Date: April. 13, 2014. Monday Evening. Faculty of Computing and ICT Under Department Bachelor of Science in Information Technology Seniorr Date: April. 13, 2014. Monday Evening.

Chapter 4. Three basic building blocks of the Internet. Introduction The Internet is basically a hierarchy that allows any Internet connected device in one geographic location, talking to another Internet connected device in another geographic location. The way that the information is transmitted varies greatly, and in some countries, wireless ham radios are even used to transmit email. Keep in mind that the word "connected" is used very loosely here. Ahmed Abdillahi Sanco

Open Systems Interconnection Models ( OSI Model) The Open Systems Interconnection (OSI) Model The seven open systems interconnection layers (OSI) are a staple of most networking textbooks. The idea is that a network will work on many different levels, or "layers" each of which will perform a supporting function for the next layer. Open Systems Interconnection Models ( OSI Model) Application Layer Presentation Layer Session Layer Transport Layer Network Layer Link Layer Physical Layer Ahmed Abdillahi Sanco

Application layer: The application layer is provided by the program that uses TCP/IP for communication. An application is a user process cooperating with another process usually on a different host (there is also a benefit to application communication within a single host). Examples of applications include Telnet and the File Transfer Protocol (FTP). The interface between the application and transport layers is defined by port numbers and sockets, Ahmed Abdillahi Sanco

Transport layer: The transport layer provides the end-to-end data transfer by delivering data from an application to its remote peer. Multiple applications can be supported simultaneously. The most-used transport layer protocol is the Transmission Control Protocol (TCP), which provides connection-oriented reliable data delivery, duplicate data suppression, congestion control, and flow control. Ahmed Abdillahi Sanco

Network layer The internetwork layer, also called the internet layer or the network layer, provides the “virtual network” image of an internet (this layer shields the higher levels from the physical network architecture below it). Internet Protocol (IP) is the most important protocol in this layer. It is a connectionless protocol that does not assume reliability from lower layers. IP does not provide reliability, flow control, or error recovery. These functions must be provided at a higher level. IP provides a routing function that attempts to deliver transmitted messages to their destination. Ahmed Abdillahi Sanco

The Network layers are the first three, being the physical link layer, the link layer, and the Network layer. Since the Internet is based on the Internet protocol which is in the Network Layer, and since the Internet can run on any number of different types of layers below that, we normally are not too concerned with the physical layers unless we are building an Ethernet cable, or transmitting an Internet signal through wireless means, and not to interested in the link layer unless we are registering a network card or router MAC address with our service provider. Ahmed Abdillahi Sanco

The top three layers (session, presentation, and application layers) are for program communication, and are completely independent of the network so that the two communicating programs could even be on the same machine. We also sometimes include the transport layer when discussing the Internet, and often link the transport with the network layer as in the TCP/IP protocols. Transmission Control Protocol (TCP) is in the transport layer, and Internet Protocol (IP) is in the Network layer. Most Internet based functions such as the world wide web, and email, use TCP/IP, so this is a basic building block for the Internet. . Ahmed Abdillahi Sanco

The transport layer also makes sure that the top three layers are network independent The Simple Network Management Protocol (SNMP) is an application-layer protocol that facilitates the exchange of management information between a network management system (NMS), agents, and managed devices. SNMP uses the Transmission Control Protocol/Internet Protocol (TCP/IP) protocol suite. Ahmed Abdillahi Sanco

The Basic Components of SNMP? • Agent A network-management software module, such as the Cisco IOS software, that resides in a managed device. An agent has local knowledge of management information and makes that information available by using SNMP. • Network Management Systems (NMS) Run applications that monitor and control managed devices. NMS provide resources required for network management. Ahmed Abdillahi Sanco

Portals and its Types What is a portals? A portal is a mechanism that is used in e-marketplaces, e-stores, and other types of Electronic Commerce e.g E-learning. In other words a portal is an information gate way, it attempts to address information overload by enabling people to search and access relevant information. Information Portal: A single point of access through a web browser to business information inside and/or outside and organization.

Types of Portal There are six major types of portal which are as following: 1: Commercial (Public) portal: these portals offer content for diverse communities and are the most popular portals on the internet. 2: Corporate Portals: provide organized access to rich content within relative narrow corporate and partners communities. 3: Publishing Portals. 4: Personal Portals. 5: Mobile Portals: A portal accessible via a mobile device. 6: Voice Portals: a portal accessed by telephone or cell phone.

Electronic Catalogs What is an Electronic Catalogs? Is the presentation of product information in an electronic form; the backbone of most e-selling sites. Catalogs have been printed on paper for generations. Recently electronic catalogs on CD ROM and the internet have gained the popularity. Electronic catalogs consist of product database, directory and search capabilities and a presentation function.

Classification of Electronic Catalogs 1: The dynamics of the information presentation: Information is presented in motion pictures or animation. 2: The degree of the customization; catalogues may be standard or customized. In standard catalogues merchants offer the same catalog to any customer. In customized catalogs content, pricing, and display are tailored to characteristics of specific customers. 3: Integration with business processes.

Ahmed Abdillahi Sanco