Network Communications PDF

NETWORK COMMUNICATIONS Scientists had intended to type in “LOG” through an “Interface Message Processor”, but UCLA ARPANET (Advanced Research Projects undergraduat...

NETWORK COMMUNICATIONS Scientists had intended to type in “LOG” through an “Interface Message Processor”, but UCLA ARPANET (Advanced Research Projects undergraduate Charley Kline only Agency Network) got as far as sending two characters before the system An experimental system that crashed. pioneered the then-radical idea of The exercise was repeated networking different kinds of successfully a few hours later computers together The project was sponsored by the WHO SUPPLIED THE TECHNOLOGY? US Department of Defense Advanced Research Projects AT&T supplied the 50 kbps Agency (DARPA) connection between the two sites, with engineers set up an analogue HOW DID ARPANET WORK? phone call to confirm the receipt of messages. ARPANET initially connected four independent network nodes situated Government contractor BBN (Bolt at UCLA, Stanford Research Beranek and Newman) supplied Institute (SRI), the University of the Interface Message Processor California-Santa Barbara (UCSB) (IMP) that connected nodes on the and the University of Utah nascent network. The first node of the ARPANET was The October 29, 1969 established when networking communication was significant hardware was installed at UCLA and because it represented the first use connected to a host computer on of a wide area packet switched September 2, 1969. network, a pioneering communications technology that still WHAT WAS THE FIRST ARPANET underpins modern communications The first ARPANET message sent networks. using the prototype packet-switching network was a failed attempt to stimulate a basic login process. * 9 - 10:30 Two characters - L and O - typed into a computer terminal at UCLA were successfully transmitted to a computer at the Stanford Research Institute, some 352 miles (566 km) away, before the connection was lost. HOW DID THE ARPANET BECOME THE Packet Switching(1960) > ARPANET(1970) INTERNET? > TCP/IP(1980) > WWW(1990) > Commercial intern(2000) ARPANET went international in 1973 with satellite links linking the TIMELINE OF COMPUTER NETWORKS Unversity College of London in - In 1957, Advanced Research England and the Royal Radar Project Agency was formed by the Establishment in Norway to US US universities. - In 1961, the Idea of ARPANET was proposed by Leonard Kleinrock. Access to the ARPANET was further - In 1965, the term packet was used expanded in 1981 when the US by Donald Davies. National Science Foundation - In 1969, ARPANET became (NSF) created the Computer functional, and the Internet was Science Network (CSNET). This officially born. eventually led to the creation of the - In 1971, Ray Tomlinson sent the NSFNET project in 1986. first email, and the foundation for Wi-Fi was laid with the use of a This laid the groundwork for the ALOHAnet. creation of the Internet as we now - In 1973, Robert Metcalfe developed know it. ARPANET was the Ethernet at Xerox PARC, and the precursor to the modern Internet first experimental VolP call was made. The ARPANET project disbanded in - In 1976, the first true IP router was 1990, but the project helped seal developed by Ginny Strazisar. partnerships within the telecoms - In 1978, Bob Kahn invented the industry that laid the groundwork for TCP/IP protocol for networks the creation of the modern Internet developed. and the World Wide Web. - In 1981, Internet Protocol version 4, or IPV4, was officially defined in COMPUTER NETWORKING RFC 791* in 1981. - A collection of computers capable of - In 1983, DNS was introduced by transmitting, receiving, and Paul Mockapetris. exchanging voice, data, and video - In 1988, details about network traffic. firewall technology were first published 1988. - A computer network consists of - In 1996, IPv6 was introduced. two or more computers that are - In 1997, the first version of the linked in order to share resources, 802.11 standards for Wi-Fi was exchange files, or allow electronic introduced in June 1997, providing communications. transmission speeds up to 2 Mbps. 3 ELEMENTS OF COMMUNICATIONS COMPONENTS OF A NETWORK-Media - The medium provides the channel - Message source (Sender), over which the message travels from Message Destination (Receiver), source to destination. Channel (Transmission Medium). - Modern networks primarily use three COMPONENTS OF A NETWORK types of media to interconnect 3 categories of network components: devices and to provide the pathway - Devices over which data can be transmitted. - Media These media are: - Services - Metallic wires within cables - Glass or plastic fibers COMPONENTS OF A NETWORK-Devices - Wireless transmission End devices - On metallic wires, the data is - These devices form the interface encoded into electrical impulses that between users and the underlying match specific patterns. communication. - Fiber optic transmissions rely on - Examples of end devices are: pulses of light within either infrared - Computers or visible light ranges. - Network printers - In wireless transmission, patterns of - VolP phones electromagnetic waves depict the - TelePresence endpoint various bit values. - Security cameras - Mobile devices NETWORK TOPOLOGIES - A host device is either the source or Topology Diagrams destination of a message transmitted - There are 2 types of topology over the network diagrams including: - Physical - Identify the Intermediary Network Devices physical location of - Interconnect end devices intermediary devices, - Connect the individual hosts to the configured ports, and cable network and can connect multiple installation. individual networks to form an - Logical - Identify devices, internetwork. ports, and IP addressing - Examples of intermediary network scheme. devices are: Star topology - Network access (switch and - All communications have to go wireless access points) through the central concentrator, - Internetworking (routers) which is a switch. It is the central - Security (Firewalls) component of our network. - The central concentrator plays an important role; if it fails, all the connections will go down.  - However, if a cable fails, only one spoke routers could be simple node (host will be brought down). routers, while the headquarters has a powerful firewall that inspects all Extended Star traffic. - a network with an additional networking device connected to the Hybrid main networking device. - A mix of different network - Typically, a network cable connects topologies. to one switch, and then several other - The LAN is located in New York with switches connect to the first switch two buildings and a core layer. - Each building has access and Full Mesh distribution layer switches. The - Each device is connected to all other access layer switches are connected devices. with Partial mesh to the distribution - The advantage is that the network layer switches. The distribution layer has full redundancy. If a link fails, switches use full mesh. there are still backup links we can - The buildings are connected with use to route packets. full mesh to two core layer - The downside is that its expensive switches. for each link. TYPES OF NETWORK Partial Mesh INFRASTRUCTURES - An alternative to full mesh - A trade-off between cost and - A computer network is basically a redundancy. group of nodes connected together - The Los Angeles and New York sites to share data. are the most important ones, so they - Device in this system shares files, are connected to all other sites. programs, or any other data with There is no direct connection each other. There are different between San Francisco, Detroit and types of networks, small, medium Miami. and large, according to the need. Hub and Spoke PERSONAL AREA NETWORK - We have one central device called - The smallest network type is PAN the hub, and the other devices are (Personal Area Network). A PAN is a called spokes. The HQ of this network around a single person. company is in New York. This is where all company resources are - It covers a very small area, which is located. There are also branch almost a maximum of 10 meters far offices that need to access the from a person. headquarters resources. - Traffic between spoke routers is often routed through the hub router because of security reasons. The LOCAL AREA NETWORK pools of storage devices to multiple servers. - Covers mainly a building or a site. So, it has a distance limitations. With Campus Area Network these characteristics. It is smaller - It is used mainly within a site that than MAN and WAN. In LANs, both connects different buildings and copper and fiber optic cables can departments. be used. - It is one of the most used network Virtual Private Network types in today’s world. - It is a private network that uses public Internet to connect remote METROPOLITAN AREA NETWORK locations, this is mainly used by company networks or as private - In MANs, mainly fiber optic cables usage at homes. are used. This is because of the covered distance. Virtual Local Area Network - With this network type, a switched - Fiber optic provides good network can be divided into different performance for these types of broadcast domains. By doing this, it networks. Wireless technology can provides security, scalability, and be also used for MANs. efficiency in a switched network. - MANs are costly networks, and it Network Devices need experienced network - It is a piece of software or hardware engineers integral to communication between a computer and an internet network. WIDE AREA NETWORK - It plays 2 roles: - It is the largest network type used in - Establishing a network computer networks. connection - It covers large geographical areas. It - Maintaining, protecting, and can also connect other small and enhancing that connection. medium networks like LANs and MANs. - It is slower than MANs and LANs. OTHER TYPES OF NETWORK WLAN(Wireless LAN) - It covers a small area to provide a wireless connection to laptops, phones, or any network devices. SAN (Storage Area Network) - A dedicated high-speed network that interconnects and presents shared