Department of Computer and Information Science
Exam
EXAM
(Tentamen)
TDDI07
Distributed Embedded Software and Networks
(Distribuerad inbyggd programvara och nätverk)
2011-12-19 08-12
On-call (jour):
Massimiliano Raciti, +46 762 388815
Admitted material:


Dictionary
Pocket calculator
General instructions:











The assignments are not ordered according to difficulty.
Please answer in English (the course language).
Read all assignments carefully and completely before you begin.
Use a new sheet for each assignment and use only the front page.
Before you hand in, order the sheets according to assignment, number each sheet, and fill
in AID-number, date, course code and exam code at the top of the page.
Write clearly. Unreadable text will be ignored.
Be precise in your statements.
Motivate clearly all statements and reasoning.
Explain calculations and solution procedures.
If in doubt about the question, write down your interpretation and assumptions.
Grading: U, 3, 4, 5. The preliminary grading thresholds are:
U: 0-20p
3: 21-27p
4: 28-34p
5: 35−40p
Good Luck!
TDDI07, Distributed Embedded Software and Networks
1/3
Department of Computer and Information Science
Exam
1. Introduction
(4p) Describe the difference between infrastructure-based networks and ad-hoc networks.
What are the benefits and the drawbacks of each of these paradigms?
2. MAC Protocols
a) (3p) Describe three problems of MAC that can cause energy waste.
b) (1p) Name the two major problems that make the classical MAC protocols unusable in
wireless settings.
c) (2p) What is the main idea behind Sensor-MAC (S-MAC)?. What happens when no
traffic is present in the active period?
3. Routing Protocols
a) (3p) Describe the difference between proactive and reactive protocols. Describe also a
reactive protocol of your choice.
b) (2p)What is a maximal independent set? What can it be used for?
4. Dissemination and Collection
a) (2p) Explain the difference between push and pull in gossip-based message
dissemination.
b) (1p) How does the fan-out parameter f affect the dissemination of a message in epidemic
algorithms?
c) (3p) What is a collection tree? Which metric does CTP use to measure the cost of a link?
What does datapath validation consist of?
5. Synchronization and positioning
a) 1p) Consider the following clock timestamps of the same event e: C1(e)=5, C2(e)=7,
C3(e)=9, C4(e)=10. What would be a suitable choice of precision if the nodes were to be
synchronised with an internal clock synchronisation algorithm?
b) (3p) Describe the firefly synchronisation model. Which are the improvements proposed
to make the model applicable in real environments?
c) (3p) To determine its position, a node need knowledge of some other nodes position,
direction and distance, two positions and two directions, three positions and distance or
possibly some other combination. Describe three possible sources (measures) of the
distance information, and relevant problems.
6. Quality of Service
a) (2p) Take a stand on the following sentences and mark whether they are true or false:
•
IP-Telefony is elastic in terms QoS requirements
•
Video streaming is tolerant and adaptive in terms of QoS requirements
•
FIFO scheduling is considered to be fair in QoS terminology
•
Security is an enforcement-level QoS parameter.
b) (2p)What is admission control? Explain how it is used in the context of IntServ.
7. Dependability and Security
a) (2p) Identify the fault-error-failure chain in the following scenarios:
•
The transmission of a world cup football game in all countries stopped for
35 minutes due to a software misconfiguration that crashed the central live
server in the head quarters of the media company which is in charge of
relying the game
TDDI07, Distributed Embedded Software and Networks
2/3
Department of Computer and Information Science
•
Exam
In Java 1.6.0_21, the company field was changed from 'Sun Microsystems,
Inc' to 'Oracle.' Some applications depend on that field to identify the
virtual machine. For example, all Eclipse versions since 3.3 including the
recent Helios release (2010) have been reported to crash with an
OutOfMemoryError due to this change.
b) (2p) Explain the benefits and drawbacks of using Intrusion Detection (Misuse detection
or Anomaly Detection ) as opposed to using cryptography in wireless networks.
8. Power Management
a) (2p) Describe what are the rate capacity and the relaxation effects of batteries and
explain how they can be exploited to improve their performance.
b) (2p) Describe the timeout-based power management policy.
TDDI07, Distributed Embedded Software and Networks
3/3