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Lesson 6 The link layer
Objective Responsibilities of link layer in TCP/IP protocol

Link Layer in the TCP/IP Protocol

Question: What are the responsibilities of the link layer in the TCP/IP protocol?
The link layer is responsible for establishing communication between machines at the level of a physical connection.
For example, the link-layer protocols move data from an ethernet[1] card across 10BaseT[2] wires, or from a serial port[3], through a modem, and across the phone network. Examples of link-layer protocols are FDDI[4], which is used for fiber optics networks; the familiar ethernet protocol; and PPP[5], which is used across phone lines and other types of point-to-point connections. Link-layer protocols are typically concerned only with the local network[6]. Moving data across wide area networks[7], or between different types of physical networks, requires the capabilities of the network layer.

What are the Responsibilities of the link layer in the TCP/IP protocol

[1]Ethernet: A LAN developed by Xerox in 1976. Ethernet became a widely implemented network from which the IEEE 802.3 standard for contention networks was developed. It uses a bus topology and the original Ethernet relies on CSMA/CD to regulate traffic on the main communication line.
[2]10BaseT: A variant of Ethernet which allows stations to be attached via twisted pair cable.
[3]Serial port: A connector on a computer to which you can attach a serial line connected to peripherals which communicate using a serial (bit-stream) protocol.
[4]Fiber Distributed Data Interface (FDDI) : FDDI is a 100 Mbit/s ANSI standard local area network architecture. It is based on optical fibre (though it can be copper cable, in which case it may be called CDDI).
[5] Point-to-point protocol (PPP): A protocol for connecting to the Internet. PPP provides error checking and compression of the IP and TCP headers.
[6] Local Area Network: A collection of computers and other hardware components linked by physical cabling that permits any device on the network to interact with any other device.
[7]Wide Area Network. A network that extends over distances greater than one mile.