ECE 438/638: Computer Communications
Problem Set 1
Spring 2013
Due: 1:25 pm in class, Wednesday, January 23
Assigned reading: Peterson and Davie, Chapter 1. Each problem carries equal weight. Most of these
problems are similar to exercises found at the en
ECE 6380: Computer Communications
Problem Set 4
Summer 2016
Due: 6 pm Monday, June 6
Assigned reading: Peterson and Davie, Chapter 2. Each problem is worth 10 points
1. Binary exponential backoff
Assume that four hosts connected to an Ethernet have been i
ECE 438/638: Computer Communications
Problem Set 4 Solutions
Spring 2013
Each problem is worth 10 points
1. Binary Exponential Backoff.
We are told that host A chooses the first slot. In order for this transmission to be successful we need that
the other
ECE 438/638: Computer Communications
Problem Set 1 Solutions
Spring 2013
Each problem is worth 10 points.
1. Making sure we correctly convert units, y KB is 8 210 y bits and x Mbps is x 106 bits per second.
The transmission time is (8 1,024 y) / (x 100000
ECE 438/638: Computer Communications
Problem Set 4
Spring 2013
Due: 1:25 pm in class, Friday, March 1
Assigned reading: Peterson and Davie, Chapter 2. Each problem is worth 10 points
1. Binary exponential backoff
Assume that four hosts connected to an Eth
ECE 438/638: Computer Communications
Problem Set 2 Solutions
Spring 2013
Each problem is worth 10 points
1. Encoding. Encoding for sequence 1001 1111 0001 0001
10 0 1 1 1 11 00 0 10 0 0 1
NRZ
clock
Manchester
NRZI
2. Encoding Chapter 2, number 4.
One can
ECE 438/638: Computer Communications
Problem Set 5
Spring 2013
Due: in class, Friday, March 15
Assigned reading: Peterson and Davie, Chapter 3. 638 students are responsible for Section 3.4. Section
3.4 is optional for 438 students. All problems have equal
ECE 438/638: Computer Communications
Problem Set 3 Solutions
Spring 2013
Each problem is worth 10 points
1. Sliding Window Algorithms.
(a) For the link between A and B we need the transmission time of a frame and the propagation
delay. The transmission ti
ECE 438/638: Computer Communications
Problem Set 5 Solutions
Spring 2013
All problems carry equal weight.
1. Datagram forwarding. Chapter 3, number 4. Notice that table entries with the same output
port as the default entry are removed from the table. Thi
ECE 438/638: Computer Communications
Problem Set 6 Solutions
Spring 2013
All problems carry equal weight.
1. Spanning Tree Algorithm for Intelligent Bridges.
The resulting spanning tree is shown in the figure. Notice that the bridges B3, B5, and B7 do not
ECE 438/638
Computer Communications
Harlan Russell
Department of Electrical and Computer Engineering
Clemson University
ECE 438/638 Spring 2014
Set 1:Overview
1
Copyright Notice
Copyright 2014 All rights reserved. Permission to reproduce this document
an
ECE 438/638: Computer Communications
Problem Set 2
Spring 2013
Due: 1:25 pm in class, Friday, February 8
Assigned reading: Peterson and Davie, Chapter 2.1-2.5. All problems have equal weight.
1.
2.
3.
4.
Encoding. Chapter 2, number 1
Encoding. Chapter 2,
ECE 438/638: Computer Communications
Problem Set 3
Spring 2013
Due: 1:25 pm in class, Friday, February 22
Assigned reading: Peterson and Davie, Chapter 2. Each problem is worth 10 points
1. Sliding Window Algorithms. Consider two full-duplex point-to-poin
Name:
ECE 438/638: Computer Communications
Exam 1
Spring 2016
Monday, February 29
1. Reliable retransmission protocols. 25 points
Consider two full-duplex point-to-point links connecting nodes
A, B, and C as shown in the figure. The nodes use store-andfor
Partial Solutions. You must show your work.
Problem 1. Part 1. Show the RTT is 16 msecs (between A and B). Show the throughput is 3 Mbps.
Notice this is less than 4 Mbps.
Part 2. Notice we require the throughput for the A-B link to be less than or equal t
Name:
ECE 438/638: Computer Communications
Exam 1
Spring 2015
Monday, March 2
1. Reliable retransmission protocols. 25 points
Consider two full-duplex point-to-point links connecting
4 Mbps
320 Kbps
nodes A, B, and C as shown in the figure. The nodes use
Partial Solutions for 2007/2008 first exams from ECE 4380/6380
Here are partial answers for selected problems from the example exams. On the exam, you must show
your work to receive full credit.
Fall 2007 Exam 1
Problem 1. Reliable retransmission protocol
Partial Solutions. You must show your work.
Problem 1. Part 1. Show the RTT is 228 msecs (between A and B).
Part 2. Show the throughput is 35 Kbps.
Part 3. The link B to C limits the throughput. Show the window size must be larger than 9.12.
Therefore, th
Name:
ECE 438/638: Computer Communications
Spring 2016
Exam 2 (Each of the 4 problems is worth 25 points)
Monday, April 4
Graduate students (638): For problem 1, you only need to answer any 8 of the short answer questions.
Undergraduate students (438): Fo
ECE 438/638: Computer Communications
Problem Set 6
Spring 2013
Due: in class, Friday, March 29
Assigned reading: Peterson and Davie, Chapter 3. 638 students are responsible for Section 3.4. Section
3.4 is optional for 438 students. All problems have equal
ECE 438/638: Computer Communications
Problem Set 7 solutions
Spring 2013
1. Multiple subnets on a LAN.
(a) DHCP will have considerable difficulty sorting out to which subnet various hosts belonged;
subnet assignments would depend on which server answered
ECE 438/638: Computer Communications
Problem Set 8 Solutions
Spring 2013
All problems carry equal weight.
1. Distance-vector routing.
(a)
Node As first update to its routing table just contains the information from node B, plus the
cost of the link to B.
Implementation of Network Software
Reading
Peterson and Davie Section 1.4
Beejs Guide to Network Programming (link)
Additional reference reading
Donahoo and Calvert, The Pocket Guide to TCP/IP
Sockets, C Version (on reserve in library, C#, Java)
Ch. 2 and
Direct Link Networks
Reading: Peterson and Davie, chapter 2
All hosts directly connected by physical medium
Point-to-point links
Multiple-access links
Next: protocols to enable an error-free channel
Outline
Encoding
Framing
Error detection
Reliable
Direct Link Networks
Reading: Peterson and Davie, chapter 2
All hosts directly connected by physical medium
Point-to-point links
Multiple-access links
Next: protocols to enable an error-free channel
Outline
Encoding
Framing
Error detection
Reliable
Shared Access Networks
Multiple senders on some medium
Buses (Ethernet, including links in switched form)
Radio, satellite
Need method to moderate access
Fair arbitration
Good performance
ECE 438/638 Spring 2014
Set 4: Shared Access
1
Typical Assump
Direct Link Networks
Reading: Peterson and Davie, Ch. 2
Outline
Encoding
Framing
Error detection and correction
Reliable transmission
Multiple-access media (MAC examples)
Bus (Ethernet)
Wireless
802.11 Wi-Fi
802.15.1 Bluetooth
802.16 WiMAX
Ad hoc
Switching and Forwarding
Reading: Peterson and Davie, Chapter 3
Outline
Store-and-Forward Switches
Bridges and Extended LANs
ECE 438/638 Spring 2014
Set 6: Switching
1
Organization of Course Topics
(Shared) link
You are
here
Switched network
Internetwork
Overview
Forwarding vs. routing
Forwarding: to select an output port based on destination address
and routing table
Routing: process by which routing table is built
Goals for routing
Find lowest cost or best path between two nodes
Propagate changes
Internetworking
Outline Chapters 3 and 4
Switches and Bridges
Simple internetworking
IP, ARP, DHCP, ICMP, VPN
Best effort service model
Routing
Global internet (and Section 9.1 for DNS)
Global addressing scheme
Hierarchical routing
Future internetworking:
Name:
ECE 438/638: Computer Communications
Spring 2015
Exam 2 (Each of the 4 problems is worth 25 points)
Monday, April 6
Graduate students (638): For problem 1, you only need to answer any 8 of the short answer questions.
Undergraduate students (438): Fo
Name:
ECE 438/638: Computer Communications
Fall 2009
Exam 2
Friday, November 13
Each of the 4 problems is worth 25 points.
Graduate students (638): For problem 1, you only need to answer any 8 of the short answer questions.
Undergraduate students (438): F
Partial Solutions. You must show your work.
2.1. Show that bridges 4, 5, and 6 do not forward data packets. B3 is the designated port for LAN A.
Note the root port for B5 has a tie (and select LAN B).
2.2. B2 -> B7 -> B1 -> B8 -> B3
2.3. Many solutions ar
Partial Solutions. You must show your work.
2.1. Show that bridges 4, 5, and 6 do not forward frames. Note tie for B5 root port and LAN A
designated port.
2.2. B2 -> B7 -> B1 -> B8 -> B3
2.3. Many solutions are possible. One relabels B3 as B1. Watch for t