Quality-of-Service in Wireless Communication
In this exercise we will set up the QoS features in our WLAN.
In this exercise you have to setup a WLAN Access Point to perform Quality-of-Service for a specified traffic in the WLAN. We use the Cisco AP1200 Access Point which offers also 54 Mb/sec speed. But for this exercise we reduce the maximum speed to 2 Mb/sec.
All you need is the Microsoft Internet Explorer Version 6 and higher. You can connect to our exercise computer using the Remote Desktop Connection from Microsoft. Please allow to download and install Activ-X components in your browser to receive the remote desktop plug-in when you open the connection to the exercise.
PC vhb12
192.168.20.159
WLAN 802.11g Interface
Ethernet Interface 2 192.168.20.101
To the Internet Ethernet Interface 1
VHB24 is your exercise computer to which you are connected via the Windows Remote Console Interface.
The WLAN interface of the exercise computer is used to test the correct setup of the Access Point (Cisco AP1200).
The exercise computer also has two Ethernet interface which are connected on one side to the Internet and on the other side to the Ethernet interface of the Access Point. This
second Ethernet interface can be used to setup the Cisco AP1200 from the scratch. The setup is done over a web interface of the Access Point.
This exercise computer (vhb24) is also used for other exercises. The exercises 4 (Management and Troubleshooting) and 5 (Security Setup).
The Cisco AP1200 supports also QoS for a wide range of applications and protocols. Usually QoS is used to prioritizing to real time traffic such as Voice or Video Streams, VoIP , etc..
But it is not possible to show the advantages of QoS in a virtual laboratory. All we can show is some measurement with and without QoS enabled.
For this measurement we use an traffic generator application which sends UDP packets over the WLAN interface. Two streams are send. We also reduce the maximum Radio Speed of the Access Point to 2 MBits/second. This makes it easier to results without too much stressing the rest of the network.
We expect, that the load of the both streams will nearly equal without QoS. But when one Stream is prioritized using QoS the load of that stream will increase while the other will decrease.
To use QoS on that Access Point we have to define a filter rule which describes the protocol, MAC or IP address of the traffic which should be prioritized.
vhbWLAN24 192.168.20.0
PC vhb24 WLAN
Cisco AP1200 192.168. 20.40
Setup QoS in WLAN 802.11 Introduction
Prerequisits
Specify a filter rule Enable the QoS Policy
PREREQUISITS
We assume, that you have successfully finished the exercises 4 (Management and
Troubleshooting ) and 5 (Security in WLAN 802.11). And that you have enough experience to setup and use a WLAN in the virtual laboratory.
The following exercise is based on the setup of the Access Point from the exercises before.
Anyhow it is a good idea to completely initialize the Access Point for this exercise
Load the QoSconfig.txt configuration file from the Desktop to the Access Point using the web frontend of the Access Point.
Reset the Access Point using the RestartAP1200 shortcut from the Desktop. The Restart button on the web page of the Access Point DO NOT WORK correctly.
Also setup the local WLAN profile for LEAP (if no Certificates are installed) accordingly to the current authorization scheme of the Access Point. Because LEAP do not need Certificates.
Before you can continue you must have a running WLAN connection and must be able to ping 192.168.20.1 from the exercise system vhb24.
SPECIFY A FILTER RULE
Open the SERVICES folder and select Filters. You might see that QoS and Filters are disabled at that point.
Open the IP Filters folder.
Enter the Filter Name Test1
Scroll down the window until you find the UDP Port entry fields.
Find the UDP Port settings and select Custom.
Enter the Port Value 20001.
In the Action Field, select Forward.
Click on Add.
Check the Filter Classes box for the entry from above is listed.
Click on Apply.
Open the APPLY FILTERS folder.
Select the filter specification Test1 for all IP Incoming and Outgoing Interfaces.
Click on Apply.
If the Access Point do not response you have made a mistake in the filter definition. All you can do now is to completely reset the Access Point by using the InitializeAP1200 shortcut on the Desktop and initialize the Access Point again.
ENABLE THE QOS POLICY
Open the SERVICES folder and select QoS. You might see that QoS is disabled at that point.
Open the RADIO-8022.11G ACCESS CATEGORIES folder.
Check the last two Categories to be enabled.
Click on Apply.
Open the QoS POLICIES folder.
Enter the Policy Name: Streaming (i.e) Select Test1 in the Filter field.
Select Voice <10msLatency(6) in the same line.
Click Add.
Check that in the Classifications box the new filter classification appears.
Click on Apply.
Go back to the SERVICES folder.
Notify that both Filters and QoS are enabled now.
Test the QoS implementation Reduce the maximum speed
Do Test 1 Do Test 2
REDUCE THE MAXIMUM SPEED
Now we have to limit the maximum radio speed to 2 Mb/s in order not to overload the rest of our network in the virtual laboratory.
Open the NETWORK INTERFACES folder and select Radio-802.11G.
Open the SETTING folder.
Disable all other Data Rates except 1.0 and 2.0 Mb/sec.
Click on Apply.
Check that the current radio link works with 2.0 Mbps and that you still have connection.
TEST 1
In this test, three streams of UDP data are transmitted from a remote server o the local exercise system via Wireless LAN connection. The streams use the ports 20001, 20002 and 20003. For each stream 200 UDP packets each 512 Bytes long are send per second. The approximate network load should be around 3 times 1 MBit/sec. The stream is generated for 30 seconds and stops automatically.
Because the UDP traffic for port 20001 is prioritized, this traffic should be received faster than the other ones.
To start the Traffic Generator you have to click on the icon QoS-Traffic Generator on the desktop.
Click on QoS Traffic button to start the Traffic Generator program on the remote server.
To start the Traffic Client program you have to click on the icon QoSTraffic Client on the desktop
The Traffic Client program is a program that receives the UDP streams and counts the number of received packets. The different data streams can be started and stopped individually. For this test you must start all three streams at the same time!
First the Traffic Client program checks if the Traffic Generator program has been started. If it is not started, the Traffic Client waits until you have started the Traffic Generator again (see above).
Press key 7 to start the traffic and watch the counters. The first one (Port 20001) should go much faster than the other ones.
If the result is not what we expected you can run this test again. But you have to stop all ports by pressing the keys 4,5 and 6 before you can repeat this test!
Press key 8 to end that test. The server process stops also automatically.
TEST 2
Now you should repeat the test before but with QoS disabled!
Connect to the Access Point using the web browser!
Open the SERVICES folder and select QoS. You might see that QoS is enabled at that point. Please uncheck the enabled Admission Control settings
Uncheck the last two Categories to be disabled.
Click on Apply.
Notify that QoS is disabled now.
Repeat the test from before. Start the Traffic Generator and the Traffic Client programs and press key 7 to start the stream
As a result all three streams should be received at the same speed, because none is prioritized.
.
End the Traffic Client program by pressing key 8.
The QoS exercise is finished. Now you can logout the exercise system.
