Ok, I've been posting, asking questions, reading and banging my head against the walll over the frequent disconnects and wonky Ack's with the SR9. FINALLY!!! I have found out what I was doing wrong with my AP set-up. I suggest others to try this and confirm.

I run 5mhz channel spacing with the SR9, so we are operating in G mode.... I also run the DUDE on my network, so I can see the tx/rx connect rate. Something that has alway's puzzled me is the fact that the tx rate constantly goes back to the 6Mbs rate..... well lets face it, we want to be connected at the maximum rate at all times.

I read a post on the forums explaining basic / supported rates. http://forum.mikrotik.com/viewtopic.php?f=7&t=18657

Here is what I did.... I always set my clients to a maximum supported rate of 24Mbps and a basic supported g rate of 6.

I set the AP basic G rates from 6-24 and Supported rates from 6-36. VOILA! My clients are all holding the connection with no disconnects for over 2 hours. Before, they would disconnect every 1/2 hour or so.

Man... I'm happy!

On the post you reference Sten says:

basic-rate is used for broadcast and multicast packets (which are not ACKed and therefore must be sent at an reliable rate).
basic-rate is also used for association and beacons.
supported-rates are simply used for unicast packets (which are ACKed)

for each basic-rate there must be a supported-rate but not (necessarily) the other way around.
at "default" settings the basic-rate will be at the lowest rate for that mode (B and B/G = 1mbit, A or G-only = 6mbit) but supported-rates will vary on the success of transmission on each rate.

So now that your connections seem more reliable, what exactly do you feel the change that made the difference was. From what Sten says the basic default rate was 6 anyway and you made the supported rate 24. Was the default supported rate higher and limiting its ability to connect faster than 24 what you feel was the difference?

Just trying to figure out exactly what you did that made the difference and why.

Thanks,
Scott

On the post you reference Sten says:

basic-rate is used for broadcast and multicast packets (which are not ACKed and therefore must be sent at an reliable rate).
basic-rate is also used for association and beacons.
supported-rates are simply used for unicast packets (which are ACKed)

for each basic-rate there must be a supported-rate but not (necessarily) the other way around.
at "default" settings the basic-rate will be at the lowest rate for that mode (B and B/G = 1mbit, A or G-only = 6mbit) but supported-rates will vary on the success of transmission on each rate.

So now that your connections seem more reliable, what exactly do you feel the change that made the difference was. From what Sten says the basic default rate was 6 anyway and you made the supported rate 24. Was the default supported rate higher and limiting its ability to connect faster than 24 what you feel was the difference?

Just trying to figure out exactly what you did that made the difference and why.

Thanks,
Scott

From what I can see (Looking at a single client unit) the TX rate dropped to 6mbps when the connection was Idle.... so what I would see in the dude on a client connection is a 24mb RX and a 6Mbps TX. When the connection is active (client moving data) the TX would move to say 18 or 24Mbps. Once Idle the the TX would drop to 6Mbps. Now that I changed the basic rates 6-24 on the AP the same client sits at the 24Mbps TX rate and sometimes drop to 18Mbps. I think that sitting at a higher rate if any interferance is encountered the client TX now has a lower rate to fall to like 9 or 6. I'm just guessing... I have only had a few weak clients disconnect then reconnect whereas before it seemed like the majority of my 900 clients would reset.

Interesting. Will this work in regular 2.4ghz I wonder? BTW what do you guys recommend B or G?

Interesting. I'm still trying to wrap my head around *how* this would help, not arguing that it does. Just trying to figure out why...

I see that it would take less air time for just general link traffic, but will the speed still drop to 6Mb during noise or poor signal or will it just cut out?

My guess it that it does it by limiting the attempts to connect at a higher rate. Typically wireless routers attempt to transmit at the highest speed possible and then adjust downwards as package losses become unacceptable. By giving up the higher speeds, you limit the wasted attempts at the higher speeds. Also, different speeds are attained by changing protocols. Perhaps the lower (6mbs) protocols are more stable in this case. Mind you, back in the days when I experimented with SOHO linksys routers, I used to fix the speed at 5.5 mbs to keep the best throughput speed at long ranges.

Interesting. I'm still trying to wrap my head around *how* this would help, not arguing that it does. Just trying to figure out why...

I see that it would take less air time for just general link traffic, but will the speed still drop to 6Mb during noise or poor signal or will it just cut out?

After a day straight of running it with this configuration I have found that on the one particular AP where all clients would drop several times a day only 5 of the 17 are dropping now. This is much improved..... what I'm thinking is that since I run the DUDE the SNMP probing might be working better because the clients are staying connected at higher rates.... and I'm thinking that if there is noise / interference that the tx speed drops to 6mbps but stays connected now. All in all, much better.

One further note, I am going to be removing the Ubiquity cavity filters and adding some new ones that are tuned for 5.0Mhz on the appropriate center frequencies for each sector. I'm hoping that going this will eliminate any inband / out of band interference.

Hytanium, who did you get the new cavity filters from?

DCI

dci.ca

Do you need to add them to both the clients and the AP or just the AP?

Just AP

Wow, fairly pricey. Please let us know how they work as compared with the ubiquity filters. At twice the price, they better be good. I also noticed that they are 5.5mhz wide. Do you order them by the frequency?

Wow, fairly pricey. Please let us know how they work as compared with the ubiquity filters. At twice the price, they better be good. I also noticed that they are 5.5mhz wide. Do you order them by the frequency?

we've had to resort to using 2 of the ubiquiti filters, one of each model, back to back, to get by some of the interference problems we've seen in some areas...

that give us 16mhz to work with, at costs roughly the same as one of the 5.5mhz ones...

Last I checked, the 5MHz filters costs nearly $1000 USD. I have a source for UB filters for about $220 USD.

Different filters, different purposes, but...

WOW

This was amazing, your recommendations made one of our most problematic backhauls MUCH more reliable. It's very prone to interference and noise and we can't afford a filter yet.

Jumped from a TX/RX of 16/34 on the AP side to the high 50's/mid 60's
signal strength jumped way higher also!

MUCH better! THANKS!!!!

Good to hear! Just as a note, If anyone needs SR9 cards I have a bunch (30+), I have discontinued 900 service on one of my sites due to a Canopy co-locate.

i am interested maybe, email me billing at fcwireless

dot net

hytanium, if you still have a couple SR9's left, lmk. skeller47[at]gmail[dot]com

Ubiquiti has some great info on their site about this very isue with SR9 cards and the need to limit data rates.

Here is an excerpt from their white paper.

http://www.ubnt.com/downloads/SR9_Mtik_PtP.pdf

2.) Lower signal level and narrow bandwidth links benefit from limiting Data
Rates: At high and mid signal levels in 20MHz mode, the auto rate setting works
well, but when getting to lower signal levels (in -80's dBm), it appears link stability
(response times) improves with limiting the maximum data rate. This also becomes
even more important when operating narrow channel links at lower signal levels. It
is recommend to limit lower signal level links and especially lower signal 5/10 MHz
channel links to 18Mbps. This strategy also is beneficial in high random noise
environments.

It does not appear to work on their other cards.

J.