specify, nor provide, any communication method that considers the physical specification of a host or network.

Therefore, a misunderstanding of the link layer of the Internet protocol suite arises: with some 'experts' stating the link layer handles physical data transportation.

The link layer provides an operating method for delivering frame data on local network links, but it is unconcerned with the physical data transmission, and simple assumes the network hardware is capable of delivering the data.