lOSI Model Key Terms Table Appendix C Definitions 1. Physical Layer – is the 1st layer of the OSI or bottom layer, transmits and receives signals and specifies the physical details of cables, NICs, connectors, and hardware behavior. 2. Data Link Layer – is the 2nd layer of the OSI model and is responsible for managing access to the network medium and delivery of data frames from sender to receiver or from sender to and intermediate device, such as a router. 3. Network Layer- is the 3rd layer of the OSI model handles logical addressing and routing of PDU’s across internetworks. . Transport Layer – is the 4th layer of the OSI model and is responsible for reliable delivery of data streams across a network. Layer 4 protocols break large streams of data into smaller chunks and use sequence numbers and acknowledgment to provide communication and flow control. 5. Session Layer – is the 5th layer of the OSI model and is responsible for setting up , maintaining, and ending communication sequences( called sessions) across a network. 6. Presentation Layer – is the 6th layer of the OSI model, data can be encrypted and /or compressed to facilitate delivery.
Platform-specific application formats are translated into generic data formats for transmission or from generic data formats into platform-specific application formats for delivery to the Application layer. 7. Application Layer – is the 7th layer of the OSI model, provides interfaces that enable applications to request and receive network services. 8. Signaling – Method for utilizing electrical, light, energy, or radio waves to convey data in between networked computers 9. Synchronous – uses a clock signal to arrange communications in between devices 10. Asynchronous – this does not uses a clock signal in it 11.
Bandwidth – is the amount of details in which can be carried on a given transmitting medium. 12. Point-to-point topology – A topology in which cabling creates a direct link between two devices: used most often in WANs or in wireless networks to create a wireless bridge. 13. Multipoint connection – Three or more devices are connected by a single transmitting medium 14. MAC – (Media Access Control) which makes sure routing devices on a network transmit data to the intended location 15. LLC – Rational Link Control which controls data link between two or more computers on a single subnet 16.
SAP – (Service Access Point) used on a multiprotocol LAN 17. Access Method – Principles which define how a computer places data onto a network wire and how it receives data from the identical wire 18. CSMA/CD – Carrier Sense Multiple Access having crash recognition 19. Gateway – A software program or hardware which links two different kinds of network by changing data from one network to a different or from one operating system to a different one 20. Hubs – Multiport link point utilized to link network devices through a wire segment 21. Bridges – connect two LAN’s, making them appear as one 22.
Token passing – Method of arbitration which uses a particular data packet transferred around a network 23. Polling – Method of arbitration which has a single device servicing as a channel access admin Functions 1. Physical layer – it changes data packets to physical signals that are 1’s and zeros and then later sends the physical signals to the destination 2. Data Link layer – splits data that is obtained from the network layer into frames the physical layer can transmits. 3. Network layer – creates, keeps, and closes network links between networks. Makes routing selections and relays data from one network to another 4.
Transport layer – handles mistake correction, splitting data into small packets it also fixes packets that have arrived out of order 5. Session layer – Allows users to setup control and end a link also is in charge of user authorization 6. Presentation layer – this layer is to guarantee that applications on different ends of a network link can communicate 7. Application layer – this layer start connection requests and offers an interface to access files transfer services, printer access, and email 8. Signaling – 9. Synchronous – 10. Asynchronous – uses a start signal and a stop signal to convey their details 11. Bandwidth – 2. Point-to-point topology – is used when the devices are meant to have full control of the transmitting medium between them 13. Multipoint connection – Each devices needs to have a way to identify itself and the goal machine to which is desires to convey to 14. MAC – is exclusive to each unit connected on a network 15. LLC – is a sub-layer of the data link layer 16. SAP – lets the LLC know which protocol is being used 17. Access method – this decreases data collisions which in turn can cause data packets to be damaged 18. CSMA/CD – this evaluates the network traffic to observe crashes and begin retransmissions 19.
Gateway – it communicates with an application, set up and control sessions, converts encoded data and interprets rational and physical addressing data. 20. Hubs – transmits data packets and can copy them and sends them to each of the ports so that all units on the network can see them. 21. Bridges – this can link a ring network to a bus network 22. Token passing – the unit that is the “token” can transfer data of the network medium 23. Polling – The channel access admin can allow authorization to units to transmit data on the communication channel