Data Communications and IP Calculation

This document covers topics such as the different layers of the OSI model and their roles, IP subnet calculation, the role of IP, MAC, and ARP protocols, and a case study on network design and upgrading to IPv6.

Running head: DATA COMMUNICATIONS AND IP CALCULATION
Data Communications and IP Calculation
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Question 1: Different layers of OSI model and their roles
Functions of OSI layers
The seven layers of the OSI reference model each perform specific set of functions.
Physical layer, the first layer of OSI is responsible for conveying a bit stream of light signal
and electric impulse. Data can be send and received by means of hardware which can include
network cards, motherboard sections and cables. Protocols associated with these components
of the physical layer can be RS232, fast Ethernet and ATM. OSI model’s second layer is the
data link layer which involves encoding and decoding of data packets takes place (Zhao et al.,
2018). It is also used in furnishing knowledge of transmission protocol and handling errors
surrounding physical layer. The network layer or third layer of OSI model is responsible for
providing routing and switching mechanisms through virtual circuits that are used to transfer
data packets from node to node. The transport layer or fourth layer of this model ensures
complete transfer of data between hosts and end system. The session layer or fifth layer of
OSI terminates, establishes and manages connections among the applications. The
presentation layer or sixth layer, helps in convert data into forms, which is understandable for
the application layer. The application layer or seventh layer supports the application
processes and the end-users processes (Alotaibi et al., 2017). Service quality, communication
pattern, data syntax constraints are identified and privacy and authentication of user are
considered.
The application, session and presentation layer are the software layer whereas
network, physical and data link layers are the hardware layers. Transport layer, heart of the
OSI model separates the software and hardware layers.
The internet layer perform the function of packet switching networking that is based
on the connectionless network layer. This layer is responsible for holding the whole

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architecture of the model. This help in free moving of the packets over the internet. The order
of receiving and sending the packets are different. This layer uses Internet Protocol. Whereas
the network layer allow the interconnection of different networks. The networking layer of
the OSI model is compared to the TCP/IP model. The network layer routes the data from
node to node and the internet layer transfer the data packets and provides routing facility over
the internet (Goralski, 2017). Both these layers are engaged in transferring data packets but
internet layer transfer it over internet so it called as internet layer in the TCP/IP model.

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Question 2: IP Subneet Calculation
Hands-On Project 2.3
1. & 2. Enter the addresss www.gestioip.net/cgi-bin/subnet_calculator.cgi and in the web
page that opens please check that ipv4 radio button is chosen.
3. In the IP address field give the IP 192.168.0.0 as input

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4. The appropriate subnet mask for the class C IP address 192.168.0.0 that is 24
(255.255.255.0 – 254) is chosen from the BM dropdown and then calculate is button is
pressed to find the results.
5. The results of the of the subnet calculation is provided, since 192.168.0.0 is a class C IP
address, the bitmask is 24 and in the last line the IPv6 address mapped to this IPv4 address is
given.

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6. Then the browser is closed by clicking the cross button.

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Hands-On Project 3.2
Wireshark is started
Ethernet is chosen as it carries the configured IPv6 address 2001::109
On clicking start recording is started.

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By entering ‘cmd’ in run, the command prompt window is opened.
The IPv6 address of another computer in the LAN network is pinged.

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After the successful result, the command prompt is closed with the ‘exit’ command and the
wireshark recording is also stopped.
Next the the packets recorded in wireshark are filtered using the ipv6 filter.

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One of the ipv6 packets is selected from the list.
The IPv6 field of the packet is then expanded.

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Thereafter, in the IPv6 field, the traffic section is expanded.
Contents of the IPv6 field of the packet are:
Payload length: 40
Next header: ICMPv6 (58)
Hop limit: 128
Source: 2001::108

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Destination: 2001::109
The IPv6 field is then collapsed
The wireshark file is then saved as ch03_IPv6Fields and wireshark is closed.
Question 3: Role of IP, MAC and ARP protocols
There are two type of address for every network device. The IP address is the logical
address and the MAC address is the physical address. In a local area network a hardware

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address which is unique is provided by the MAC address. An IP adder is considered as a
unique identifier which is provided to every machine in a network. IP address is very
important in data communication because of its unique identification number one system in
the network can connect to the other networks over the internet. IEEE manages the media
access control address (Toskala, Holma, & Metsala, 2016). This is how MAC address helps
in data communication. IEEE distribute unique hardware identification number that is the
MAC address and matching of MAC address is zero. Both the MAC address and the IP
address is important in data communication because MAC address help the physical
communication of computers over the network and the IP address helps in logical routing
between the computers in the network.
In local area network using Ethernet, there is a 48-bit long address long. As the
protocol differ in each LAN, there is separate request for Ethernet, data interface that are
fiber distributed, ATM and other protocols. The physical machine address, which is physical,
is called as MAC address. A correlation between MAC address is maintained using ARP
cache and its IP address. Address Resolution Protocol maps IP addresses to MAC address
(Yamaura, Tanaka & Sugasawa, 2015). When a packet meant for a host machine in a LAN
appears to the gateway. This gateway requests ARP for finding suitable MAC addresses
which suits the respective IP address. ARP then finds the suitable MAC address from the
cache and in case it gets the address it gives it so that packets can be converted to a correct
packet length and correct format and then it send it to the machine. Broadcasting a request
packet in the required format to every machine in local area network to look after the fact that
machine knows that it carry the IP address associated with it in case ARP do not find the IP
address in the ARP cache (Fountain, 2018). ARP also informs the ARP cache that it had send
the packet to the media access control address for future reference. Thus, it can be said that

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ARP gives a set of rules for developing correlation and allow conversion of address in both
direction.
Question 4: Case study
Requirements summary
Sites Departments Connections required
Headquarters Sales Department 22400
Marketing Department 11200
Branch 1 Advertising Department 2800
Online Sales Department 5600
Branch 2 Product Support Department 1400
Technical Support
Department
700
Sales and Marketing 2
Marketing and Advertising 2
Advertising and Online
Sales
2
Online Sale and Product
Support
2
Product Support and
Technical Support
2
Technical Support and Sales 2

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Design of Network
Figure 1: Router Interconnection Design
Detailed IP Addressing
The major network as selected for this scenario is – 180.71.0.0/16
Available IPs in major network – 65534
Required number of IP addresses – 44112
The IP addresses available in the subnets allocated are – 64512
Since there exists six routers for every six department, six additional number of
subnets are required for interconnecting routers of these departments (Geib & Black, 2017).
Hence, a total of 12 subnets have been created.

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Sales
The subnet with network address - 180.71.0.0 is chosen for the headquarters’ Sales
department. Total IP addresses required by the department - 22400. For allocating these
connections almost half of major network is required. As a result, CIDR becomes 17 the
respective subnet for which is 255.255.128.0 (here 1 host bit has been borrowed). Thus
available number of networks are 27 = 128. Every network of the subnet contains 254 IP
addresses resulting in a total of (128*256 - 2) = 32766
Marketing
Network address selected for the Marketing department of headquarters -
180.71.128.0. Number of IP addresses, the department requires - 11200. For allocating these
connections, a network half the size of Sales is required. As a result, CIDR becomes 18, the
respective subnet for which is 255.255.192.0 (here 2 host bits has been borrowed). Thus
available number of networks are 27 + 26 = 192. The 64 available networks of this subnet
each contain 254 IP addresses resulting in a total of (64*256 - 2) = 16382.
Advertising
Network address selected for the Advertising department of headquarters -
180.71.224.0. Number of IP addresses, the department requires - 2800. For allocating these
connections CIDR becomes 20, the respective subnet for which is 255.255.240.0 (here 4 host
bits has been borrowed). Thus available number of networks are 27 + 26 + 25 + 24 = 240. The
64 available networks of this subnet each contain 254 IP addresses resulting in a total of
(16*256 - 2) = 4094.
Online-Sales
The subnet with network address - 180.71.192.0 is chosen for the headquarters’ Sales
department. Total IP addresses required by the department - 5600. For allocating these

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connections CIDR becomes 19, the respective subnet for which is 255.255.224.0 (here 3 host
bits has been borrowed). Thus available number of networks are 27 + 26 + 25 = 224. The 32
available networks of this subnet each contain 254 IP addresses resulting in a total of (32*256
- 2) = 8190.
Product-Support
The subnet with network address - 180.71.240.0 is chosen for the headquarters’
Product Support department. Total IP addresses required by the department - 1400. For
allocating these connections CIDR becomes 21, the respective subnet for which is
255.255.248.0 (here 5 host bits has been borrowed). Thus available number of networks are
27 + 26 + 25 + 24 + 23 = 248. The 8 available networks of this subnet each contain 254 IP
addresses resulting in a total of (8*256 - 2) = 2046.
Technical-Support
Network address selected for the Product-Support department of headquarters -
180.71.248.0. Number of IP addresses, the department requires - 700. For allocating these
connections CIDR becomes 22, the respective subnet for which is 255.255.252.0 (here 6 host
bits has been borrowed). Thus available number of networks are 27 + 26 + 25 + 24 + 23 + 22 =
252. The 4 available networks of this subnet each contain 254 IP addresses resulting in a total
of (4*256 - 2) = 1022.
Each of the routers assigned to the respective departments will be requiring additional
subnets for interconnecting purposes. Because there are six routers, number of subnets
needed for interconnecting is six. These interconnections are Sales-Marketing, Marketing-
Advertisement, Advertisement-Online services, Online Services-Product Support, Product
Support-Technical Support and Technical Support-Sales. The assignable IPs of the subnets
allocated are 180.71.252.21-180.71.252.22, 180.71.252.17-180.71.252.18, 180.71.252.1-

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180.71.252.2, 180.71.252.5-180.71.252.6, 180.71.252.9-180.71.252.10 and 180.71.252.13-
180.71.252.13 respectively.
Upgrading from Ipv4 to IPv6
For upgrading routers as well as hosts to IPv6, the functionalities ofIPv4 can be
retained to provide compatibility for IPv4 protocols as well as applications. The routers and
the hosts are said to be in dual stack (Martinsen, Reddy & Patil, 2018). For a dual stack based
approach, associated subsets of routers as also the hosts needs to be upgraded in attempt to
support IPv6 in addition to IPv4. Forr this purpose, upgraded nodes are ensured to be
interoperable with the IPv4 nodes via IPv4 which were not upgraded. Thus, the upgrading
process to dual stack from the IPv4 configuration ar not eliminating services at all.

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References
Alotaibi, A. M., Alrashidi, B. F., Naz, S., & Parveen, Z. (2017). Security issues in Protocols
of TCP/IP Model at Layers Level. International Journal of Computer Networks and
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Fountain, J. G. (2018). U.S. Patent No. 9,992,168. Washington, DC: U.S. Patent and
Trademark Office.
Geib, R., & Black, D. (2017). Diffserv-interconnection classes and practice (No. RFC 8100).
Goralski, W. (2017). The illustrated network: how TCP/IP works in a modern network.
Morgan Kaufmann.
Martinsen, P., Reddy, T., & Patil, P. (2018). Guidelines for Multihomed and IPv4/IPv6 Dual-
Stack Interactive Connectivity Establishment (ICE) (No. RFC 8421).
Toskala, A. A., Holma, H. K., & Metsala, E. M. (2016). U.S. Patent Application No.
15/024,878.
Yamaura, T., Tanaka, S., & Sugasawa, N. (2015). U.S. Patent No. 9,130,957. Washington,
DC: U.S. Patent and Trademark Office.
Zhao, J., Bai, J., Zhang, Q., Yang, F., Li, Z., Zhang, X., ... & Bai, R. (2018, December). The
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