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Bigforky
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WDS connected via cat5 - is this feasible?

Mon Aug 24, 2009 5:36 pm

Guys, I have a question about using the 'roaming' access point functionality with WDS...

The issue I have is the physical building I need to cover with decent wireless is a radio nightmare. Its a large freezer building about 100 meters by 50 meters and it broken up into about a half dozen rooms. Since all the walls in the facility are metal, and inside the rooms are full of metal racking loaded with frozen food wireless doesnt work very well moving from room to room - and a connection only via wireless to the other AP's would not work well when the doors close (which is most of the time).

My goal is to put in a bunch of mikrotik AP's and have them run on the same SSID with the same key code so the forklifts can travel freely from room to room without loosing network connectivty. Since the walls and doors are metal creating a very RF tight seal between the rooms, I need to connect the various AP's with physical cat5 cabling.

Is there a way to configure the Mikrotik boards to run WDS, but maintain the connectivity between them with physical cabling vs wireless peers with WDS?

Thanks in advance for the help!
 
rpress
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Re: WDS connected via cat5 - is this feasible?

Mon Aug 24, 2009 8:41 pm

What you want is simple roaming, I don't think you need WDS. Just set each AP to the same SSID, WPA key, and in your case, channel, and you should be fine.
 
andreacoppini
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Re: WDS connected via cat5 - is this feasible?

Tue Aug 25, 2009 12:40 am

side-note... MikroTik doesn't do roaming very well (in other words: MikroTik doesn't do anything to assist in roaming at all)

Other vendors have used standards like 802.11r and CCX to assist the clients with roaming from one AP to the other, and having diversity antennas helps a great deal when you have mobile devices in a highly reflective, indoor environment like the one you're suggesting... and MikroTik stubbornly refuse to implement diversity. The new 11n support has introduced a form of diversity, but that is still in beta.

And to go back to your original question, as rpress said, what you want is simple roaming. Roaming is primarily a client-side feature, so make sure you are using good quality client devices.
 
Bigforky
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Re: WDS connected via cat5 - is this feasible?

Tue Aug 25, 2009 12:57 am

OK...thanks guys...leave it up to the mobile forklift computers to figure out the jump....

So then...just for my ongoing mikrotik education, WDS is more of a means to put in essentially AP repeaters to expand the area of an AP's coverage without then need for additional cabling - correct?

Thanks again...
 
andreacoppini
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Re: WDS connected via cat5 - is this feasible?

Tue Aug 25, 2009 1:09 am

Yes. WDS is for bridging wirelessly between two APs.
 
JwTPN

Re: WDS connected via cat5 - is this feasible?

Tue Aug 25, 2009 8:44 am

Why not use one AP but run "Leaky" Coax through the freezer area from end to end?
the savings in buying/maintaining lots of Active gear will most likly pay for the cost of such coax after a short amount of time.

Cheers

Justin
 
Bigforky
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Re: WDS connected via cat5 - is this feasible?

Tue Aug 25, 2009 5:28 pm

JwTPN...leaky coax...wow. After years of being an amateur radio enthusiest I have now found use for the roll of rg59 that's been floating around in my closet. It's quite the opposite concept of what I have been doing with coax for years.....

If that actually works - that would be quite clever. this sounds like a heck of an experiment....
Does anyone have any suggestions on what coax perferoms the best (or worst depending on the perspective) for this sort of scenerio? RG6 or RG58 would be the easiest to obtain - but I wouldnt have an aversion to trying something different.

There are a ton of reasons to install fewer AP's - you just need to ask anyone who has tried to terminate ethernet cabling when it's -15 F outside (it gets quite brittle).

Thanks for the great ideas guys...time to start playing and see what happens...
 
andreacoppini
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Re: WDS connected via cat5 - is this feasible?

Tue Aug 25, 2009 6:17 pm

Leaky coax does not = bad coax! :) It's a special type of coax cable with slits in the shielding. Usually the slits are cut in specific lengths in a specific pattern tuned to the wavelength of the signal it should leak.

See http://www.networkworld.com/newsletters ... less1.html and http://www.commscope.com/andrew/eng/pro ... 13611.html

And.. did you say RG-59/RG-6? That's 75 ohms, forget using it for WiFi. WiFi is 50 ohms. At best you could use RG-58, but that would possibly be the worst choice you'd ever make (besides working in the wireless world :) ).


I would personally avoid leaky coax due to the amount of noise it picks up along the way, but I've never used it myself so I can't really judge.
 
Bigforky
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Re: WDS connected via cat5 - is this feasible?

Tue Aug 25, 2009 8:37 pm

Touché andreacoppini -….lossy vs leaky coax….I really set myself up for that one and earned a good chastising.

The noise issue does concern me a little….but I would never know unless I actually tried it. We do have one advantage (or curse) and that the building is a perfect faraday cage so external RF is a non issue…however there is a ton of metal objects for RF to bounce off of, and plenty of sources of electrical interference like blower motors and lighting.

The concept is interesting to say the least. I’m not convinced this will be solution for us; but it certainly makes for an interesting tavern discussion some evening with my radio cronies.
Regardless, we are way off topic of my ‘misunderstanding’ about WDS’s capabilities. I’m a better person now, and hopefully someone else will benefit from this as well….

Thanks!
 
JwTPN

Re: WDS connected via cat5 - is this feasible?

Wed Aug 26, 2009 12:09 am

yes andreacoppini had it right, its a special coax (usualy 1/2" or larger) with slits in it.

Used a bit on cell site builds in things like shopping malls etc, very good for discrete and hard to do site in fill.
RFS and Andrew (comscope) both do 2.4ghz "Radiating Coax" and theres even multiband stuff for deploying cell phone and wifi...

Cheers
 
andreacoppini
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Re: WDS connected via cat5 - is this feasible?

Wed Aug 26, 2009 1:17 am

mind you.. leaky coax exists and it's sold, so it must have been deployed successfully by some.

I guess.. :?
 
Zapnologica
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Re: WDS connected via cat5 - is this feasible?

Fri Oct 09, 2009 8:16 am

Yes. WDS is for bridging wirelessly between two APs.

Instead of using WDS would it be faster to just get a RB with 2 mini pci cards and set one to station and one to bridge?

Wouldn’t this allow 100% throughput on each "bridge" vs. +-50%?

So MIkrotik does not support combining several wireless networks together t form one. Like a cell phone provider network would have?


If you just name both your networks the same name and password and you searched your client.
Wouldn’t you just find 2* your ssid name instead of 1* your ssid name @ a better signal?


Reason im asking is, I would like to put up 3 * 90 degree sectors with a RB433H and they will overlap slightly.

i want the covered area to pick up one stronger signal as the clients are all spread out?

And in the future would like to put up more towers in nearby areas that "repeat that network"?
 
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Re: WDS connected via cat5 - is this feasible?

Fri Oct 09, 2009 9:05 am

yes that would work, but it relies on the client to initiate the roaming between APs. Some AP vendors assist by implementing 802.11i for seamless roaming, but MikroTik doesn't. If you use a MikroTik AP in this way, clients will have to take a 'break-before-make' approach, which results in a lot of packet losses.

What you want to achieve, having multiple base stations with the same SSID, is definitely achievable. In fact it is how most WISPs are set up. In your case, the client will not roam between APs very often (if at all!).
 
Zapnologica
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Re: WDS connected via cat5 - is this feasible?

Fri Oct 09, 2009 6:47 pm

So would i just set it up with having the same SSID?
 
andreacoppini
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Re: WDS connected via cat5 - is this feasible?

Sat Oct 10, 2009 12:48 am

yes of course.

same SSID, same frequency band
 
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Re: WDS connected via cat5 - is this feasible?

Sat Oct 10, 2009 3:51 pm

will you pick up 1 or 2 networks then?

how do cellphone providers do it?
 
andreacoppini
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Re: WDS connected via cat5 - is this feasible?

Sat Oct 10, 2009 9:44 pm

Depending on the client.

The Windows client will show you each individual AP as a separate entry (all with the same SSID), but once you're connected, it will automatically choose which AP it will connect to based on signal strength.

In your setup I'm assuming you will have MikroTik or Ubiquity CPEs (clients). Not sure about the Ubiquity, but MikroTik will show you each AP as a separate entry as well (like Windows), but as long as the SSID is the same, it will connect to the AP with the strongest signal. Should that AP become unavailable for any reason (powered off, reset, moved, etc), the client will scan for another AP with the same SSID and connect to that one instead.

There can be as many APs as you want, as long as they all have the same SSID, the client will always connect to the one with the best signal.

Conceptually, cellphone systems are very similar to WISPs, but keep in mind that cellphone technology (GSM or UMTS nowadays) was built from the ground up with voice in mind, over long-ish distances, with small, low powered CPEs (mobile phones).. so it will always be much more robust than you will ever get with an 802.11 based setup like MikroTik, or any other license-free technology.


-- Sidenote: I'm oversimplifying here, there are many features in MikroTik to control which client connects to which AP, but a search in the Wiki, the forum and the docs should give you a good idea how all this works.
 
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Re: WDS connected via cat5 - is this feasible?

Sat Oct 10, 2009 11:55 pm

same SSID, same frequency band
Say again? I thought the whole idea was to keep the channels clean. So first channel 1, then 6 then 11 and then back to 1?
 
andreacoppini
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Re: WDS connected via cat5 - is this feasible?

Sun Oct 11, 2009 11:44 am

Yes exactly... that's why I said same frequency band, not same frequencies.
 
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Re: WDS connected via cat5 - is this feasible?

Sun Oct 11, 2009 9:42 pm

Yes exactly... that's why I said same frequency band, not same frequencies.
I wasn't listening properly. Sigh.

Thanks.
 
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Re: WDS connected via cat5 - is this feasible?

Wed Oct 21, 2009 6:46 pm

oh ok.

I thought that there way maybe a way to make it use it as one.

So say you had one AP and you get a signal of -80 then you put up annother one then your get -69?


so that the client like combines the wireless to one and increases speed and signal?
 
andreacoppini
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Re: WDS connected via cat5 - is this feasible?

Wed Oct 21, 2009 7:07 pm

So say you had one AP and you get a signal of -80 then you put up annother one then your get -69?

so that the client like combines the wireless to one and increases speed and signal?
That is definitely something which will NOT happen. Whatever technology you use, it's always a one-to-one connection. One client radio associates with one AP radio. One AP radio can have multiple client radios, but each client must associate with one, and only one, AP radio.

With that out of the way...

Let's say you you have an AP powered on and an client is connected and has a -80dBm signal strength. While that client is happily connected, you power on a new AP. This new AP is closer to the client, so it would have a -69dBm signal strength. What happens next depends on the client. The client could:
- Immediately roam to the new AP with a better signal; This is how most laptops behave.
- Stay on the same 'old' AP, until it gets disconnected. When it does get disconnected, it will scan the air and find the better AP, and associate with that. This is how a MikroTik station behaves.
- Stay on the same 'old' AP, even if it gets disconnected and tries to reconnect. This is how very badly designed wireless devices work (some phones, cheap wireless print servers, etc). These are known as 'sticky' clients, because they will try to associate with the last AP they have connected to.. no matter what.


BTW, please don't post on this thread anymore, we've gone off-topic way too much.
 
Zapnologica
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Re: WDS connected via cat5 - is this feasible?

Tue Nov 10, 2009 7:37 am

Does Mikrotik not have a "repeater: option.

I have seen on a commercial wireless ap that it had a repeater function.

IT connected to the other AP via lan and then just repeated the wireless.

So do large WISP networks like Iburst or Neoltel set up their networks like that with.

Have loads of ssid’s?


Ok i just really thought there was a way to combine them cause its quite unethical, as each client only makes use of one radio,

It would be really cool if it could like split the data over each radio according to its signal strength.
 
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Re: WDS connected via cat5 - is this feasible?

Wed Nov 11, 2009 9:46 pm

Can i mikrotik RB be setup to act as a repeater????
 
andreacoppini
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Re: WDS connected via cat5 - is this feasible?

Wed Nov 11, 2009 11:47 pm

Repeater, yes: http://wiki.mikrotik.com/wiki/Wireless_repeater

But what you're asking for is not repeater, you're looking for the regular AP mode. http://wiki.mikrotik.com/wiki/Making_a_ ... ireless_AP

You can have as many APs as you want, as long as they all have the same Band and SSID (not necessarily same channel), the clients will always connect to the one with the best signal.
 
Zapnologica
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Re: WDS connected via cat5 - is this feasible?

Thu Nov 12, 2009 6:45 am

With a repeater would the client also just choose the strongest tower???

Or does the repeater just streangthen the ame channel,ssid etc.?
 
andreacoppini
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Re: WDS connected via cat5 - is this feasible?

Thu Nov 12, 2009 10:40 am

A repeater appears just like any other AP to a client.

The only difference between a repeater and a regular AP is that the regular AP connects to the network via a wire, while a repeater uses another AP to hop off from.
 
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Re: WDS connected via cat5 - is this feasible?

Thu Nov 12, 2009 1:00 pm

So i if have a Ap then 1km away a repeater of that AP, both with Omnis on and i setup a client in the middle of the two im still going to find 2 networks.



Do you think that they are ever going to design technology that combines the wireless.

Cause i just cant grab the concept, its so point less haveing to APs covering 1 area when its only going to use one. its just liek bad planing,

to do it efficianlty you have to plan your network layout so well and have a map with each AP's coverage.

The only reason i can think why i would want to do this is if each AP was overloaded and coulnt cope with the clients.

Just a thought,

Say you picked up 2 networks (your tower) one has signal of -75 and te other -60

if you had a RB with 2 wireless cards couldnt you set them up like a bridge, so the one card connects to the one AP and the other to the 2nd AP.
 
andreacoppini
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Re: WDS connected via cat5 - is this feasible?

Thu Nov 12, 2009 2:42 pm

So i if have a Ap then 1km away a repeater of that AP, both with Omnis on and i setup a client in the middle of the two im still going to find 2 networks.
You are going to see two APs. Like I said, a client doesn't know if an AP is a wired AP or a repeater. If the client is in the middle it will just connect to the one with the best signal, that's all it cares about.
Do you think that they are ever going to design technology that combines the wireless.

Cause i just cant grab the concept, its so point less haveing to APs covering 1 area when its only going to use one. its just liek bad planing,

to do it efficianlty you have to plan your network layout so well and have a map with each AP's coverage.
Yes, and that is partly the reason why GSM telephony is so expensive.. part of those costs go towards planning and maintaining coverage throughout the expected coverage area. Broadband wireless is very similar to GSM telephony in concept. You have a number of 'cells' (wireless=APs, GSM=base stations) which have a determined coverage depending on the antenna they use. If they use omnis, they have a 360deg coverage. If you need to extend coverage further away, you add another cell, and you get another 360deg coverage around that new cell. Clients (wireless=stations, GSM=mobile phones) constantly look for a better cell and 'move' (wireless=roaming, GSM=handover) between the cells to ensure a good connection.

The client uses the network name (wireless=SSID, GSM=Network ID) to decide if a cell is part of the same network or part of another, foreign network. So as long as all the cells are broadcasting the same network name, the client device will keep moving between cells to achieve the best signal.

phew.. that's a mouthful..
See http://en.wikipedia.org/wiki/Cellular_network for all the technical info.
The only reason i can think why i would want to do this is if each AP was overloaded and coulnt cope with the clients.
Yes, and just imagine if you could, in theory, cover the whole of USA (or even just a whole city) with just one GSM cell, you would have thousands, possibly millions of client devices fighting for their turn to access the cell... that would simply not work.... same goes for wireless. So you have many 'small' cells each handling a bunch of clients.

The other reason why you'd take a cell approach is because RF power (especially microwave frequencies which are used by wireless) gets lost very quickly in the air, so you would need a very, very, very, very powerful transmitter to cover a whole country with just one AP.. and your clients would need just an equally huge transmitter at their homes to transmit back to the AP.
Just a thought,

Say you picked up 2 networks (your tower) one has signal of -75 and te other -60

if you had a RB with 2 wireless cards couldnt you set them up like a bridge, so the one card connects to the one AP and the other to the 2nd AP.
Yes, you could, because the RB has 2 wireless cards, which means you have 2 clients. To the AP, the two clients appear as two independent clients, the AP doesn't know they are physically in the same box.

Hope this helps.

PS: this topic is starting to sound like a wireless support line.. please create a new topic if you have new questions.
 
Zapnologica
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Re: WDS connected via cat5 - is this feasible?

Thu Nov 12, 2009 6:30 pm

Thanks allot,

last q,
can wireless roam from one ap to annother easily?? like could you be making a skype call in a car while driving around your tower and it wont like disconnect as it changes Aps.
 
andreacoppini
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Re: WDS connected via cat5 - is this feasible?

Thu Nov 12, 2009 6:39 pm

MikroTik is not really built with roaming in mind, so it doesn't work very well in a standard configuration.

However there were some people on this forum who were trying to use it for streaming video feeds off F1 cars, I don't know how that worked out but you could do a search.
 
Zapnologica
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Re: WDS connected via cat5 - is this feasible?

Tue Nov 17, 2009 8:00 am

Well i have some feed. back

I just tried it at home.

but i named all my 4 AP's the same name and pasword. and all the computers/phones only pick up one network and it works amazingly well. i pretty much have ful signal over my whole house.

and with the roaming, i have a nokia N97 i can walk from one side of the house to the othere and it jumps between AP's as i go along.

i must say i am quite impressed.

Thanks for all the help.

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