582202
Introduction to Data Communication (4 cr, 2 cu)
Liisa
Marttinen
Separate
examination 17.11.2006
Write
the name of the course, date, your name, student number and
signature on every separate sheet. Books and calculators are not
allowed.
-
ADDRESSES [18 p]
- Explain
what kind of addresses are used in the different layers of the
TCP/IP stack. (10 p)
- How
do the different layers get to know the address that is used in the
layer below in order to be able to use its services? (8 p)
-
ETHERNET [18 p]
- How does a station in a
traditional Ethernet using the CSMA/CD protocol proceed when it
wants to send a frame? Show how the stations A, B and C handle the
situation where station A is sending, and during the sending of A:s
frame stations B and C want to start sending. Explain the
functionality until all the stations have succeeded to send their
frame without collisions. (10 p)
- An Ethernet switch
has interfaces to several Ethernet segments. How does the switch
know into which interface it should send the frame. What
information is needed, how this information is collected and
stored? What does the switch do when it does not know which
interface to use to reach the receiver? (8 p)
-
EMAIL IN THE INTERNET [24 p]
Student A. Innokas at the
University of Helsinki sends a short email message to his friend B.
Eager who studies in London.
- What happens in the
application layer? What application layer protocols are used and
when are they used, so that the message composed by A. Innokas can
be delivered to the mailbox of B. Eager and that he can read the
message from his home PC? What messages are sent by these protocols?
(Not necessary to know the exact format of the messages. It is
enough to tell the meaning.) (10 p)
- What happens in the
transport layer? What transport layer segments and in which order
are needed to transport the messages of the application layer? (10
p)
- What is the role of
the network layer in transferring the email message? (4 p)