Associate Level Material
Appendix C

OSI Model Key Terms Table

Use the following table to define the key terms related to the OSI model. Describe the functions of any hardware connectivity devices and tools listed.

|Term |Definition |Function |
| | |(if applicable) |
|Physical layer |Will convert bits into signals for outgoing|This will change the data packets to |
| |messages and signals into bits for incoming|physical signals which symbolize 1’s and |
| |messages.. |0’s and then later will send the physical |
| | |signal to the destination. |
|Data link layer |Will work with frames and is intermediary |The layer splits data that is obtained from|
| |between Network layer and Physical Layer. |the network later to the frames and the |
| | |physical layer can transmit. It will also |
| | |package data into frames which are workable|
| | |by the network layer. |
|Network layer |Will handle the logical addressing and will|Will be able to create and keeps and closes|
| |translate logical network addresses(IP) |network links within the different networks|
| |into a physical address (MAC) |.Makes routing selections and relays data |
| | |from one network to another. |
|Transport layer |Will manage data transfer from one |Goes over the mistakes and makes |
| |application to another application from an |corrections, will split data into smaller |
| |across network |packets. Will rerecord packets as they are |
| | |arriving if they are out of order. |
|Session layer |Allows two computers to have on going |Will allow users to set up control and end |
| |communication |links. Will build up checkpoints in the |
| | |data streams as an attempt to avoid |
| | |resending packets. Also in charge of user |
| | |authorization. |
|Presentation layer |Handles data formatting and translation. |Ensures there is change. Will make sure |
| | |that applications on different ends of the |
| | |network links can communicate. |
|Application layer |Provides interfaces for the applications to|This will begin connection requests and |
| |access network services. |offers an interface to access file |
| | |transfers |
|Signaling |Used for electrical, light, energy or radio|Electrical signals are the most typical. |
| |waves to convey data between networked |Can understand data by current state or |
| |computers |transition method. |
|Synchronous |Will use a clock signal to arrange | |
| |communications between devices. | |
|Asynchronous |Same as asynchronous but does not need a |Has a start signal, the payload of the |
| |clock signal. |datagram or the frame. Has stop signal to |
| | |give their details. |
|Bandwidth |Amount of details that are carried on a | |
| |certain transmitting medium. | |
|Point-to-point topology |Cabling creates a direct link between two |used when devices are wanting to monopolize|
| |devices |the transmitting medium between them. |
|Multipoint connection |Has 3 or more devices that are all |All individual devices will need to have a |
| |connected by 1 transmitting medium. |method to identify themselves and the goal |
| | |machine to which it desires to convey. |
|MAC |Manages access to the physical medium and |The function will be different to each |
| |therefore communicates with the physical |depending on the network being used. |
| |Layer | |
|LLC |Controls data link communication and |Rational link control layer is a sub layer |
| |defines the use of logical interface points|of the data link layer |
| |(SAPs) | |
|SAP |Service Access Point- used on multiprotocol|Let’s the LLC recognize which protocol is |
| |LAN |being used |
|Access method |Principles which define how a computer |Decreases data collisions which cause |
| |places data onto a network wire and how it |damaged packets. Can also be known as |
| |receives data from a wire that looks |arbitration. |
| |exactly the same. | |
|CSMA/CD |Media access method which a device must |Used in Ethernet and IEEE. Will evaluate |
| |first listen to the medium to be sure no |network traffic to watch for crashes and |
| |other device is transmitting. |will begin retransmissions |
|Gateway |Software program / hardware that links 2 |Recognized as upper layers. Should |
| |different kinds of networks by changing |communicate with application and set up and|
| |data from one network to another or from |control sessions. They will convert encoded|
| |one operating system to another |data and interpret rational and physical |
| | |addressing. |
|Hubs |A network device that performs the same |Will transmit data packets or duplicates |
| |function as a repeater but has several |them to each one of the ports. Will allow |
| |ports to |all networked untis to easily see them |
| |connect a number of devices; sometimes | |
| |called a multiport repeater | |
|Bridges |Connects 2 LAN’s and makes them come up as |Links ring network to bus network. |
| |1. Can also connect 2 portions as a single | |
| |signal. | |
|Token passing |Type of arbitration which will use a |The only unit that can transfer data over |
| |particular data packet and transferred |to the network’s transmitting medium is the|
| |around a network. |“token” |
|Polling |Method of arbitration which has a single |Will allow authorization to units to |
| |device serving as a channel access admin. |transmit data on the communication channel |
| | |by channel access admin. |