Figure 1 Wireless Network Connection dialog
Revised: August 26, 2005
By Richard G. Baldwin
File: FwlProj070.htm
This laboratory project was prepared specifically for the benefit of my students who are enrolled in ITNW 1351, Fundamentals of Wireless LANs.
The project was designed under the assumption that students enrolled in the course have successfully completed the prerequisite course, ITNW 1325, Fundamentals of Networking Technologies.
The project design also assumes that the students are actively studying the material in the prescribed textbook for this course, which explains such complex topics as the IEEE 802.11g wireless specification.
Another browser window
I recommend that you open another copy of this document in a separate browser window so that you can easily view the discussion and the figures at the same time.
The purpose of this project is to teach you how to change the IEEE Wireless Network Mode for the Linksys router, and to illustrate the results of making those changes.
The following equipment is required to complete this laboratory project:
Two important configuration aspects of a Linksys router are listed below:
You will experiment with changes to the Wireless Network Mode in this project and will experiment with changes to the Transmission Rate in a future project.
Project setup
You will begin the project by manually disconnecting any wireless connections that you may have with the Linksys router.
Then you will physically connect an RJ-45 patch cable between the wired NIC on your computer and the Linksys router so that you can configure and re-configure the router independently of any requirement to maintain a wireless connection to the router.
Following that, you will use your browser to open a wired session with the Linksys administrator panel.
Making a wireless connection in Mixed mode
Then you will open a wireless connection with the Linksys router using your combination IEEE 802.11b/802.11g NIC.
You will set the Wireless Network Mode to Mixed and observe certain characteristics of your existing network connection (note that Mixed is the default factory setting so it will probably already be set to Mixed).
Disabled mode
Then you will set the Wireless Network Mode to Disabled and observe the impact that this has on your existing wireless connection.
G-Only
Following that, you will set the Wireless Network Mode to IEEE 802.11g only.
Having set the router to the G-Only mode, if you have access to a wireless NIC that supports only IEEE 802.11b, you will attempt to use that NIC to open a wireless connection with the router, and observe the result. If you don't have access to such a device, you will simply skip that part of the project.
B-Only
Following that, you will set the Wireless Network Mode to IEEE 802.11b only, and observe the impact that has on your existing connection.
Restore the router to normal
Finally, as the last step in the project, you will set the Wireless Network Mode back to either Mixed or G-Only and leave it in that mode in preparation for future projects.
Close all wireless connection
Go to the Wireless Network Connection dialog shown in Figure 1 and manually Disconnect any wireless connection that may currently exist between your computer and the Linksys router. By now you should know how to do this without the need for detailed instructions.
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Connect a patch cable
Connect an RJ-45 patch cable between one of the connectors numbered 1 through 4 on the back of the Linksys router shown in Figure 2 and the wired NIC on your computer.
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Access the Linksys administrator panel
Open your browser and point it to http://192.168.1.1/. This should access the Linksys administrator panel, producing a screen output similar to that shown in Figure 3.
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Now you are ready to begin experimenting with the Wireless Network Mode.
Open a wireless connection
Go back to the Wireless Network Connection dialog shown in Figure 1 and open a wireless connection with the Linksys router using your combination IEEE 802.11b/802.11g NIC.
When you are successful in opening that connection, the linksys network in the Wireless Network Connection dialog should show Connected on the right side of the dialog.
Observe the Wireless Network Connection Status
Open the Wireless Network Connection Status dialog shown in Figure 4 and observe the value of Speed. If you have a strong signal, the speed should be 54.0 Mbps, which is the default transmission speed for IEEE 802.11g.
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Set Wireless Network Mode to Mixed
Go to the administrator panel in your browser and select the Wireless tab. Then select Basic Wireless Settings. Your browser window should look similar to Figure 5, which has been scrolled to the right to make the important information fit in this narrow publication format.
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What choices are available?
If you pull down the choice box labeled Wireless Network Mode, it should present you with the following four choices:
These are the choices that you will be working with during this project.
Default mode
The default factory setting for Wireless Network Mode is Mixed, so your router will probably already be set to Mixed. If not, set it to Mixed.
Implement the change in mode
If it was not necessary to change the mode to Mixed, skip the following two steps.
If it was necessary to change the setting to Mixed, do the following:
Set Wireless Network Mode to Disabled
Now pull down the choice box in the administrator panel and select Disabled.
Click the Save Settings button near the bottom of the administrator panel. Once again, when you get the message Settings are successful in the administrator panel, click the Continue button.
New state of the administrator panel
The browser should return to the Basic Wireless Settings page, but now the Wireless Network Mode should show Disabled.
Try to manually disconnect and connect your wireless connection
Using the Wireless Network Connection dialog shown in Figure 1, try to manually Disconnect and Connect your computer to the Linksys wireless router. It should no longer be possible to do so.
Furthermore, the linksys network should no longer appear in the Wireless Network Connection dialog shown in Figure 1.
Try to view the Wireless Network Connection Status dialog
Try to view the Wireless Network Connection Status dialog shown in Figure 4.
It should no longer be possible to view that dialog (unless you somehow became connected to a different wireless router).
Wireless connections are impossible
By setting the Wireless Network Mode to Disabled, you have made it impossible for this router to support wireless connections.
Wired connections are still possible
Note, however, that the wired capability of the router still works.
That's good, because otherwise there would be no way for us to re-enable the wireless capability of the router short of pressing the reset button and returning the router configuration to the default factory settings.
Set Wireless Network Mode to G-Only
Now use the choice box and the Save Settings button on the administrator panel to set the Wireless Network Mode to G-Only.
Is there a linksys network?
Go to the Wireless Network Connection dialog in Figure 1 and see if the the linksys network is listed there. If not, click the Refresh network list link in the upper left corner of the dialog under Network Tasks.
Should display all network that are within range
The system should search for and display all active wireless network routers that are within range.
(When I did this, the linksys network was automatically reconnected. If the linksys network was not automatically reconnected for you, click the Connect button to manually reconnect it.)
Has the Wireless Network Connection Status changed?
Observe the Wireless Network Connection Status dialog shown in Figure 4. It should look the same as before.
Can operate in two network modes concurrently
The Linksys router is capable of communicating concurrently with computers using either IEEE 802.11b and IEEE 802.11g NICs.
When the Wireless Network Mode is set to the default value of Mixed, it will communicate with either or both types of NICs at the same time for different computers.
Constrained to IEEE 802.11g only
However, by selecting G-Only, you have constrained the router to communicate only with IEEE 802.11g NICS.
(If you happen to have a computer equipped with the older IEEE 802.11b NIC, you should be able to confirm at this point that it can no longer communicate with the Linksys router.)
Experiment with B-Only
Use the Wireless Network Connection dialog in Figure 1 to manually disconnect your computer from the Linksys router.
Go to the administrator panel and set the Wireless Network Mode to B-Only.
Go to the Wireless Network Connection dialog in Figure 1 and manually Connect to the linksys network using your combination IEEE 802.11b/802.11g NIC.
Observe the Wireless Connection Status
Now view the Wireless Connection Status dialog and compare it with Figure 4.
Do you see anything different between the two?
My results
Figure 6 shows the result of this experiment that was produced on my computer.
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The main difference
The main difference between Figure 6 and Figure 4 is the transmission speed.
For Figure 4, the router was transmitting data at 54.0 Mbps. However, it was only transmitting at 11.0 Mbps in Figure 6.
What happened?
The explanation
When the router was configured to support both IEEE 802.11b and IEEE 802.11g communications (Mixed) in Figure 4, the combination IEEE 802.11b/802.11g NIC operated in the preferred G-mode.
However, when the router was configured to support only IEEE 802.b (B-Only) in Figure 6, the combination NIC operated in the slower B-mode.
Differences between 802.11b and 802.11g
As you will recall from the material in the textbook, one of the most obvious differences between 802.11b and 802.11g is the upper limit on transmission speed under strong signal conditions.
IEEE 802.11g is faster
IEEE 802.11g can operate at various transmission speeds up to 54 Mbps. However, 802.11b is limited to a maximum transmission speed of 11 Mbps.
Both modes automatically drop back to slower transmission speeds in the case of weak signal conditions. This will be the topic for a future project.
Restore your Wireless Network Mode
Now set your router back to either Mixed or G-Only and leave it in that mode in preparation for future projects.
Disconnect and connect your computer from the Linksys wireless router and confirm that the transmission speed returns to 54 Mbps.
Copyright 2005, Richard G. Baldwin. Reproduction in whole or in part in any form or medium without express written permission from Richard Baldwin is prohibited.
Richard has participated in numerous consulting projects and he frequently provides onsite training at the high-tech companies located in and around Austin, Texas. He is the author of Baldwin's Programming Tutorials, which have gained a worldwide following among experienced and aspiring programmers. He has also published articles in JavaPro magazine.
In addition to his programming expertise, Richard has many years of practical experience in Digital Signal Processing (DSP). His first job after he earned his Bachelor's degree was doing DSP in the Seismic Research Department of Texas Instruments. (TI is still a world leader in DSP.) In the following years, he applied his programming and DSP expertise to other interesting areas including sonar and underwater acoustics.
Richard holds an MSEE degree from Southern Methodist University and has many years of experience in the application of computer technology to real-world problems.
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Figure 2 Back panel of Linksys router
Figure 3 Linksys router administrator panel.
Figure 4
Figure 5
Figure 6