NAME: YANKSON RUTH
INDEX NUMBER: 6842416
COURSE: CSM 478 COMPUTER NETWORKS
DATE SUBMITTED: MONDAY, 22ND JUNE, 2020.
IP Address: 195.143.208.133/25
a. The IP address, 195.143.208.133/25 is a class C IP address.
b. The address is on the subnet 195.143.208.128
c. The NetID is 195.143.208.128
d. The HostID is 0.0.0.5
e. The SubnetID is 195.143.208.128
f. The site address is 195.143.208.133
g. The address, 195.143.208.133, in BITWISE notation is 11000011.10001111.11010000.10000101
h. The /25 represents the subnet mask which is used to determine the portion of the address that is network
and the portion for the host.
i. The dotted decimal notation of the /25 is 255.255.255.128
The bitwise notation equivalent is 11111111.11111111. 11111111.10000000
j. Suitable network design for the organization ensuring most efficient usage of addresses.
With the organization, being a rural bank with five branches scattered across Ghana, a tree topology will be
used for the physical layout of its network.
A Wide Area Network (WAN) from the Internet Service Provider (ISP) will be used to link the all the 5
branches to one another, and to the headquarters. The WAN will be set up as a Virtual Private Network (VPN)
with branch sites connected via the Internet. With a VPN server and software, plus the installation of a
network-based Intrusion Prevention System at each branch and the headquarters, a higher level of protection
is ensured.
Each branch of the organization will be assigned a router which will enable it to connect to the internet and
communicate with other branches. All routers will be set up with the surest internet securities as well.
By subnetting the organization’s allocated address of 195.143.208.133/25 into 8 subnets where each can
support 14 (thus, 24 – 2) hosts, a single subnet address will be allocated to each branch.
The subnet address allocated to each branch will be further subdivided to cater for its various departments and
groups of hosts.
Internally, each department or host with needs in common will be connected to a switch which will be linked
to the branch’s router.
There will be a segment of the network provided for special hosts such as servers, printers and other shared
network devices.
There will be high speed links to servers and hosts from network devices.
Workstations will be connected to their own full duplex interface on a switch.
Servers, printers, scanners, and other shared network devices will be connected to their own full duplex
interface with a switch.
Subnetting the allocated address block
Since the headquarters is assigned an address block of 195.143.208.133/25, it would have to be sub-netted to
8 subnets to support all the branches, where the first subnet will be used for the network and the last for the
broadcast address.
Number of bits required to support 16 subnets
2n = 8
2n = 23
n=3
Hence 3 bits in binary from the host portion to be appended to the network portion is required to support 8
subnets.
Network Host
11000011.10001111.11010000.1 0000000
Network Subnet Host
11000011.10001111.11010000.1 000 0000
Network Host
11000011.10001111.11010000.1000 0000
Total bits = 32
Host bits = 4
Network mask bits = Total bits – Host bits
= 32 – 4
= 28
Hence the network mask = /28
= 255.255.255.240
Various Subnets
Networ Network ID Subnet Host Subnet Address Host ID Range
k ID
1 11000011.10001111.11010000.1 000 000 195.143.208.128/28 195.143.208.129 –
0 195.143.208.142
2 11000011.10001111.11010000.1 001 000 195.143.208.144/28 195.143.208.145 –
0 195.143.208.158
3 11000011.10001111.11010000.1 010 000 195.143.208.160/28 195.143.208.161 –
0 195.143.208.174
4 11000011.10001111.11010000.1 011 000 195.143.208.176/28 195.143.208.177 –
0 195.143.208.190
5 11000011.10001111.11010000.1 100 000 195.143.208.192/28 195.143.208.193 –
0 195.143.208.206
6 11000011.10001111.11010000.1 101 000 195.143.208.208/28 195.143.208.209 –
0 195.143.208.222
7 11000011.10001111.11010000.1 110 000 195.143.208.224/28 195.143.208.225 –
0 195.143.208.238
8 11000011.10001111.11010000.1 111 000 195.143.208.240/28 195.143.208.241 –
0 195.143.208.254
Networ Network ID Subnet Number of Broadcast ID
k Mask Usable Hosts
1 195.143.208.128 /28 14 195.143.208.143
2 195.143.208.144 /28 14 195.143.208.159
3 195.143.208.160 /28 14 195.143.208.175
4 195.143.208.176 /28 14 195.143.208.191
5 195.143.208.192 /28 14 195.143.208.207
6 195.143.208.208 /28 14 195.143.208.223
7 195.143.208.224 /28 14 195.143.208.239
8 195.143.208.240 /28 14 195.143.208.255
For each of the 5 branches, a subnet address will be selected from the list of networks ranging from 2 to 8,
with network 1 assigned to the headquarters. And each subnet with a broadcast ID will support 14 hosts with
ID range as shown in the table above.
k. A total number of 8 subnet addresses:
i. 195.143.208.128/28
ii. 195.143.208.144/28
iii. 195.143.208.160/28
iv. 195.143.208.176/28
v. 195.143.208.192/28
vi. 195.143.208.208/28
vii. 195.143.208.224/28
viii. 195.143.208.240/28
l. The IP address, 195.143.208.133/28, resides on the subnet address, 195.143.208.128/28
m. The site address is 195.143.208.133
n. The NetID is 195.143.208.128
o. 195.143.208.133 = 11000011.10001111.11010000.10000101
Network Portion Host Portion
11000011.10001111.11010000.1000 0101
Network Portion Host Portion
00000000.00000000.00000000.0000 0101
0101 in decimal notation = 5
Hence the HostID is 0.0.0.5
p. Given IP address = 195.143.208.133
Subnet mask = 255.255.255.240
In bitwise notation
IP address = 11000011.10001111.11010000.10000101
Subnet mask = 11111111.11111111.11111111.11110000
Bitwise AND = 11000011.10001111.11010000.10000000
Hence the SubnetID is 195.143.208.128
q. A network diagram that can be used for the implementation of the organization’s network.
r. The functionality of each of the devices in the network and their purposes.
i) A router is a network device that operates on layer 3, the network layer of the OSI model. It is also known
as a layer 3 switch, and routes data packets based on their IP addresses. Routers connect LANs (Local Area
Networks) and WANs (Wide Area Networks) together and have a dynamically updating routing table based
on which they make decisions on routing the data packets.
Routers are being used on the network because they are very efficient in WANs. They enable the network to
be divided into different broadcast domains, which contribute to speeding up communication on the network.
Routers also provide the network with the advantage of ensuring a high level of internet security.
ii) A switch, on the OSI model, is a data link layer device. It is a multiport bridge with a buffer and a design
that can boost its efficiency and performance in a network by performing error checking before forwarding
data packets in unicast mode. Thus, it selectively forwards data packets from source to the appropriate
destinations.
Switches are being used on the network because of their advantage of providing the network with more
collision domains to drastically reduce data traffic and also, prevent intruders from gaining access to
transferred data packets on the network.
s. Internet connectivity for hosts at each branch.
Internet connectivity between and among hosts on the network will be via Local Area Networks (LANs).
Hosts can also connect to the branch’s Wi-Fi by providing a specific password in order to be allowed on the
Wide Area Network, and to communicate with hosts on other branches.
t. Types of connections in network diagram
Each branch runs on a Wide Area Network (WAN) and Local Area Network (LAN). A WAN is
a telecommunications network that extends over a large geographical area for the primary purpose
of computer networking. Wide area networks are often established with leased telecommunication circuits.
A local area network (LAN) is a computer network that interconnects computers within a limited area such as
a residence, school, laboratory, university campus or office building.
Business, as well as education and government entities use wide area networks to relay data to staff, students,
clients, buyers and suppliers from various locations across the world. In essence, this mode of
telecommunication allows a business to effectively carry out its daily function regardless of location.
Hosts on the network are also connected using point-to-point topology and point-to-multipoint topology. Point
to multipoint connects one to many points. Point to multipoint topology provides multiple paths from a single
device to multiple devices. Point to multipoint topology is typically used as a Wide Area Network (WAN)
topology.
u. The protocols for devices communication in network diagram
TCP/IP: TCP and IP are two separate computer network protocols. IP is the part that obtains the address to
which data is sent. TCP is responsible for data delivery once that IP address has been found.
Transmission Control Protocol TCP is one of the main protocols in TCP/IP networks. Whereas the IP protocol
deals only with packets, TCP enables two hosts to establish a connection and exchange streams of data. TCP
guarantees delivery of data and also guarantees that packets will be delivered in the same order in which they
were sent.
UDP: User Datagram Protocol is a connectionless protocol that, like TCP, runs on top of IP networks. Unlike
TCP/IP, UDP/IP provides very few error recoveries services, offering instead a direct way to send and receive
datagrams over an IP network. It's used primarily for broadcasting messages over a network.
UDP is a communication protocol used across the Internet for especially time-sensitive transmissions such as
video playback or DNS lookups. It speeds up communications by not requiring what’s known as a
“handshake”, allowing data to be transferred before the receiving party agrees to the communication. This
allows the protocol to operate very quickly, and also creates an opening for exploitation.
v. Protocols for 3 applications communication on network
HTTP: Hypertext Transfer Protocol, HTTP is the protocol used to transfer data over the web. HTTP uses a
server-client model. HTTP is the underlying protocol used by the World Wide Web and it defines how
messages are formatted and transmitted, and what actions web servers and browsers should take in response to
various commands. A client, for example, may be an office computer, laptop, or mobile device. The HTTP
server is typically a web host running web server software, such as Apache or Internet Information Services
(IIS). When you access a website, the client browser sends a request to the corresponding web server and it
responds with an HTTP status code. If the Uniform Resource Locator (URL) is valid and the connection is
granted, the server will send the client browser the webpage and related files. This will be utilized by the
organization’s servers at the main branch which will have HTTP enabled giving all on the network direct
access to certain http addresses to access company information.
POP3: Post Office Protocol version 3 (POP3) is a standard mail protocol used to receive emails from a
remote server to a local email client. POP3 allows users to download email messages on their local computer
and read them even when offline. When POP3 is used to connect to a user’s email account, messages are
downloaded locally and removed from the email server. In this case, if a user accesses their account from
multiple locations, that may not be the best option for them. On the other hand, if POP3 is used, the user’s
messages are stored on their local computer, which reduces the space their email account uses on the web
server. By default, the POP3 protocol works on two ports:
Port 110 - this is the default POP3 non-encrypted port.
Port 995 - this is the port you need to use if you want to connect using POP3 securely.
This will be carried out by the private emailing system enabled and controlled by the servers on the
organization’s network.
FTP: FTP, File Transfer Protocol, is a standard Internet protocol for transmitting files between computers on
the Internet. FTP is built on a client-server model architecture using separate control and data connections
between the client and the server. An FTP server offers access to a directory, with sub-directories. Users
connect to these servers with an FTP client, a piece of software that lets you download files from the server,
as well as upload files to it. FTP uses two basic channels to operate. The command channel carries
information about the task itself, what files are to be accessed, if commands are registering and so on. The
data channel then transfers the actual file data between devices. In our case this will be done between the
servers and a remote client.
w. The addressing mechanism in the movement of packets from one branch to the other.
Packets are transferred between a source interface and a destination interface, thus from one device on a
branch network to a different device on another branch network. when a command is issued on a branch
network to send a message to another branch’s device, the sending device forwards those message packets
onto the local network. The device interface with the destination IP that is specified in the packet header then
retrieves the packet from the local network after the routers have read the necessary headers to determine the
destination IP and MAC addresses, and the best path to reach it. Since the destination address is not on the
branch’s local network, the packets are then forwarded to the next adjacent network or hop and the routers
check packet headers and hop it to the right destination branch’s local network where the packet is then
forwarded to the device which contains the destination MAC address in the packet’s header after a few hops.
x. Assuming each branch has 8 workstations and a network printer, the network diagram has 96 collision
domains.
y. The network diagram has 19 broadcast domains.
z. The network diagram provided, is an ultramodern network design that uses cutting edge technology to
supply the organization with not only a high-speed network, but is also fortified with internet safety, privacy,
and security to the highest degree. It entrusts users with the capacity to control and manage the network in its
capacity with absolute ease, with no complexity whatsoever, as it is also it is easy to be reconfigured. Due to
the topology used, all computers have better access to the network, and is supported by many hardware and
software venders. With a private VPN, the ISP can easily be changed for a better one, in case there arises a
problem that requires the change. And for a very durable and stable network for a not so large organization,
which would surely keep growing, this is the best to invest in.
