View Full Version : PtP BulletM2 link with good DL but Low UL
sbyrd
10-13-2009, 12:47 PM
I have a 9mile ptp link with bulletM2s. I am getting ~-58dbm to -61dbm on both sides of the link with 89-100% ccq and MCS5 to 7 modulation rate on a 20Mhz channel. Now my issue is when I do a speedtest to our server (speedtest.net mini) on the Station side I get 20meg/2meg. I thought it might be a problem with the laptop I was using so I installed it anyway. This ptp link feeds 6 Canopy APs feeding ~100 customers. On monitoring of the link I have seen bursts up to 10meg on the dl side, but never have I seen more than 2 meg on the upload side. I have confirmed this with speedtests at multiple customer sites.
What could be the issue? Is it an ack timing thing (using static ack time) or something else. If more information is needed let me know I will provide it.
UBNT-Mike.Ford
10-13-2009, 12:50 PM
I have a 9mile ptp link with bulletM2s. I am getting ~-58dbm to -61dbm on both sides of the link with 89-100% ccq and MCS5 to 7 modulation rate on a 20Mhz channel. Now my issue is when I do a speedtest to our server (speedtest.net mini) on the Station side I get 20meg/2meg. I thought it might be a problem with the laptop I was using so I installed it anyway. This ptp link feeds 6 Canopy APs feeding ~100 customers. On monitoring of the link I have seen bursts up to 10meg on the dl side, but never have I seen more than 2 meg on the upload side. I have confirmed this with speedtests at multiple customer sites.
What could be the issue? Is it an ack timing thing (using static ack time) or something else. If more information is needed let me know I will provide it.
Hello,
Yes please increase the ACK timing (leaving it static) on the RX side of the link (the side that is only getting 2Mbps). Increment it in small values and see if the speed improvies.
Thanks,
Mike
sbyrd
10-13-2009, 04:25 PM
Hello,
Yes please increase the ACK timing (leaving it static) on the RX side of the link (the side that is only getting 2Mbps). Increment it in small values and see if the speed improvies.
Thanks,
Mike
Instead of incrementally increasing the ACK on the RX side, what about setting that side to Auto ACK? I tried auto ACK on both sides earlier and it lead to instability on the link so I am not sure if I want to try auto or not. What would you recommend.
MaximumISP
10-13-2009, 04:50 PM
He already did recommend that you try increasing
the ack in small incriments on the recieve side
have you done that, did it have any effect
just say NO to auto ack on the M gear for now
sbyrd
10-14-2009, 10:01 AM
Hello,
Yes please increase the ACK timing (leaving it static) on the RX side of the link (the side that is only getting 2Mbps). Increment it in small values and see if the speed improvies.
Thanks,
Mike
I am still unclear as to which side to increase the ACK for. My setup is this:
Tower 1 TX to Tower 2 at 20meg
Tower 1 RX from Tower 2 at 2meg
Do I increase the ACK on Tower 1 or Tower 2? Also, when would I know if I need to decrease my ACK time? For instance my link is 9mile but I have the ACK at 10.8miles. Could my ACK be too high? What are the indicators of a too high ACK vs a too low ACK?
I know I could just keep changing the numbers and see what is better or worse, but I cannot just make these changes on a whim. I have 100 customers on this tower with a few that work exclusively from home online. Also, to test the TX from Tower 2 to Tower 1 I have to drive out to the tower after hours climb it or setup a radio on the tower to test my bandwidth. So I would like to have a good idea what I need to look for before I start messing with the tower link.
Since its a PtP link, I would set the ACK on both sides to a fixed value. At least 10% GREATER than the actual physical distance. Within reason, you won't have any problem setting it too high, like 30% greater...just no need to. Personally I'd go with 15% in case you run into path goblins that screw the timing.
sbyrd
10-14-2009, 10:51 AM
Well, I already have it set at 20% greater and still am having low TX throughput from Tower 2 to Tower 1. Are you indicating that you don't think the ACK is the reason for the low bandwidth. Do you have another idea?
UBNT-Mike.Ford
10-14-2009, 01:01 PM
Hello,
Are you currently testing with AirMax off or on?
THanks,
Mike
sbyrd
10-14-2009, 01:09 PM
Airmax is off as this is a ptp link so I did not see any benefit by using it.
UBNT-Mike.Ford
10-14-2009, 01:22 PM
Airmax is off as this is a ptp link so I did not see any benefit by using it.
Can you test with it on and see if the speed comes up?
Thanks,
Mike
sbyrd
10-14-2009, 01:28 PM
So, earlier you said I should increase my ACK. Are you now backing off of that recommendation, because I have not had a chance to test that yet. Also, I am still unclear as to which side I would increase the ACK on. Tower 1 (20meg TX) or Tower 2 (2meg TX).
I will give either ACK increase or Airmax a try, but I would like to know which one you recommend adjusting first.
UBNT-Mike.Ford
10-14-2009, 01:30 PM
So, earlier you said I should increase my ACK. Are you now backing off of that recommendation, because I have not had a chance to test that yet. Also, I am still unclear as to which side I would increase the ACK on. Tower 1 (20meg TX) or Tower 2 (2meg TX).
I will give either ACK increase or Airmax a try, but I would like to know which one you recommend adjusting first.
Oh I didnt see that you did not test. Adjust the ACK timing on the Tower 2.
THanks,
