‫All right, so since there's really nothing much to say about the physical layer, I mean, because
‫in this course we're really looking at the digital side of networking.
‫I'd like to just skip that and start with the second one.
‫The data link layer.
‫The datalink layer is a second layer and the Osai Open Systems Interconnection seven layer reference
‫model.
‫Now it responds to service requests from the network layer above it and issues service requests to the
‫physical layer below it, right?
‫So the data link layer is responsible for encoding bits into packets prior to transmission and then
‫decoding the packets back in the bits at the destination.
‫And --, by the way, are the most basic unit of information in computing and communications.
‫Packets are the fundamental unit of information, transport in all modern computer networks and increasingly
‫in other communications networks as well.
‫So the data link layer is also responsible for.
‫Logical link, control, media access control, hardware, addressing error detection and handling and
‫defining physical layer standards.
‫It provides reliable data transfer by transmitting packet with a necessary synchronization, error control
‫and flow control.
‫The data link layer is divided into two sub layers.
‫First, the media access control Mac Sub Layer governs protocol access to the physical network medium
‫through the Mac addresses that are typically assigned to all ports on a router.
‫Multiple devices on the same physical link can uniquely identify one another at the data link layer.
‫Mac addresses are used in addition to the network addresses that are typically configured manually on
‫ports within a network.
‫Now, secondly, the Logical Link Control, or LLC sub layer, manages communications between devices
‫over a single link of a network.
‫This sub layer supports fields in link layer frames that enable multiple higher layer protocols to share
‫a single physical link.
‫So here we have some protocols and the data link layer and some physical media and connection methodologies
‫in the physical layer.
‫Ethernet and 8.2.1 one wireless LAN are the best known protocols of the data link layer.
‫Ethernet is the name of the most commonly used network protocol that controls how data is transmitted
‫over land, which is a local area network.
‫Now you need to have a network interface card in the device that you want to connect to the network.
‫I know it probably seems pretty obvious to you, but I just wanted to make sure that we're all on the
‫same page.
‫A wireless local area network, or W LAN, is a wireless computer network protocol that links two or
‫more devices using wireless communication within a limited area such as a home or school computer lab
‫or office building.
‫And this gives users the ability to move around within a local coverage area and still be connected
‫to the network.
‫Most modern lands are based on the eye Tripoli 8.2.1 one standard and are marketed under the Wi-Fi brand
‫name.