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www.tranzeo.com
12/12/2005
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– TR-CPQ
Simple Testing for QoS Issues
It is actually extremely easy to disturb any real time delay sensitive traffic to show the effects of
Bandwidth Loading.
Measuring the effect on RTT and showing jitter
A simple test can be performed using e-mail and the ping utility.
1. From a Command Windows type:
ping <IP_ADDRESS OR DOMIAN> -t
. In our example, we
are pinging Yahoo.com
2. Using an e-mail application send an e-mail containing 1 or 2 high resolution photographs.
3. Observe what happens to the ping time. You should see something similar to the results below.
Notice how the ping time goes from 10’s of milliseconds to 1000’s of milliseconds with a large amount
of variation.
Pinging www.yahoo.akadns.net [66.94.230.45] with 32 bytes of data:
Reply from 66.94.230.45: bytes=32 time=23ms TTL=50
Reply from 66.94.230.45: bytes=32 time=450ms TTL=50
Reply from 66.94.230.45: bytes=32 time=426ms TTL=50
Reply from 66.94.230.45: bytes=32 time=549ms TTL=50
Reply from 66.94.230.45: bytes=32 time=396ms TTL=50
Reply from 66.94.230.45: bytes=32 time=640ms TTL=50
Reply from 66.94.230.45: bytes=32 time=406ms TTL=50
Reply from 66.94.230.45: bytes=32 time=488ms TTL=50
Reply from 66.94.230.45: bytes=32 time=642ms TTL=50
4. When the background traffic stops the response time reverts to a normal and consistent time
illustrating how the local network traffic has the greatest impact on the internet delay and jitter. Notice
how the ping time only varies within the single digit milliseconds in the absence of background traffic.
Reply from 66.94.230.45: bytes=32 time=118ms TTL=50
Reply from 66.94.230.45: bytes=32 time=20ms TTL=50
Reply from 66.94.230.45: bytes=32 time=22ms TTL=50
Reply from 66.94.230.45: bytes=32 time=22ms TTL=50
Reply from 66.94.230.45: bytes=32 time=20ms TTL=50
Reply from 66.94.230.45: bytes=32 time=16ms TTL=50
Reply from 66.94.230.45: bytes=32 time=21ms TTL=50
Reply from 66.94.230.45: bytes=32 time=21ms TTL=50
RTT on a Tranzeo Wireless Technologies QOS enabled router
Repeating the same “ping” test with background traffic on a Tranzeo Wireless Technologies router
