TIETOJENKÄSITTELYOPIN LABORATORIO

Tik-76.148 Tietokoneverkot (3 ov) TENTTI 28.11.1995

Tenttikysymyksiä on yhteensä 5:

1) Internetworking

Brief explanations (1-2 sentences) can be used for the following:

Explain how to use the following devices:

a) repeater

b) bridge

c) router

d) application gateway

e) Explain (with a picture) at which OSI layer 1-7 each of these devices work

f) Explain the differrence between a repeater and a bridge

g) Explain the differrence between a bridge and a router

h) Explain with an example how bridges can be used for routing. If bridges are used for routing, does this make them routers? Why/Why not?

i) Explain how static routing can be implemented, and give an example

j) Explain how to implement dynamic routing, and give an example

2) Network Management

a) Network Management Systems are defined in terms of "managers" and "agents". Briefly explain their functions and roles.

b) Brietly explain these concepts- "managed objects", "management information base"

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Explain how and where they are used(see 2a). Drawing a simple picture may help.

c) Some network management strategies use polling techniques to get management information from the managed network elements- Other strategies use event driven notifications from network elements.

Explain the advantges and disadvantages of these strategies.

d) A simple management system must extract performance information from a network and log this information onto a single disk. The management information received is 100 bytes long per managed network element. Information is continuouslyextracted by polling each network element once every 10 minutes. There are 50000 network elements in the network to be polled.

Assuming no compression of data stored to disk is used, what size disk is needed to store 1 month's (30 days) worth of information?

What is the average rate (kb/second) that this information is stored onto the disk, assuming it is immediately stored onto the disk?

3) OSI-malli

a) Luettele OSI-mallin kerrokset ja kerro kunkin kerroksen tärkeimmät tehtävät (yksi lause/kerros

b.) Luettele (perusteluineen) ainakin neljä (4) syytä OSI-mallin tekemiselle. Toisin sanoen miksi OSI-nialli on kehitetty ja mihin asioihin siitä toivottiin apua?

e) Kuinka hyvin OSI-mallissa on mielestäsi onnistuttu edellä (kohdassa 3 e) olevassa kohdassa mainittujen seikkojen osalta? Toisin sanoen. kuinka käyttökelpoinen OSI-malli on mielestäsi yllä luettelemiesi seikkojen osalta tänä päivänä?

d) Mainitse ainakin kaksi selitystä perusteluineen sille, että nykyinen Internet-verkko perustuu OSI-protokollien sijasta TCP/IP-protokolliin.

4) Multimedia (10 pistettä: a-2, b-4, c-4)

a) Mitä multimedialla tarkoitetaan

.ja kuinka multimediasovelluksia voidaan luokitella tiedonsiirtoverkon näkökulmasta?

b) Millaisia vaatimuksia multimediatiedonsiirto asettaa tiedonsiirtojärestelmälle? Voit vertailla vaatimuksia esiin. perinteiseen tiedostonsiirtoon (esim. ftp) tai etäpäätekäyttöön (esim. telnet).

c) Miten nykyiset tiedonsiirtoverkot soveltuvat mielestäsi multimediatiedon siirtoon (muista perustelut)? Mieti asiaa ainakin kolmen (3) erityyppisen verkon kannalta.

5) TCP/IP

a) Describe the main functions of the IP protocol

b) Describe shortly the trasnport protocols of the TCP/IP protocol suite. (connectionless/conn. oriented, reliability, addressing)

c) The figure describes a network where TCP/IP-protocols are used. A user at workstation A sends an email to a user at workstation C. Which network and transport layer protocols are needed in each computer (A,B,C) and why?