Regular Member
throwingwaves
Posts: 577
Registered: ‎01-05-2010
Posts: 577
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Registered: 01-05-2010

Airmax and PTP Links

I had time this afternoon to play with one of my ptp links that only has 2 subs on it, but any way.

I noticed with airmax on my ping times (latency) was higher then without it on. Both units are running 5.2.1 beta 4

5MHz channel widths
Min: 1.5 ms Avg: 1.72 ms Max: 5.35 ms 56 byte size
Min: 2.03 ms Avg: 3.16 ms Max: 5.73 ms airmax 56 byte size
Min: 1.47 ms Avg: 1.61 ms Max: 4.83 ms 56 byte size
Min: 2.08 ms Avg: 3.92 ms Max: 8.54 ms airmax 56 byte size
Min: 4.91 ms Avg: 5.11 ms Max: 7.32 ms 1400 byte size
Min: 5.9 ms Avg: 7.65 ms Max: 11.68 ms airmax 1400 byte size

10 MHz channel width
Min: 1.08 ms Avg: 1.15 ms Max: 1.31 ms 56 byte size
Min: 1.42 ms Avg: 1.88 ms Max: 3.38 ms airmax 56 byte size
Min: 2.85 ms Avg: 2.88 ms Max: 2.92 ms 1400 byte size
Min: 3.22 ms Avg: 3.43 ms Max: 3.55 ms airmax 1400 byte size


All my test were used with 50 packet sent and i had 0% packet loss on all the links, I even stopped and restarted a few test to had out the results with airmax on.

Is this normal? I understand that airmax is going to have a little more overhead but why does it add twice the latency? Is there any real benefit to run airmax on PTP links?
Ubiquiti Employee
UBNT-sriram
Posts: 157
Registered: ‎08-12-2009
Posts: 157
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Registered: 08-12-2009

Re: Airmax and PTP Links

Hi rtrice81,
Is it using PTP No ACK ? If so please post results again without NOACK mode. Secondly the primary benefit is seen when you measure latency under load.
Sriram
Regular Member
throwingwaves
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Registered: ‎01-05-2010
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Re: Airmax and PTP Links

no this link is only 5.6 miles long, what do you mean underload? when i used under airmax with larger packet sizes it got worse.
i have the ack set staticly 120% of the link distance as it so it the most stable there.
do you want me to still try it using the No Ack option?
Ubiquiti Employee
UBNT-sriram
Posts: 157
Registered: ‎08-12-2009
Posts: 157
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Registered: 08-12-2009

Re: Airmax and PTP Links

By underload I meant have some TCP/UDP traffic passing on the link while you measure latency to see the difference.
Regular Member
throwingwaves
Posts: 577
Registered: ‎01-05-2010
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Registered: 01-05-2010

Re: Airmax and PTP Links

ok i will run some speed test from a website while i am testing the ping times.
Regular Member
throwingwaves
Posts: 577
Registered: ‎01-05-2010
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Re: Airmax and PTP Links

Min: 1.08 ms Avg: 1.62 ms Max: 8.38 ms
Min: 1.35 ms Avg: 2.95 ms Max: 21.33 ms this was with airmax on

these results are while running a speedtest from speedtest.net
Ubiquiti Employee
UBNT-sriram
Posts: 157
Registered: ‎08-12-2009
Posts: 157
Kudos: 37
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Registered: 08-12-2009

Re: Airmax and PTP Links

Can you give me remote access so I can check this out. My email address is sriram@ubnt.com
New Member
VIGINETIP
Posts: 14
Registered: ‎12-04-2010
Posts: 14
Registered: 12-04-2010

Same

test

PTP 1
Distance 21 Km
A = Center City and much noise
B = low noise Coach Terminal Area
Results
configuracion 1 = Airmax = off = Asimetrico Speed Test = 50 Mbs/15Mbs.
configuracion 2 = Airmax=noack=on Speed test = 65Mbs/55Mbs Ping Promedio = 7 ms
PTP 2
Distance 20 Km
A = low noise Coach Terminal Area
B = low noise Coach Terminal Area
Results
configuracion 1 = Airmax = off = Asimetrico Speed Test = 70 Mbs/50Mbs. 2ms ping
configuracion 2 = Airmax=noack=on Speed test = 20Mbs/15Mbs Ping Average = 9ms