(i) Sketch the differential Manchester encoding for the
bit stream of 0001110101. Assume the line is initially
in the low state. [3]
(ii) The following data fragment occurs in the middle
of data stream for which the character-stuffing algorithm
is used. [3] DLE, STX, A, DLE, B, DLE, ETX. What is
output after stuffing?
(iii) Consider two host computers HC1 and HC4 connected
via two switching nodes HC2 and HC3 in a store and forward
network [HC1]- [HC2]- [HC3]- [HC4] Ignoring processing
time in the hosts and switching nodes and assuming transmission
rates of 10 k bits/s. Calculate the time to send a 3
K bit message from HC1 to HC4 in case a whole message
is transmitted as a single block. [6]
(iv) Discuss the tradeoff, which have to be considered
infixing a maximum message length within a communication
system. [5]
(v) What is the advantage of frequency modulation over
amplitude modulation and at what cost? [3]
(vi) Discuss the relative advantages and disadvantages
of the following:
· Terrestrial links (switched and leased connection)
· Satellite links
· Radio links
· Optical fiber transmission [10]
2 (i) Define and discuss the importance of the following
terms in data communication: · Band
· Bandwidth
· Wavelength [6]
(ii) Discuss the finite limits of a transmission path
with Shannon’s and Nyquist’s formulae. [9]
3 (i) Discuss types of errors and how they are managed
at DLL (Data Link Layers). [6]
(ii) What is HDLC ( High Level Data Link Control) protocol?
Discuss its importance in data communication. What are
the different types of frames? Discuss briefly. [9]
4 (i) Compare the effect of node failure in CSMA/CD
and token passing ring. [7]
(ii) Why is an Ethernet not suitable for real time
applications? Explain. Which of the LANs is most suitable
for such a purpose and why? [8]
5 Compare the following:
· Connection oriented and connectionless gateways.
[6]
· Transparent Bridge and Source Routing Bridge.
[6]
· Virtual circuit service and Data gram service.
[3]
6 (i) Give the speed of proposed Broadband and ISDN
channel. [2]
(ii) List some features of ISDN that you think will
be useful to you. [5]
(iii) What is ATM? What can ATM offer to reduced bandwidth
bottlenecks that traditional LAN technologies cannot
provide? [8]
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