Pharos University in Alexandria
Faculty of Engineering
Communications and Computer Networks
Sheet 5
Pharos University in Alexandria
Communications and Computer Networks
Course Code: CE 363
Faculty of Engineering
Lecturer: Dr. Amr Elsaadany
Computer Engineering Department
T.A: Eng. Nehal Fathi
Sheet 5
1. How does an NNI differ from a UNI?
2. Discuss the Frame Relay physical layer.
3. In the following figure a virtual connection is established between A and B. Show the
DLCI for each link.
4. Determine which of the following statements are true and which are false
a) There are sequence numbers in Frame Relay.
b) Data Link Connection Identifier (DLCI) Identifies the PVC Link in ATM.
c) Frame Relay uses cells of only 53 bytes each (5 bytes of header and 48 bytes of
payload).
d) One of problems of packet switching is multiplexing different sized packets
which create unacceptable delay.
e) A cell network is based on permanent virtual circuit routing.
Pharos University in Alexandria
Faculty of Engineering
Communications and Computer Networks
Sheet 5
Assignment:
5. An AALl layer receives data at 2 Mbps. How many cells are created per
second b the ATM layer?
6.
If an application uses AAL3/4 and there are 47,787 bytes of data coming into the CS,
how many padding bytes are necessary? How many data units get passed from the
SAR to the ATM layer? How many cells are produced?
7. UsingAAL5, show the situation where we need of padding.
a. 0 bytes (no padding)
b. 40 bytes
c. 47 bytes