The Communication Mechanisms of the TCP/IP Model - Essay Example

of the of the 23 March X-Stream Server The report will demonstrate the communication mechanism on data networks and aligns them with each layer of TCP/IP model. Moreover, we will address Open System Interconnection (OSI) model where applicable. Likewise, every layer will illustrate the technological process and methods linked with X stream when accessed from home or a remote location. Furthermore, we have made an assumption of the home connection, i.e. the client premises equipment CPE will be an ADSL router with an Internet connection from the Internet Service Provider ISP. TCP/IP Model Prior to examining the mechanism of accessing X-stream from home, understanding the fundamental concepts of the TCP/IP model is essential. Fig 1.1 demonstrates the comparison of the OSI and TCP/IP Model. Likewise, the TCP/IP model is equipped with Internet Layer Application layer, Transport layer and Data link Layer. The application layer functions on protocols such as Simple Mail Transfer Protocol (SMTP), Hyper Text Transfer Protocol (HTTP), File Transfer Protocol (FTP) and vice versa The transport layer functions on Transmission Control Protocol (TCP) and User Datagram Protocol (UDP) The internet layer functions on Internet Protocol (IP), Address Resolution Protocol (ARP), and Internet Control Message Protocol (ICMP) The data link layer or network interface layer functions on Ethernet, token ring and vice versa However, to access the X stream from home or remote location, the functionality of these five layers will be discussed, as Fig 1.1 shows the similarities of these two models, i.e. OSI model and TCP/IP model. Figure 1.1 TCP/IP and OSI Model Image retrieved from: (Dulaney) One more image named as Fig 1.2, illustrates the semantics of every layer for an exchange and transmission of data from the home or remote location to the X stream server. Primarily, user interacts with the application layer by using protocols such as File transfer protocol FTP, User Data Gram Protocol UDP, and Hyper Text Transfer Protocol HTTP for originating a request to move it to the next level, i.e. transport layer. After receiving the request, transport layer constructs the header and fills the packet with data prior to transfer the data packet to the next layer, i.e. the network layer. Likewise, the network layer will assign the IP address to the data packet received as an input from the previous layer. Moreover, the assigned IP address will redirect the data packet to its destination, i.e. Ethernet. Likewise, Ethernet is located at the network access layer that relays the data packets or transmission to the relevant segment, i.e. from the network access layer of the X stream to the network access layer of the home user or remote location, as shown in Fig 1.2 Figure 1.2 Example demonstration via TCP/IP Model Protocol Layering So far, TCP/IP model has been discussed briefly along with its functions and associations with each layer. Similarly, protocol layering is addressed in fig 1.3, as it demonstrates the functionality of layer to layer and Protocol Data Units PDU’s along with packet headers while accessing X stream from home or a remote location. By addressing four layers of the TCP/IP model, four PDU’s will be considered on each layer. As the request or message originates again from the application layer that is considered as the fourth layer of the TCP/IP model. Likewise, the four PDUs are abbreviated as 1-PDU, 2-PDU, 3-PDU and 4-PDU. Figure 1.3 Image retrieved from (Kurose 888) The fourth layer, i.e. an application layer that is also called as a high layer, establishes a message or request donated by ‘M’. Likewise, the message comprises many parameters that need to be filled by the application end depending on criteria set. For instance, a traditional message or request may consist of parameters such as type of message and related data. The message or request from the home computer or a remote location is transmitted as a message ‘M’. The third layer of the TCP/IP protocol stack, as illustrated in Fig.1.3, entertains this message as an input. Layer three of the source, i.e. the home computer or a remote location, breaks down 4-PDU in two different parts donated as ‘M1’ and ‘M2’. Moreover, the layer three of the source combines with these two different parts, i.e. M1 and M2 that are marked as headers that facilitate in establishing 3-PDU breakdowns into two different parts. Headers are linked to the required information, i.e. the source and destination located at the third layer for activating services on the fourth layer (Kurose 888). Similarly, the construction carries forward for the source as well, i.e. the home computer or a remote location. The headers are added up, as they pass via each layer till the last layer, i.e. construction of 1-PDU. As soon as 1-PDU is created, it is on the go for transmission from the home computer or remote location to the X stream’s physical layer on the OSI model. Likewise, the destination, i.e. the Xtream server, takes an input of 1-PDU from the source, i.e. the home computer or remote location, and sends the request to the protocol stack, on every layer, similar headers are removed. Lastly, message M1 is constructed again from M1 and M2 for transmitting to the destination, i.e. X stream server (Kurose 888). Network Access Layer The network access layer is linked with the data link layer and to the physical layer as well for establishing connectivity. Likewise, the connectivity will be established by the home or remote computer from wired network for data transmission to the destination, i.e. X stream server. Although, various data carriers are available that may perform the same tasks but with different speeds and security. Few of them are Broadband, ATM, Delay tolerant Networks, Public Switched Telephone Networks, Global systems for mobile communication etc. As mentioned earlier, we will demonstrate the connectivity of the home computer via ADSL, the DSL physical architecture will be considered. However, a prerequisite for an ADSL connection requires the telephone exchange of that particular region to be digital. As ADSL connection requires digital end to end connectivity, local telephone exchanges known as PSTN are now capable of supporting digital transmission. The home computer will establish connectivity via an ADSL router that is considered as a Client Premises Equipment (CPE). The DSL router established connection from a DSLAM known as the ?“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." 1). The DSLAM is located at the exchange and is connected by the router. There may be more than one DSLAM’s in the exchange, as more than one Internet service providers are available. Depending on the model and type, DSLAM contains cards that are inserted in the slots just like the PCI slots in the home computer. Moreover, these cards have ports that are used to tag the telephone line of the customers in order to provide ADSL service from the telephone exchange. Figure 1.4 Physical ADSL Architecture Image retrieved from http://www.gis.net/~sotis/dslexp.html Fig 1.4 shows the association of each device that plays its role to establish connectivity. We will not discuss each component of the ADSL architecture, as the Internet backbone connects with the ISP. The physical layer summarizing the connectivity from the home user to the X stream server includes the ADSL router as the first component. Likewise, the request relays from the main distribution frame to the DSLAM. The DSLAM redirects the traffic to the Internet backbone router for redirecting it to the ISP. The backbone router then forwards the request to the relevant network, i.e. X stream network / server. The association of the data link layer with the Network access layer sends a frame from the physical Internet connection via a transmission adapter. Likewise, the transmitting adapter sends the transmission from the home network that is received from the receiving adapter from the X stream network. The location of these adapters is located at the sending and receiving of both nodes. Moreover, (Kurose 888) the data link layer also provides link accessibility and framing capability led by reliability of transmission and flow control. Furthermore, it also supports error correction and control in full or half duplex modes. Network Layer The network layer has the function of logical addressing required for routing transmission to the required destination. Router performs this job, as it is considered to be an intelligent device that takes routing decisions. Likewise, the data transmission is received and transmitted to the internetwork by routers via IP addresses. Moreover, there’re many routing protocols that are used for update the routing database along the way to the destination. As per the scenario, a home computer comprising an ADSL router will use a Routing Information Protocol (RIP) to transmit the routing details for the particular connection request. Likewise, router will decide the routing protocol for delivering the packet to destination. Some of the routing protocols are Open shortest path first (OSPF) is used to determine the shortest and traffic free path and Border Gateway Protocol (BGP) is also used for exchanging routing details from router to router to keep the routing table updated. Fig 1.5 shows all the parameters for an IPv4 IP packet header. Figure 1.5 IPv4/IPv6 Packet Header Image retrieved from (Morrow and Vijayananda 336) Transport Layer Transport layer is constructed on two core protocols, i.e. TCP and UDP. The transport layer extracts the input from the session layer for passing the connection to the network layer. However, in the transport layer, connection can be broken down into two channels (if required). Likewise, the TCP due to its characteristics of a connection oriented protocol ensures sustainability of the connection along with error correction whereas the UDP possessing characteristics of a connection less protocol do not ensure sustainability or error correction. However, it is effective for high quality videos and voice communication that can still continue if any packet is damaged during the transmission. Some of the examples for UDP are VoIP based applications that also support video streaming from a web cam at the same time. Application Layer Application layer is physically present at the screen of the computer, i.e. users can interact with it, configure it, manage it and customize it according to the requirements. Few protocols are associated with the application layer. Each of these can be defined as: FTP: Used for uploading or downloading videos, images, and documents to share with friends from a virtual terminal. SMTP: Used for delivering messages from the Internet. It is usually associated with electronic mails that may also use Post office Protocol (POP3) for downloading emails stored on the server. DNS: “A dedicated server or a service within a server that provides DNS name resolution in an IP network. It turns names for Web sites and network resources into numeric IP addresses. DNS servers are used in large companies, in all ISPs and within the DNS system in the Internet, a vital service that keeps the Internet working” ("DNS Server" 1). RIP: The routing information protocol exchanges information from routers to update their routing table. SNMP: Simple Network Management Protocol is configured with network management application that identifies and alerts for any event associated with downtime, malfunction, status, health etc. HTTP: Hyper Text Transfer Protocol is used for sending user request from the web client to the web server via an Internet browser. Conclusion We have explored all the communication mechanisms that are performed on each layer of the TCP/IP model and its association with the OSI model where applicable. A home user or a remote location will request a data transmission from an application working on the application layer. Along with the IP address, the network layer will receive the request as an input, process it and forward it for transmission to the transport layer. Likewise, the transport layer will relay the request forward, requesting for a connection request to the network access layer that in the end, establishes a connection from the home network or a remote location to the X stream server. Works Cited Kurose, James F. Computer Networking . Pearson Education US. Print. "Dslam." Computer Desktop Encyclopedia (2011): 1. Print. Morrow, Monique J., and Kateel Vijayananda. Developing IP-Based Services: Solutions for Service Providers and Vendors (the Morgan Kaufmann Series in Networking). Morgan Kaufmann. Print. Dulaney, Emmett A. CompTIA Security+ Study Guide: Exam SY0-301. Sybex. Print. "DNS Server." Computer Desktop Encyclopedia (2011): 1. Print. Read More