I am trying to setup a wireless network in Arlington, TX. There are a four two story buildings. These units have a huge negative cashflow so I am working with a sub $1000 budget. I cannot pay for a professional survey. And it is impossible to run wires or use existing wire. We are trying to provide minimal Internet service to all units (25). Our service is delivered to an un heated building/utility closet. (We have a comcast cable modem, Static IP, 6-8Mbs service.) The units installed need to handle (-20F - 120F) operating tempratures.
Our intention is to provide minimal QoS. This is not intended to support VOIP or music download, but rather enable our clients to read their email and browse the Internet.
There are no trees that would interfere with this project. The lay out is as follows: (Note please forgive my drawing I had a very difficult time lining things up. I had to use dots and number signs to denote space, otherwise, all my lines would get squished together!)
Note: the dots (.) represent interior space, and the number signs (#) represent exterior space. The dash and vertical bars (-|) represent exterior walls. The extrior walls are stacco and the building are not very deep (they are about 20 - 25ft deep.
The service comes to the little building marked X. Building D is the farthest building and blocked by building C. The end units on building D are about 150 ft away from the building marked X.
Our plan is to place two ValuePoint "SuperAP 530g" (300mW) each with 7dBi ominidirectional antena. One at location X, and the other on the middle of building C facing the buildiing D (marked with *). The theory being that while the unit in X may be strong enough to send a signal the building D, the clients in the building D may not be strong enough to send a signal that would travel through building C.
The ValuePoint engineer assures me that AP530g can be set up so that they are bridged togehter and additionally act as Access Points.
I have at least one dilema. I would think that we also need a router/firewall/NAT and we need to find an inexpesive one that works in our temprature range (-20F - +120F).
My questions are:
1. Do you guys see something obviously wrong with the design/setup?
2. Can you suggest an inexpesive router (given our temprature requirement)?
3. Is there a better alternate solution?
4. Do we need a router? Can the access point alone work? The ValuePoint engineer seemed to think one was necessary. Although, he could not recommend one.
Best regards,
Patrick
M/Q
10-12-2006, 08:41 PM
I have lots of questions.
1. Are you expecting the 2 radios to service the entire complex just by themselves?
2. When you say 23 units is that the number of clients?
3. Is this structure existing already? If so have you thought about Google Earth and if a satellite image of the facility, as that would be easier to understand.
4. Do you realize if you bridge the two radios the second one and expect it to act as an AP as well, it will lose have of it throughput?
5. If you expect just the two devices to paint the entire area and all of the units to have coverage, have you made any tests at all to see if this is possible? There could numerous physical and electrical obstructions that will block the signal.
6. Do you have any kind of QoS agreement with the clients as they all will expect to have connectivity?
7. Did the ValuePoint representative feel this was a workable situation? If so what kind of guarantee did they offer if there were problems?
If I am looking at this correctly and you only have $1K to spend I would try a different approach, albeit a little radical, I think it would work and have a better chance of giving everyone the required amount of coverage.
Remember I said radical, as it uses consumer grade devices that have been flashed with a third party firmware. A LinkSys WRT54GL is approximately $60. The DD-WRT firmware is free and it turns the device into a very powerful and configurable device. With that in mind, I would determine how many devices would be required to cover each building sufficiently.
The topology I am considering is to have a WRT54GL at the cable modem as a bridge client. Then on building C have another WRT54GL as the other bridge client. Connect that router to another WRT54GL that is configured as an AP. Also if building C needs other APs to cover it fully have them connect to the switch portion of that AP.
Next on each of the other buildings have another WRT54GL acting as an AP client. At each building then have the required WRT54GL connected to the respective AP Client and servicing the clients of that respective building.
Cable Modem
|
| Signifies Ethernet cable
|
>- WRT54GL acting as bridge client at building X
<>
<> Signifies wireless link
<>
>- WRT54GL on building C acting as other bridge link
.|
.>- WRT54GL acting as AP
.<>..<>..<>..|
.<>..<>..<>..>- APs required to cover building C
.<>..<> ..>- AP client on building A
.<>..<> .|
.<>..<> .>- APs required to cover building A
.<> ..>-AP client on building B
.<> ..|
.<> >- APs to cover building B
.>- AP on building D
|
>- APs to cover building D
The WRT54GL acting as the backbone AP on building C may require a healthy omni-directional antenna, where as the AP clients on the rest of the buildings may require a small directional antenna pointed at building C. Small weather proof boxes and using PoE to power the devices on the roof only requires running Cat% up to the roof.
The whole key to this is the new firmware DD-WRT which takes a mediocre device and turn it into a totally configurable device that can act as an AP, AP client, bridge client, router and WDS repeater. This link will describe the firmware.
http://www.dd-wrt.com/dd-wrtv2/index.php
I told you it was strange, but I personally feel that this approach has a much better chance of succeeding. The total number of radios depends on what is required to cover each building. The for sure number of radios is 6 and with all of the ancillary equipment I suspect it still will be under $1K.
patrickjhill
10-13-2006, 01:02 AM
M/Q thank you for your thoughtful response. I have been reading your posts, I am amazed at your wealth of knowledge in this area, and the frequency of your contribution to the community--many thanks!
I have attached a marked up image of the property in question.
1. Are you expecting the 2 radios to service the entire complex just by themselves?
Yes. There are only a few units that have computers. This is not a high end neighborhood. Although, the hope is that eventually all tenants would have computers.
2. When you say 23 units is that the number of clients?
There are 25 units. And eventually all would have a computer. The expectation is that the peak load would be 15 simultaneous computers.
3. Is this structure existing already? If so have you thought about Google Earth and if a satellite image of the facility, as that would be easier to understand.
I have attached a marked up satellite view.
5. If you expect just the two devices to paint the entire area and all of the units to have coverage, have you made any tests at all to see if this is possible? There could numerous physical and electrical obstructions that will block the signal.
No. There is no money to do a survey. I am very confident that service to A, B, and C would not be a problem there is no entity nearby to interfere, there is no concrete barrier, and there are no trees in the way. Building D is another story. And it would require a prayer or two.
6. Do you have any kind of QoS agreement with the clients as they all will expect to have connectivity?
None. If the tenant is a heavy user and unsatisfied then they could get their own service. This is to offer minimum service to low income tenants.
7. Did the ValuePoint representative feel this was a workable situation? If so what kind of guarantee did they offer if there were problems?
I was speaking to a SALES engineer. He seemed confident about their ability to deliver. I understand that they sell equipment used for hotel and hot-spots. And we would expect similar traffic. Is there a question that I should ask? And is there a measure that should reply with? For example, should I ask them what is the XXXX of your device? and they should say that their device's XXXX is YYYY or better and it would support ZZZ simultaneous clients.
Remember I said radical, as it uses consumer grade devices that have been flashed with a third party firmware. A LinkSys WRT54GL is approximately $60. The DD-WRT firmware ...
Wow this sounds cool. However, I have an environment issue the location that that Internet arrives (marked with X in the satelite image) is unconditioned and in Dallas area it could from blow freezing to 120F inside of the unconditioned building. So I would still need that first bridge/router to be outdoor unit (i.e. be able to operate between -20F and +120F) Is there an outdoor version of WTR54GL?
golfnut
10-13-2006, 01:58 AM
If you're going the route that M/Q suggested with dd-wrt, which is a very good idea considering the budget, you can also make it a hotspot with user QoS.
This will keep near-by people from accessing the network without a username and password. You can also limit bandwidth by user. A few folks downloading music will make it really bad for everyone else without some controls.
The only catch is you need a Linux pc on the network to take advantage of the hotspot features with dd-wrt. If you understand Linux, I'll walk you through the steps.
Greg
M/Q
10-13-2006, 08:30 AM
I have run that particular router to those extremes on numerous occasions, but it is not as per the LinkSys specification. I am in MN and the cold is not the problem it is the heat obviously.
I also had assumed that the buildings had flat roofs, but it appears that they are the typical sloped variation. That makes it a bit more difficult unless you have access to the attic area. If you have access to the attic, is there a way to run cable down into the ceilings? If both of those are possible then my approach is still feasible. If not then you will have to try and paint the buildings as you suggested.
I have serious doubts about the two outside radios being able to penetrate to all points of the buildings. Are those double sided dwellings or just single side by side? In reality there are many cases where the RF signal can not get from one side of the house to the other and that may only be 30-40 ft. What is in the rooms (aka microwave, refrigerator, metal studs, etc will mess up the signal).
IMO, you do not need a professional site survey. Just take an AP, set it up on X and see what kind of coverage you get. It does not have to be fancy, just something to get an idea. With that information you can move that AP to C and see how that coverage area develops. Just maybe the two devices will be enough if the structures are not obstructing or reflecting the signals.
I really would not want to try this cold, I have many ideas as to how to accomplish this. But, I would not want to guess, as that most likely will fail and end up costing more money. A minimal amount of testing would easily dictate which is the best solution.
patrickjhill
10-13-2006, 12:02 PM
The units are side-by-side. I.e. the signal needs to penetrate the building, but needs not go all the way through the building (end units on C may have problems as the signal may have to go through too many walls.)
My problem is that I am in San Francisco, the property is in Arlington, TX. Even a rudimentary survey as you suggest is not possible.
I guess I just have to jump in and see what happen.
However, if I am going with the painting the buildings with two APs solution. I still need a recommendation for a router that would work in exterme heat and would be inexpensive. Any suggestions?
M/Q
10-13-2006, 05:23 PM
I would like to ask what you would like the router to do? The gateway device will act as an DHCP server and that is all you really need. Unless you are going to have some kind of firewall, throughput control or other applications. If this is just for public access and the tenants can not expect any kind of security (no encryption etc) then a router is not really needed.
Reason, I mention this that a good outdoor router will kind of blow your budget. The only other option I would consider is an enclosure that had a heat sensitive fan installed in it.
patrickjhill
10-13-2006, 05:53 PM
I have to confess this is not my area of expertise.
The ValuePoint engineer indicated that I would need something in front of their access point. Here is his exact quote:The access point can work without a router but you will not be able to do NAT which means that you need your Internet provider to give you a large enough block of IPs to accomodate your maximum amount of concurrent users. Obviously I only have one IP address so I need something that does NAT/DHCP.
Firewall would be nice. As that would possibly prevent DOS attacks. At home I have a Comcast cable modem and I know that my firewall blocks of millions of unauthorized access to my network. It seems like there are some who have nothing better than to be annoying.
If I can limit the bandwidth usage by a single user that would also be nice. But I have to stay within my budget. I may have room to go up 10% but not much more.
I have looked at Linksys they have AP's that work in extreme heat, but they do not seem to have router functionality either.
D-Link seems to have router/AP that operate in extreme heat, but the seem too expensive.
Cisco et al seem so expensive that are completely out of my project's league.
1. I would love it if you could suggest one device that would provide the minimal functionality that I would need (I cannot even name what that functionality is--I suspect you know better that I would know). That would be reasonably priced, and would operate in extreme heat.
2. I would also like to hear your other option of box with heat sensitive fan and what would you choose as the device inside?
3. Do you have a link to someone that sells the box with heat sensitive fan?
M/Q
10-13-2006, 06:51 PM
OK, you missed some questions. Sorry I get anal as it is important to know the details. Are you going to have log in ability and wireless encryption? That is important and needed information. If there is not going to be encryption then a firewall is a moot point and not required, all public IP addrs gets the port scans so it is not a big deal.
Also if you remember Greg brought up a huge point, how do you intend to control the allocated bandwidth? This is always a problem and is not easily solved, especially at your financial constraints. Please understand that a person in a car sitting in the parking lot can then steal your throughput bandwidth. Or one person goes nuts on Bit Torrents the whole system will crash or almost grind to a halt. If you remember that is why I asked about a QoS statement and how you would enforce it. Good intentions aside, when users get involved, expect the worse.
I understand your zeal, but you are not on location. The point I am trying to make is that if you are not diligent now, you are going to regret this and unless you have a non-responsibility clause you will be called all of the time, even to a point where this becomes a financial night mare. Trust me, been there done that. I also want to mention that I have not used Value Point devices, nor have any of my colleagues, bothersome. If there is any feed back on them from the members, I would really appreciate learning about it. Other-wise, I might suggest staying with the proven vendors.
Next question, is the cable gateway going to have a public IP address on its internal interface? This is also important to know, as then the sales engineer is correct. This will segue into one of my mini sermons. I am very disappointed at the IT industry as they call a router by so many different names. The cable modem by definition is a router. Now whether it has NAT and the DHCP server enabled will have to be found out by interfacing with the cable people. Residential cable for the most part does, as you can hook up a computer directly to it.
Hence my question as to if it has a public IP addr on the internal interface then you will need a NAT device. NAT and DHCP are different animals. Simply put DHCP is required to hand out IP addrs as well as other pertinent information to all of the downstream devices aka client computers. That is needed regardless of whether you are connected to the Internet or not. Kind of like mail addresses, just so that everyone knows where everyone else is.
Now NAT comes into play when you try to access another network (ie Internet). Remember you only have one public IP addr, yet you intend to have 25 computers possibly accessing the Internet. The NAT device is what keeps track of all of that information. The router remembers which device on the internal network asked for what. Simply put, the NAT device alters the traffic to appear as if it all is coming from itself using the public IP addr. Then when the information returns, the NAT device will send the traffic to the correct internal computer since it remembers which device asked for what.
Enuff of lecture 102. But, it might help you to understand what is taking place.
So, my next mini sermon is that I have a problem with saying what I would suggest when it comes to hardware. I mention something and it turns out to be not appropriate, then I am in trouble. My first thought is to get these open questions answered first. Please forgive me, but your haste to get to what to buy is a dead give away of youre not getting burnt enough. So lets work through this first.
patrickjhill
10-13-2006, 08:15 PM
Hi again M/Q,
Thank you once more for your well thought out reply. I appreciate your questions, and I wish I had complete answers for them, but I am away from the site and am working with sever budget restrains, and oppressive Dallas heat in an unconditioned room.
I suspect that some of your caution is that you are normally responsible for QOS of the space you design. And this is in part due to the fact that either the user is not in the position to get alternate service or is being charged for the service. For example, your client is a hotel and the hotel guest cannot get their own DSL service.
This site does not have those issues. It has no QoS requirements, and no one is charged. Additionally, the user is perfectly welcome to obtain alternate service. Both DSL and Cable modem are available in the area.
________________________________________________
Given your reply to my previous post we would need at least a minimal router that does NAT and DHCP. I just don't know where to get one that can operate in the heat and be within my budget.
My main problems are first the heat, and second the budget. Golfnut/Greg mentioned a Linux box that could limit a user burning the whole bandwidth. A Linux configuration would not be a problem, however, I do not have a PC that can operate in the oppressive 120F temperature for extend periods. And I suspect obtaining one, would cost a bundle (given my budget.)
That is why I am saying if there is an appliance that can do it fine, if not, then we must do without it.
Since I am away from the site, and we are talking about very very harsh operating environment, I have to stay with minimal setup that can be restarted by the flip of a switch.
Additionally, in my limited experience the problem people stealing bandwidth is gated by the limited range 802.11 devices. This neighbourhood is not very densely populated, so even if a few people use the service for free that would be OK.
So to summarize:
* NAT / DHCP are required.
* Devices must be able to work in extreme heat for sustained periods (7 months a year the temperature in that room will exceed 110F).
* Devices must be appliances that are easy to restart. (PC/Linux box is not likely candidates)
* Login is plus but not required.
* WEP / WPA is plus but not required.
* Firewall is a plus but not required.
* Limiting bandwidth usage is a HUGE plus, but not required. (The issue can be explained to the community and let them work in a cooperative manner. Should problem arise, the issue can be mitigated with another letter or with a hardware device.)
* We have a commitment to get the service up ASAP, but we have no commitment for the QOS.
* There is genuine desire to offer the best service to people who cannot afford their own connection and make it as useful and as equitable as possible. However, there is budget limitation that cannot be circumvented. Any user who needs a higher quality of service can get their own cable modem or DSL.
M/Q
10-13-2006, 08:48 PM
Great Post. Ok you just have to realize that these threads live a long time and I feel that I would not have been responsible if I did not point out the weaknesses in your logic. Also no disrespect intended at all, as I have been there.
The only devices that I can come up with right now are actually wireless devices as most wired routers are not built to withstand the requirements you are talking about. These links are to great devices that will do what you want and more as it will allow you to have more control over the login aspect. The heat ranges are almost to your requirements, and remember I would not worry about the cold as electronics love cold. You will just have to disable the wireless portion or use this as the active device at X.
I do want to at least point out that these recommendations are based on your financial stipulations. These are consumer/low end business grade devices, but they meet your requirements.
golfnut
10-13-2006, 09:03 PM
The Linux box does not have to reside at that location. You could place it in CA with you however, it must be accessible over the Internet with a static IP for the WRT to communicate with it.
The hotspot feature of dd-wrt (not the Sputnik thing) can communicate with a remote pc for the login page, user authentication, bandwidth controls, session times, etc. For your setup, you don't need an expensive PC to do this. The login process consumes very little processor power.
You -will- want some bandwidth controls. A few users loading up some music to download before going off to work will bring the network to a crawl for everyone else and it may be a little difficult to track the abusers. With Linux Free RADIUS you can limit bandwidth by user.
Greg
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