Latency problem

I’m a customer with 900 MHz Canopy gear and I have a latency problem that doesn’t make sense. My stats look good. Jitter is from 2-6 (usually 2 or 3 but I’ve seen it jump to 6), RSSI is 1380-1450, link efficiency is 100% up and down, and radio power level is -79 dBm yet if I ping any web sites, the latency of the ping can be anywhere from 30 to 1000+ ms. Watching the pings they jump all over the place with patterns like 30, 60, 80, 40, 120, …

My location is in the trees so there is a need to penetrate some but most of the LOS to the tower is unobstructed. My house is at the top of a hill though and the roof location of the SM isn’t greatly higher than the brow of the hill. I’m 1.5 miles from the tower. I don’t seem to be losing my registration. I’m setup for 906 MHz and 924 MHz and the SM seems to jump between them sometimes. When the system was first installed, it was working without these latency issues and they started a couple months after the install.

Its configured to use 2X but changing it to 1X didn’t help the latency. The scheduling is set to Hardware and its using version 7.3.6. Transmitter output power is 26. The SM is using a 17 db yagi.

Does anyone have any suggestions on how to solve the latency being all over the map?

You say you’re only 1.5 miles from the tower and your power level is at 26 with a 17 db yagi, you need to have someone look at the sessions page on the access point and what the power level of your SM is at, i’m willing to bet your power is too high, what you can do on your side if you have access is start turning the power level down 2 or 3 at a time until you can’t register anymore. Then just pick a level like 3 or 4 higher than that level.

Hey!

Ummmm . . .

I think you have misconstrued something in the original post, pcpolo: He said his dBm was at -79, and his RSSI is right around 1400, with a good amount of flux in both RSSI and jitter.
It was the transmitter output level set in the SM which was at 26. If he backs that off, he’ll likely loose registration right away. It needs to be bumped up to 28, in the hope that that little extra will be enough to keep him from re-registering.
IMHO 8)

is this latency to the AP or to the customer? my guess would be its a pps or a traffic problem

How do I tell whether the SM is re-registering? I sat and watched the main status page for a long period of time (updating every 3 seconds) and it always showed the status as registered.

How do I ping the SM or AP? I get a default gateway address on my router so is this the address of the SM or the AP? There is also the address I use to view the canopy stats. Is that the address of the AP or something else?

When I ping the address of my default gateway, I see the ping times all over the place just like when I ping any outside web host.

To help clear up -some- of this…I’ll try my best:

Hey!

Ummmm . . .

I think you have misconstrued something in the original post, pcpolo: He said his dBm was at -79, and his RSSI is right around 1400, with a good amount of flux in both RSSI and jitter.
It was the transmitter output level set in the SM which was at 26. If he backs that off, he’ll likely loose registration right away. It needs to be bumped up to 28, in the hope that that little extra will be enough to keep him from re-registering.
IMHO Cool


It is my understanding, unless I am wrong, that this information is incorrect. When you adjust the SM power level it does not have anything to do with what the customer can see on their SM for RSSI level, etc. What it does do is lower the stats that the AP can see from your SM on the sessions page of the AP. The RSSI/Jitter that you see on the main page is the signal the SM gets from the AP. It does not corrolate 100% with the power level on the SM because that adjusts the signal the AP gets from the SM (which is what is shown in the AP sessions page). Even if it was too “hot” and too “blinding” I would think that would effect other customers, and not directly effect him -too- much.




How do I ping the SM or AP? I get a default gateway address on my router so is this the address of the SM or the AP? There is also the address I use to view the canopy stats. Is that the address of the AP or something else?


The address you use is most likely the SM IP. Go to Start Menu -> Run -> Command and type ping x.x.x.x -t and it will do a consecutive ping to the SM. Replace “X” with the IP you use to log into the SM with.

It would be helpful if your ISP was on here, because if they have NAT enabled and you have high pingtimes to your gateway…your gateway could be the SM and there could be another problem. However, if they have NAT disabled and no router client-side, it could be their network that has a huge delay, etc.

It’s really hard to say without knowing their network setup and all the other fancy stuff.

Edit: To my knowledge the only way to see re-regs of the SM would be to check the AP sessions page.

Quote:
Hey!

Ummmm . . .

I think you have misconstrued something in the original post, pcpolo: He said his dBm was at -79, and his RSSI is right around 1400, with a good amount of flux in both RSSI and jitter.
It was the transmitter output level set in the SM which was at 26. If he backs that off, he'll likely loose registration right away. It needs to be bumped up to 28, in the hope that that little extra will be enough to keep him from re-registering.
IMHO Cool


It is my understanding, unless I am wrong, that this information is incorrect. When you adjust the SM power level it does not have anything to do with what the customer can see on their SM for RSSI level, etc. What it does do is lower the stats that the AP can see from your SM on the sessions page of the AP. The RSSI/Jitter that you see on the main page is the signal the SM gets from the AP. It does not corrolate 100% with the power level on the SM because that adjusts the signal the AP gets from the SM (which is what is shown in the AP sessions page). Even if it was too "hot" and too "blinding" I would think that would effect other customers, and not directly effect him -too- much.


True, you are usually effecting other customers when the power level on the SM is too "hot". But I have also noticed that an SM can be so high, that it is see reflections from itself and also desensitizing itself from the best AP on the tower. It might not be the case in this situation but it would be at least worth a try to turn the power level on the SM and see what happens. Especially since they are only 1.5 miles out, on a 17dm yagi, and turned up to 26 on the power level. That seems like a bitch much to me but then again I don't know what the noise floor is like there.

This is not an end user forum. Please contact your ISP regarding solving this issue.

Hey!

I know from my own experience that turning down the power on the SM weakens the link to the tower, and this guy is shooting just over a hill, through trees, and he’s on 900MHz. We operate 900 MHz in a hilly, wooded area, and the signal he describes is just barely acceptable.

You are correct in that there is a difference between what is on the AP sessions page and what is on the SM status page: Basically, it’s how which ever end your looking at sees the other side of the link. But if you turn down the transmitter output power, you’ll only worsen a signal that’s already at -79 dBm.

Having tediously adjusted the output power of 70+ SMs off of our 900MHz omni antenna, to make sure that the close people weren’t desensing the antenna from seeing the more distant clients, I have never seen a situation where turning down the output power on the SM did anything but lower the RSSI and dBm (and raise the jitter), as seen from either the AP sessions page or the SM status page.

Further, from my own practical experience, the signal will get slightly worse when the radio is put under load, that is to say when it’s actively being used to pass data. I would be interested if the link test you are doing is ten second or the default 2 second variety.

It is odd that you’re able to get 100 percent up and down on a regular basis, especially if it’s a ten second test you’re running, and I wouldn’t want to get sidetracked on the transmitter output power thing if I’ve misconstrued your problem entirely.

Here’s a thought: What if whoever is running the network keeps the transmitter output power stock in all his 900MHz radios? Isn’t 26 the default?

It could very well be that new clients are being added between the guy with the problem and the AP site. And if. in theory, no effort is being made to turn down the transmitter output power on those hypothetical radios, the AP would have a hard time seeing past them to our friend witht the latency issue. I bet that’s it. :roll:

(Yes, the AP sessions page is where to look for re-registrations. Don’t forget to compare the number of re-regs against the uptime of the AP: If the AP gets restarted every day and you have 25 re-registrations, that’s bad. If it’s been two months since someone kicked the AP and you have 25, maybe not that big a deal.)