Time: Approximately 60 minutes.
Materials: Internet-connected workstation, printed Lab Handout, LAB
RESULTS (Spreadsheet to Record Observations), and SLIDES (students can share the slides
Familiarity with web browser and (2) understands concept of a URL for a
home page expressed as a domain name
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
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
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”
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
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.
that Unix and Linux operating systems have a
similar utility called traceroute to detect the number
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.
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.
as unit of time = 1/1000 of a second.
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
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
begin by paraphrasing the definitions of the terms from your step #1
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.
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.
will take measurements using the school’s domain (e.g., bcc.edu) and also mit.edu, and record results
on their printed LAB RESULTS
to measure the number of internet hops by invoking the tracert
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
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.
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
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.
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.
briefly, ask for some typical lab results for, say, yahoo.com.
Demonstrate the an “Internet Weather Report” site such
These sites are examples of websites that measure
“weather” (aka “traffic”) based on frequent
“pings” to routers of major internet providers
weather” is a detected outage of a router, indicated by 100% packet
to think about factors that affect transmission speeds, and complete the
Lab Handout by stating their conclusions..
Lab Handout forms with LAB RESULTS spreadsheet attached.