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lctn
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I should be rockin, but am only crawling

Tue Oct 12, 2010 7:35 pm

I am have almost completed an upgrade for a member school district. We went with "N", but are having very disappointing results with the finished links.


Boards: 433AH
Cards: SR17
Antennas: 32 Db dish with DP feed horns
Distance 7 miles
Db level 68-70

Using 5 Ghz N only

Both chains are checked and CCQ is 85-100+ % with low traffic.

Once traffic gets past 3Mb, CCQ bounces all over the place and often dips into the single digits, with ping times going into 400-900 ms.

When traffic dies down, connection speed will come back to 54/130 or 130/130

Have tried every frequency in the 20 MHZ range, but nothing helps.


Any ideas?
 
ericsooter
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Re: I should be rockin, but am only crawling

Tue Oct 12, 2010 8:07 pm

Sounds like either the dishes are not completely aligned or maybe the fresnel zone is obstructed. I would think at 7 miles with 32db dishes your signal should be in the 60's; possibly 50's if higher powered card. Those 4ft dishes have a very narrow path and are extremely sensitive; the azimuths and elevations need to be perfect.
 
lctn
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Re: I should be rockin, but am only crawling

Sun Oct 17, 2010 10:03 pm

Tower installer certifies all dishes are aligned perfectly now. I am getting -49db-52-db on 7 mile links, but still have the same problem. Band-width test always start at 20+ Mb, and then dwindle down to 4Mb (max) in a 10 seconds or less. The speeds never go back up and ping times run from 400-1000 ms, then drop back down to 1 ms when band-width test is terminated. CCQ is always 85-100% before running tests and link shows it is locked in between (N Wireless only) 117Mb-130Mb. I changed everything from bridged to routing between all interfaces, but that did not change throughput either.

I see I had a typo on my hardware. I am using SR71-15 cards on 433AH boards and using 5 Ghz Wireless N Only.
 
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colebert
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Re: I should be rockin, but am only crawling

Sun Oct 17, 2010 10:21 pm

Are you using nstreme?

Post screenshots of your config for us to review.
 
lctn
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Re: I should be rockin, but am only crawling

Sun Oct 17, 2010 10:46 pm

I am not using nstreme.

Let me know if you need more of the configs
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lctn
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Re: I should be rockin, but am only crawling

Sun Oct 17, 2010 10:47 pm

Station config
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colebert
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Re: I should be rockin, but am only crawling

Mon Oct 18, 2010 12:20 am

DEFINITELY use nstreme. It makes these kinds of links work right. Turn it on for both sides.

Turn off CSMA and enable Polling. Dynamic or Best Fit framer modes work well.

Can I see a shot of your ADVANCED and HT MCS tabs?
 
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Re: I should be rockin, but am only crawling

Mon Oct 18, 2010 12:39 am

Those CCQ's are looking sick, Maybe try another freq? Are you sure than 5.1-5.3ghz is supported by your dishs?
 
lctn
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Re: I should be rockin, but am only crawling

Mon Oct 18, 2010 12:45 am

AP Advanced and HT-MCS Tabs
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lctn
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Re: I should be rockin, but am only crawling

Mon Oct 18, 2010 12:46 am

Station Advanced and HT-MCS Tabs
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lctn
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Re: I should be rockin, but am only crawling

Mon Oct 18, 2010 12:50 am

We get the same results no matter what frequency is used
 
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colebert
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Re: I should be rockin, but am only crawling

Mon Oct 18, 2010 12:50 am

OK, seriously. You need to enable NSTREME as I outlined about and do the following:

1. Set HW Retries to 15 on both sides
2. Uncheck set Data rates tab to manual
3. Uncheck all 802.11a rates (no rates remaining)
4. Uncheck all MCS rates except for MCS8

Do the above on both sides of the link.

You should have a solid, high throughput link if you do these things.

If you get a solid link, raise the MCS rates until you are happy with the results. I prefer to lock in my rates to a specific one rather than letting it alternate. You have good enough SNR to do this.

No one is going to be able to help you more until you've done these things. Report back and let me know.
 
lctn
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Re: I should be rockin, but am only crawling

Mon Oct 18, 2010 1:18 am

I was responding to the other person's question with my last post.


OK.. I did everything you posted. It shows registration at 13 Mb, and band-width speed shows a total of 7-8Mb when testing "both". That is almost twice as much as I had before, so making progress. I tested 5180, 5320, and 5745. All run about the same.
 
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colebert
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Re: I should be rockin, but am only crawling

Mon Oct 18, 2010 1:31 am

Turn on Adaptive Noise Immunity and set it to "AP & CLIENT MODE".

Double-clikc on your wireless interface, go to the registration tab, double click on your connection, go to the signal tab, and give me a screen shot of that. Both client and AP please.

Also, let me see your HT MCS tab (client and AP), nstreme tabs (client and AP), and Tx power tab on the AP side.
 
lctn
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Re: I should be rockin, but am only crawling

Mon Oct 18, 2010 1:51 am

Experimented while waiting for a response. Enabled mcs 10 and mcs 12. Had 26 Mb each way. Put it back to mcs8 for now.

Ap config info #1
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lctn
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Re: I should be rockin, but am only crawling

Mon Oct 18, 2010 1:51 am

Ap config #2
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lctn
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Re: I should be rockin, but am only crawling

Mon Oct 18, 2010 1:52 am

Station config #1
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lctn
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Re: I should be rockin, but am only crawling

Mon Oct 18, 2010 1:53 am

Station config #2
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colebert
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Re: I should be rockin, but am only crawling

Mon Oct 18, 2010 1:58 am

OK, 97%/97% is pretty solid for 802.11n. Just do MCS15 on both sides and see what you get.

Do you want to go faster? If so, go to HT tab on each side and enable Extension Channel as "above control."

Do a bandwidth test and tell me your CCQ ratings (under the registration tab).

I think you are close to being done.
 
lctn
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Re: I should be rockin, but am only crawling

Mon Oct 18, 2010 2:10 am

I checked mcs 8 - 15 in supported and basic. let me know if that is incorrect.

I changed to "above control" and now have just under 60Mb throughput.

Very cool!

I have two other schools with the same equipment and problem. They will be thrilled to get this fixed.

Thank you!
 
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colebert
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Re: I should be rockin, but am only crawling

Mon Oct 18, 2010 2:18 am

Happy to help.

FYI, bandwidth test in Winbox is not a good measure of throughput. You most likely have much more than that as bandwidth test maxes out the CPU power of the RB. It can't produce enough packets to do a real test. I have a single chain 802.11n that gets 60meg at MCS6 so you are likely going to have about double that.

Keep an eye on your CCQ. For a link like this, it should be 90%+ under no load and 80%+ under load ideally (in my opinion.)

Don't get cute with multiple MCS rates. Just lock in what works and eliminate rate shifting. (e.g., MCS15 only)

Since you have so much throughput, consider enabling WPA2-AES encryption since this link will probably be passing FERPA type data as it is for a school. Won't hurt overhead much.

PS: If you don't mind... my karma rating is a little low. :D
 
Beccara
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Re: I should be rockin, but am only crawling

Mon Oct 18, 2010 2:33 am

2nd'ing the 80%+ CCQ's under load. You really do need to hook 2 computers up either side with btest.exe and test that way as we've had issues with AP's actually getting 40-60% more bandwidth out of a link than the RB's btest showed
 
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tgrand
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Re: I should be rockin, but am only crawling

Tue Oct 19, 2010 4:18 am

disable periodic calibration on your advanced tab.
Calculate your ack timeout value and hard code the ack timeout.
 
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colebert
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Re: I should be rockin, but am only crawling

Tue Oct 19, 2010 4:28 pm

It's nstreme, bro. No ack.
 
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tgrand
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Re: I should be rockin, but am only crawling

Tue Oct 19, 2010 6:37 pm

Still must disable periodic calibration.
 
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Re: I should be rockin, but am only crawling

Tue Oct 26, 2010 12:28 pm

Hi,

I'm trying to build PtP link as described in this thread, everything looks good but when i'm starting any bandwidth test (not MT built-in) on PCs connected,
connection drops with message 'connection lost, not polled for too long'. Ping is OK, < 1ms. RB411AH + R52Hn on both sides.
Any ideas?

Thanks in advance, Grzegorz.

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