concept of protocol and standard

Protocols

In information technology, a protocol (from the Greek protocollon, which was a leaf of paper glued to a manuscript volume, describing its contents) is the special set of rules that end points in a telecommunication connection use when they communicate. Protocols exist at several levels in a telecommunication connection. For example, there are protocols for the data interchange at the hardware device level and protocols for data interchange at the application program level. In the standard model known as Open Systems Interconnection (OSI), there are one or more protocols attach layer in the telecommunication exchange that both ends of the exchange must recognize and observe. Protocols are often described in an industry or international standard.

StandardsA common set of rules.

 

Standards Organization

Standards creation Communities

IEEE (Institute of Electrical and Electronics Engineers)
IEEE's Constitution defines the purposes of the organization as "scientific and educational, directed toward the advancement of the theory and practice of Electrical, Electronics, Communications and Computer Engineering, as well as Computer Science, the allied branches of engineering and the related arts and sciences." The IEEE is incorporated under the Not-for-Profit Corporation Law of the state of New York, United States. It was formed in 1963 by the merger of the Institute of Radio Engineers (IRE, founded 1912) and the American Institute of Electrical Engineers. It has more than 400,000 members in more than 160 countries, 45% outside the United States.In pursuing these goals, the IEEE serves as a major publisher of scientific journals and a conference organizer. It is also a leading developer of industrial standards (having developed over 900 active industry standards) in a broad range of disciplines, including electric power and energy, biomedical technology and health care, information technology, information assurance, telecommunications, consumer electronics, transportation, aerospace, and nanotechnology. IEEE develops and participates in educational activities such as accreditation of electrical engineering programs in institutes of higher learning.
IEEE is one of the leading standards-making organizations in the world. IEEE performs its standards making and maintaining functions through the IEEE Standards Association. IEEE standards affect a wide range of industries including: power and energy, biomedical and health care, Information Technology (IT), telecommunications, transportation, nanotechnology, information assurance, and many more. In 2005, IEEE had close to 900 active standards, with 500 standards under development. Wireless Networking standard.

HTTP Methods

 HTTP Methods

HTTP methods are similar to commands given to an application. Depending on the method used in the request, the server's response will vary. Successful responses to some request methods do not even contain body data.
The HTTP/1.1 standard defines the methods GET, POST, OPTIONS, HEAD, TRACE, PUT, DELETE, CONNECT. The most often used methods are GET and POST.

• [GET]is used to retrieve an entity of information without the need to submit additional data in the message body. Before HTTP 1.0, GET was the only method to request information.
• [POST]is similar to a GET request, but POST always includes a message body in the request message to send information of any type to the server. Usually information submitted via POST is used to generate dynamic content, for further processing, or the information is simply stored to be used by other applications. POST is a method that was introduced with HTTP version 1.0.

To send information to the server with GET, the client has to append it to the request URI. That causes several difficulties however:

• The length of the request URI can cause problems at the server,
• some clients can only transmit a Request URI of a certain length
• most clients display the additional Request URI information to the user

Even though POST is the better way to transmit additional information to the server, some applications use GET for that purpose, especially for small amounts of data or to allow bookmarking of the URL.
All other methods are rarely used and will only be covered briefly:

• [HEAD]This method asks for the header of a reply only. It can be used when checking for the existence of a certain document on a web server. The response will look exactly as if requested via GET but will not include the message body
• [OPTIONS]Using this method a client can query a server for the available methods and options concerning a resource.
• [TRACE]The TRACE method is similar to ping in TCP/IP. The request message contains a mandatory header field called Max-Forwards. Each time the message passes a proxy server, the value of that field is decremented by one. The server that gets the message with a value of zero will send a reply. If the server to whom the message is addressed gets the message, it will send a reply regardless of the value in the max-forwards header field. Using a sequence of these requests, a client can identify all proxy servers involved in forwarding a certain request.
• [PUT]used to transmit files to a server. This method is similar to the PUT command used in FTP. This imposes a security threat and is therefore almost never used.
• [DELETE]This method asks the server to delete the file addressed in the URI. Since this method imposes a security risk no known productive HTTP servers support that method. The DELETE method is very similar to the DELETE command in FTP.
• [CONNECT]is a command used to create a secure socket layer (SSL) tunnel through a HTTP proxy server. A proxy server addressed with that method would open a connection to the target server and forward all data regardless of its content. That way a secure connection can be established from client to the server even though a proxy server is in use.

Types of computer networks, protocols and standards

Types of computer networks, protocols and standards

1. 1. Computer Networks Introduction to computer networks
2. 2. Objectives • Define computer networks • Classify computer networks • Protocols & Standardization
3. 3. Computer Networks ? • A large number of separate but interconnected computers do the specific job. • A collection of autonomous computers interconnected by a single technology.
4. 4. Interconnected ? Two computers are said to be interconnected if they are able to exchange information.
5. 5. Types of Networks Classification based on transmission technology Broadcast links. Point-to- point links.
6. 6. Broadcast networks • Have a single communication channel that is shared by all the machines on the network. Host H1 H2 H3 H4 H5H6 Communication channel
7. 7. Broadcast networks • Short messages (also called packets) sent by any machine are received by all the others. • An address field within the packet specifies for whom it is intended. • Upon receiving a packet, a machine checks the address field. • If the packet is intended for the receiving machine, it processes the packet; otherwise it is just ignored. • This mode of operation is called broadcasting
8. 8. Bus Topology Ring Topology
9. 9. point-to-point networks • Many connections between individual pairs of machines. • To go from the source to the destination, a packet on this type of network may have to first visit one or more intermediate machines.
10. 10. Note: • As a general rule, smaller, geographically localized networks tend to use broadcasting, whereas larger networks usually are point-to-point
11. 11. Types of Networks Classification based on Scale (physical size) •LAN • MAN •WAN
12. 12. Local Area Networks • Within a single building or campus of up to a few kilometers in size. • They are widely used to connect personal computers and workstations in company offices and factories to share resources (e.g., printers) and exchange information.
13. 13. Three characteristics of LANs size, transmission technology, topology. few kilometers in size single cable , speeds of 10 Mbps to 100 Mbps Bus, Ring
14. 14. Metropolitan Area Networks • A MAN covers a city. • Ex:- cable television network
15. 15. Wide Area Networks • WAN, spans a large geographical area, often a country or continent. • The hosts are connected by a communication subnet, or just subnet for short. • The hosts are owned by the customers, whereas the communication subnet is typically owned and operated by a telephone company or Internet service provider.
16. 16. Subnet • The job of the subnet is to carry messages from host to host, just as the telephone system carries words from speaker to listener. • The subnet consists of two distinct components: –transmission lines and –switching elements.
17. 17. Transmission lines move bits between machines. They can be made of copper wire, optical fiber, or even radio links. Switching elements are specialized computers used to connect two or more transmission lines.
18. 18. Principle of Subnet • When a packet is sent from one router to another via one or more intermediate routers, the packet is received at each intermediate router in its entirety, stored there until the required output line is free, and then forwarded. • A subnet using this principle is called a store- and-forward or packet-switched subnet.
19. 19. • Routing algorithms are used to choose the path between source and destination.
20. 20. Wireless Networks • wireless networks can be divided into three main categories: 1. System interconnecti on 2. Wireless LANs 3. Wireless WANs.
21. 21. System interconnection • Connecting the components of a computer together using short-range radio. • Bluetooth to connect the components without wires. • Bluetooth also allows digital cameras, camcorders, scanners, and other devices to connect to a computer by merely bringing them within range.
22. 22. System interconnection using Bluetooth Configuration
23. 23. Wireless LANs • These are systems in which every computer has a radio modem and antenna with which it can communicate with other systems.
24. 24. Wireless WAN • Example:- cellular networks • cellular wireless networks are like wireless LANs, except that the distances involved are much greater and the bit rates much lower.
25. 25. Protocols & Standardization • Human analogy
26. 26. What is a protocol? • The formal specifications and conventions that govern and control the communications and data exchange. • Protocols are the standards for communications, networking, and internet networking..
27. 27. Standards • Traditional standards –Ex: TCP/IP • Judicial Standard o ISO/OSI

Networking and its criteria

NETWORKS

A network is a set of devices connected by communication links.A node can be a computer,printer or any other device capable of sending or receiving data generated by other nodes on the network.


DISTRIBUTED PROCESSING

Most networks use distributed processing in which task is divided among multiple computers.instead of one single large machine being responsible for all aspects of a process ,separate computers handle asubset.

NETWORK CRITERIA

A network must be able to meet a certain number of criteria. The most important of these are performance,reliability,and security.

Performance 
Performance can be measured in many ways including transit time and response time.Transit time is amount of time required for a message to travel from one device to another.Response time is the elapsed time between an inquiry and a response.

Reliability
In addition to accuracy of delivery,network reliability is measured by the frequency of failure,the time takes a link to recover from a failure and the networks robustness in a catastrophe.

Security
Network security issues include protecting data from unauthorized access,protecting data  from damage and development and also implementing  policies.