Networks

Running Head: Networks 0 | P a g e
Networks
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Networks 1 | P a g e
Question 1
Transmission Control Protocol (TCP) uses sequence and acknowledgment number to maintain
the packet tracking between two end hosts. It is a way to maintain record of the data in the
network. All the packets have delivered to both the end successfully. Sometimes, few packets are
missing in the network because of the fault in the network or anything else. Below diagram is
shows TCP connection between client and server (Certiology, 2018).
Source: ( Stretch, 2010)
In above diagram, client sends request to the server then server sends desired packets to the
clients as per request. In between, server sends four segments to the client. In addition, client is
missing segment -2 because of network issues. Therefore, it sends an AcK-1 to the server to
informing about segment loss (Cisco, 20018). However, server already sends segment-3 and
segment-4. Client does not accept the segment-3 and segment -4, as it is missing segment-2.
Client again sends an Ack-1 to the server then server sends all the remaining segments (Dye, et
al., 2007).

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It is a not proper way of data transfer. Therefore, selective acknowledgement concept is applied
for data transfer as shows in below diagram.
Source: ( Stretch, 2010)
In above diagram, Selective Acknowledgement (Sack) working process is showing with different
steps. It reduces the traffic of the network, as well as unnecessary retransmissions of the
segments. According to this approach, it is not necessary to sends all the packets again, as
previous segment is lost in the network (Forouzan, 2007). It is a way to reduces segment
retransmissions. If any segment is lost in the network then a Sack is send with an
acknowledgement packet. Therefore, no need to retransmission of packet, as they already
receives segments by client. It requires retransmission of selected lost segment to the client
( Stretch, 2010).
Selective acknowledgement is beneficial for handling flow control and congestion control. TCP
is used this thing to reduce retransmission rate of segments. Segments are losses because of
network faults. Therefore, it is not necessary to resend the already sends packets (Gapiński,
2014).
There are many packets, which are lost because of faulty internetworking devices. Therefore, it
is not necessary to send all those packet, which are sends after the lost packet. In network,

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different types of issues are occurred, such as attenuation, distortion, and noise. There are many
things in the network, which creates an issue for data transfer (Velte & Velte, 2013). Therefore,
it is big task to reduce packet losses. A basic task reduces data losses in the network and
increases the efficiency of the network. Computer networks are having many things to transfer
data from one source to destination. Mainly media is the reason for data losses, as data loss rate
is high in wireless media, because of medium and technology as compared to wired media
( Stallings, 2018).
TCP transmission is having best way to data transfer. However, it is uses connection-oriented
approach for data transfer. It is measured that, TCP is more reliable then UDP data transmission.
Data loss is a different thing but remedy after data loss is very important in data transfer
(Mitchell, 2018). Data communication is highly required in the present era with high efficiency
and security of data. Therefore, data losses are not tolerable in the data transmission (Sunshine,
2013). It is a common thing that, if any segment is already send to the client then it is not
necessary to resend it. Selective acknowledgement provides low rates of retransmission in the
TCP transmission of segments (Kenneth C. Mansfield & Antonakos, 2009).
Reliable transmission is requiring for data transmission and it is a way to handle packet loss in
data transfer. TCP transmission is reliable because of connection-oriented approach. Selective
acknowledgement approach is best way to reduce retransmission on already sends packets.
TCP transmission is best way to data transmission. Selective acknowledgement is best thing to
reduce the unnecessary transmission of the rest segment in the network. It improves the
performance of the channel as well as efficiency of the network. Traffic is also reducing in the
communication channel from the selective acknowledgement technique. It is a way to identify
the selected segment to resend to the receiver.
Data communication is not easy to maintain all the operation of the data transfer. Therefore, it is
necessary to improve the efficiency of the network through reduce unnecessary traffic of the
communication channel. It is necessary to reduce network faults because of traffic and technical
problems. However, physical damage is a huge issue in front of communication medium.

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Question 2
a. As per given details, it is mention in the table that nine subnet mark has been created. All
the details are based on the concept of networks (Hogg & Vyncke, 2008). It is based on
the network and host ids. There are many things to manage in deciding subnet marks
(Lammle, 2011). Subnet mask is based on the number of bits (Goldstein, 2017). Given
data is provided in the table.
Subnet mask Subnet mask in binary Number of
subnets
Number
of hosts
255.255.255.0 11111111 11111111 11111111 00000000 20 = 1 28 –2 =254
255.255.255.128 11111111 11111111 11111111 10000000 21 = 2 27 –2 =126
255.255.255.192 11111111 11111111 11111111 11000000 22 = 4 26 –2 =62
255.255.255.224 11111111 11111111 11111111 11100000 23 = 8 25 –2 =30
255.255.255.240 11111111 11111111 11111111 11110000 24 = 16 24 –2 =14
255.255.255.248 11111111 11111111 11111111 11111000 25 = 32 23 –2 =6
255.255.255.252 11111111 11111111 11111111 11111100 26 = 64 22 –2 =2
255.255.255.254 11111111 11111111 11111111 11111110 27 = 128 21 –2 =0
255.255.255.255 11111111 11111111 11111111 11111111 28 = 256 20 –2 =0
b. Nine-subnet mask has founded in the part (a). We can use seven subnets for creating
networks with hosts of different quantities. It is based on the number of bits. Class C is
having 8 bit for hosts (Darwich, 2011). Therefore, we can generate different subnet
masks. It is a way to create different subnets based on the requirement of the host
(Kivisaari, 2000).
c. In case of IPv6, 2 addresses are deducted because of zero is a network address and 255 is
broadcast address. Therefore, we cannot assign these addresses to the host. Every
network is having all zeros and all ones (Goldstein, 2017). Therefore, it is necessary to

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avoid those addresses to avoid ambiguity in the network. It is necessity to secure both the
addresses as they are having a special purpose in IPv4 configuration (Kivisaari, 2000).
d. CIDR notation for the 201.168.67.0 IP address is 201.168.67.0/25. In Classless Inter-
Domain Routing, mention number of bits after the IP address, such as 201.168.67.0/25.
Here, 25 is number of bits for network id. It is used for creating number of networks
(Tanenbaum, 2014). It is a type of super netting and it borrows bits from the network id.
There are many advantages of the CIDR, such as managing network with desired host’s
requirements. There is a best way to solve issues of classful addressing.