Networking

DIY: Setting up wireless access points as repeaters to extend wireless range

Do you have a need for wireless access, but your location is too large for only a single wireless router to cover? Without having to pay for a costlier router or boosters, here's what you can do.

I have received this request on a number of occasions, so I thought I would address it here as it makes perfect sense (and will save quite a bit of money). The situation is this: You have a need for wireless access, but your location is too large for only a single wireless router to cover. You don't want to have to pay for a costlier router (with an extended range), boosters don't seem to work, and you want to keep all of your clients/employees on the same wireless network. What do you do?

Believe it or not, this is actually fairly simple to take care of. What you will need is this:

  • Two wireless routers. To make things simple, I would suggest the same model with the same firmware.
  • A working network connection.
  • A machine you can temporarily  hard-wire into the routers so you can set them up.

Since every wireless router is different, I am going to speak in fairly general terms. It shouldn't be that much of a challenge to translate these general terms into that which can be applied to your specific routers.

Let's make sure we know exactly what we are doing:

  • Adding two wireless access points (Wireless Routers) using the same SSID so that wireless coverage.
  • Set up wireless security on both routers.
  • Set up routers such that there are no DHCP or channel conflicts.

Okay, now that we know what we are doing, let's do it!

Step 1: Configure SSID

The first step is the easiest step. What you need to do here is to configure both routers so they have the same SSID. This should be fairly straight forward. If these routers do not have the same SSID, when a mobile device moves to a different coverage location that mobile device will have to join the new network.

Step 2: Configure wireless security

Just like you did in step 1, you need to configure both wireless routers so that their security is the same. This means the security type as well as the password must be the same. If this differs, the mobile device will not be able to seamlessly roam between networks.

Step 3: Configure DHCP

This is where things get a bit tricky. You need to set up both routers so that IP addresses will be handled properly and neither router will issue a DHCP conflict. The first thing to do is assign each wireless router a static IP address. Let's use the 192.168.100. address scheme. We'll assume the 192.168.100.1 address is taken by the gateway, so you will use 192.168.100.2 and 192.168.100.3 for your wireless routers. We'll assign .2 to the primary wireless router and .3 to the secondary router. Now, here's another trick - when you are configuring the static IP addresses for your routers, you will want to only have one router on at a time (or only have one router on the network at a time.) When the router turns on it will most likely default to 192.168.100.1, so get one router working with a static IP address and then get the second working with the static IP address.

With the static IP addresses set you now must address DHCP. We can only have one router handing out DHCP or there will be addressing conflicts. So on the secondary router, turn DHCP off. On the first router you will turn it on, but you will also configure DHCP so that it will begin handing out addresses at the 192.168.100.4 address. You must not allow it to use the .3 address as that is being used for the secondary wireless router.

Finally, you'll want to make sure the primary and secondary wireless routers are not on the same channel and the channels are far enough apart as to not cause conflict (you could use channels 6 and 11 to make sure you won't have channel problems.)

Step 4: Locate and fire up!

The final step is to locate the routers such that, between the two, your entire building will be covered. Remember, the two routers will need to be able to "see" one another by way of ethernet. The easiest way to handle this is by plugging each into a wall jack that is directly connected to your network (and on the same IP address scheme as your routers.) If you don't have the ability to do this, you might have to run a cat5 cable from one to the other (which can run up the cost on this little project). When they are in place and connected, it's time to fire up both routers and get them online. When they are on line, grab a mobile device and connect to one of the routers. Once you have a connection made, walk from one router to the next to make sure you remain connected. You should. If so, congratulations, you just saved yourself some cash!

About

Jack Wallen is an award-winning writer for TechRepublic and Linux.com. He’s an avid promoter of open source and the voice of The Android Expert. For more news about Jack Wallen, visit his website getjackd.net.

34 comments
jackscale
jackscale

Hallo Jack  thanks for the good article -  I have a problem in a warehouse where we use Pick by Voice WLAN modules ( Vocollect) and also WLAN modules in our mobile scales ( this to weigh the picked goods at pick level and have them checked by the Ware house management system )


We have several AP's   - we drive around and we see that the Pick by Voice devices switch from Access Point to the next one ( with a higher signal )   BUT  our scale WLAN devices do not switch to the next AP......   this continue's untill the scale lost connection completely ....   


so when no longer connected we do a complete Power Off / On of the scale WLAN  and now the scale WLAN connects to the local AP  ????   Is this a QoS problem ??  how can we solve this ??

Will each AP send out a beacon which we do not see ??? 


look forward to your input 


best regards 


Jacob Blom 

www.ravas.com

thenewbie
thenewbie

can this be done with more than 2 routers/repeaters? lets say 6 repeaters with the same process? thanks

armchairnavigator
armchairnavigator

Just a quick comment - Jack Wallen, might i suggest you stick to writing works of fiction ?

heinmg
heinmg

I followed your guide quite carefully and, I'm happy to report, it all works perfectly. My main router is located upstairs in my two-storey house; coverage downstairs was always a bit spotty. The range of good wifi reception is now excellent, and the shift between the two routers is seamless. I think I may subsequently have looked a bit of a loon, strolling around in my garden with a cellphone pointed at various windows, but your guide was worth it.

chrislomns
chrislomns

I appreciate robo_dev's comments but even more so I was looking for some reviews on how to set up a network using my already existing repeater. I checked out http://www.wirelessrouterrepeater.com and they have tonnes of reviews so I thought I would share since I it is a hassle to find anything online which helps you hook up two different brands. I guess thats how each company keeps you using their stuff. Also, I've come to find that you need to know exactly what you are looking for before spending all sorts of time trying to setup your network correctly. Seems like no one likes to spend the time researching what advantages come with a repeater, router or whatever they need. Gotta love overspending! LOL!

grantk65
grantk65

I have a D-Link G604T Wireless modem router and i want to add a D-Link DI-624 Wireless router. How can i link them together wirelessly

montaser_sawi22
montaser_sawi22

what about the gateway in my Repeater If my access point has : IP: 192.168.1.2 subnet mask : 255.255.255.0 gateway: 192.168.1.1 Repeater : IP: 192.168.1.3 subnet mask: 255.255.255.0 gateway: ?? can I make my gateway 192.168.1.1 or 192.168.2.2, because I connect my repeater to cable ?? Help me please

robo_dev
robo_dev

The title is wrong; the title should be 'how to setup two access points' while using two routers. The concept of a 'repeater' is not even addressed at all. Let me try to clarify this. I really wish we could attach a Visio diagram here. First of all, I might mention that I worked for five years installing and supporting Cisco WLAN networks and bridges for both point-to-point bridging as well as warehouse automation projects. I designed a WLAN for one of the largest warehouses in Europe, and have deployed WLAN bridges in Hawaii, Texas, and even Georgia. I know what works, and I know what does not. There are essentially four classes of WLAN access devices: Routers Access Points (AP) Bridges Repeaters A WLAN router is nothing more than a AP with a wired router and switch attached to it. If you turn off DHCP in the router, give it a static IP, and plug this gizmo into a LAN using it's LAN port, it's effectively a poor-mans AP. Remember that WLAN devices are layer 2 devices (mac layer bridge), except for the router, obviously. Layer two means it's all one happy broadcast domain, from a DHCP or Microsoft Networking perspective, and that the IP addresses of each device are only for configuration and management, nothing more. Even though WLAN devices are layer 2 devices, there are some issues to address. The most critical issue is that if you create a network loop, your entire LAN will stop working. Thus if, for example, you plugged two WLAN routers into the LAN and they had the ability to create a bridge or repeater between them, then there are two paths that traffic can follow. A network loop will overwhelm your ethernet switches in most cases and kill your LAN, or at least slow the lan to a crawl. To prevent network loops, there is a protocol called Spanning Tree Protocol, which is enabled by default on most Access Points, as well as most enterprise-class ethernet switches. Also, someone here mentioned having multiple DHCP servers with non-overlapping scopes on the network. That will work, in theory, but keep in mind that these devices will not both normally be the default gateway. The second DHCP server will have to be handing out addresses with the default gateway IP and DNS address of the OTHER DHCP server device....so from both a support and a sanity perspective, my advice would be to keep itsimple and have only one DHCP server. An AP is a mac-layer bridge that often can have multiple radios, as well as an Ethernet interface. The advantage of multiple radios is that they do not interfere with each other, so that if one radio is 802.11a (5.8GHZ) it steers clear of a 802.11g radio (2.4GHZ). For metro-area WLANs, make that first radio be 3G, GSM, or WiMax. There are two flavors of bridges: A point-to-point bridge looks like an AP, but only connects to another bridge. A 'client bridge' can connect to an AP and function exactly as a client...things like print servers are client bridges. To confuse things, some APs can do double-duty and act as a bridge and an AP, establishing a wireless connection to the root AP, while allowing clients to connect. To confuse things more, you can do multi-point bridging or even mesh topology. Repeaters are Access Points with no ethernet connection. However, a repeater has to be able to authenticate and associate to the AP. In this case if it has only one radio, the throughput is cut-in-half, as the same radio must talk to the client and the root AP. A typical use for a repeater would be a shipping yard or car dealer parking lot. A repeater would be hung on a light pole so it can talk to the WLAN in the main office, while giving good signal coverage to mobile WLAN devices outside. The article title mentions creating a repeater. In order to do this, the AP must be able to function as a WLAN bridge with clients. This means that the second AP must be able to authenticate and associate to the first AP, then the second device must be able to allow clients to connect to it, which also must associate and authenticate to it. If you just configure two WLAN routers with the same SSID, the one connected to the LAN will work, the other will do absolutely nothing, of course, unless you plug it into the LAN, as the article mentions. But again, that's not a repeater, that's just a pair of APs plugged into the LAN. I hate to mention the obvious, that many routers can be configured to be access-points only, and that this would make a lot more sense. The only reason to use a router in router-mode is if you are on such a tight budget that you cannot afford a $100 Access Point. Note too, that some people might expect that two WLAN routers could function as a bridge, so that a wired ethernet device connected to one device will connect to a wired ethernet connected to the other one....this will ONLY work if that capability is built into the device, as the first router has to be able to connect as a client to the second one. With WLANs there is the concept of 'Roaming'. I won't try to explain it all here, but roaming means that the layer-2 network connection is maintained, but the client has to re-associate and re-authenticate in the background to the second device, so that the IP address can be maintained. There is a protocol called Inter Access Point Protocol (IAPP) that takes care of this. Having two access points within radio range of each other is not roaming, and it really tends not to work well. As the client moves, it will stay associated to the first network, then possibly attempt to connect to the second network, or most likely just stop working. Since the effective radio range of an AP is typcially like 100-300 meters, it's very unusual that a client will go completely out of range of one device, unless it's like a football stadium sized building. (And when it does, the connection will drop). Normally, when you have multiple APs on a wired LAN, you configure them so that a device can roam between the two networks using IAPP or some similar mechanism. http://features.techworld.com/mobile-wireless/435/wlan-roaming--the-basics/ I don't know if I explained this any better than the original article or not. My post is not meant as any criticism, but more as an attempt to clarify things.

pgit
pgit

I always turn DHCP off on the wifi routers and everyone gets and address from the gateway device. Only exception is if one of the wireless routers IS the gateway device, then of course it's the DHCP server. But I rarely go this route. I usually convince folks they don't want a wireless transmitter blaring out the presence of their perimeter firewall/gateway device. An antique box (P-III nowadays) in the broom closet running smoothwall normally handles that for my less than wealthy customers.

jlwallen
jlwallen

This column is typically for those with far smaller budgets than many of you. A lot of clients on such small budgets won't be dealing with a Windows SBS server or Windows Server period, so DHCP is typically handled by wireless routers or wired routers. Yes there are better ways to do this, but the method I described does work. Naturally if you have the budget, there are much better solutions for this. But when you're seriously strapped, the best solution is the cheapest.

james.knott
james.knott

I have read through the article a few times, but don't see where you mention that the routers should be connected to the local network through a LAN, not WAN port, so that the WiFi is bridged to the network. Also, there's no problem with having more than one DHCP server, provided that they don't hand out duplicate addresses. The easiest way to do that is to simply configure each with different address ranges within the subnet. Also, some DHCP servers will check to see if an address is in use, before issuing it. Further, there are some devices from Asus, D-Link etc. that are designed for this use. I have an Asus WL-330gE portable access point, which can be plugged into an existing network to provide WiFi access. It also has other functions, including "hotspot" sharing and repeater.

dbc_techrepublic
dbc_techrepublic

Don't get me wrong, this works. However be aware that current wifi standards do not offer "roaming" capability. In all current wifi networks you will lose range with wifi AP#1 and drop your connection first before the device starts looking for a new connection and finds AP#2 more suitable. You get extended range but the experience may not be more or less seamless depending on the connection requirements of the application you are using.

tony
tony

is simple - note the requirement that both routers are connected via a wired connection. Thus the router that has DHCP turned off passes the DHCP request via the wire to the other router. If doing this with a wireless access point and an ADSL router, note that some routers have a facility for DHCP relay - instead of turning the DHCP off you give it the address of the active DHCP server. Secondly, if you do this with anything such as a Windows SBS network (2003 or 2008) and you end up with the router connected to the network with DHCP on, this will cause the DHCP service on SBS to stop. Restart DHCP on the server and all should be well. Generally with a Windows server running DHCP, it is wise to retsrat the DHCP server any time you have been messing with network devices that have the capability to run a DHCP service, whether it is enabled or not. It will save you a lot of time trying to find out what is wrong only discover that the server's DHCP is not functioning correctly.

jacobus57
jacobus57

Perhaps I am being dim, but if the point of this exercise is to use two routers to cover a large area, but only one can handle DHCP assignments, then 1. this will not work for non-mobile machines (at least those out of range of the primary router), and 2. mobile users will have to be in range of the primary router every time they connect with the network, THEN migrate to their workspace. If these things are true, it is a very kludgy solution. If they are not true, please tell me what I am missing!

pgit
pgit

Nice summary of things, I would like your similarly concise take on how STP works if you've got the time and the unction. I find myself tracking down a lot of STP traffic on several small (and simple) LANs I maintain, it always comes from a win 7 or vista machine. I have only seen it in use on one cisco router, none of the low end consumer routers or APs I have dealt with originate or respond to STP as far as I can tell. So yes, it's enabled by default on the latest windows machines, but just what the heck is it doing? It appears the answer is "wasting bandwidth." Is this something these systems are actually using? Where/when/how would it come into play? (that is how would I know STP is actually needed?)

chrisbedford
chrisbedford

One of my clients has her DSL and WiFi in a room on one side of the house, the study, and requires her secretary to sit in the dining room not 120 feet away. Sounds simple, but the design of the house, plus its construction (mostly clay brick, some reinforced concrete) meant I had to set up a repeater in the dining room. Did I mention no cabling allowed? Heh... modern architecture plus aforementioned construction mean it's just not an option to run cat 5 from one to the other. Anyhow I set up a powerful AP in the study and a standard AP in the dining room, with a high-gain antenna. The d/room AP was set in repeater mode and all worked well for about three months. Then all of a sudden the d/room user started losing connection more than she was on line. I walked around with NetStumbler and came to the conclusion that the signal strength just wasn't good enough any more - who knows what affected it, but it appears that in these marginal circumstances someone parking a large van across the road could cause problems. Anyway I set up a third AP, identical to the 2nd one, also with a 7 dB antenna and also in repeater mode, about half-way between the other two - in the hallway linen closet, as it happens - and all is well again. Fortunately in this situation there is only one (and an occasional second) user who require(s) a connection in the dining room, and then only for Web (Google calendar) and e-mail. I can see where any more users, with for example some file and print sharing, would require a bit of capital outlay on chasing cables into the structure...

pulverpa
pulverpa

As someone who works for non profits with little budget and unregulated spaces that wander through out a building, I thank you for this article. Working for companies that have money to do things right is a luxury that I enjoy when I get the chance but often by choice I get to work with small non profits who each come to the table with a motley collection of parts, routers, different OS's and the desire to get the job done on a shoe string. You do what you can and this type of article really helps us out. Yes I know better ways of doing it as well but often a solution like this will provide a workaround.

jlwallen
jlwallen

I did forget to mention that the routers should be connected through the local LAN and not WAN. The reason why I brought up only have one router handing out DHCP was for simplicity. If you have the both handing out DHCP you would need to make sure one router handed out one range of addresses while the second router handed out a different range.

Neon Samurai
Neon Samurai

Some routers offer an option to include the WAN port as a regular switched port giving you five switch ports instead of four switch ports and one uplink. I know DD-WRT does this specifically but can't confirm if linksys/netgear also provide the option through factory firmware. If the router does not provide the setting, one will need to use a regular switch port instead of the wan port though.

jlwallen
jlwallen

If you do have a Windows server serving up DHCP, you would want to turn DHCP off on both routers so the Windows server could hand out the addresses.

daboochmeister
daboochmeister

Is it required internally for other functions being performed on the SBS server? Just curious.

gavgold
gavgold

The access point is just to get you onto the network and is separate to the DHCP server. The DHCP request is broadcast by the device looking for the IP address and this will be replied to by whatever DHCP server receives the request. The wireless network will carry the request to the DHCP server and then carry the response back to the requester. It is not dependent on the device already having an IP address. That's how I understand it anyway.

oldbaritone
oldbaritone

under the heading DHCP - "We can only have one router handing out DHCP or there will be addressing conflicts. So on the secondary router, turn DHCP off." edit: Most routers including low-cost consumer versions send DHCP both over wireless and on the hardwire when DHCP is enabled. The two routers are connected by hardwire, so it doesn't matter which one originates the connection, DHCP always comes from the primary. You are correct, and it's mentioned in the article.

Neon Samurai
Neon Samurai

router 1 = 192.168.0.1 (dhcp offering 192.168.0.100-254) router 2 = 192.168.0.2 router 2 is within range of router 1 or connected by wire; it's a client node underneath router 1. The only thing router 2 is doing is providing a wifi connection for machines too far away from router 1. Router 2 is working as a switch that happens to have wireless ports in addition to it's four wired ports. [Router 1 [ Router 2 ] ] Client 2 connects to Router 2 over wired port or wireless. Client 2 broadcasts out a DHCP request for an IP address. Router 2 transers the broadcast packets as it would any other network packets (due to being a switch or "smart hub"). Router 1 recieves the broadcast packets from Client 2 care of Router 2. Router 1 dhcp server sends back an IP address. Router 2 transers the addressed packets back to Client 2 through normal network switch behavior (packets addressed by MAC address and ARP tables). Client 2 recieves the network packets from Router 1 care of Router 2 and configures itself to use the DHCP issued IP address. The easiest setup for a small group of machines may be to use two different SSID. Set half the wireless machines to connect to router 1 via SSID 1. Set the other half to connect to router 2 via SSID 2. If router 1 and router 2 are within the same wifi bubble range, you don't have all your wireless clients trying to connect to one router that can't support that much wireless at once. If router 1 and router 2 are outside of each other's wireless bubble (but connected by wire), you have the same network covering a larger area than one wifi bubble's range. I believe setting the same SSID on both routers would give you the "roaming" between wifi bubbles without your network connection resetting (as it would for different SSID). The last one I've not done before though so can't tell you from personal experience.

Neon Samurai
Neon Samurai

The DHCP and DNS services talk to each other with DHCP adding DNS entries. DNS and Active Directory often get dropped on the same server in smaller networks; Active Directory relying on DNS. - that'd be the first guess that comes to mind but my experience is more on the *nix side these days. If the network is big enough to have dns and active directory on seporate servers, it's probably big enough to buy propper business class routers, switches and access points rather than this soho router hack.

Neon Samurai
Neon Samurai

My only grief with it as been hardware/software overwelming.. I can't clearly identify which causes the grief but after time under heavy network load, it seems to have issues. Give it a reboot and it'll probably be fine. Let it go long enough to crash forgetting all it's settings; that's where the config backup becomes important. I'd like to see them stabalize it a lot more.. at least on the Netgears that ship with it or have vendor sponsored dd-wrt versions available. Still, the oddity remains, my workbench router gets as much network traffic as my home router. The only difference is regularily turning the wireless off and on which seems to keep the work bench router rock solid. Sometimes the job justifies doing a dedicated box for routing if not purchasing a dedicated business class router. Having gained experience with it, I wouldn't put dd-wrt in a node that required maximum up-time.

pgit
pgit

Then saw your new comment here. I almost mentioned, but didn't, that I hate dd wrt and the ilk. Of course the home or small business wants to minimize costs, so a lot of them tell me they'll go the router-dd wrt route rather than a dedicated computer based hardware firewall. Less space, less electricity, sometimes less cost. But dd wrt is temperamental, it's created more problems for me than any other single object save the big-un; windows. But I expect and understand the windows problems. The stuff dd wrt has done has cost me a heck of a lot of time, on several occasions, because the assumption was it was working properly. That and I'm not happy with a couple of the operational considerations of using a router in some circumstances. DMZ on the same set op ports, pin hole and port forwarding methods and web access to configurations are a couple things I dislike about these things. Much rather have a nice debian system accessible through ssh, with separate hardware interfaces for various network segments. But again a home user with 3 computers and a play station isn't going to be easily convinced, not when they will have to have the router in the works anyway. I have gotten a few people to set up smoothwall on an old junker that was gathering dust in a closet. I really don't consider it overkill to have a full-blown computer/OS sitting on the perimeter in any situation. Having dd wrt or other after market firewall is a heck of an improvement over the stock system most low end routers ship with, which is sad. I don't understand that with much better FOSS alternatives freely available the manufacturers don't avail themselves of it. Nevertheless, call me old-school perhaps but I just can't fully trust these typical router setups the way most folks seem to do.

pgit
pgit

And for the record the same is true with a Linux server on the back end. I make it a habit of minimizing the amount of work (and thus reliance upon) a simple router has to do.

Neon Samurai
Neon Samurai

It defaults to 1440 minute lease times though it also offers many other features left out of factory stock firmware (outside of Netgear who are shipping dd-wrt factory installed). Sadly, the hardware still gets overwhelmed, just gave my router it's weekly reboot. When it stops taking https admin connections, I know it's close to falling over and in need of a reboot.

chrisbedford
chrisbedford

Such parameters as length of lease, as well as loads of other network addresses can be set. Most WiFi-enabled routers will hand out client address, gateway, and DNS server (the same as gateway) on either a 3- or 7-day lease, and that's it. If you want something as basic as to use the Windows Server as your local DNS server (pretty much obligatory, if you are running AD) you'll need to use Windows' DHCP as well

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