questions regarding change in jitter values
I am currently working on QoS calculations for UDP traffic over a wireless network.
I have seen some strange things happening with packet transmissions and jitter times.
I was wondering if you could explain or have seen similar issues. When trying to send
a 1 meg UDP stream from a Windows XP box, through a Cisco 1200 series access
point and down to a RedHat9 laptop I see some strange fluctuations in packets sent
and jitter changes.
[ 3] 52.0-52.5 sec 64.6 KBytes 1.06 Mbits/sec 1.377 ms 0/ 45 (0%)
[ 3] 52.5-53.0 sec 67.5 KBytes 1.11 Mbits/sec 3.826 ms 0/ 47 (0%)
[ 3] 53.0-53.5 sec 64.6 KBytes 1.06 Mbits/sec 1.412 ms 0/ 45 (0%)
[ 3] 53.5-54.0 sec 67.5 KBytes 1.11 Mbits/sec 3.280 ms 0/ 47 (0%)
[ 3] 54.0-54.5 sec 64.6 KBytes 1.06 Mbits/sec 1.314 ms 0/ 45 (0%)
[ 3] 54.5-55.0 sec 67.5 KBytes 1.11 Mbits/sec 4.084 ms 0/ 47 (0%)
[ 3] 55.0-55.5 sec 64.6 KBytes 1.06 Mbits/sec 1.105 ms 0/ 45 (0%)
[ 3] 55.5-56.0 sec 70.3 KBytes 1.15 Mbits/sec 3.441 ms 0/ 49 (0%)
[ 3] 56.0-56.5 sec 63.2 KBytes 1.03 Mbits/sec 1.062 ms 0/ 44 (0%)
[ 3] 56.5-57.0 sec 67.5 KBytes 1.11 Mbits/sec 3.665 ms 0/ 47 (0%)
[ 3] 58.0-58.5 sec 64.6 KBytes 1.06 Mbits/sec 1.015 ms 0/ 45 (0%)
[ 3] 58.5-59.0 sec 61.7 KBytes 1.01 Mbits/sec 0.904 ms 0/ 43 (0%)
[ 3] 59.0-59.5 sec 70.3 KBytes 1.15 Mbits/sec 1.185 ms 0/ 49 (0%)
[ 3] 59.5-60.0 sec 63.2 KBytes 1.03 Mbits/sec 1.184 ms 0/ 44 (0%)
[ 3] 60.0-60.5 sec 68.9 KBytes 1.13 Mbits/sec 1.098 ms 0/ 48 (0%)
Here you can see the jitter varies drastically every half second interval and seems
to be increasing in delta until the 58.0-58.5 and after. Then the jitter intervals
are close again and slowly begin to increase in difference once again. There
is no packet loss but I do see a difference in the number of packets sent each
interval. Secondly, I noticed that when I increase the bandwidth closer to the
theretical wireless maximum without packet loss, the jitter does increase
between intervals but is not nearly as wide as with a lower bandwidth.
Any thoughts?