Project Overview

Student Learning Objectives

Procedure

Content Material

Assessment

Links to Course Competencies

Supplementary Resources

Recommendations

 

 

Real World Learning Objects: Science

Measure Internet Transmission Speed Using ping

Procedure

Time: Approximately 60 minutes.  

 

Materials: Internet-connected workstation, printed Lab Handout,  LAB RESULTS (Spreadsheet to Record Observations), and SLIDES  (students can share the slides sheets).

 

Prerequisites:  (1) Familiarity with web browser and (2) understands concept of a URL for a home page expressed as a domain name  (e.g.,  www.yahoo.com). 

 

Background:  The name “ping” comes from naval sonar, where a sound wave or “ping” is sent underwater to determine if there is any echo from a nearby object.  Echoes from nearby objects will bounce back faster than those from more distant objects.   Similarly, internet ping utilities send out a signal (actually a packet of test data) and then monitor for the time it takes a bounce-back message from the target computer system to reach the system that issued the original “ping.”

 

Students should be aware that TCP/IP is the agreed-upon convention or protocol for sending messages over the internet, and that all messages are sent in the form of “packets” that consist of a short header that contains the target address, and a “payload” of data.   

 

Ping is one of the oldest and most useful internet utilities.  See, for example, “Connected, An Internet Encyclopedia – Ping” at

http://www.freesoft.org/CIE/Course/Section3/8.htm . 

Ping is available on virtually every computer system and the utility is included as part of the bundle of programs available under operating systems as diverse as Linux, Windows XP and even on mainframe systems.  Occasionally, system administrators “protect” key utilities but by and large, even very well-secured corporate and educational networks allow users access to ping as a basic diagnostic utility.  Therefore, the procedures outlined here for Windows XP should work in any school computer lab.  (Minor changes may be needed for other operating systems.)  

 

Tracert  is a utility available on Windows XP computers.  Tracert is invoked like ping, and replies with a list of all the router computer sites (“routers”)  through which a packet is passed in order to reach the target computer, based on test packets sent from the origin (i.e., your computer).  Students will use this facility to measure hop-count, or number of hops between their computer and the destination computer, as a factor that generally affects ping time. 

 

Note that Unix and Linux operating systems have a similar utility called traceroute to detect the number of hops.  

 

Implementation: This RWLO can be used as a classroom exercise or initiated in the classroom and then continued as a homework activity in order to demonstrate the learning objectives.  Each student can be assigned to a group for this exercise (see step #7 below).  The members of the group will obtain individual data while working as part of a collaborative unit.  The group will submit a “team” result and a summary report following instructions provided in the Student Directions.  

 

 

Steps:

Classroom Session 

 

1.         Briefly, discuss or review terms TCP/IP,  packet, ip-address, and URL.  Use of a slide illustrating a network with nodes identified as ip-addresses is helpful. 

·        ip-address as a group of 4 numbers that represents a node on a network.  (Note: Initial exercise will demonstrate equivalence between domain name format e.g. www.yahoo.com and a specific ip-address.)

·        A “packet” is a grouping of bytes used to transmit data over internet.

  

2.         Define millisecond as unit of time = 1/1000 of a second.

 

3.         It is suggested that the instructor allow students to partner or work in small groups for this lab, and that work groups be encouraged to help each other before requesting instructor help

4.         Distribute printed copies of (1) Lab Handout ( “Student Procedures for In-Class Lab”), and (2) the LAB RESULTS spreadsheet.  Students should also have printed copies (may be shared) of SLIDES illustrating the basic procedures.

5.         Students begin by paraphrasing the definitions of the terms from your step #1 above.  

 

6.         Briefly demonstrate invocation of a COMMAND screen from lab computer (e.g. START, PROGRAMS, ASSESSORIES, COMMAND PROMPT), and how ping can be invoked and the typical response.

 

7.         By following the instructions in the Lab Handout, students will use ping to measure transmission time to a site, and will observe that a site like www.yahoo.com can also be designated using a numeric ip-address. 

·         Students will poll high volume sites like yahoo.com, amazon.com, and kola.de (in Germany) and record date/time and turnaround times and also note any packet loss. 

·        Students will take measurements using the school’s domain (e.g., bcc.edu) and also mit.edu, and record results on their printed LAB RESULTS spreadsheet.

8.         Demonstrate tracert to measure the number of internet hops by invoking the tracert  utility. 

·        Students will test for the number of hops between their computer station and the target site(s).  The hop-count for each target site will be added to the LAB RESULTS data previously recorded.

·        Students should see through their investigations that some target sites will take less “hops” than others, and usually this relates to turnaround time for a packet to travel over the internet. 

o       If the follow-up assignment to repeat similar tests from “home” is assigned, then it will be possible to evaluate hop-count results using different connections.  This will likely lead to a comparison of hops for same site via different ISP vendors. 

o       In the optional follow-up lab, http://www.toast.net/performance allows students to quickly demonstrate download and upload speed against a reference host.  Students can compare results from home or other Internet access points with results obtained at school. 

o       Classroom discussion should touch upon the impact of “busy” times or networks (e.g., in certain neighborhoods where there are many cable modem users at a particular time, or in a school lab) as well as the importance of the ISP’s connection and equipment.

 

 

9.         Very briefly, ask for some typical lab results for, say, yahoo.com.   Demonstrate the an “Internet Weather Report” site such as

http://weather.uci.edu    or    www.internettrafficreport.com

These sites are examples of websites that measure “weather” (aka “traffic”) based on frequent “pings” to routers of major internet providers (“ISP’s”).  “Bad weather” is a detected outage of a router, indicated by 100% packet loss. 

 

 

10.    Ask students to think about factors that affect transmission speeds, and complete the Lab Handout by stating their conclusions.. 

11.    Collect the Lab Handout forms with LAB RESULTS spreadsheet attached.