TCP/IP Protocols, IP Addressing, Wireless Networking Essay.

a) As we have seen, the Internet layer of TCP/IP has two protocols – IPv4 and IPv6. The transport layer provides two main protocols TCP and UDP (along with some special-purpose, minor protocols). But these are for very differentreasons. Why are the Internet and Transport layers very different in providing two protocols? 

b) Since UDP does very little that is different from IP, why do we even have a transport layer such as UDP? (7 marks)

c) Describe how DDoS attacks may be mounted against TCP and UDP services. In what way will being connection oriented be different for TCP and UDP? (

2 IP Addressing

1. a) Perform the following boolean operations on the given bit patterns
2. not 11100010
3. 11100010 or 00001110
4. 11100010 and 00001110

b) What are the subnet masks for the following slash address blocks? 

1. /9
2. /17
3. /31

c) Are the following address masks legal? If so, what are their slash forms? If not, why are they not legal?

255. 255.255.248.0
256. 255.224.252.0
257. 255.255.255.224
258. 255.255.156.0

d) How many computers are in networks with the following address blocks? (2 marks)

1. /13
2. /26

e) A small company is assigned the class C network 205.67.35.0. You need to divide this network to provide subnets for three departments using fixed-length subnetting. The departments are approximately the same size. Show the network and broadcast addresses for each subnet. Show the slash notation. How many hosts are on each subnet? Are the resulting subnets class C networks?

3 Wireless

a) Explain why CSMA/CD scheme used in traditional Ethernet LANs cannot be used in 802.11 wireless LANs.

b) A supermarket uses WiFi to enable staff to check inventory levels and to perform price checks. Staff have complained that the wireless scanners they use to check stock levels do not work reliably in some isles. The supermarket manager has contracted you to diagnose the wireless problems and correct them.

The supermarket is 60m by 40m.

Assume that the useful range of WiFi within the warehouse will be 15m radius.

The access points are organised into a grid with the following channel allocations:

You have determined that the channel allocations are not optimal, how would you improve upon the current channel allocations? 

As you are reconfiguring the access points you notice that none of them currently have any security enabled. Is this a problem, and if so,

what type of security would you recommend? 

TCP/IP protocols

a. The transport layer of the OSI model deals with end to end communication between the hosts. The two fundamental correspondences administrations given by TCP and UDP are based on the connectionless bundle exchange benefit given by the Internet Protocol (IP). Many system interfaces are characterized to bolster IP. The remarkable piece of the figure below is that the greater part of the higher layer conventions get to the system interfaces through IP. This is the thing that gives the capacity to work over numerous systems.

The network layer use the UDP protocol which is connection less for sending the data packets in the network. On the off chance that the Transport layer gives an association situated support of the network layer, then the system layer must go before all exchange of data with an association setup strategy. In the event that the association situated administration incorporates confirmations that edges of data are moved effectively and in grouping by the Transport layer, the network layer can then accept that the parcels it sends to its neighbor navigate an error free transmission.

Then again, if the Transport layer is connectionless, then each edge is sent freely through the information interface, most likely in unverified way (without affirmations or retransmissions). For this situation the system layer can't make suspicions about the sequencing or rightness of the bundles it trades with its neighbors.

                                 

1. A portion of the capacities given by the transport layer can be given inside the systems, however different capacities can't. For instance, the vehicle layer gives capacities toward the end-framework to make up for the impediments and weaknesses of the system layer, keeping in mind the end goal to meet prerequisites (e.g. QoS) of the upper layer. For instance in TCP/IP, IP gives just best exertion benefit. To give the solid administration required by a few applications - that is, to make up for the weaknesses of best exertion benefit - TCP sets up associations and executes blunder control on a conclusion to-end premise. One can envision that a specialist organization could consolidate this mistake control work at the edge of its system. Then again, one of the fundamental reasons for the vehicle layer is to permit numerous procedures at last frameworks to share a system benefit. This can't be accomplished inside the system.
2. The decision of UDP versus TCP relies on upon your utilization case and of the sort of DDos. For basic data transfer capacity eating DDos it doesn't make a difference much on the grounds that if all transmission capacity is utilized by the assault there will be no more movement for your application, regardless of if UDP or TCP based. UDP may have a slight preferred standpoint for this situation in light of the fact that UDP without anyone else's input does not require various bundles for an association foundation.

The implementation of the UDP protocol in the network would help to consume less resource than the implementation of the TCP. A three way handshake protocol is required to be implemented for the prevention of the spoof attacks that are mainly based on the IP address. An SSL connection can be used for encrypting the connection and securing the network from DDOS attacks.

2.

Boolean Operation

= 00011101

OR Result

Result in binary	11101110
Result in decimal	238
Result in hexadecimal	ee

11100010 and 00001110

AND Result

Result in binary	10
Result in decimal	2
Result in hexadecimal	2

/9 = 255.128.0.0

/17= 255.255.128.0

/31= 255.255.255.254

255.255.248.0= /21

255.224.252.0=

1111111.11100000.11111100.00000000

It is not a legal subnet mask because a subnet mask is required to be filled with 1 from the left hand side. For this reason the alternative notation is required to be used and with /x and the x is described as the number of 1 bits. It also specifies the bits from the left hand side that can be used for the identification of the network and the bits that can be ignored dues to their difference from each of the node in the subnet.

255. 255.255.255.224= /27
256. 255.255.156.0= it is also an illegal subnet.
257. 11111111. 11111111. 10011100

A valid Prefix for 4 bit wide net is /28 (32-4) with subnet mask 255.255.255.240 only. It results in 11111111 11111111 11111111 11110000.

1. /13= 524286
2. /26= 62

Subnet Name	Needed Size	Allocated Size	Address	Mask	Dec Mask	Assignable Range	Broadcast
A	250	254	205.67.32.0	/24	255.255.255.0	205.67.32.1 - 205.67.32.254	205.67.32.255
B	250	254	205.67.33.0	/24	255.255.255.0	205.67.33.1 - 205.67.33.254	205.67.33.255
C	250	254	205.67.34.0	/24	255.255.255.0	205.67.34.1 - 205.67.34.254	205.67.34.255

All the IPs are in class c network

The physical qualities of WiFi make it outlandish and unreasonable for the CSMA/CD system to be utilized. This is because of CSMA/CD's tendency of "tuning in" if the medium is free before transmitting the data packets in the network. Utilizing CSMA/CD, if an impact is distinguished on the medium, end-gadgets would need to hold up an arbitrary measure of time before they can begin the retransmission procedure. Consequently, CSMA/CD functions admirably for wired systems, notwithstanding, in remote systems, there is no chance to get for the sender to distinguish impacts a similar way CSMA/CD does since the sender is just ready to transmit and get parcels on the medium however is not ready to detect information navigating that medium. In this manner, CSMA/CA is utilized on remote systems. CSMA/CA doesn't recognize crashes (dissimilar to CSMA/CA) yet rather stays away from them using a control message. Ought to the control message crash into another control message from another hub, it implies that the medium is not accessible for transmission and the back-off calculation should be connected before endeavoring retransmission.

1. The range of the wifi access point is 15m whereas the size of the room is 60 by 40 meter in dimension. In the event that an access point on channel 1 is transmitting, all the adjacent clients and the access point with the same channel would cause delay in the transmission. The outcome is that throughput is antagonistically influenced. Close-by access points and customers need to hold up any longer to transmit in light of the fact that they need to proceed. The pointless medium dispute overhead that happens on the grounds that all the access points are on a similar channel is called co-channel impedance (CCI). The fixed channel allocation can be replaced by dynamic channel allocation for resolving the problem faced by the staffs faced in the inventory.
2. The wireless access point is required to be secured from external access and secure the network from unauthroised access. The reconfiguration of the wireless access point with 802.1X security protocol can help the supermarket to secure its wireless network and manage the network traffic in the network easily. Dynamically varying encryption keys are used for securing the network and it has the capability to process the request faster because its algorithm needs less processing power and can work well on old devices with less computational power. The association ought to build up a solid remote security approach to address all the use alternatives of remote systems and the sorts of data that can be transmitted. The strategy ought to layout a system for the advancement of establishment, assurance, administration and use methods. Security and operation rules, benchmarks and work force parts ought to likewise be obviously characterized.

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