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sclawrenc
Posts: 24
Registered: ‎08-26-2008

Multiple Access Points

I have 5 linksys access points setup at a hotel and would like to know how the best way to configure them would be. I would like all of them to be the same SSID and security so it looks like one network. Which mode will provide the best signal and which channel should they all be on? Right now, i have them setup on 1,6, and 11 with two of them farthest apart overlapping. They are online fine, but I wanted to make sure it was the optimal setup since I am not real happy with the signal strength. So I guess my main question is which channel they should be on? The same or alternating channels of 1,6, or 11? Thanks for your input.
Expert
Expert
Posts: 12,649
Registered: ‎07-16-2006

Re: Multiple Access Points

It seems as if you already have the best set up possible. Same SSID. Same wireless security. Different channels.

If you are not happy with the signal strength then you need more access points or place them differently. Signal strength is not affected by SSID, security or channel assignments (the latter unless you have a lot of interference on a particular channel of course).
sclawrenc
Posts: 24
Registered: ‎08-26-2008

Re: Multiple Access Points

That's what I thought, but it seems I read in another post by Fred that he uses the same channels in AP mode so I wanted to clarify. If I set them all to the same channel, same ssid, and same security in AP mode, what would happen? Do you think it would be better to set them up in pairs repeating each other? For example, ap mode and repeater on ch6, then another in ap mode and repeater on ch1, and then another in ap mode and repeater on ch11?

 

This network was already in place, and I just secured it using wpa so I didn't have anything to do with the placement of the ap's. 3 of them are in a basement with about 40 feet apart from each other on different channels, but they have to travel through very thick concrete walls.

 

Thanks for your input and all suggestions are very welcome.

Expert
Expert
Posts: 12,649
Registered: ‎07-16-2006

Re: Multiple Access Points

1. If all access points use the same channel they will interfere. Put a client device in the middle of two access points. It's connected to one of them. Transfers data at 10 Mbit/s. This will "knock off" 10 Mbit/s on the second access point. Plus, transmissions on the second access point interfere with client. If you use the same channel, they will share the same bandwidth...

2. Using the same channel is sometimes necessary as some wireless clients have trouble roaming otherwise...

3. A repeater always will reduce available bandwidth to 1/2 as all traffic is repeated. Unless you have very little traffic or you only need for little bandwidth on each client avoid repeating if possible. As you have wires in place, use them. That's always better.
sclawrenc
Posts: 24
Registered: ‎08-26-2008

Re: Multiple Access Points

So it is in agreement by everyone that if you have wires running to each access point from the switch/router, the channels should be different on each access point? In my case of 5 access points, I know to put one on 1, one on 6, and one on 11, but what about the other two access points? Should I use one of the inbetween channels such as 3 or 9, or just use the main channels again like 1, 6, or 11, depending on which one has the least interference?

 

Also, I know that usually the WPA2 AES usually has the best wireless performance. Is that the same case with these linksys access points? Do people usually have better wireless results using a particular securtiy encryption with these?

 

Again, I really appreciate your help.

sclawrenc
Posts: 24
Registered: ‎08-26-2008

Re: Multiple Access Points

gv,

 

I just spoke with linksys support via chat and here is what they said. They said that if you have all the wap's wired into to a router, then you should/can set them all to the same channel. I asked this question several times and they said it would work just fine and in fact they recommend doing that way as long as the SSID and security is set to the same. I then asked how that wouldn't interfere with each other, and if they go into a WDS mode, and they said yes. However, when i spoke with linksys chat a few days, ago the person I got said to put them on separate channels. Maybe it will both work fine?

 

So it seems that my confirguration of separate channels is not what linksys recommends when all the settings are the same. What are your thoughts on this? I am currently studying for the CCNA exam and the wireless portion even says to put them on different channels and then alternate them so they dont interfere. How would these linksys wap's be any different? I guess they must have some way to talk to each other since they are all on the same network?

Expert
Expert
Posts: 12,649
Registered: ‎07-16-2006

Re: Multiple Access Points

[ Edited ]
Of course it will work if all access points are on the same channel. But again: they will interfere unless you put them so far apart that you are not able to receive the signal of two or more APs at any place.

Please remember: each channel has a basic bandwidth of 54 Mbit/s available under ideal circumstances. If you put two APs in the same range on the same channel they will interfere. They "share" the bandwidth of 54 Mbit/s. If you have wireless devices connected at lower data rates during their transmissions they will lower the total bandwidth available very much.

You don't need a CCNA do understand that two APs in range of each other on the same channel will interfere. It's a matter of basic radio transmissions. If one APs transmits something to a wireless client it will interfere with transmissions of the other APs. As 802.11 is based on ethernet protocols the basic transmission method is (simplified): check if the channel is clear at the moment. Start transmitting and listen at the same time for other transmissions. If you receive another transmission while you are transmitting you have a interfering transmission, i.e. another AP/wireless device started transmitting about the same time. If that happens abort transmission and retry after a random interval.

Now play this through in some scenarios and you'll see it's better to put them on different channels.

I know the Linksys level 1 support is sometimes not very good. I guess depending on to which call center they have connected you to. Just trust me on this: Linksys APs are not different from Cisco APs or other APs. The CCNA material is right. Actually, any wireless controller does this automatically and assigns different channels in its APs. And APs on the same channel will of course interfere if they are in range of each other.

APs in AP mode don't have to talk to each other. There is no need. All they provide is a link to your LAN. As they are wired into your network there is no need to talk to each other. They don't even have to know about each other. The whole roaming process of a wireless client is implemented and handled on the client. The client decides at some point to try another close by APs if the existing link gets too weak. (This may be different for a controller-based setup...)

I have setup wireless networks like this several times and they all work fine. There are really only very few wireless devices which have trouble roaming unless the APs operate on the same channel. Those devices must loose the existing connection before they try to reconnect to a different AP which leads to a short interruption of connectivity. Thus, unless you have a lot of roaming users (i.e. moving between APs), you have a lot of wireless devices which have this problem, and you very much depend on the roaming service (let say you have 20 VoIP phones connected which have to move around a lot) there is absolutely no reason to put all your APs on the same channel and dramatically reduce the available bandwidth for your wireless network...
Message Edited by gv on 03-16-2010 09:50 AM
sclawrenc
Posts: 24
Registered: ‎08-26-2008

Re: Multiple Access Points

Thanks gv. That's what I thought, but when I spoke with linksys and they told me to use the same channels, I was a bit confused on how that would work. There is a guy named FredZ that posts in these forums, and I think I saw him mention you could also put them on the same channels as long as they are on the same network. Do you know what he meant by that?

 

Thanks again.

Expert
Expert
Posts: 12,649
Registered: ‎07-16-2006

Re: Multiple Access Points

I cannot comment on something which I did not read myself. Maybe it was a special case. Or it was a different scenario, e.g. a repeater setup.

I can tell you that a standard setup of wireless access point which are all connected by ethernet into the same LAN basic interference rules apply. There is no reason to put them in the same channel. Each access points works completely independently from the others. A wireless client picks one and connects to it (using the MAC address of the AP). After that, the traffic between the client and the AP is standard wireless traffic which will interfere with other APs on the same channel, regardless whether those APs use the same SSID or not whether they have the same keys or not... The other APs only become relevant in the moment where you roam...
sclawrenc
Posts: 24
Registered: ‎08-26-2008

Re: Multiple Access Points

Here is what FredZ said:

 

To answer your questions directly:



-The WAP'S might be in a signal overlap (90' apart) should I have them on different channels?



No, signal overlap is only an issue if the 2 signals are on different networks.

 

Your senario posses a few more questions.

I assume the WAP54Gs are wired to the BEFSR41 as the WAP54G cannot be used as a repater for it. Read the bottom of the AP Mode page of the WAP54G for more information.

Security is always an issue regardless of how long it is on for. Always try and use WPA2 where possible

 

 

Here is a probable setup for you.

Set all WAP54Gs to the same channel, and set the security to WPA2 and set the pass phrase on each AP so they are different.

 

And here is another post he says the samething:

 

The WAP54G supposedly supports WDS, so setting all the WAP54Gs up on the same channel with the same SSID and security is the way to create a single seamless wireless network.

If the signal is spotty then try a different channel (1,6,11) or you may need to have more devices to achieve full coverage, or you could even try high gain antennas.

 

Any thoughts on that gv or FredZ?

 

As always, thanks for your information and hard work on these forums.