Chapter 10: Network and Internet Protocols PDF

NETWORKS & INTERNET PROTOCOLS  INTODUCTION Modern world scenario is ever changing. Data Communication and network have changed the way business and other daily affair works. Now, they highly rely on computer networks and internetwork. Introduction (con.) Software modules in one system are...

NETWORKS & INTERNET PROTOCOLS  INTODUCTION Modern world scenario is ever changing. Data Communication and network have changed the way business and other daily affair works. Now, they highly rely on computer networks and internetwork. Introduction (con.) Software modules in one system are used to communicate with one or more software modules in the distance System. Such interfaces across a distance are termed as “peer-to-peer” interfaces; and the local interfaces are termed as “service” interfaces. The modules on each end are organized as a sequence of functions called “layers”. The set of modules organized as layers is also commonly called a “protocol stack”  Introduction (con.) Over the years, some layered models have been standardized. The ISO Open Systems Interconnection (ISO/OSI) layered model has seven layers and was developed by a set of committees under the auspices of International Standards Organization (ISO).  Classification of Computer Networks 1. Based on Transmission Mode 2. Based on Time in Transmission Type 3. Based on Authentication 4. Based on Geographical location 5. Based on Reliability Classification of Computer Network 1. Based on Transmission Mode Transmission mode defines the direction of signal flow between two linked devices. There are three types of transmission modes. Classification of Computer Network 1. Based on Transmission Mode Simplex Half – Duplex Full Duplex Classification of Computer Network Based on Transmission Mode Simplex In simplex mode, the communication is unidirectional. Among the stations only one can transmit and the other can only receive. Classification of Computer Network Based on Transmission Mode Half-Duplex In half-Duplex mode, the communication is bidirectional. In this both station can sent and receive but not at the same time. Classification of Computer Network Based on Transmission Mode Full-Duplex In Full-Duplex mode, both stations can transmit and receive simultaneously. Classification of Computer Network Based on Time in Transmission Type Synchronous Transmission Asynchronous Transmission Classification of Computer Network Based on Time in Transmission Type Synchronous Transmission In synchronous Transmission both the sender and the receiver use the same time cycle for the transmission. We send bits one after another without start/stop bits or gaps. It is the responsibility of the receiver to group the bits. Classification of Computer Network Based on Time in Transmission Type Asynchronous Transmission In Asynchronous Transmission we send one start bit at the beginning and one stop bit at the end of each byte. There may be a gap between each byte. Bit stream is divided into packets. Classification of Computer Network Based on Authentication Peer to Peer Connection Server Based Connection Classification of Computer Network Based on Authentication Peer to Peer Connection In peer-to-peer networks, there are no dedicated servers. All the computers are equal and, therefore, are termed as peers. Normally, each computer functions as both a client and a server. No one can control the other computers. Classification of Computer Network Based on Authentication Server Based Connection Most networks have a dedicated server. A dedicated server is a computer on a network which functions as a server, and cannot be used as a client or a workstation. A dedicated server is optimized to service requests from network clients. A server can control the clients for its services. Classification of Computer Network Based on Geographical location Local Area Networks (LAN) Wide Area Network (WAN) MAN (Metropolitan Area Network) Classification of Computer Network Based on Geographical location Local Area Networks (LAN) LAN is a small high speed network. In LAN few numbers of systems are interconnected with networking device to create network. As the distance increases between the nodes or system it speed decreases. So it is limed to few meters only. Networks which cover close geographical area.  LAN used to link the devices in a single office, building or campus. It provides high speeds over short distance. Systems are connecting directly to Network. The LAN is owned by private people. Classification of Computer Network Based on Geographical location Wide Area Network (WAN) WAN is collection of network (or LAN). This network speed is less than the LAN network speed. WAN network connect systems indirectly. WAN spread over the world may be spread over more than one city country or continent.  Systems in this network are connected indirectly. Generally WAN network are slower speed than LAN’s. The WAN network are owned or operated by network providers. If it is owned by a single owner then it is called Enterprise network. Often these types have combination of more than one topology. Classification of Computer Network Based on Geographical location MAN (Metropolitan Area Network) Metropolitan area network is an extension of local area network to spread over the city. It may be a single network or a network in which more than one local area network can share their resources. Classification of Computer Network Based on Reliability Reliability is maintained by authentication. Connection-oriented This type of communication establishes a session connection before data can be sent. This method is often called a "reliable" network service. It can guarantee that data will arrive in the same order. Connection less This type of communication does not require a session connection between sender and receiver for data transfer. The sender simply starts sending packets to the destination. A connectionless network provides minimal services. Topology Topology refers to physical layout including computers, cables, and other resources; it determines how components communicate with each other.  Bus In the bus topology, all of the computers are connected in a straight line. Terminators must be used at each end of a bus segment to prevent signals from bouncing. A single break in the cable would take down the entire network.  Star In the star topology, all of the computers are connected through a central connection point (hub). A single break in the cable would only take down communication to one computer. A hub failure would take down the entire network.  Ring In the star topology, all of the computers are connected through a central connection point (hub). A single break in the cable would only take down communication to one computer. A hub failure would take down the entire network.  Mesh In the mesh topology, all of the computers are connected to all other computers. Typically used in a WAN environment. Provides fault tolerance in the event of a connection failure. Hybrid Different types of topologies can be used together to form a hybrid topology. Protocol Protocols mean set of rules. It is a formal description of message formats and the rules two or more machines has follow to exchange messages. The key elements of a protocol are syntax, semantics and timing. Syntax Syntax refers to the structure or format of the data, meaning the order in which they are presented. Semantics Semantics refers to the meaning of each section of bits. Timing Timing refers to when data should be sent and how fast it can be sent.  Internetworking Technologies Internetworking Technologies tell how the Internet accommodating multiple underlying hardware technologies and how they are interconnected and formed the network, and set of communication standard which  the network used to inter-operate. The lowercase internet means multiple networks connected together, using a common protocol suite. The uppercase Internet refers to the collection of hosts around the world that can communicate with each other using TCP/IP. While the Internet is an internet, the reverse is not true. Network Infrastructure or Transmission Infrastructure:  Access Network An access network is the part of a telecommunications network which connects end system to the first router or subscribers to their immediate service provider as shown in figure 1. Figure 1 Network Infrastructure Access networks can be loosely divided into three categories: Residential access networks, connecting a home end system into the network. Institutional access networks, connecting an end system in a business or educational institution into the network. Mobile access networks, connecting a mobile end system into the network Core Networks: Core network connects all the routers to each other and ISP (Internet service provider). It is a main back bone for internet. Core network uses circuit switching and packet switching for data transmission.  ISPs :( Internet Service Provider) In internet bottom-to-top the hierarchy consists of end systems (PCs, workstations, etc.)Connected to local Internet Service Providers (ISPs). The local ISPs are in turn connected to regional ISPs, which are in turn connected to national and international ISPs. The national and international ISPs are connected together at the highest tier in the hierarchy. Component of Internet: Component of Internet: Hardware or Network device: Hub Router Bridge Repeater Switch Gateways Hardware or Network device: Hub It is uses to connect systems or nodes or networks. It has direct connection to a node (point to point connection). It suffers from high collision of data, results to data loss. A hub takes data from input port and retransmits the input data on output port.  Hardware or Network device: Bridge It is used to connect two networks. It divides the collision domain based on number of ports or interface present in a bridge. It uses the packet switches that forward and filter the frames using LAN destination address. Bridge examines the destination address of frame and forwards it to the interface or port which leads to the destination. It uses the routing table for routing frame from one node to other using MAC address.  Hardware or Network device: Switch It is similar to bridge. It has more number of interfaces as compared to bridge. It allows direct communication between the nodes. It works in Data Link Layer. It uses MAC address for data transmission and communication.  Hardware or Network device: Router It is used to connect different types of network (types- architecture/ Protocol). It work similar to bridge but it uses IP address for routing data. Router can't be used for connecting Systems. It works in Network Layer.  Hardware or Network device: Repeater Repeaters are used to extend LAN. It has only two ports and can connect only two segments of a network. Multiple repeaters can be used to connect more segments. (Segment is a logical section of the same network). Repeaters amplify the signal so that the signal is as strong as the original signal. Repeaters operate at the Physical layer of OSI reference model.  Hardware or Network device: Gateways Gateways make communication possible between systems that use different communication protocols, data formatting structures, languages and architectures. Gateways repackage data going from one system to another. Gateways are usually dedicated servers on a network and are task- specific. System, Software and Protocols:  Two types of system are used in Internet Client system: User which access data from internet Server System: Host data for users using HTML files.  Software or Applications and protocols: Chat IRC (Internet Relay Chat E-mail FTP Hosting Search Engine Telnet www TPC/IP Software or Applications and protocols: Chat IRC (Internet Relay Chat is used for live discussions on the Internet. Ecommerce - Taking orders for products and services on the Internet. Software or Applications and protocols: E-mail Exchanging electronic letters, messages, and small files. Software or Applications and protocols: FTP File Transfer Protocol is the most common method of transferring files between computers via the Internet. Software or Applications and protocols: Hosting Making information available to others on the Internet. Software or Applications and protocols: Search Engines These tools are really a part of the World Wide Web and are often used when looking for information because the Web has grown so large and is without any inherent organizational structure. Software or Applications and protocols: Telnet Creation of a dumb terminal session to a host computer in order to run software applications on the host system. Software or Applications and protocols: World Wide Web This is largest, fastest growing, part of the Internet, the part for which Internet browsers like Netscape’s Navigator and Microsoft’s Explorer were designed.  Business is the leading factor fueling the rapid growth of the Web making information, advertising, and product ordering readily available to everyone with Web access. TCP/IP Browser WAN Protocols WAN Protocols Frame Relay Frame relay is used to connect large number of sites in the network because it is relatively inexpensive to do so. The service provider gives you a frame relay circuit and is charged for the amount of data and the bandwidth you use as oppose to T1 circuit that charges with a flat monthly rate whether you use partial bandwidth or the full bandwidth regardless. Frame relay is a high performance WAN protocol that operates at the Data Link layer and the Physical layer of the OSI model. Integrated Services Digital Network (ISDN) Integrated Services Digital Network (ISDN) is designed to run over existing telephone networks. It can deliver end to end digital service carrying voice and data. ISDN operates at OSI model, physical layer, data link layer and network layer. It can carry multimedia and graphics with all other voice, data services. Services Digital Network (ISDN) Integrated Services Digital Network (ISDN) is designed to run over existing telephone networks. It can deliver end to end digital service carrying voice and data. ISDN operates at OSI model, physical layer, data link layer and network layer. High Level Data Link Control (HDLC) High Level Data Link Control (HDLC) is a bit oriented data link layer frame protocol that has many versions similar to LAP, LAPB, and LAPD. CISCO routers default encapsulation is HDLC, but it is proprietary to CISCO. OSI model OSI (Open System Interconnection), developed by the International Organization for Standardization (ISO), was the solution designed to promote interoperability between vendors. It defines architecture for communications that support distributed processing.  The OSI model describes the functions that allow systems to communicate successfully over a network. Using what is called a layered approach, communications functions are broken down into seven distinct layers. Figure 2 Interaction between layers in OSI model.  The seven layers, beginning with the bottom layer of the OSI model, are shown in figure 2.Routers are used as intermediate node to create a link between A and B end system. OSI model layers are dependent on each other. Each layer serves the upper layer and also depends upon the services from the lower layer. OSI model also provide the layer abstraction.  Layers are dependent on each other for services but in terms of protocol they are independent. In each layer information is added into original data as header but in data link layer trailer is added into the data as shown in figure Figure 3 Exchange of data using OSI model OSI Model Layer Layer 1: Physical Layer Layer 2: Data Link Layer Layer 3: Network Layer Layer 4: Transport Layer Layer 5: Session Layer Layer 6: Presentation Layer Layer 7: Application Layer  r d is e L o of t h f a r n g o e f e n n i “Th e begi M” th S D O WI