1
7
SP1
Assignment 2
1
of
10
Due : 11:59PM, Sunday
1
4
th
M
ay
20
1
7
RMIT University
School of Computer Science
And Information Technology
Cpt
-
250
Data Communication
and
Net
-
Centric Computing
Assignment #2
Study Period 1
, 201
7
1
7
SP1
Assignment 2
2
of
10
Due : 11:59PM, Sunday
1
4
th
M
ay
20
1
7
Warning regarding Plagiarism
All answers must be your own original work. You mus
t complete
this assignment on your own, and the answers you submit must be
your own work and in your own words.
You may discuss the problems
with others
, and on the discussion
board, but any answers that share substantial commonality with
those of other st
udents will be considered plagiarism.
Direct quotes are not permitted and quotes from the lecture
material are also not permitted. All answers must be in your own
words. All ideas must be properly referenced
–
so you must
understand and summarize all exter
nal sources.
You must not provide nor show your answers to anyone, and you
must not discuss details of your answers in person or on the
discussion board. You are responsible for the security of your
work.
This means not allowing anyone else access to you
r computer files,
papers, printouts or disks. Remember that plagiarism and other
forms of cheating are considered serious academic offences, which
in turn have academic penalties. Computer Science & Information
Technology now routinely uses plagiarism dete
ction software on
electronically submitted assignments.
The minimum penalty for plagiarism is loss of marks for
assignment. If this means that a hurdle requirement is not met, it
could result in failing the course.
Please be careful.
Introduction and O
bjectives of Assignment 2
This assignment covers all aspects of Data Communication and
Net
-
Centric Computing. This assignment has
75
marks
and is
worth 20% of your final score.
Include workings in all your answers. Partial credit may be given
for appropr
iate calculations, even where your final answer is
incorrect.
Due Dates and Assignment Submission
This assignment is to be completed by each student individually
and independently. The final version of your Assignment #2 is to
be submitted electronically
using
B
lakboard
on or
before
Sunday
M
ay
1
4
th 201
7
(11:59pm)
.
You should submit a single PDF file which includes, on every
page, a one
-
line header
or footer
giving your name, student
1
7
SP1
Assignment 2
10
of
10
Due : 11:59PM, Sunday
1
4
th
M
ay
20
1
7
The
first question asks
you to cons
truct a f
ormula for Pa
cketisation d
elay
.
a)
Let
the payload of a cell/packet be
P
bytes.
Consider a digitally
encoded voice source
en
coded at a constant rate of 64 k
bps. Assume
each cell
/packet
is entirely filled before the
cell
/p
acket
is sent
into the
network.
Derive a formula
for calculating
the packetis
ation delay in
milliseconds
,
i
n term
s of P.
When streaming
data that is time
-
sensitive
like voice
, it is kn
own that gaps
in
the transmissi
on of 20m
s
or
more
ca
use
a notic
e
able
and unple
asant
echo.
With this in mind
, let
’
s compare
the
packetization
delay of
small and
large
ce
lls/packets.
b)
Use t
he formula
derive
d
in part (
a) to
d
etermine the packetization
delay for
;
i.
P
=1,500 bytes (roughly corresponding to a
l
arge
Ethern
et
packet
payload
)
ii.
P
=5
0
bytes
(corresponding
roughly
to an ATM cell
payload
).
Next,
we
use
the formula for Trans
mission delay to
compare
that
d
elays
for
small and la
rge cells/packet
s.
c)
A transm
ission link has a data
rate of
R=155 Mbps.
C
alculate the
transmission delay
for
i.
L=1
,
500 bytes
ii.
L=50
bytes.
d)
Comment on the advantages of using a small ATM cell.
Marks 16
End of Assignment