Computer Communications & Networks - Lab Report Example

? The approach for accessing X stream from a remote location encompasses Open System Interconnection (OSI) as well as the TCP/IP model. There are many methods, procedures, technologies and processes that are associated with each layer of these two OSI models. However, in order to explain the connectivity of X stream from a remote location or home, we will align findings with the TCP/IP OSI model. TCP/IP Model The TCP/IP model is not completely aligned with the OSI model. Unfortunately, there is no existence of an agreement associated with the description of the TCP/IP model. Usually, it is considered and agreed that the TCP/IP model has less layers than the OSI model i.e. Application layer, Transport layer, Network layer and Network access layer. TCP/IP model is illustrated in Exhibit 1.1 below. Exhibit 1.1 TCP/IP Model Image retrieved from (Network Communication Architecture and Protocols: TCP/IP Four Layers Architecture Model. 2007. Javvin Technologies, Inc, pp. 4-4.) The application layer incorporates protocols including FTP, SMTP, Telnet etc. These application layer protocols send data to the next layer i.e. transport layer. The transport layer than constructs the header and data to send it via Transmission control Protocol (TCP) or User Data gram Protocol (UDP). Likewise, the network layer assigns the IP address and delivers the packet to the required Ethernet present at the network access layer. An example of data transmission between X stream and home computer is illustrated in Exhibit 1.2. The example shows the involvement of each layer in sequence in order to deliver the connection request to the X stream server from the home user. Exhibit 1.2 Example demonstration via TCP/IP Model Protocol Layering After discussing the layers of the TCP/IP Model, we will now discuss protocol layering on these layers in order to explain the access mechanisms that are carried out when a home user wants to access the X stream. However, protocol layering is not easy, as it may seem difficult to understand initially. As discussed before, we will demonstrate the connection of X stream from home user via TCP/IP model that works on four layers. These four layers are associated with four types of protocol data units (PDU’s) i.e PDU 1, PDU2, PDU3 and PDU4. Exhibit 2 shows the initiation of a packet from the application layer i.e. layer four. Exhibit 2 Image retrieved from (James F. Curose & Keith W. Ross, 2000) Likewise, layer four creates a message M and is considered to be PDU 4, as it is associated with the highest layer. The message M incorporates several parameters that are modified and customized by the application itself. Parameters may include sender name, type of the message and related data. The home computer passes the data of the complete message M to the layer three of the protocol stack. The exhibit 2 shows layer three that is the home computer breaks the PDU 4 in to two parts i.e. M1 and M2. Likewise, the layer three is the home computer that combines with M1 and M2 which are called headers for developing PDU 3 in to two separate layers. Likewise, headers holds the additional information that is required by sender and the receiver on layer three to deploy the service from layer three to layer four. Accordingly, the process continues in the source and adds more headers while travelling through each layer till PDU 1 headers are created. Now PDU 1 is ready to be transmitted from the home computer to the X stream server via physical layer i.e. the physical link. On the other side i.e. X stream network receives PDU 1 and routes them to the protocol stack. Likewise, at every layer, the headers representing similar values are removed. Lastly, M is reconstructed from M1 and M2 and router to the X stream application. Network Access Layer Network layers is integrated with physical and data link layer that is responsible for physically connecting the computer with the wired or wireless medium for data transmission from the X stream. There are different types of wired networks available based on different technologies and methods, some of them are Public Switched Telephone Networks (PSTN), Delay Tolerant Networks (DTN), Global systems for Mobile Communication (GSM), Broadband etc. In case of a Digital Subscriber Line (DSL) connection, home computer sends digital data that is transmitted from the local loop i.e. the telephone exchange of that region. However, analog exchanges are now re-engineered to digital telephone exchanges, as DSL connection requires digital end to end transmission. Likewise, DSL connections requires DSL modem that demux and mux the transmission to synchronize with the DSLAM equipment residing in the telephone exchange. DSLAM is defined as ?“DSL Access Multiplexor, A central office (CO) device for ADSL service that intermixes voice traffic and DSL traffic onto a customer's DSL line. It also separates incoming phone and data signals and directs them onto the appropriate carrier's network” (Dslam. 2011). These DSLAM are interconnected by a backend router that routes the request from the home user to the respected Internet Service Provider (ISP). Moreover, DSLAM’s physical infrastructure contains cards that are inserted in to all available slots. However, number of slots depends on the number of customers in that particular exchange. Each DSLAM card contains ports, the number of ports and available options for number of slots vary from model to model of a DSLAM. The telephone line of the customer is tagged with the telephone line that becomes the carrier for data exchange from the client premises equipment (CPE). Exhibit 3 Physical Network Architecture Image retrieved from (Zyxel Cable Telco50 RJ11 300cm for VES and IPDSLAM - 57-110-043300B . Available: http://www.broadbandbuyer.co.uk/Shop/ShopDetail.asp?ProductID=5011 [1/20/2012, 2012].) Exhibit 3 demonstrates the communication of a CPE i.e. the home user to the X stream that can be assumed at the location of a data center. Exhibit 3 also illustrates the IP backbone network that is involved after the request is redirected from the exchange router connected to the DSLAM. In case of an ISP, the IP backbone will drive the request from the home user to the relevant router and then to the corresponding network containing the X stream. The data link layer of transmitting a frame via a communication link. However, the frame is transmitted by a transmission adapter and is received at the other end by the receiving adapter. These adapters are present at the sending and receiving nodes. Moreover, link layer protocol provides link access and framing, reliable delivery of frames, flow control of transmission, detecting and correcting errors in the transmission and modes of full and half duplex (James F. Curose & Keith W. Ross, 2000). Network Layer The inputs of this layer incorporate logical addressing in order to route data to the relevant destination. Routing carries out by intelligent network devices called routers. Routers forward packets of data across an internetwork to the relevant destination by utilizing the Internet Protocol (IP) (IP Router. 2007). Likewise, from the X stream, routers redirect data to the home computer. However, different protocols can be used by the router to choose the shortest and suitable path for robust communication In order to examine the IP v4 packet header; Exhibit 4 demonstrates all the parameters along with the comparison of IPv4 and IPv6. Exhibit 4 IPv4/IPv6 Packet Header Image retrieved from (Morrow, Vijayananda, n.d ) IP is considered to be the fundamental concept in the provision of reliable delivery of data. Exhibit 4 shows the difference between IPv4 and IPv6 data grams. Moreover, the network layer is responsible for delivery the connection request from the home user to the X stream from the series of interconnected networks. Along with the transmission, the network layer provides encapsulation of datagrams, reassembly and fragmentation of data packets, diagnostics and error handling for ensuring sustainable connectivity. Transport Layer The transport layer takes the input from the session layer and forwards the transmission to the network layer. However, data transmission may also result in splitting data streams wherever required. The transport layer encompasses two protocols i.e. transmission control protocol and User Datagram Protocol. The TCP is a connection oriented protocol that ensures reliable delivery of data along with error correction, if a packet is corrupt or damaged. Moreover, the UDP is a connectionless protocol does not ensure reliable delivery and error checking of the missing or corrupted packets. If the home user request a video streaming service, most probably, after establishing connectivity, UDP till take in charge for this kind of service. UDP is best suited for application that needs high bandwidth with connection less characteristics. VoIP is a best example that is also categorized a UDP based protocol. If two people are talking on a VoIP enabled applications, their voice can break on a low quality signal that may have been caused by low bandwidth or service quality resulting in a lag in the conversation that is recovered instantly. Application Layer Application layer is associated with applications that interact with the users. As mentioned in the beginning, protocols that are associated with application layer are Telnet, File transfer protocol (FTP), Simple Mail Transfer Protocol (SMTP), Domain Name Service (DNS), Routing Information Protocol (RIP), Simple Network Management Protocol (SNMP) etc. The telnet protocol provides a connection based on shell based interface to execute commands from a remote location. Likewise, FTP provides a facility to download or upload files, pictures and videos to and from a remote location. Moreover, RIP is responsible for updating the routing tables by collecting and sending the information to the first hop router. Likewise, the router updates a routing table and requires the information of the home user to be recognized. RIP is usually a built in feature in a DSL router. If an user initiates a connection request by entering the URL of the X stream server in the web browser, the routing information of the home user is carried out till the last destination i.e. the X stream server or network. However, router encompasses other routing protocols as well for deciding the best and traffic free route to the destination. One of the examples is Open shortest Path First (OSPF), Border Gateway Protocol (BGP) etc. DNS is also associated with translating the name based URL of the X stream server in to numeric addresses, as routers understand numeric values. Moreover, SNMP is associated with network management that can be monitored and analyzed by different applications. For instance, Network Management System is configured with SNMP to monitor the uptime and availability of network components and UPS etc. Conclusion In summary, Processes, methods and techniques are discussed in detail for each layer of the TCP/IP model. The first request was initiated from the physical layer along with the IP that was recognized on the network layer. The network layer forwards the transmission to the next layer i.e. transport layer. Lastly, home computer gets access via an application layer by using Hypertext transfer protocol (HTTP), telnet, or HTTPS. We have also discussed several routing protocols and their roles in ensuring robust connectivity from home to the x stream. Furthermore, DSL physical infrastructure is also discussed in detail in diagrams to get better insights and involvement of network devices in case of a DSL home connection. In addition, we have also discussed the applications and protocols that are functional at the application layer. Lastly, we have discussed diagrams for TCP/IP model, DSL Physical Infrastructure, comparison between IPv4 and IPv6 headers and the methodology of protocol data units (PDU’s). Bibliography Network Communication Architecture and Protocols: TCP/IP Four Layers Architecture Model. 2007. Javvin Technologies, Inc, pp. 4-4. James F. Curose & Keith W. Ross (2000). Computer Networking A Top Down Approach. 4th ed. London: Addison - Wesley. 62. Dslam. 2011. Computer Desktop Encyclopedia, , pp. 1. IP Router. 2007. Network Dictionary, , pp. 260-260. MORROW, M.J. and VIJAYANANDA, K., n.d, Developing IP-Based Services: Solutions for Service Providers and Vendors (The Morgan Kaufmann Series in Networking) Morgan Kaufmann. Read More