Understanding Data Communications - Assignment Example

Data Communications Name: Institution: Date: Question 1: Transport Layer a. The TCP/IP model has four layers, the application layer, the transport layer, the internet layer, and the network access layer. The internet layer has two protocols, the IPv4 and IPv6. The transport layer has two protocols, TCP and UDP. However, these layers are for different reasons. For the internet layer, the IPv4 and IPv6 are for the Internet Protocol version 4 and 6 respectively. The role of the internet layer is to pack data into IP datagrams or data packets that contain source and destination address information for the forwarding of datagrams between source and destinations. It also routes the datagrams with respect to the specified IP addresses. On the other hand, the role of transport layer is to allow the source device and the destination device hold a conversation. The transport layer establishes basic data channels that the application uses for data exchange. The transport layer has to protocols; the TCP and UDP. The exchange of data between the devices on in the communication channel may happen in two different ways, these two different ways are responsible for the TCP and the UDP. In the TCP, the data makes its way across from source to destination, that is, it is connection based. On the other hand, the UDP is not connection based meaning that one system can send a load of data to another and the relationship ends (Kumar & Rai, 2012). TCP is also established on reliability and all data is acknowledged whereas UDP is unreliable and there is no data acknowledgement. Whereas there are no two ways of identifying the source and the destination devices through the IP addresses in the internet layer, there are different ways that data packets can transit between the source and the destination in the transport layer. Either the IPv4 or the IPv6 will identify the AIP address the same way while the TCP and UDP will transfer data packets differently. As a result of this, the internet and transport layers differ in providing two protocols. b. Even though the UDP does very little that is different from IP, there are many differences between the IP and the UDP that provides enough grounds why UDP still exist. First of all, the UDP is suitable for applications that requires fast, efficient transmission that may include among other the games. The UDP has also been used in servers that answer small queries from huge numbers of clients because of its stateless nature. This means that there are applications that better perform when been transmitted in the UDP as opposed to when attempts are made to transmit it in the TCP/IP protocol. The other reason that the UDP continue to be in use despite offering not more than what is offered by the IP is the fact that since the error recovery is not attempted under the UFP, it is faster compared with the IP. This is possible because the UDP is a “best effort” protocol compared with the IP that has comparatively lower speed. The UDP is useful and works best in small simple transactions where session context is no absolutely necessary. Some examples of this include the DNS (Domain Name System) and the NTP (Network Time Protocol). These examples support very efficient query or response transaction model. UDP has also been preferred for the applications that are simple and easy because it does not need the overhead that is necessary to detect reliability. In such uses, the use of IP will only increase the overheads for the protocol (Kumar & Rai, 2012). The UDP is also efficient in that it does not need to maintain the unexpected deception of data flow. The UDP is also simple to use for networks because it requires less processing at the transmitting and receiving of hosts. As a result of these advantages of the UDP over the IP, it has continued to be used despite the fact that it does very little that is different from IP. c. The DDOS tacks are mounted against the TCP and UDP services differently. The UDP is however more susceptible to DDOS than the TCP because of its features that make it possible for attacks to happen. The UDP lacks the session context implying that the majority of the transactions happening over this protocol are encrypted. This means that they are not only possible to be tapped by third parties, but they are also highly possible to pass attacks. This happens when a third party, and not the intended recipient generates a response to dupe original querrier (Huston, 2015). For the DDOS, the UDP servers need to answer all queries. All queries need to look genuine and attacker exploit this by placing an IP address of the intended victim in the source address of the UDP packet. As a result, many queries are sent to the same address denying the access. For the TCP, the attackers exploits a weakness in the installation to perpetrate an attack (Kumar & Rai, 2012). The TCP is connection-oriented meaning that when a message or a file is sent, it will get delivered unless the connection fails. On the other hand, the UDP is not connection-oriented meaning that when data is sent, there is no assurance that it will be delivered. Question 2: IP Addressing a. i. NOT 1110001 = 0001110 ii. 11100010 or 00001110 = 11100010 Or 00001110 = 11101110 iii. 11100010 and 00001110 11100010 And 00001110 = 00000010 b. /notation subnet Mask i. /9 255.128.0.0 ii. /17 255.255.128.0 iii. /31 255.255.255.255 c. i. 255.255.248.0. This is legal. The slash notation for this one is /21 ii. 255.224.252.0. This is not legal. This is it has not exhausted the third set of the decimals before going for the fourth. Furthermore, it does not have any exponential of two to represent it. iii. 255.255.255.224. This is legal with the slash notation of /27. iv. 255.255.156.0. This is not legal, this is because it falls between the slash notations /18 and /17 and it does not have a multiple of 2 as number of IP addresses. d. i. /13 – this falls in the subnet mask of 255.248.0.0 with the power of 2 being 19, therefore, the number of IP addresses are 524,288. ii. /26 – this falls in the subnet mask of 255.255.255.192 with the power of 2 being 6. Therefore, the number of IP addresses are 64. e. The class networks 205.67.35.0. This appears like an illegal value for Address. However; It is important to note that the class C mask only uses the last octet for host addressing. Therefore, in the last octet, the subset zero is utilized (Singh, 2015). The slash notation = /24 Therefore, the total number of hosts = 254 Hosts on each subnet = 85 These are resulting class C subnets because they have been distributed from the last octet of the class network provided. Question 3: Wireless a. The CSMA/CD scheme that is used in the traditional Ethernet LANs cannot be used in 802.11 wireless LANs because of a number of reasons include the mode of operation and the use of the network infrastructure. Whereas the CSMA/CD operates on wires, the 802.11 is wireless. The CSMA capabilities include improving the performance when there is higher medium utilization. When the medium is attached to different nodes, each node will monitor whether there is current flowing in the cables before it can transmit data. When the cable is declared free, then the node will transmit. There are instances when two or more nodes will transmit at the same instance and thus causing the collision. This scheme institutes the Collision Detection (CD) to ensure that when there is a collision in data streams, it is corrected immediately. Most important is that this happens through the cable medium. When it comes to the 802.11 wireless LANs, this medium is not cables, it provides the basis for wireless network products through the use of the Wi-Fi brand (Kim & Lee, 1999). Therefore, this difference implies that the implementation of the cable monitoring and the collision detection that is performed by the CSMA/CD on the Ethernet LAN cables cannot be performed on the 802.11 Wireless LANs medium. This answers the question why CSMA/CD scheme that is used in traditional Ethernet LANs cannot be used in 802.11 wireless LANs. b. In the channel allocations seen above, each access point (AP) designated by the channel could be undermined by the weak signal strength or interference of from other channels. From the explanation, it is clear that the useful range of WIFi within the warehouse was effective within a radius of 15M, whereas the channels allocated or the access points were 20M by 20M square. This implies that there was possible channel interference. Therefore, it was important that the channel optimization was conducted to improve the access and the quality of the WiFi signal strength in every access point. The objective of this optimization will see to it that to ensure that the maximum coverage and throughput is provided, the signal that is estimated at each access point within the allocated channels should be greater than the threshold with which the minimum rate is guaranteed. In this approach the maximum of channel utilization will be minimized at every channel allocation or access point (Haidar, et al., 2008). It will also be ensured that for much allocated channel, there will be only one access point bandwidth that can be used by the clients to ensure there is not interference. It will also be ensured that the total traffic demand at every allocated channel will be less than the wireless link bandwidth that is provided by an access point. Finally, in order to optimize or improve the current channel allocation, it will be ensured that there is non-overlapping channel condition within minim channel distance. For instance, in the current state, the useful range of the WiFi within the warehouse 15 M radius. Assuming that the access point is at the center of every allocated channel, it implies that the access range is a diameter of 30M while the allocated channel is only 20 meters wide (Lee, et al., 2002). Therefore, the minimum channel distance will be lowered while the signal strength remain the same to ensure that there is no overlapping and at the same time increase the signal strength within every allocated channel. II. While reconfiguring the access points, I noticed that none of them currently have any security enabled. This is a major problem because it poses threat to the company data from the malicious attackers who might perpetrate DDOS or accessing the network without the authority. The unsecure WLAN is open to accidental associations or casual eavesdropping that could jeopardize the company data. The securing of the company wireless network will protect the company from unwanted security concerns and will control the individuals who can access the wireless network (Phifer, 2014). Depending on the functions of each channel allocation, the company would like to exclude the other channels from access this network, therefore, security will be necessary. With security, it means that the inventory access point cannot access sales access point unless there is prior knowledge. The securing of the networks will also protect the irresponsible use of network by clients or unsecured “rogue” access points. However, addressing this will be easy because the WLAN comes with standard security with authentication and encryption that can be enabled to secure the network, these authentication and encryption features are disabled by default whenever the wireless network is implemented. The enabling with allow the shared-key authentication allowing the users to access the network if they have the key. It is also recommended that the Wired Equivalent Privacy is enabled to feed the same key tonto the RC4 cipher to encrypt the data frames (NetGear, 2010). Only the access points or the allocated channels with the key can access the network and the key will also decrypt the data frames transmitted from other stations. Bibliography Haidar, M. et al., 2008. Channel SAssignment in an IEEE 802.11 WLAN Based on Signal-toInterferrance Ratio. CCECE/CCGEI , pp. 69-73. Huston, G., 2015. Transport Protocols. [Online] Available at: https://labs.apnic.net/?p=729 [Accessed 18 May 2017]. Kim, J. H. & Lee, J. K., 1999. Performance of Carrier Sense Multiple Access with Collision Avoidance Protocols in Wireless LANs. Wireless Personal Communications, 11(2), pp. 161-183. Kumar, S. & Rai, S., 2012. Survey on Transport Layer Protocols: TCP & UDP. International Journal of Computer Applications, 46(7), pp. 20-25. Lee, Y., Kim, K. & Choi, Y., 2002. Optimization of AP Placement and Channel Assignment in Wireless LANs. Seoul National University. NetGear, 2010. 5 Steps to Secure the Wireless Network. NetGear Connect with Innovation, pp. 1-4. Phifer, L., 2014. WLAN security: Best practices for wireless network security. Tech Target. Singh, A. K., 2015. Internet Protocol (IP) Address – Subnetting and Supernetting. International Journal of Emerging Trends & Technology in Computer Science (IJETTCS), 4(5(2)), pp. 87-90. Read More