The Data Link Layer of the OSI model

A network interface controller (NIC)The Data Link Layer is Layer 2 of the seven-layer OSI model of computer networking.  The Data Link layer deals with issues on a single segment of the network.

Layer two of the OSI model is one area where the difference between the theoretical OSI reference model and the implementation of TCP/IP with the competing Department of Defense (DoD) model. As we will discuss with the implementation of TCP/IP there is one lower layer called the network interface layer that encompasses Ethernet.

Physical Layer Topology in computer networking

Physical Layer Topology in computer networkingA network topology refers to the layout of the transmission medium and devices on a network. As a networking professional for many years I can honestly say about the only time network topology has come up is for certification testing. Here are some basic definitions.

Physical Topology:

Physical topology defines the cable's actual physical configuration (star, bus, mesh, ring, cellular, hybrid).

The Internet Family of Protocols The TCP/IP protocol suite

TCP/IP protocol suite graphiicThe Internet Model of computer networking is not merely a reduced version of the OSI Reference Model with a straight line comparison of the four layers of the TCP/IP model to seven layers of the OSI model, as we explain here, and in the next page on the difference between the Internet and OSI reference model

The Internet protocol suite commonly known as TCP/IP is a set of communications protocols used for the Internet and similar networks. TCP/IP is not a single protocol, but rather an entire family of protocols.

The network concept of protocols establishes a set of rules for each system to speak the others language in order for them to communicate. Protocols describe both the format that a message must take as well as the way in which messages are exchanged between computers.

Transmission Control Protocol (TCP) and the Internet Protocol (IP), were the first two members of the family to be defined, consider them the parents of the family. Protocol stack describes a layered set of protocols working together to provide a set of network functions. Each protocol/layer services the layer above by using the layer below.


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