Sign in with
Sign up | Sign in
Your question

Multiple WAPs

Last response: in Wireless Networking
Share
October 12, 2004 9:27:04 PM

Archived from groups: alt.internet.wireless (More info?)

I'm trying to plan out a wireless network for a building, including multiple
WAPs. I want users to be able to roam between access points seamlessly.
Maybe I'm just being dense, but I can't seem to find any information on
exactly how to set this up. Google hasn't helped much.

What I think I'm seeing is that you can connect multiple WAPs to a single
wired router. The WAPs should be configured with the same SSID and
encryption, but the broadcast channels would have to be different (if
they're in range of each other). This would allow some sort of
technological magic to happen between the WAPs and wireless devices, and
roaming would occur without the user noticing.

Am I on the right track here?

Thanks!

ADY
--
adyoung (at) sbcglobal (dot) net

More about : multiple waps

Anonymous
October 12, 2004 10:33:18 PM

Archived from groups: alt.internet.wireless (More info?)

On Tue, 12 Oct 2004 17:27:04 -0500, MousePad spoketh

>I'm trying to plan out a wireless network for a building, including multiple
>WAPs. I want users to be able to roam between access points seamlessly.
>Maybe I'm just being dense, but I can't seem to find any information on
>exactly how to set this up. Google hasn't helped much.
>
>What I think I'm seeing is that you can connect multiple WAPs to a single
>wired router. The WAPs should be configured with the same SSID and
>encryption, but the broadcast channels would have to be different (if
>they're in range of each other). This would allow some sort of
>technological magic to happen between the WAPs and wireless devices, and
>roaming would occur without the user noticing.
>
>Am I on the right track here?
>
>Thanks!
>
>ADY

Yes.

Lars M. Hansen
http://www.hansenonline.net
(replace 'badnews' with 'news' in e-mail address)
Anonymous
October 13, 2004 9:50:00 AM

Archived from groups: alt.internet.wireless (More info?)

On Tue, 12 Oct 2004 17:27:04 -0500, "MousePad"
<adyoungentirely.too.much.junk.mail.in.my.mailbox@sbcglobal.net>
wrote:

>I'm trying to plan out a wireless network for a building, including multiple
>WAPs. I want users to be able to roam between access points seamlessly.

So does everyone else. Dream on.

>Maybe I'm just being dense, but I can't seem to find any information on
>exactly how to set this up. Google hasn't helped much.

There's plenty available with Google. Search for "wireless roaming".
The problem is that you'll find very little commodity hardware that
claims to do it seamlessly. There are no current specifications for
how to do roaming and how to handle the handoff.

IEEE 802.1f defines the best practices for wireless roaming.
http://standards.ieee.org/getieee802/download/802.11F-2...

802.1r is the proposed fast wireless roaming standard. I don't this
it's available for general consumption quite yet.

See article:
http://www.winnetmag.com/Windows/Article/ArticleID/2329...
There's a short list of vendors in the above article that provide
proprietary wireless roaming solutions.

>What I think I'm seeing is that you can connect multiple WAPs to a single
>wired router. The WAPs should be configured with the same SSID and
>encryption, but the broadcast channels would have to be different (if
>they're in range of each other).

Correct. Use the same SSID so that Windoze XP and other client will
automatically switch to the "best" access point signal if you select a
particular SSID as the "prefered" SSID. Actually, I don't think you
have to select preferred as once associated with an SSID, Windoze XP
SP2 will try to stay associated. The non-overlapping channels (1, 6,
and 11) are to prevent RF interference between WAP's.

>This would allow some sort of
>technological magic to happen between the WAPs and wireless devices, and
>roaming would occur without the user noticing.

Magic? Here's the problem. Your Windoze laptop client radio connects
to an access point, an associates an SSID with the access points BSSID
(same as MAC address of the wireless access point). Now, you move to
a different location, the signal evaporates, and you pickup another
access point with the same SSID. Just one problem, different MAC
address. Are you gonna give up on the old MAC address and switch to
the new address? Sure, but after how long a delay? Meanwhile, the
original access point still has your client radios MAC address in its
bridging table, and is furiously trying to get your attention. Your
laptop is still trying to talk to the old access point.

Eventually they will both give up, but if it takes too long, you may
find yourself with two (or more) access points trying to get your
attention. Meanwhile, the switch in the router is going nuts as your
client radios MAC address is seen moving from port to port. At least
this can be done fairly quickly. Anyways, lots of other things can go
wrong during roaming.

The usual solution is to use very short DHCP lease times, force a
disconnect when the client radio switches to a different access point,
and deliver a new IP address to the client via DHCP. This will drop a
connection in progress, trash a VPN connection, and ruin a VoIP phone
call, but will not really affect normal email and web browsing (other
than a small delay).

>Am I on the right track here?

Yeah, sorta. If you can tolerate disconnects and re-assigned IP
addresses when switching WAP's, then you're done. Just about anything
with control over the DHCP lease time will work. If you absolutely
want seamless roaming, you'll need to find a proprietary solution.
Plan on emptying your bank account.

Due to lack of detail on your proposed system, I don't wanna offer a
specific hardware recommendation. However, you might wanna look into
a "wireless switch" such as:
http://www.symbol.com/products/wireless/ws_5000_brochur...
which are intelligent switches, with brain dead radios attached. With
all the brains in the central box, port switching and roaming is much
easier. See the section in the above URL for some detail on roaming.



--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831.336.2558 voice http://www.LearnByDestroying.com
# jeffl@comix.santa-cruz.ca.us
# 831.421.6491 digital_pager jeffl@cruzio.com AE6KS
Related resources
October 13, 2004 1:59:02 PM

Archived from groups: alt.internet.wireless (More info?)

"Jeff Liebermann" <jeffl@comix.santa-cruz.ca.us> wrote in message
news:qaepm012kq58nv6nols1c7kc5clg76efln@4ax.com...

>>Am I on the right track here?
>
> Yeah, sorta. If you can tolerate disconnects and re-assigned IP
> addresses when switching WAP's, then you're done. Just about anything
> with control over the DHCP lease time will work. If you absolutely
> want seamless roaming, you'll need to find a proprietary solution.
> Plan on emptying your bank account.

There's a lot of good information there. Thank you very much.

Since I don't have money to burn, I'm thinking that I need to stick with
basic WAPs and a switch. I'll keep the number of access points to a
minimum. One per floor will likely be enough. In practice, I don't think
there will be a whole lot of roaming around the building. Most users will
stay in one area.

I can upgrade in a year or two, once roaming standards are more complete and
equipment is more cost-effective.

ADY
--
adyoung (at) sbcglobal (dot) net
Anonymous
October 13, 2004 4:03:38 PM

Archived from groups: alt.internet.wireless (More info?)

On Wed, 13 Oct 2004 09:59:02 -0500, "MousePad"
<adyoungentirely.too.much.junk.mail.in.my.mailbox@sbcglobal.net>
wrote:

>Since I don't have money to burn, I'm thinking that I need to stick with
>basic WAPs and a switch. I'll keep the number of access points to a
>minimum. One per floor will likely be enough. In practice, I don't think
>there will be a whole lot of roaming around the building. Most users will
>stay in one area.

That will work. No need for anything special. If you can run CAT5
between WAP's, you're fine. I forgot to mention WDS (Wireless
Distribution Something). Effectively, each access point becomes a
repeater. Bandwidth is cut in half every time you have to store and
forward some packets, but it completely eliminates the CAT5 run
between floors. I don't like this method, but it does work.

>I can upgrade in a year or two, once roaming standards are more complete and
>equipment is more cost-effective.

Upgrade? I don't think so. Most manufacturers do not support
products past their useful market lifetime. In a year or two, you
won't be able to find much firmware for any of the newer acronyms.
Getting WPA support for older client cards is almost impossible. If
you wanna go with the bleeding edge and possibly preserve your
hardware investment, methinks that the 3rd party open source firmware
for the WRT54GS series is the best bet. The other alternative is to
build a central switch using a Linux box and use dumb 802.11 access
points.

--
Jeff Liebermann jeffl@comix.santa-cruz.ca.us
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 AE6KS 831-336-2558
October 13, 2004 7:20:56 PM

Archived from groups: alt.internet.wireless (More info?)

"Jeff Liebermann" <jeffl@comix.santa-cruz.ca.us> wrote in message
news:9iuqm05uo6sgv1a5q4ofo552gf635j8hg2@4ax.com...

> That will work. No need for anything special. If you can run CAT5
> between WAP's, you're fine. I forgot to mention WDS (Wireless
> Distribution Something). Effectively, each access point becomes a
> repeater. Bandwidth is cut in half every time you have to store and
> forward some packets, but it completely eliminates the CAT5 run
> between floors. I don't like this method, but it does work.

The building's already wired with CAT5. That won't be a problem.

> Upgrade? I don't think so. Most manufacturers do not support
> products past their useful market lifetime. In a year or two, you
> won't be able to find much firmware for any of the newer acronyms.
> Getting WPA support for older client cards is almost impossible. If
> you wanna go with the bleeding edge and possibly preserve your
> hardware investment, methinks that the 3rd party open source firmware
> for the WRT54GS series is the best bet. The other alternative is to
> build a central switch using a Linux box and use dumb 802.11 access
> points.

By "upgrade" I meant "replace." /:) 

ADY
--
adyoung (at) sbcglobal (dot) net
October 13, 2004 9:15:40 PM

Archived from groups: alt.internet.wireless (More info?)

MousePad wrote:
> "Jeff Liebermann" <jeffl@comix.santa-cruz.ca.us> wrote in message
> news:qaepm012kq58nv6nols1c7kc5clg76efln@4ax.com...
>
>
>>>Am I on the right track here?
>>
>>Yeah, sorta. If you can tolerate disconnects and re-assigned IP
>>addresses when switching WAP's, then you're done. Just about anything
>>with control over the DHCP lease time will work. If you absolutely
>>want seamless roaming, you'll need to find a proprietary solution.
>>Plan on emptying your bank account.
>
>
> There's a lot of good information there. Thank you very much.
>
> Since I don't have money to burn, I'm thinking that I need to stick with
> basic WAPs and a switch. I'll keep the number of access points to a
> minimum. One per floor will likely be enough. In practice, I don't think
> there will be a whole lot of roaming around the building. Most users will
> stay in one area.
>
> I can upgrade in a year or two, once roaming standards are more complete and
> equipment is more cost-effective.
>
> ADY

FWIW, I agree w/ Jeff's points in principle, in practice I've set up
many-a-sites as you've described with cisco aps, all set w/ same ssid
and have had no problem roaming between. granted nobody was doing
anything like VoIP calls, etc... but i think most
non-super-latency-sensitive tcp traffic will be fine.

good thing you have the cat5 ran, repeating is a nightmare. Although
there are products out there now that handle the issue _VERY_ well with
multiple radios. check out http://www.strixsystems.com.

Jeremy
Anonymous
October 14, 2004 2:47:28 AM

Archived from groups: alt.internet.wireless (More info?)

On Wed, 13 Oct 2004 05:50:00 GMT, in alt.internet.wireless , Jeff
Liebermann <jeffl@comix.santa-cruz.ca.us> wrote:

>On Tue, 12 Oct 2004 17:27:04 -0500, "MousePad"
><adyoungentirely.too.much.junk.mail.in.my.mailbox@sbcglobal.net>
>wrote:
>
>>I'm trying to plan out a wireless network for a building, including multiple
>>WAPs. I want users to be able to roam between access points seamlessly.
>
>So does everyone else. Dream on.

Maybe I have some weird setup, but when I walk between my 11G AP at the
front of my house and my 11B one at the rear, WinXP apparently seamlessly
shifts from one AP to the other when the signal strength of the first
vanishes.

It might depend on what you expect - for me, its good enough to have the
same IP address on each AP, and for the laptop user not to notice any
disconnection.
--
Mark McIntyre
CLC FAQ <http://www.eskimo.com/~scs/C-faq/top.html&gt;
CLC readme: <http://www.ungerhu.com/jxh/clc.welcome.txt&gt;


----== Posted via Newsfeed.Com - Unlimited-Uncensored-Secure Usenet News==----
http://www.newsfeed.com The #1 Newsgroup Service in the World! >100,000 Newsgroups
---= 19 East/West-Coast Specialized Servers - Total Privacy via Encryption =---
!