| A | B |
|---|
| Application | Provides network services to application processes (such as email, ftp, and telnet) |
| Presentation | Insures data is readable by the receiving system. Deals with data representation |
| Session | Establishes manages and terminates sessions between applications |
| Transport | Handles information flow control, fault detection and recovery, and data transport reliability |
| Network | Provides connectivity and path selection between two end systems |
| Data Link | Provides for the reliable transfer of data across media using physical addressing and the network topology. |
| Physical | Consists of voltages, wires, and connectors |
| Communication across the layers of the reference model is achieved because of | special networking software programs called protocols |
| A protocol is a controlled sequence of | messages that is exchanged between two or more systems to accomplish a given task. |
| Timing is crucial to network operation because protocols | require messages to arrive within certain time intervals |
| Protocol Functions | Identifies errors; applies compression techniques |
| Protocols decided on how to | announce sent data, announce received data, address data, the data is to be sent |
| To do their work, many protocols depend on the | operation of other protocols in the group or suite of protocols |
| the dominant protocol standard for inter-networking | The Transmission Control Protocol/Internet Protocol (TCP/IP) suite of protocols |
| Hypertext Transfer Protocol (HTTP) | governs how files such as text, graphics, sounds, and video are exchanged on the Internet or World Wide Web |
| HTTP is an | application layer protocol. |
| daemon | a program that services HTTP requests |
| HTTP client software | another name for a web browser. |
| Hypertext Markup Language (HTML) | a page description language; use it to indicate to web browser software how the page should look |
| HTML includes tags to indicate | boldface type, italics, line breaks, paragraph breaks, hyperlinks, insertion of tables, and so on. |
| The telnet application is used to . | access remote devices for configuration, control, and troubleshooting |
| File Transfer Protocol (FTP) is an application that | provides services for file transfer and manipulation. |
| FTP uses the | Session layer to allow multiple simultaneous connections to remote file systems. |
| Simple Mail Transport Protocol (SMTP) provides messaging services over | TCP/IP and supports most Internet e-mail programs |
| Domain Name System (DNS) provides access to name servers where network names are | translated to the addresses used by Layer 3 network protocols. |
| Transmission Control Protocol (TCP) is the primary Internet protocol for the | reliable delivery of data. |
| TCP includes facilities for end-to-end connection establishment, error detection and | recovery, and metering the rate of data flow data into the network. |
| TCP identifies the application using it by | a "port" number. |
| User Datagram Protocol (UDP) offers a | connection-less service to applications. |
| UDP uses lower overhead than TCP and can | tolerate a level of data loss. |
| Network management applications, network file system, and simple file transport use | UDP |
| Internet Protocol (IP) – IP provides source and destination addressing and packet | forwarding from one network to another toward a destination. |
| Internet Control Message Protocol (ICMP) is used for | network testing and troubleshooting. |
| Internet Control Message Protocol (ICMP) enables | diagnostic and error messages. |
| ICMP "echo" messages are used by the | PING application to test if a remote device is reachable |
| Routing Information Protocol (RIP) operates between router devices to | discover paths between networks. |
| In an intranet, routers depend on a routing protocol such as RIP to build and maintain information about how to | forward packets toward the destination. |
| RIP chooses routes based on the | distance or "hop count". |
| Address Resolution Protocol (ARP) is used to discover the local address (MAC address) of a | station on the network when its IP address is known. |
| End stations as well as routers use ARP to | discover local addresses. |
