ADSL Performance Testing

ADSL Testbed
Testing Parameters
Test Methods
Test Results

ADSL Testbed

To understand the function of ADSL in the communication network, please click here.

We have ordered 1 CO and 1 RT modems from Aware, inc. then we can do some network performance testing using the following testbed.
Please click here to get the relative documents of the x200 modems

ADSL testbed (LAN interface)

To setup the ADSL test enviroment, we need to get the following items:

1. CO & RT modems (with LAN interface, from Aware, inc.)
2. Loop & Impairment simulator(DLS400)
3. Hub & Protocol analyzer (HP advisor LAN, HP inc.)
4. Server, client PCs
5. Application software/test software (from NSTL)

When setting up the testbed, one must take care the cable type: Crossover or Straight through. Here list the rules for Ethernet devices connection:

1. Client to Client use a crossover cable.
2. Client to Hub use a straight through cable.
3. Hub to Hub use a crossover cable.
4. Router and PC interfaces are considered client interfaces, the X200 is a client interface.

One must be careful that if the connection can not be setup, the first thing I suggest to do is shut down the whole system including two modems then reboot. Sometimes it needs to restart system to get connected. I don't know why but it is the truth. Changing the hardware connection is the last thing I’ll do.

And when you are leaving, pls make sure each device is switched off.

ADSL Performance Parameters

We will test the following basic parameters:

1. Throughput
2. Latency
3. BER (depending on the modems we will get)

And if we can go further, we may test influence of the ADSL on some high-level applications, such as video, audio service and the influence of background traffic noise (such as internet access). NSTL software Loadrun.exe can also be used to test network performance.

Testing Methods

Line speed

We can use some available software to test line speed. Here list some shareware for network performance monitor:

1. DU meter v2.21
2. Net. Medic v1.2.2
3. Online Meter v3.1

We can use these software to determine the downstream and upstream speed of the ADSL test system.
HP advisor LAN can also be used to test the link speed (throughput)

Latency

As to the measurement of delay, a simply way to test the round trip delay is:

1. Connect two PCs with 10 Base-T cable
2. Use ping function of OS, get the average value of the round trip delay
3. Set up the LAN system using ADSL modems.
4. Use ping to get the round trip delay
5. The defference between these two delay values is the average round trip delay on ADSL modems

But we still should get some way to test the single trip delay. Because the delay for ADSL downstream and upstream are different. We may use the HP Internet Advisor LAN module to perform the test

BER testing

HP advisor LAN may be used to test the BER
And we need to test the BER under certain line condition.

Useful Links

This website may be useful for you:
http://www.aspergantis.com/adsl/

ADSL Physical Layer Parameters Test Results

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