Advantages And Disadvantages Of Protocol Layering, Bandwidth Sharing, Wireless Ad-hoc Networks, And Network Configuration Commands In An Essay.

Advantages and Disadvantages of Protocol Layering

a) Forouzan identifies one of the advantages of protocol layering as allowing intermediate devices to be less complex by not requiring all layers (Section 2.1.1, pp34). Given that modern routers, switches, and other intermediate devices often provide web interfaces for administering/configuring the device:
i) Explain why all layers are required to be present for such devices; and
ii) Briefly discuss whether Forouzan’s identified advantage is still relevant.

b) In the Week 1 Class Slides in CloudDeakin, on page 49 is a figure illustrating the encapsulation and decapsulation of data as it moves from source host to destination host. The router is illustrated as having (i) two physical layers and (ii) two data link layers. Explain why these are required and describe how they would be used when a datagram
passes through the router.

Hint: Consider that there are three basic phases of data passing through a router: data arriving, processing by the router, and data outgoing.

a) Consider creating a new type of network where the network cable (copper) has a large bandwidth and will be shared between several users.
i. Briefly describe how this network could be constructed either as a low-pass channel using TDM, or as several bandpass channels using FDM.
ii. Identify one advantage and one disadvantage for each approach (note that it is possible that an advantage for one approach could be a disadvantage of the other approach).
b) You are employed by an organisation that stores and processes large volumes of highly sensitive data. After moving to new premises (a new building), you discover that the wired network between the data storage units and computation units is much higher latency than previously. Your colleague suggests using an ad-hoc wireless network between the two units will resolve the matter.
i. Briefly explain two potential problems with this approach.

ii. Considering each of the four components of latency (propagation time,transmission time, queuing time, and processing delay), identify and explain one possible cause and how to resolve it.

a) The ARP protocol is used to identify an Ethernet address for a given IP address and the information discovered using this protocol is temporarily kept by a device in its “ARP cache”. Consider eliminating the ARP protocol by having devices periodically broadcast their Ethernet and IP addresses instead, and explain the advantages and disadvantages of this approach.
b) Referring to the Week 3 slides and training videos for examples of CRC and Internet checksum calculations:
i. Demonstrate the generation of the CRC code for the following input:
Dataword: 1010 1100
Divisor: 1011
ii. Demonstrate the generation of the 16-bit Internet checksum for the following
input:
Dataword 1: 0011 0011 0011 0011
Dataword 2: 0110 1110 0110 1110
Dataword 3: 1000 0100 0010 0001

a) Consider configuring an IP address on a router and a switch.
i. Give an example of the commands used to configure an IP address on both a router and a switch. Use your own IP address and subnet mask (do not re-use those that appear on the practical task).
ii. Briefly explain why the switch’s IP address is not applied to a physical interface.
b) Briefly explain the problem with the telnet tool and identify an alternative tool and explain how it solves/eliminates this problem.
c) Briefly discuss the need for the IPCP protocol and describe what it is used for.

1. One benefit provided by a layered approach is reducing complexity with networking devices and protocol communication for a network by having specific protocols and devices working in particular layers. However, for some network devices such as modern routers and switches have to have settings for more than one layer. The router for example has settings for the network, data link and physical layers. Modern layer 3 switches also have been manufactured with the ability to operate at both the data link and network layers.

It is important therefore for all layers to be present in such devices because their functionalities require them to work with more than one layer in the networking communication models.

1. Forouzan’s statement, that protocol layering reduces device complexity is not relevant in today’s modern networking world. This is because, for effective and efficient communication and data transmission success, networking devices and protocols need to be used and implemented in more than one layers. Like in the case of the router in figure 1 below. The router is illustrated as being need by the network, data link and physical layers. This clearly demonstrates that protocol layering may still bring about data transmission complexities.
2. In figure 1 below, illustrating encapsulation and decapsulation processes of how data is sent from the source node to the destination node,  the router is depicted as having two pairs of both data link and physical layers.

 The router uses three stages to process data. It has input ports, a switching fabric and output ports (Kurose & Ross 2000). A datagram is received on the first set of physical and data link layers(incoming link), processed in the network layer  and then forwarded to the second set of physical and data link layers(outgoing link).  When a datagram arrivers in a router, it goes through the incoming link. The incoming link is represented by both the physical and data link layer functionalities before being forwarded to the networking layer for routing. The network layer then forwards the datagram to the routers outgoing link represented by data link and physical layer. The layers perform the reverse process of the incoming link functionalities before releasing the datagram for decapsulation on the receiver side.

Figure 2 below shows the router architecture, with input and output ports. The input ports, represents the incoming data link and physical layers used to receive a datagram.  The output ports, represent the outgoing data link and physical layers used to forward a datagram to the recipient device for decapsulation process.

• Input ports– represent a datagram’s incoming link with both physical and data link layers.  They provide a physical layer functionality that receive and terminate an incoming physical link. They also perform the data link functionality that is required to interoperate perform lookup and forwarding to a router’s switching fabric.
• Switching fabric –joins the incoming and outgoing links and performs the routing and network management processes. The switching fabric represents the networking layer where routing takes place through routing protocols. It is in this layer that a datagram is moved from an incoming port to the outgoing ports after the routing process is complete and the right destination address has been identified through the routing tables.
• Output ports– represents the datagrams’ outgoing link with both physical and data link layers. These perform the reverse of what happens at the data link and physical layers at the input ports. It represents the decapsulation process where data packets go through the reverse process of what happens during encapsulation. On the receiver side, data packets have to have the headers fixed on the sender side at every layer, so that the message can reach recipient in the right format.

1. Constructing low- pass channel using TDM and multiple band pass channels using Frequency Division Multiplexing(FDM)
2. Description of low-pass channel using TDM

Time-division multiplexing (TDM) is a digital procedure that allows multiple connections to share the bandwidth of a line (Forouzan 2007). Simply, TDM is a digital multiplexing technique for combining several low-rate channels into one high-rate one.  In TDM, signals are separated into same equal fixed-length time periods. When multiplexing is done, the signals are transmitted over shared media and reconstructed back to their original format during de-multiplexing (Techopedia 2017). As a replacement for sharing a bandwidth portion like in FDM, TDM shares time.

2. Description of several pass channel using FDM

Frequency-division multiplexing (FDM) is an analog technique applied when the bandwidth of a link measured in hertz is bigger than combined bandwidths of all the signals to be transmitted (Forouzan 2007). These modulated signals can then be combined into a single compound signal and be transmitted by the link. Though FDM is considered an analog multiplexing technique, it can still be used to connect together digital signals for sending. In other words, it is possible to convert digital signals to analog signals, and the using FDM to multiplex them.

1. Pros  and Cons  of both low pass and several pass with  TDM and FDM
2. Advantages of low-pass channel and Time Division Multiplexing(TDM)

• Highly  reliable  and efficient operations because it uses digital signals which are faster and only easy to process
• Full available channel bandwidth can be utilized for each channel
• Inter-modulation distortions are absent
• TDM circuitry operations are less  complexenabling simple transmissions
• Crosstalk  problems are  not severein TDM

2. Advantages of several-pass channel and FDM

• Multiple signals can be transmitted  concurrentlywhich optimizes network resources such as bandwidth
• FDM does not require synchronization between the  transmitter  and receiver  nodes to operate
• Demodulation of FDM is easy and simplified
• Narrow band fading  with FDM is slow and only a single channel can get  affected

3. Disadvantages of low-pass channel and TDM

• Synchronization is needed for accurate operationsand for TDM to work in an effective manner
• Because of narrowband dwindling, TDM channels  are likely to be wiped outwhich can easily waste network resources
• Timing jitter which delay network packets

4. Disadvantage of several pass channel and FDM

• Requires large bandwidth for the communication channel to work effectively
• Suffers intermodulation distortions  which affect and damage data signals
• Requires filters and modulators and filters in large numbers
• FDM is greatly affected by crosstalk which damages data signals at the receivers side
• FDM channels are  affected by  wideband fading and degenerate with increase in transmission distance

1. Security concerns– Ad-hoc wireless networks operate without infrastructure and therefore do not make use of central access points. They are therefore susceptible to numerous kinds of attacks since there is no central way to secure data transmission from one node to another (Sareen & Kumar 2015). Since the organization deals and works with highly sensitive data, implementing an ad-hoc network will make it prone to attacks, both from authorized users and malicious intruders including eavesdropping to active attacks such as theft and manipulation. As a result, the organization can suffer huge data losses and fail to achieve its aims and objectives.
2. Network management difficulties resulting to network congestion– managing an ad-hoc network is problematic (Sareen & Kumar 2015). This is because it doesn’t not have management devices such as routers for the network devices. If the network devices are many, it becomes almost impossible to manage them. In addition, an ad-hoc network doesn’t not provide scalability and therefore cannot span over a wide area.  The organization operates and processes large volumes of data to and from storage units to computing units. Weak links in an ad-hoc network cannot maintain such kind of traffic and can result to high latency. An ad-hoc network can also not be able to span over a wide geographical region. This is because, it only works well with a smaller number of network devices. An ad-hoc network with many than required will be very hard to manage, maintain and troubleshoot. Such can only increase processing and queuing delays for the organization’s data transmission.
3. Latency is the time it takes for a data packet to travel from its source of origin to its destination (O’ Reilly Media 2013). According to a White Paper published by 03b Networks (2016), some causes of latency include the following: propagation delay, processing delay, queuing time and transmission time.  

• Propagation delay– represents the amount of time necessary for a data packet to travel from the sender device to receiver device. It is therefore a function of distance over speed with which a data signal transmits.
• Transmission delay- represents the amount of time needed to push all the bits in a data packet into a communication link.  It is therefore a function of the length of a data packet and data rate of the communication link. Higher transmission delay is directly proportional to network latency. The longer the rate of transmission, the higher the network latency.
• Processing delay- represents the amount of time needed to, evaluate bit-level errors, process the packet headers as well as determine the destination address of a data packet. Longer processing delay increase network latency.
• Queuing delay- represents the amount of time that a data packet takes waiting in the queue till the time it can be processed. The longer the amount of time a packet waits in line, the higher the latency and network lag.

Proficient data transmission in a wireless ad-hoc networks is both complex and challenging task due to the nonexistence coordination of control nodes in central devices and access points in the network (Sarshar, Rezaei & RoyChowdhury 2006). As a result, the fact that an ad-hoc network lacks infrastructure makes it extremely difficult to guarantee data packet reliability over many traffic routes (Tuli & Kumar 2014). Network routing algorithms and network management protocols therefore, have to work in a manner that is self-governing. As such, an ad-hoc network is expected to powerfully and efficiently route and direct data traffic from any source point to destination point.

Bandwidth Sharing Techniques

                 In an ad-hoc wireless network, processing delay is the component that directly affects latency and can increase latency, resulting to network congestion and security challenges. Because of the fact that the organization in question deals with large data volumes, it will take a long time before checking bit-level errors, determine packet headers since the volumes of data will require to be divided into smaller packets and perform all the necessary actions requires to process data packets before transmitting them.

Processing delay can be solved through network monitoring, and network optimization. By monitoring the network, challenges can be identified and solutions for them implemented to help in reducing internet latency.

By use of network optimization tools, which automate the process of network monitoring. Network optimization tools are designed to facilitate network congestion  avoidance and therefore reduction of network latency (Hasham 2016). This tools are built to handle data transmission routes. They can consequently produce instant and real-time internet map performance and help direct and route data traffic through paths with the least latency rates (Mohamed, Fahmy & Pandurangan 2013). Network optimization tools will not only provide solutions that are just limited to decreasing internet latency, but will also decrease jitter, packet data loss and heighten network bandwidth.   

1. The Address Resolution protocol (ARP) is used to translate between internet IP addresses and Local Area Network LAN IP addresses (Kurose& Ross 2000).
2. Address Resolution protocol is similar to Domain Name Systems (DNS), which resolves device names to their respective IP addresses. Nevertheless, there is one significant difference between the translators. Domain Name System resolves hostnames for hosts anywhere in the Internet, while Address Resolution Protocol, only translates IP addresses for hosts on the same Local Area Network.

Address Resolution Protocol (ARP) is a very significant when it comes to IP networking. Address Resolution Protocol (ARP) is used to join the Network layer to the Data-Link layers of the OSI model. Since the Network layer works with IP addresses and the Data Link layer works with physical (MAC) addresses, it is important to match the two for network smooth functioning of data routes.

This means that, Address Resolution Protocol is therefore used to connect IP addressing to our Ethernet addressing (MAC Addressing) for devices in a network. For a device to communicate with another device on a network, it must have an Ethernet MAC address (physical) for the device. If the address is not on your device in the Local Area Network (LAN), it is required to go through the router (default gateway). In such a case, the router will act as the destination MAC address that your device will connect with for any kind of communication.  If Address Resolution Protocol was done away with, and instead have devices broadcast their Ethernet addresses and IP addresses, there would be advantages and disadvantages of following such an approach as follows.

Advantages of eliminating ARP for Ethernet to IP addresses translation

• Reduces ARP spoofing and eavesdropping
• Reduces network attacks that may come as replies to ARP requests by malicious hackers and intruders.  
• Reduces attempts to attack network through denial of service attacks
• Stops ARP flooding multiple viruses send a lot of ARP traffic in an attempt to discover hosts to infect
• Reduces network traffic since there are no ARP requests and responses on the network
• Reduced ARP cache poisoning by network attacks
• Less bandwidth consumes
• Simplifies network management

Wireless Ad-hoc Networks

Disadvantages of eliminating ARP for Ethernet to IP addresses translation

• Lack of clear network routes
• There will be no way to facilitate address translation of  the second and third layers of the OSI model
• Unstreamlined IP and MAC addresses
• Lack of Ethernet address determination
• Data traffic storms since there are no clear Mac address routes for devices

1. Cyclic redundancy check(CRC) and Checksum

1. A cyclic redundancy check (CRC) is a code used to detect errorsin data packets and is commonly used in digital networks and data storage devices to detect any unintentional changes to fresh data. Blocks of data packets incoming into these systems receive a small data value. The data value is usually attached to, and based on the remainder of a particular polynomial division of their total contents. On repossession, the calculation is reiterated and, if the check values do not match one another, action to correct the error is taken against corrupted data cyclic redundancy checks are used for data errors correction. Below, the cyclic redundancy check  (CRC) code is made up by the data word + the remainder

                  100110

1011) 10101100

           1011

             0011

             0000

                0111

                0000

                   1110

                   1011

                      1010

Data word = 1010 1100

Remainder = 1010

The CRC code is the data word + remainder = 10101101010

1. Check sum can be used to detect errors from a derived from a block of digital data. Such errors can occur   during data transmissionor during data storage. A checksum is typically applied to a data file after it is received from the sender so that it can be verified for any error that may have occurred during data transmission. Typically, checksums are regularly used to confirm   data correctness and integrity but cannot be trusted to verify and confirm data authenticity in network packets.

To generate the Internet checksum of the following input

Data word 1    0011 0011 0011 0011

Data word 2    0110 1110 0110 1110

Data word 3    1000 0100 0010 0001

0011 0011 0011 0011

0110 1110 0110 1110

1000 0100 0010 0001 Add one’s complement

0111 1011 0101 1110 sender

                                          1000 0100 1010 0001

                                         0011 0011 0011 00                  Doesn’t not match one’s complement

                                    +   0110 1110 0110 1110  Receiver   

                                         1000 0100 1010 0001

                                         0111 1011 0101 0110

1. Router and Switch IP Address configuration
2. Commands for configuring an IP address on a router
3. enable
4. configure terminal
5. hostname Router1
6. enable secret class
7. line console 0
8. password cisco
9. login
10. line vty 0 4
11. password cisco
12. login
13. interface Ethernet 0/0
14. ip address 192.168. 2. 6 255.255.255.0
15. no shut down
16. interface Ethernet 0/1
17. ip address 192.168.3.10 255.255.255.0
18. no shut down
19. end

Commands for configuring an IP address on a router

1. enable
2. configure terminal
3. hostname Switch1
4. enable secret class
5. line console 0
6. password cisco
7. login
8. line vty 0 15
9. password cisco
10. login
11. interface Vlan1
12. ip address 192.168.2. 63 255.255.255. 0
13. exit
14. ip default gateway 192.168.2. 64
15. end
16. The switch IP address is not applied to a physical interface but to a VLAN port. A virtual Local Area Network (VLAN) is a grouping of network devices that frequently communicate with one another (Mitchell 2017). VLANs are used to aggregate and segregate different networks and allow the provision of sharing the same physical space and resources, with no interaction for network devices that need to be separated for reasons of traffic management, economy, simplicity and economy.  By creating a VLAN on the switch port and not a physical port therefore, a network has the following benefits

• Provision and  support for network security since it becomes possible to separate networks in a LAN by putting highly sensitive networks on their own and with high- tech security controls and authentication procedures
• Virtual Local Area Networks(VLANs) provide the functionality to separate broadcast domains
• Virtual Local Area Networks(VLANs) provides the capability to connect network devices on the switch but these devices could belong to a different network
• Allows maximum use of switch ports by ensuring that all switch ports are used. This is because many devices can be fixed on the switch and belong to entirely different networks.
• Virtual Local Area Networks(VLANs)  provides a gateway to the multiple network’s  interface
• Virtual Local Area Networks(VLANs) avoid broadcast storms and reduce network congestion
• Virtual Local Area Networks(VLANs)  provide network adaptability and flexibility
• Virtual Local Area Networks(VLANs) provide facilitation for  network segmentation and separation
• Virtual Local Area Networks(VLANs) provide easy and streamlined network communication across the entire computer network
• Virtual Local Area Networks(VLANs) allow network administrators to  simplify network design and manage the network

1. Telnet command is a user command as well as a basic TCP/IPprotocol used for obtaining access to remote computers (Rouse 2006). With Telnet, a user or a network administrator can be able to access another   computer remotely. Unlike web protocols that only provide specified file requests for users, telnet allows you to log on a computer with  much more access and user privileges to data and applications in that computer. Telnet therefore provides more powerful capabilities and functionalities.  Telnet is universal, saves a lot of time and allows trouble shooting and error fixing in a simplified manner with its text based interface.

The telnet tool PuTTY is an SSH client software application that uses a secure shell protocol to link to a remote computer (Anand, 2015). Though most popular and widely used, it can have issues such as bad key exchanges and mismatch in packet length. It generates packet related errors such as oversized packets.  This happens when there’s a limited amount of memory or encryption errors generating unexpected results and data.

An alternative telnet tool to deal with the challenge is KiTTY. KiTTY is a variant of PuTTY and has been designed to work as a Windows SSH Client (Cannon 2014). KiTTY offers all the features that PuTTY has to offer and includes many more features including portability, session filters, session icons, predefined shortcut commands, running local scripts remotely etc.

With the added features and being a fork of puTTY, KiTTY has a lot of improvements programmed in it. It is able to deal with packet length related problems since it has features to cater for that.

1. Internet Protocol Control Protocol (IPCP) is a Network Control Protocol(NCP). Internet Protocol Control Protocol is required since it is used for creating, configuring, enabling and disabling Internet Protocol (IP) over a Point-to-Point Protocol connections (Kozierok 2005).  

• IPCP makes it possible to create connections between networks on point to point links. This way it enables and manages to crease session controls in multiple separated network nodes without the need to create network infrastructure. This reduces time consumption and makes data transmission fast and reliable. They also facilitate remote networking capabilities.
• IPCP makes it possible to connect networking devices such as routers openly, without the need for any other host or any networking device in the middle.This reduces installation costs. It also reduces network complexity and creates smooth data routes for network traffic.
• IPCP has the capability to establish connection, data compression, authentication, and data traffic encryption to data packets.

Internet Protocol Control Protocol utilizes a packet exchange mechanism similar to Link Control Protocol (LCP).  IPCP is responsible for IP addresses configuration, as well as for enabling and disabling the IP protocol units on point-to-point link ends. IPCP can  used over a variety  of  several physical networks such as phone lines,  serial cables,  trunk lines, cell telephone lines, radio connections, and fiber optic lines such. In addition, IPCP can also be used over Internet related  connections and is also used for dial up connection access by Internet service providers .  Internet Protocol Control Protocol is used popularly by Internet Service Providers (ISPs) to create a Digital Subscriber Line (DSL) network services links with clients. Internet Protocol Control Protocol (IPCP) is used together with other Network Control Protocol including Point to Point (PPP) protocol.

PPP is frequently utilized as a data link layer protocol for connecting asynchronous over synchronous network circuits. Together Point to Point (PPP) and Internet Protocol Control Protocol (IPCP) work in an integrated manner to provide functionality to connect point to point network nodes without the need for network devices. Point to Point (PPP) requires that the circuit delivered be bidirectional. Internet Protocol Control Protocol (IPCP)  was aimed to function  with other  various network layer protocols such as Internet Protocol(IP), Internetwork Packet Exchange (IPX), NBF, DECnet.  Internet Protocol Control Protocol (IPCP)   is much more reliable and dependable because it cross checks to ensure that data packets arrive the same way they leave the sender’s device. Internet Protocol Control Protocol (IPCP) also resends destroyed data packets.

References

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Cannon, J. (2014), 20 windows SSH Clients You can use to connect to your Linux server, [Online], Available: https://www.jasoncannon.me/20-windows-ssh-clients-you-can-use-to-connect-to-your-linux-server.html [Accessed 1 Aug 2017].

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Kurose, J & Ross K. (2000), Computer Networking: A top-down approach featuring the Internet

Kozierok, C. (2005), The TCP/IP Guide: IPCP Network Protocol, [Online], Available: https://www.tcpipguide.com/free/t_PPPNetworkControlProtocolsIPCPIPXCPNBFCPandothers.htm [Accessed 1 Aug 2017].

Mitchell, B. (2017), what is a virtual VLAN? [Online], Available: https://www.lifewire.com/virtual-local-area-network-817357 [Accessed 1 Aug 2017].

Mohamed, R, F., Fahmy S, & Pandurangan, G. (2013), Latency-Sensitive Power Control for Wireless Ad-hoc Networks, [Online], Available: https://www.cs.purdue.edu/homes/fahmy/papers/q2swinet.pdf [Accessed 2 Aug 2017].

O’Reilly Media Inc. (2013), Primer on Latency and Bandwidth, [Online], Available: https://hpbn.co/primer-on-latency-and-bandwidth/ [Accessed 1 Aug 2017].

03b Networks (2016), what is network latency and why does it matter? [Online], Available: https://www.o3bnetworks.com/wp-content/uploads/2015/02/white-paper_latency-matters.pdf [Accessed 1 Aug 2017].

Rouse, M. (2006), TechTarget:  Telnet, [Online], Available: https://searchnetworking.techtarget.com/definition/Telnet [Accessed 3 Aug 2017].

Sareen, P &  and Kumar, P. (2015), A study of ad-hoc networks, International Journal of Advanced Research in Computer Science, Volume 6, No. 7, September-October 2015, [Online], Available: https://www.ijarcs.info/index.php/Ijarcs/article/viewFile/2568/2556 [Accessed 31 July 2017].

Sarshar N, Rezaei B, & Roychowdhury V (2006), Low Latency Wireless Ad-Hoc Networking: Power and Bandwidth Challenges and a Hierarchical Solution, [Online], Available: https://arxiv.org/pdf/cs/0604021.pdf [Accessed 3 Aug 2017].

Techopedia (2017), Time Division Multiplexing (TDM), [Online], Available: https://www.techopedia.com/definition/9669/time-division-multiplexing-tdm [Accessed 3 Aug 2017].

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