Course:
Professor:
1.
HW 4 Page 3 CSC 570 601
Dr. Arne Nilsson
Design a feedback shift register encoder for a CRC with a generator polynomial G(x) = x5 + x3 + x + 1
ANSWER:
Input
STEPS USED TO CREATE
Express G(x) as bits: 1 + x + x3 + x5 (1)x0 + (1)x1 +
CSC/ECE 570 Computer Networks
Topic 4 The Data Link Layer
Wenye Wang
Wenye Wang (NC State University)
CSC/ECE 570 - Computer Networks
1 / 43
Contents
1
Background and Introduction
2
Probability Basics
3
Physical Medium and Transmissions
4
The Data Link La
CSC/ECE 570 Computer Networks
Topic 3 Physical Medium and Transmissions
Wenye Wang
Wenye Wang (NC State University)
CSC/ECE 570 - Computer Networks
1 / 18
Overview of the Course
1
Background and Introduction
Wenye Wang (NC State University)
CSC/ECE 570 -
CSC/ECE 570 Computer Networks
Topic 2 Probability Basics
Wenye Wang
Wenye Wang (NC State University)
CSC/ECE 570 - Computer Networks
1 / 24
Overview of the Course
1
Background and Introduction
Wenye Wang (NC State University)
CSC/ECE 570 - Computer Networ
ECE/CSC 570 Section 001, 601
Final Test
December 10, 2009
Questions 1 10 each carry 2 marks. Answer only by placing a check mark to indicate
whether the statement is true or false in the appropriate box, and leaving the other box
blank.
Qustions 11 15 car
CSC 570 Homework 2
1. In a constellation diagram, 16 points lie on a circle of radius A centered on the
origin. Label these 16 points as S0(t), S1(t), . , S15(t) (starting (A, 0) and then
proceed counterclockwise on this circle with angles k, k = 0, 1, 2,
CSC 570 Section 3
Computer Networks Homework 1
CSC 570 Homework 1
9. The traceroute (or tracert) program allows you to send packets to intermediate routers your
path to the destination and see those intermediate nodes as well as the round-trip-time delay
CSC 570 Section 3
Computer Networks Homework 1
CSC 570 Homework 1
4. A system has an n-layer protocol hierarchy. Applications generate messages of length M bytes.
At each of the layers, an h-byte header is added. What fraction of the network bandwidth is
CSC 570 Section 3
Computer Networks Homework 1
CSC 570 Homework 1
7. Consider sending a file of 9Mbits from Host A to Host B. There are three links and two storeand-forward routers (or switches) between A and B. (See Lecture note Class Exercise 1: Delay
C
CSC 570 Section 3
Computer Networks Homework 1
CSC 570 Homework 1
6. Compare the delay in sending an x-bit message over a k-hop path in a circuit-switched network
and in a lightly loaded (no queuing delay) packet-switched network. The circuit setup time i
CSC/ECE 570 Computer Networks
Topic 1 Background
Wenye Wang
Wenye Wang (NC State University)
CSC/ECE 570 - Computer Networks
1 / 58
Overview of the Course
1
Background and Introduction
1.1 Internet and Computer Communications
1.2 Networking and switching:
CHAPTER 1
Probability Models in
Electrical and Computer
Engineering
Designers today must often build systems that work in a chaotic environment :
A large computer system must satisfy the diverse and fluctuating processing
demands of the community it serv
ECE/CSC 570 Section 3, Fall 2016
Homework #3 Solution
1. (6 points, 3 points each) State whether the following statements are true (T) or
false (F).
F (i) Packet switching is more efficient than circuit switching, so the end-to-end delay is always smaller
ECE/CSC 570 Section 2, Fall 2016
Homework #2 Solution
1. (10 points) In a constellation diagram, 16 points lie on a circle of radius A centered
on the origin. Label these 16 points as S0 (t), S1 (t), . . . , S15 (t) (starting (A, 0) and then
proceed count
Whats a protocol?
Introduction: Roadmap
What is computer network / Internet ?
Network structure: edge vs. core
Network core
circuit switching vs. packet switching
Multiplexing, delay calculation
applications
specific msgs sent
specific actions taken
The Medium Access Control (MAC) Sublayer
Data link layer has two sublayers
Chapter 4
Medium Access Control (MAC)
layer
Application
Logical Link Control (LLC) layer
Transport
LLC
Network
Interface to higher layers
Logical Link Control (LLC)
Error contr
Introduction: Roadmap
Chapter 1: Introduction
What is computer network / Internet ?
network structure: edge vs. core
Network core
circuit switching vs. packet switching
multiplexing, delay calculation
applications
ECE/CSC 570, Fall 2016
Do Young Eun
P
ECE/CSC 570
Computer Networks
Fall 2015, Section 001,002
Shared Access Networks
Media Access Control
David Thuente
Fall 2015, CSC/ECE 570
D. Thuente
Department of
Computer
Science
00110001001110010011011000110111
Shared Access Networks
Media Access Contro
ECE/CSC 570
Computer Networks
Fall 2015, Section 001, 002
End-to-End Protocols(1)
David Thuente
Fall 2015, CSC/ECE 570
D. Thuente
Department of
Computer
Science
00110001001110010011011000110111
Transport Layer (1)
UDP
Reliable Byte Stream (TCP)
TCP Header
ECE/CSC 570
Computer Networks
Fall 2015, Section 001,002
End-to-End Protocols (2)
David Thuente
Fall 2015, CSC/ECE 570
D. Thuente
Department of
Computer
Science
00110001001110010011011000110111
Congestion Control
Outline
Reacting to Congestion
Avoiding Co
CHAPTER 2
Basic Concepts of
Probability Theory
This chapter presents the basic concepts of probability theory. In the remainder
of the book, we will usually be further developing or elaborating the basic
concepts presented here. You will be well prepared
CHAPTER 3
Random Variables
This chapter develops methods that are useful in computing the probabili.ties of
events involving numerical attributes of the outcomes of a random expenment.
The cumulative distribution function is introduced . The probability o
ECE/CSC 570 Section 3, Computer Networks
Homework #1 (Due on Sept. 8, 2016)
Grading TA: Cuiyu Kong (ckong3@ncsu.edu)
You are strongly recommended to read Chapter 1 of our Text (Tanenbaum). Solve the following problems. Some of them are taken from our text
CSC 570 Section 3
Computer Networks Homework 1
CSC 570 Homework 1
3. What are two reasons for using layered protocols? What is one possible disadvantage of using
layered protocols?
Solution :
Reasons for using layered protocols
1. Layered protocol reduces
CSC 570 Section 3
Computer Networks Homework 1
CSC 570 Homework 1
8. In the lecture slides (Class Exercise 3: Asymmetric Setting), suppose that the sender A has 3
packets to transmit to B, each of which is 50kbits. Assume all the same setting and paramete
Course:
Professor:
4.
Hw 5 Page 2 CSC 570 601
Dr. Arne Nilsson
A large population of ALOHA users manages to generate 50 requests/sec, including both originals and
retransmissions. Time is slotted in units of 40 msec.
a.
What is the chance of success on th
Course:
Professor:
HW 5 Page 1 CSC 570 601
Dr. Arne Nilsson
(Include pp 338-340 problems 2, 4, 5, and 7)
1.
Consider a slotted ALOHA system with finite population. The population can be divided up into two groups.
One group has only one member in it and t
Course:
Professor:
a.
HW 4 Page 4 CSC 570 601
Dr. Arne Nilsson
Assume that during the transmission one bit is corrupted. Show by using a feedback shift register decoder
how this will be detected.
ANSWER:
Suppose the remainder is 00011 instead of 00010. Th
Course:
Professor:
1.
HW 4 Page 2 CSC 570 601
Dr. Arne Nilsson
Given a CRC type code with a generator polynomial. G(x) = 1 + x2 + x3 + x4
a. Given a message of three bits, 101, there is always three message bits. Find the message polynomial and
the code-p
CSC 570 Section 3
Computer Networks Homework 1
CSC 570 Homework 1
1. Which of the OSI layers handle each of the following:
a. Providing reliable, connection-oriented path between source and destination.
b. Determining alternate route for packets when the
CSC 570 Section 3
Computer Networks Homework 1
CSC 570 Homework 1
5. Suppose users share a 2 Mbps link. Also suppose each user transmits continuously at 1 Mbps
when transmitting, but each user transmits only 20% of the time while remains silent for 80%
of
CSC 570 Section 3
Computer Networks Homework 1
CSC 570 Homework 1
2. A factor in the delay of a store-and-forward packet-switching system is how long it takes to
store and forward a packet through a switch. If switching time is 20 sec, is this likely to b