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nexus010
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Preamble problem

Tue Apr 08, 2008 8:32 pm

Running XR2 and XR5 on RB333 ROS 3.7.
Been having terrible throughout problems to my clients on this AP (XR2)
I spent considerable time testing this installation before putting it into production.
In trials all my clients connected with good throughput and connection rates.
Clients are 8186,2511,Crossroads and nanstations.
All working fine being fed by overloaded 8186.
When I put the entire group of clients over I started to see throughput problems.
Tried everything I could think off to no avail.(rebooting,b-g, b\g turned down power from default,enable disable wireless etc)
Ros went from 3.4 to 3.7 over this period ....no improvement.
Today while trying to work out why I was getting poor performance with a new Crossroads on this AP I turned the preamble from "both" to "short".
I lost all of my 2511's but my 8186,Nanstations and crossroads where all happy ,showing normal performance.
So I switched back to "both" to get my 2511's back on and was suprised that the throughput remained good for about 1/2 hour ,then went back to the previous abysmal scores.
Repeated the procedure with same results...

I'm going to try putting all my radios in Long see if it stabalizes....but f there is any one with the same xp I'd like to hear from you nothing I found in the forum search.
Cheers
 
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airstream
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Re: Preamble problem

Tue Apr 08, 2008 11:41 pm

Hi there,

both the XR2 and the XR5 need LOTS of juice to run properly. Some months back we had this same issue when upgrading from SR to XR cards on our RB's. (throughput slow, clients drop off randomly and yes sometimes the RB would spontanously reboot when doing a bandwidth test over the XR wireless)

the problems we were experiencing was fixed when we replaced the PSU for a 24v 3A switched adapter on the RB's that had XR's added.

Its also worth noting that RB's with more than one wireless card just fart around unless they have at least 18V going in (12v dont cut it!).
Keep tryin' its bound to work!!
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jordantrx
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Re: Preamble problem

Wed Apr 09, 2008 1:33 am

Hi there,

both the XR2 and the XR5 need LOTS of juice to run properly. Some months back we had this same issue when upgrading from SR to XR cards on our RB's. (throughput slow, clients drop off randomly and yes sometimes the RB would spontanously reboot when doing a bandwidth test over the XR wireless)

the problems we were experiencing was fixed when we replaced the PSU for a 24v 3A switched adapter on the RB's that had XR's added.

Its also worth noting that RB's with more than one wireless card just fart around unless they have at least 18V going in (12v dont cut it!).
I have a backhaul hookup that is running slow on a 36/36Mbs Link (it quotes thats my link connectivity) wiht a 69 dbm i cant get more than 5 megs at AP end. I have the AP hooked up to a 15V 1A power supply. This RB is a 133 with sr2 and 8602+ 200mw (in 5.8ghz mode) Do you think this throughput is due to power issues also? backhaul #2 is an rb112 with 8602+ with 12v 1.3 A power supply, Both are POE'd thanks -Jordan
~Agricultural WISP "ZONE"~ Beware of oncoming cattle and dont hit the farmer!!! I need to ask him about using his silo for an AP first"~

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airstream
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Re: Preamble problem

Wed Apr 09, 2008 2:40 am

Hi jordanTX,

From memory the 8602+ is a 400mw card (although it does step back the higher speed on B/G) but for 5.8 the best it will do is 100mw!. However in terms of power use - when TX'ing data it will pull 1A (just the card). look at the specs here:8602 datasheet.pdf
I have the AP hooked up to a 15V 1A power supply
says it all really, and PoE has some distance loss over cat5e (google for some PoE calculators).

It has now been noted in the RB documentation that at least 18V is required for normal operation. when using 400mw cards (XRx, SRx, etc) its a must. To be safe we went with 24v and all our problems with performance stopped on the units that we had XRx's/SRx's at.
Keep tryin' its bound to work!!
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jordantrx
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Re: Preamble problem

Wed Apr 09, 2008 2:42 am

Hi jordanTX,

From memory the 8602+ is a 400mw card (although it does step back the higher speed on B/G) but for 5.8 the best it will do is 100mw!. However in terms of power use - when TX'ing data it will pull 1A (just the card). look at the specs here:8602 datasheet.pdf
I have the AP hooked up to a 15V 1A power supply
says it all really, and PoE has some distance loss over cat5e (google for some PoE calculators).

It has now been noted in the RB documentation that at least 18V is required for normal operation. when using 400mw cards (XRx, SRx, etc) its a must. To be safe we went with 24v and all our problems with performance stopped on the units that we had XRx's/SRx's at.
Im just surprised it will kill throughput if power is not adequte... thats interesting.. But i will go get a 24 v Power supply and post back and let you all know what happens to my throughput. thanks airstream. -Jordan
~Agricultural WISP "ZONE"~ Beware of oncoming cattle and dont hit the farmer!!! I need to ask him about using his silo for an AP first"~

*Automated Billing Installer* http://wiki.mikrotik.com/wiki/AutomatedBilling Built by Krige ;-)
 
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nexus010
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Re: Preamble problem

Wed Apr 09, 2008 4:42 am

Hi Guys Thanks for your "input".
I'll grab a PS tomorrow if I can find one.
Airstream do you have a link for the PS you are using.
I'm "currently" using 24v 1a PS.
Supplier siad it would be plenty......
I see I can give it 48 V but the board does not work with IEEE802.3af compliant 48V power injectors.
Funny the crossroads can do both !
I will report the results.
Hope thats all it is.
 
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nexus010
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Re: Preamble problem

Thu Apr 10, 2008 1:48 am

Ok I have spent the day going over the potential of this being related to power and have crossed it off the list of suspects.
I started with a call to my supplier he indicated that a 24v 1amp supply should be more than adaquate.
I tested this nonetheless and saw that it was draining .25 of an amp which is 6 Watts
(.25a x24v =6w)
I thought perhaps there was a problem with the power supply so I bought a 24v 6.6 amp Ps
Installed it and tested it with no change to the power drain (.24 a).
This test was performed on the working accesspoint poe'd over 70 feet of cat5 XR5 and XR2 and enabled both connected to their respective bridges and all clients.
I see no problems whatsoever on my XR5 which is connected to 3 distant nodes
all working fine all clients being fed at normal speeds...
This XR2 is currently the only one that I'm having trouble with....

More to the Preamble issue .
I reaslised last night that the 3 senao 2511's which where previously served by a highpower low memory 8186 had no problems with "short" preamble selected for the last 3 years...
I teseted again when I enable "short" preamble in the XR2 the 2511's don't associate...
The 8186 and the Crossroads do. I get speed for awhile and then I'm back to under 400kbit.

I really don't know what to think.

Help with this would be sincerely appreciated.
Cheers
 
snowpro
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Re: Preamble problem

Thu Apr 10, 2008 4:04 am

I ran a xr5 and xr2 for a short while with 24v 1a ps but all on the xr2 was in b mode only

Did a lot of testing and throughput was good

(should go for a beer....)
 
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nexus010
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Re: Preamble problem

Thu Apr 10, 2008 4:15 am

Hey snowpro!
I've tried b mode only, not helping .what is not making sense to me is that I had an 8186 in B/G driving these clients way better than this.
I upgraded with better quality of service for more upcoming customers in mind.
I also had these same customers on a smc2888m which is atheros based enterprise bridge.
It only had 100mw out in a and b/g but it was still way better than this and no interop probs.
I don't know if this is a MT problem or Ubiquity but it doesnt make sense to me that equipment with this level of performance capacity is pretty much useless to me.
I have wasted near to 2 months since I bought this gear I'm ready to try a wrapboard with the same cards and see what happens.
Pretty much at wits end
Hows your knee ?
Really should go for that beer.
Tomorrow night ?

Cheers!
 
snowpro
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Re: Preamble problem

Thu Apr 10, 2008 7:10 am

I wonder if you tried one of those cards on a separate board like a 532. I have one you could try. Tomorrow is fine. Will call.
 
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nexus010
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Re: Preamble problem

Thu Apr 10, 2008 3:03 pm

No I haven't but lastnight I tried swapping out the XR2 for an SR2.
The clients show slower overall connection rates in registration. some that were tx11/rx5.5
are tx5.5/rx2 .Which is probably a reflection of the power and sensitivity issues with the cards.
Throughput improved to 1 mbs and but is jittery.
I was thinking of a different board this morning I'm going to wire in a Crossroads and tie it into a switch so that all that will be on the RB333 will be the XR5
FYI this setup is a transparent bridge no routes.
All interfaces tied back to a bridge stp enabled.
This was a replication of the current config at this node.
I will move to a routed network when I have a system I can work with.

Tonight is good look fwd to beer and radios LOL.
 
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airstream
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Re: Preamble problem

Thu Apr 10, 2008 9:47 pm

FYI this setup is a transparent bridge no routes.
Just worth pointing out - each bridge in your data path will halve throughput. Routed links are far better :wink:
Keep tryin' its bound to work!!
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jcremin
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Re: Preamble problem

Thu Apr 10, 2008 10:31 pm

FYI this setup is a transparent bridge no routes.
Just worth pointing out - each bridge in your data path will halve throughput. Routed links are far better :wink:
Actually, simply bridging isn't what cuts the bandwidth in half... it's using a WDS bridge that also acts as a repeater that causes the bandwidth to be cut in half.
 
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nexus010
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Re: Preamble problem

Thu Apr 10, 2008 11:24 pm

I understand the impact of wds.
I don't think I understand that the bridge would divide throughput..?
If so divide what ? the total avialable bandwidth ?
or the total speed of the ethernet interface.
Are you sayin the bridge statically devides data?
So as I have an XR5 and 3 wds connections on it that each wds interface is getting a third of the available throughput? and that the XR2 was taking 1/2 of that ?
I would have to argue that there is no evidence of that in the field
I can test a clent in the distance off one of the wds legs and see the 4800+kbit there. If what youre say is is true I shouldnt be able to see anything at all.
My understanding is that a bridge is a switch.In this case one that is deliberatly tied to the varoius required interfaces ethernet ,wlan wds(virtual)
Data flows on demand and that when the supply is exceeded from the needed source or the maximum interface speed is exceeded then you hit a wall. if one interface needs 1mb and another needs 5 but the max available is 8 the interface that needs should get all 5 not be held off at 4. What your talking about is a hub.
At least this is my understanding...
I can be corrected ........however,
I removed the SR2 altogether and put a crossroads to work.
It is wired back to its own port on the switch in my noc.
This is working fine... an unthrottled client is showing 4800+kb from speakeasy same client could not pass 200 kbit this morning.
I have other equipment that has internal bridging and I have never seen this.
It was like there was a bandwidth limiter in effect and that 2000kb was all that was available total to the XR2/SR2. I did have the limiter on earlier so I'm wondering if got "stuck" but it was not 2000kb per client if it was on it was 2000kb total.
I'm going to set up the XR2 on it's own board and do as above with the crossroads see what I get.

If what your saying about the bridging on the rb333 or ros in general is true then it makes no sense to buy a routerboard with more than one wireless interface and tie each back to a switch when you want a transparent node.
Its a waste of space and this is certainly not what I was told by the supplier.
I eagerly look forward to your comments on this because if I have missed the ball on this I need to know.
Cheers
 
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nexus010
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Re: Preamble problem

Thu Apr 17, 2008 3:57 pm

I haven't had the time to follow up on this for some time .I have been in the trenches.
I never got the Rb333 with either the XR2 or the SR2 as a standalone access point.
nor did I get them to to work with an XR5 on another RB333.
The soloution was to put up the crossroads and walk away from the rb333 setup.
I had tested this gear in a non production enviroment with three clients and a 5.8 Ghz bridge representiitve of the existing equipment I have in production in that enviroment everything was fine after ros 3.3.
After 3 weeks I put it into full prodution and gave myself and my customers a week of hell.

I was thinking well at least the crossroads is dependable I had 2 in production working fine then I lost 3 days with a third that was programed identically to the other 2 but never worked ,clients would register but never pass packets.....Did everything on gods green earth to try and make it work, including driving over 600 km back and forth to the site.

I have been asking myself how can I ever test suffiiciantly to safe gaurd against this ever happening again?
The answer is I can't, it would be irrisponsible.
The potential was tantalizing enough for me to bite and I invested a significant amount of capital to have it sit in a box in my shop,and set me back a month in a very important part of my year and a very important stage of my business.
Wasting my time reading forums instead of reading a proffesional manual has not helped with my overall sense that I'm wasting my time here.
I know there are lots of success stories I really wanted to be one of them.
I have over 100 customers 3years eperience and so it seems to me there is something fundamentally wrong when an 8186 can come out of the box and do what it should for a fraction of the cost and zero headaches (unless it's cold).
and I yet can waste a month on "better" equipment.
I don't know what the board designer was thinking with the rb333 you can't use 2 cards from the same band
on it the cards are too close you can't use 3 XR series cards the heatsinks deflect the cards. the board doesn't fit into any standard case, and the brochure doesnt warn against this.
The crossroads while it might be better (jury is out) comes with ufl connectors.
Does Mikrotik hate its customers ?
Have you not ever had to work at height swapping out a board?
ufl is for consumer junk.
Ubiquity uses MMCX ,Realtek 8186's come with a SMA connector both can support a decent size dimension of coax and a light breeze.
I will be investing my money and time elsewhere.
As a produtive WISP to any other WISP's you have my warning,
Don't waste your money or your time.....
 
SurferTim
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Re: Preamble problem

Thu Apr 17, 2008 4:53 pm

Turned power down? Then you know about the SR2/XR2 power offsets? The SR2 has a 10db power offset. I understand the XR2 is even larger. If you set tx-power to anything above 16, you will have intermittent heat problems and eventual failure, according to many here on the forum.

I went the other way. I was unhappy with the SR2 performance/cost issue. I use the R52 and R52H cards now. The only down side I can find is the ufl connector. I also would prefer mmcx. I will get my first RB300 tomorrow, so I will see first-hand. So far, I have not been disappointed with any of the MT products. I guess I'm just lucky?
 
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nexus010
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Re: Preamble problem

Thu Apr 17, 2008 7:54 pm

Surfertim are you saying turn the power down below default ?
As I understood the MT power offset issue was a problem if you manually entered in the "correct" power for the card .(XR5 and XR9 as well.)
Both by Ubiquity and MT indicate that default is correctly adjusted for the card.
Have I got this wrong?
As far as the Rb 333 goes 1 out of 3 worked fine the 4th is untested no time for that.
No time for this either.
You might want to see my other post "Not happy with your product"
 
SurferTim
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Re: Preamble problem

Thu Apr 17, 2008 8:09 pm

Just read it. I get my first RB333 tomorrow. I will be installing a R52 in it tho.

I had not heard the power offset had been corrected in the newer versions of the OS. They say you can turn it down more than in V2.9. The minimum limit used to be 14 in that entry. That is 24db. Too much for my antennas.

Can anyone verify this before I use the new version OS?

EDIT: Heck! I'll just start a new post.

What interface do you use? Winbox or CLI. I am a command-line kinda guy.
 
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Re: Preamble problem

Thu Apr 17, 2008 10:22 pm

Did you see Jordan's response to my post? I will presume that the offset has been partially corrected. If you use Winbox, then it will show the power setting and the entry it will use to obtain it. If you ssh (CLI interface), then it appears you must do the conversion and enter a number 10db less in tx-power.

If this is incorrect, I would certainly like someone to let me know.

It may be the XR2 was overheating, and that caused the malfunctions.

As someone else said in another post: I would not be too quick to give up on this O.S.
I have become quite fond of it. I use the command-line interface. And to make things clear, I am in no way connected or affiliated with MikroTik or RouterBoard, except as a customer.

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