Computer Network chap#1 lecture:2

  NETWORK TYPES

A network is the interconnection of a set of devices capable of communication. In this definition, a device

 can be a host (or an end system as it is sometimes called) such as a large computer, desktop, laptop,

 workstation, cellular phone, or security system. 

 1.Local Area Network  (LAN)

LAN stands for Local Area Network, which is a network of devices connected within a limited area, like a home, office, or school. LANs can be small or large, but they're always limited to a single area.

 LANs allow devices to communicate, share resources, and access the internet. They can connect a variety of devices, including:

Servers, Desktop computers, Laptops, Printers, IoT devices, and Game consoles.  

2. Wide Area Network :

WAN stands for Wide Area Network, which is a computer network that connects smaller networks over a large geographical area. WANs can connect offices, data centers, cloud storage, and cloud applications.

 Point-to-Point WAN :

 A point-to-point WAN is a network that connects two communicating devices through a trans mission media (cable or air). 

 Switched WAN:

A switched WAN is a network with more than two ends. A switched WAN, as we will see shortly, is used in the backbone of global communication today.

Here are some things to know about WANs:  

• Location

  WANs are not tied to a specific location, allowing networks to communicate with each other across great distances.  
• Internet

  The internet is the world's largest WAN.  
• History

  The U.S. Air Force created the first known WAN in the late 1950s, which was a network of dedicated phone lines, telephones, and modems.  
• Benefits

  WANs can provide a reliable and stable connection, and can support branch files and backups at a single location. They can also prevent data duplication and version control issues by sharing files among authorized users. 

Internet work :

A LAN or a WAN in isolation; they are connected to one another. When two or more networks are connected, they make an internetwork, or internet.

 Switching:

 An internet is a switched network in which a switch connects at least two links together. A switch needs to forward data from a network to another network when required.

Types of switched networks :  

1. Circuit-Switched Network: In a circuit-switched network, a dedicated connection, called a circuit, is always available between the two end systems; the switch can only make it active or inactive.

2.Packet-Switched Network:In a computer network, the communication between the two ends is done in blocks of data called packets. In other words, instead of the continuous communication we see between two telephone sets when they are being used, we see the exchange of individ ual data packets between the two computers.

 The Internet :

The Internet is a vast network that connects computers all over the world. Through the Internet, people can share information and communicate from anywhere with an Internet connection. 

 INTERNET HISTORY:The Internet started in the 1960s as a way for government researchers to share information. Computers in the '60s were large and immobile and in order to make use of information stored in any one computer, one had to either travel to the site of the computer or have magnetic computer tapes sent through the conventional postal system.

 TCP/IP:TCP/IP, or Transmission Control Protocol/Internet Protocol, is a set of rules that allows computers to communicate over a network, such as the internet.

Here are some key features of TCP/IP: 

  

• How it works

  TCP/IP transmits data in packets that are routed from the sender to the receiver and reassembled at the destination.  
• Reliability

  TCP/IP emphasizes accuracy and has several steps to ensure that data is transmitted correctly.  
• Compatibility

  TCP/IP is compatible with all operating systems and types of computer hardware and networks.  
• Scalability

  TCP/IP is highly scalable.  

•  Internet Today:

  World Wide Web  :saw the explosion of Internet applications due to the emergence of the World Wide Web (WWW).

• Multimedia :Recent developments in the multimedia applications such as voice over IP (telephony), video over IP (Skype), view sharing (YouTube), and television over IP has increased the number of users.

• Peer-to-Peer Applications  :Peer-to-peer networking is also a new area of communication with a lot of potential.

•  STANDARDS AND ADMINISTRATION:

•  we introduce these standards and administration entities for those readers that are not familiar with them.

• Internet Standards:An Internet standard is a thoroughly tested specification that is useful to and adhered to by those who work with the Internet.

• An Internet draft is a working document (a work in progress) with no official status and a six-month lifetime.

•            1. Maturity Levels:  

• 
  

•  Proposed Standard. A proposed standard is a specification that is stable, well understood, and of sufficient interest to the Internet community. At this level, the specification is usually tested and implemented by several different groups. 

•  Draft Standard.A proposed standard is elevated to draft standard status after at least two successful independent and interoperable implementations. Barring diffi culties, a draft standard, with modifications if specific problems are encountered, normally becomes an Internet standard.

• Internet Standard.A draft standard reaches Internet standard status after demon strations of successful implementation.

• Historic.The historic RFCs are significant from a historical perspective. They either have been superseded by later specifications or have never passed the neces sary maturity levels to become an Internet standard.

• Experimental.An RFC classified as experimental describes work related to an experimental situation that does not affect the operation of the Internet.

•  Informational.An RFC classified as informational contains general, historical, or tutorial information related to the Internet.

•  2 .Requirement Levels:

•  five requirement levels:

• Required. An RFC is labeled required if it must be implemented by all Internet systems to achieve minimum conformance. For example, IP and ICMP (Chapter 19) are required protocols.

•  ❑ Recommended. An RFC labeled recommended is not required for minimum conformance; it is recommended because of its usefulness. 

•  ❑ Elective. An RFC labeled elective is not required and not recommended. 

•  ❑ Limited Use. An RFC labeled limited use should be used only in limited situations. 

•  ❑ Not Recommended. An RFC labeled not recommended is inappropriate for general use.

Internet Administration:

the process of managing the internet through rules, policies, and standards. It involves a variety of groups, including governments, civil society, and the private sector, .

 ISOC:The Internet Society (ISOC) is an international, nonprofit organization formed in 1992 to provide support for the Internet standards process.

IAB : The Internet Architecture Board (IAB) is the technical advisor to the ISOC. The main purposes of the IAB are to oversee the continuing development of the TCP/IP Protocol Suite and to serve in a technical advisory capacity to research members of the Internet community.

IETF:The Internet Engineering Task Force (IETF) is a forum of working groups managed by the Internet Engineering Steering Group (IESG). IETF is responsible for identifying operational problems and proposing solutions to these problems.

IRTF:The Internet Research Task Force (IRTF) is a forum of working groups managed by the Internet Research Steering Group (IRSG). IRTF focuses on long-term research top ics related to Internet protocols, applications, architecture, and technology 

THE END CHAPTER