Packet Tracer - Explore a Network
Please click here to download topology 3.3.3.3 Packet Tracer - Explore a Network
Topology
Objectives
Part 1: Examine Internetwork Traffic
at Branch
Part 2: Examine Internetwork Traffic
to Central
Part 3: Examine Internet Traffic from
Branch
Background
This simulation activity is intended to help
you understand the flow of traffic and the contents of data packets as they
traverse a complex network. Communications will be examined at three different
locations simulating typical business and home networks.
Take a few moments to study the topology
displayed. The Central location has three routers and multiple networks possibly
representing different buildings within a campus. The Branch location has only
one router with a connection to both the Internet and a dedicated wide-area
network (WAN) connection to the Central location. The Home Office makes use of
a cable modem broadband connection to provide access to both the Internet and
to corporate resources over the Internet.
The devices at each location use a
combination of static and dynamic addressing. The devices are configured with
default gateways and Domain Name System (DNS) information, as appropriate.
Part 1: Examine Internetwork Traffic at Branch
In Part 1 of this activity, you will use
Simulation mode to generate web traffic and examine the HTTP protocol along
with other protocols necessary for communications.
Step 1:
Switching from Realtime to
Simulation mode.
a.
Click the Simulation mode icon to switch from Realtime mode to Simulation
mode.
b.
Verify that ARP, DNS, HTTP, and TCP are selected
from the Event List Filters.
c.
Move the slider located below
the Play Controls buttons (Back, Auto Capture/Play, Capture/Forward) all the way to the right.
Step 2:
Generate traffic using a web
browser.
Currently the Simulation Panel is empty.
In the Event List at the top of the Simulation Panel there are six columns
listed across the heading. As traffic is generated and stepped through, events display
in the list. The Info column is used
to inspect the contents of a particular event.
Note: The panel to the left of the Simulation Panel displays the
topology. Use the scrollbars to bring the Branch location into the panel, if
necessary. The panels can be adjusted in size by hovering next to the scrollbar
and dragging left or right.
a.
Click the Sales PC in the far left pane.
b.
Click the Desktop tab and click the Web
Browser icon to open it.
c.
In the URL field, enter http://branchserver.pt.pta and click Go. Look in the Event List in the
Simulation Panel. What is the first type of event listed?
____________________________________________________________________________________
d.
Click the DNS info box. In the Out
Layers, DNS is listed for Layer 7. Layer 4 is using UDP to contact the DNS
server on port 53 (Dst Port:). Both
the source and destination IP addresses are listed. What information is missing
to communicate with the DNS server?
____________________________________________________________________________________
e.
Click Auto Capture/Play. In approximately 45 seconds, a window displays,
indicating the completion of the current simulation. Click the View Previous Events button. Scroll
back to the top of the list and note the number of ARP events. Looking at the Device column in Event list, how many of
the devices in the Branch location does the ARP request pass through?
____________________________________________________________________________________
f.
Scroll down the events in the list to the series of DNS events. Select the DNS event that has the “At Device” listed
as BranchServer. Click the square
box in the Info column. What can be
determined by selecting Layer 7 in the OSI
Model? (Look at the results displayed directly below In Layers.)
____________________________________________________________________________________
g.
Click the Outbound PDU Details tab. Scroll to the bottom of the window and
locate the DNS Answer section. What is the address displayed?
____________________________________________________________________________________
h.
The next several events are TCP events enabling a communications
channel to be established. Select the last TCP
event at device Sales just prior to
the HTTP event. Click the colored
square Info box to display the PDU information. Highlight Layer 4 in the In Layers column. Looking at item 6 in
the list directly below the In Layers
column, what is the connection state?
____________________________________________________________________________________
i.
The next several events are HTTP events. Select any one of the HTTP events at an intermediary device
(IP Phone or Switch). How many layers are active at one of these devices, and
why?
____________________________________________________________________________________
j.
Select the last HTTP event at the Sales PC. Select the
uppermost layer from the OSI Model
tab. What is the result listed below the In
Layers column?
____________________________________________________________________________________
Part 2: Examine Internetwork Traffic to Central
In Part 2 of this activity, you will use
Packet Tracer (PT) Simulation mode to view and examine how traffic leaving the
local network is handled.
Step 1:
Set up for traffic capture to
the Central web server.
a.
Close any open PDU Information windows.
b.
Click Reset Simulation (located near the middle of the Simulation Panel).
c.
Type http://centralserver.pt.pta in the web browser of the Sales PC.
d.
Click Auto Capture/Play; in approximately 75 seconds, a window displays,
indicating the completion of the current simulation. Click View Previous Events. Scroll back to the top of the list; note that
the first series of events are DNS
and there are no ARP entries prior
to contacting the BranchServer.
Based on what you have learned so far, why is this the case?
____________________________________________________________________________________
e.
Click the last DNS event in the
Info column. Select Layer 7 in the OSI Model tab.
By looking at the information provided, what
can be determined about the DNS results?
____________________________________________________________________________________
____________________________________________________________________________________
f.
Click the Inbound PDU Details tab. Scroll down to the DNS ANSWER section. What is the address listed for
centralserver.pt.pta?
____________________________________________________________________________________
g.
The next several events are ARP events. Click the colored square
Info box of the last ARP event. Click
the Inbound PDU Details tab and note
the MAC address. Based on the information in the ARP section, what device is
providing the ARP reply?
____________________________________________________________________________________
h.
The next several events are TCP events, once again preparing to set
up a communications channel. Find the first HTTP event in the Event List. Click the colored square box of the HTTP event. Highlight Layer 2 in the OSI Model tab. What can be determined
about the destination MAC address?
____________________________________________________________________________________
i.
Click the HTTP event at device R4.
Notice that Layer 2 contains an Ethernet II header. Click the HTTP event at device Intranet. What is the Layer 2 listed at
this device?
____________________________________________________________________________________
Notice that there are only two active
layers, as opposed to three active layers when moving through the router. This
is a WAN connection, which will be discussed in a later course.
Part 3: Examine Internet Traffic from Branch
In Part 3 of this activity, you will
clear the events and start a new web request that will make use of the Internet.
Step 1:
Set up for traffic capture to
an Internet web server.
a.
Close any open PDU information windows.
b.
Click Reset Simulation near the middle of the Simulation Panel. Type http://www.netacad.pta in the web
browser of the Sales PC.
c.
Click Auto Capture/Play; in approximately 75 seconds, a window displays,
indicating the completion of the current simulation. Click View Previous Events. Scroll back to the top of the list; notice
that the first series of events are DNS.
What do you notice about the number of DNS
events?
____________________________________________________________________________________
____________________________________________________________________________________
d.
Observe some of the devices
that the DNS events travel through
on the way to a DNS server. Where are these devices located?
____________________________________________________________________________________
____________________________________________________________________________________
e.
Click the last DNS event. Click the Inbound PDU Details tab and scroll down
to the last DNS Answer section. What is the address listed for www.netacad.pta?
____________________________________________________________________________________
f.
When routers move the HTTP event through the network, there
are three layers active in both the In
Layers and Out Layers in the OSI Model tab. Based on that
information, how many routers are passed through?
____________________________________________________________________________________
____________________________________________________________________________________
g.
Click the TCP event just prior to the last HTTP event. Based on the information displayed, what is the purpose
of this event?
____________________________________________________________________________________
h.
There are several more TCP events listed. Locate the TCP event where the Last Device is IP Phone and the Device At
is Sales. Click the colored square
Info box and select Layer 4 in the OSI Model tab. Based on the information
from the output, what is the connection state set to?
____________________________________________________________________________________
Suggested Scoring Rubric
Activity Section
|
Question Location
|
Possible Points
|
Earned Points
|
Part 1: Examine Internetwork Traffic at
Branch
|
Step
2c
|
5
|
|
Step
2d
|
5
|
|
|
Step
2e
|
5
|
|
|
Step
2f
|
5
|
|
|
Step
2g
|
5
|
|
|
Step
2h
|
5
|
|
|
Step
2i
|
5
|
|
|
Step
2j
|
5
|
|
|
Part 1 Total
|
40
|
|
|
Part 2: Examine Internetwork Traffic to
Central
|
Step
1c
|
5
|
|
Step
1d
|
5
|
|
|
Step
1e
|
5
|
|
|
Step
1f
|
5
|
|
|
Step
1g
|
5
|
|
|
Step
1h
|
5
|
|
|
Part 2 Total
|
30
|
|
|
Part 3: Examine Internet Traffic from
Branch
|
Step
1c
|
5
|
|
Step
1d
|
5
|
|
|
Step
1e
|
5
|
|
|
Step
1f
|
5
|
|
|
Step
1g
|
5
|
|
|
Step
1h
|
5
|
|
|
Part 3 Total
|
30
|
|
|
Total Score
|
100
|
|
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