|
Ask the Expert
Q: I need a way to verify my
network is performing at the speeds that I'm paying for. How can I
verify the bandwidth I'm getting? Paul Brearley, Head
of IT, Chill.ie
|
| Peter Hendrick, Technical Director,
AirSpeed Telecom |
A: The fastest way to verify
what you're getting is via a testing site like speedtest.net, but doing something
about your speed involves a few more steps.
You should always ensure that your firewall is not delaying the
traffic, but the speed you're getting is also dependant on many
other factors, including those below.
1. Test machine: Which machine are you using to test your speed?
Perform the test from the newest and highest spec machine. This
will normally give the best results.
2. Testing time: Network and Internet congestion vary tremendously
by time of day. Try to test at a time that traffic usage is low, or
ideally when your machine is the only one connected to the
network.
3. Network card duplex settings: "Full duplex", a setting on your
network card, lets the computer transmit data and receive data at
the same time. Make sure your network card is not set to "half
duplex" -- this means the machine must wait until the other device
has stopped sending data before it can start sending data. "Auto"
is the worst setting of all: one side believes the connection is
full duplex whereas the other side believes it is half. The data
sent by one side is entirely missed by the other, resulting in
re-transmissions that can severely impact speed.
4. Symmetric or asymmetric service: If your upload and download
speeds differ dramatically, your provider is probably delivering
you a service that's asymmetric (different upload and download
speeds). Test a number of your sites to check whether this is true.
If it is, and if you've ordered a symmetric service that is
supposed to deliver the same speeds up and down, contact your
provider and tell them your results.
Get a detailed view with a traffic generator
An excellent method of testing your bandwidth is with a traffic
generator, which stress tests the connection and is often used for
commissioning tests. Iperf is a software programme that allows a
user to transmit up to a set level of traffic and test that the
receiver has received it. This programme is deployed as a
client/server: the client transmits the traffic and the server
receives it. Be aware that bandwidth available to the end users may
be constrained while the test is being run.
Run the test in both directions to test the symmetric qualities of
the link. The test can be applied to all layer2 or layer 3
connections, and, since the traffic is kept within the private
network is not subject to the vagaries of the internet.
The licensed wireless network provider AirSpeed Telecom has an
iperf server in its network and is currently developing a speed
test web interface. Watch http://www.airspeed.ie for more
information.
Got a question? All queries answered by Peter Hendrick,
Technical Director, AirSpeed Telecom. Questions may be edited for
brevity. Email to newsletter@licensedwirelessnews.ie
|
