Running "HOT"

[therealboss]

Just been up working on a node that has a WAR4 installed, B15, 3 AP's and one 5.8 feed. System is only running at 15% / 25% but there is a lot of heat on the main Intel chip, is this normal? If it gets this hot now what will it be like in the summer with the sun on it all day and more clients on it with a load of 50+%??

Anyone else noticed if the chip gets hot?

[lonnie]

It would be nice to have a more definitive number than "a lot of heat" or "hot". The chips are rated to worked at 70C which is too hot to touch. You'll find that you raise the temperatrure when you put your hand on it since you provide insulation and prevent air flow. If you can comfortably touch the unit it is not a problem.

[therealboss]

Lonnie
Did not have anything to read the temp while up the mast, but it was hot or very warm, with the back of my finger I could keep it on the chip. At a guess I would say about 45 or 50 deg C, I did not keep it covered for long but it was when I opened the box I could feel the warm air, thats what made me feel the chip. I don't think its a problem but thought I would ask to make sure, as I said if its this hot now what wil it be like in July?

The good news is that the box is running fine, I'm finding the WAR's much better than the WRAP's and can push more through them.

One question, on a war 4 running, 3 AP's (2.4GHz) and one 5.8GHz backhaul, what would you say would be the max amount of clients per radio running 2.4 ?

[lonnie]

There is no real way to put a definite number to that question of how many customers on an AP.

Everything depends on customer signals and their usage patterns. You want to ensure that customer radios are set to the highest possible rate. If they float and hit 1 mbps you have your entire system capable of only 700 kbps throughput, which I am sure is not high enough for very many users,. Make sure they are 11 mbps and consider moving to G with rates set to 36 mbps minimum. Actually G is pretty good at trying to go as high as possible so we see no increase with a fixed rate.

Also you have the concept of usage to deal with. 100 customers who are light users can likely be quite happy on a B mode AP yet 10 heavy users will likely not be happy.

You'll have to watch usage and monitor to see if you have heavy users. Consider special limits for the big users.

[greg]

I've noticed that the processor and radios both generate a fair amount of heat just sitting on my desk while I am programming it.

I configured a quad War and set it up as an AP last night (2 CM9's at 2.4ghz). The results were not too positive. I replaced two different wraps running as AP's with Prism 2511 radios. One has 16 clients on it and the other is over 30. I used the same pigtails but about 8 of the customers could not see the AP after changing over to the CM9 radios. The signal strength went down significantly across the board which I think was the cause. I put the two wraps back up this morning. I might try putting the CM9's in a wrap over the weekend to see how well that functions. It doesn't seem that there would be that significant a change but the only diff was wrap v. quad War and 2511 v. CM9.

[tog]

I would think that the difference in radios would be the only variable making the difference.

Perhaps your 2511's higher output power was necessary to reach some of those clients. Although you know the 2511 has less receive sensitivity compared to a CM9, the CM9 does have a lower output power. You can try setting the TX power to 20 to get yourself a couple of extra db or use a Ubiquiti SR2, assuming your problem is nothing more than lower transmit power no longer reaching some of your clients.

You didn't mention whether those 8 clients already had marginal/low signals. If they were receiving -84 before with a high-powered prism card...

[tony]

Also, do not forget to disable 'short preamble' on the Atheros configuration screen, as it can prevent older clients from associating.

Also note, the Atheros AP only supports 802.11b as it's lowest supported radio. The older 2Mbps wireless cards will not work as clients.

[greg]

I tried tweaking quite a few settings. No X in the Short box means short only and an X means short/long. I don't think we have any of the 2 meg cards on them. Looks to be mainly CB3's and Tranzeo with a few Wet11's in for good measure. The signals went from 50's and 60's to 70's and 80's. I had the Tx Power set to 18 and did not change it. I tried set to b only, g only and mix of b/g. That didn't seem to matter much. Seemed like the ones with problems were newer Tranzeo 90's which I believe have Atheros chipsets. I had quite a few associations last night but only 4 on each radio this morning. System seemed sluggish and I rebooted it. Many more associations but they seemed to drop off again over time.

I have to admit that the preamble box function seems reversed to me. I'll get used to it but it confuses the hell out of my techs. It says:

[ ] Short {Short preamble only}
[X] Short {to select Short/Long preamble} - Do I have that right?

[tony]

The 'X' in the box means that it will support short/long preamble (newer cards only), and without an 'X' means long preamble only (older card support, but may reduce throughput by a very tiny margin).

Are you using beta-15?

[greg]

Yup, beta-15.

[tog]

Since the two possible options are "short/long" and "long only", I think the check box does make sense the way it is.