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From: bigcatxx on 7 Aug 2007 06:28

Hi all,

My current config consist of four 3COM 3CRW554G72T (A-D below), and A
is the base router. They connect to each other by 3Com WDS now, as
cabling is not feasible for us.

A <---> B <---> C <---> D <<->> X <<->> Y
_____________________________^_______^
_____________________________| _______|
_____________________________V_______ V
_____________________________W <<->> Z

My office will be extended to a new zone beyond the AP D. By the size
of current coverage, I estimate four new AP are required (W-Z). Anyone
has experience with such large WDS configuration? Will it have any
limitation / trouble for these long chains?

In other ways, I have also try to look for alternate methods. A
promising one is the wireless repeater/extender from Linksys(WRE54G) or
Belkin(F5D7132). But someone told me that only one could be used per
wlan, so I won't be able to setup the config by extender.

Any comments on the repeaters / range extenders? or any other
suggestion for my situtation? Thanks

Patrick


------------------------------------------------------------------------
View this thread: http://www.wirelessforums.org/showthread.php?t=26585
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From: Eric on 7 Aug 2007 17:49

"bigcatxx" <bigcatxx.2uxy8z(a)no-mx.wirelessforums.org> wrote in message
news:bigcatxx.2uxy8z(a)no-mx.wirelessforums.org...
>
> Hi all,
>
> My current config consist of four 3COM 3CRW554G72T (A-D below), and A
> is the base router. They connect to each other by 3Com WDS now, as
> cabling is not feasible for us.
>
> A <---> B <---> C <---> D <<->> X <<->> Y
> _____________________________^_______^
> _____________________________| _______|
> _____________________________V_______ V
> _____________________________W <<->> Z
>
> My office will be extended to a new zone beyond the AP D. By the size
> of current coverage, I estimate four new AP are required (W-Z). Anyone
> has experience with such large WDS configuration? Will it have any
> limitation / trouble for these long chains?
>
> In other ways, I have also try to look for alternate methods. A
> promising one is the wireless repeater/extender from Linksys(WRE54G) or
> Belkin(F5D7132). But someone told me that only one could be used per
> wlan, so I won't be able to setup the config by extender.
>
> Any comments on the repeaters / range extenders? or any other
> suggestion for my situtation? Thanks
>
> Patrick
>

Repeating/WDS cuts your pipe in half and is nasty.

Run your WAP's as additional WAP's, not as "repeaters".

If you can't run cable, get the data to the WAP's by any other means
possible. Put a wireless-ethernet adapter in front of them, run it through
the powerlines with ethernet-powerline adapters, whatever it takes...




From: Jeff Liebermann on 8 Aug 2007 00:29
On Aug 7, 3:28 am, bigcatxx <bigcatxx.2ux...(a)no-mx.wirelessforums.org>
wrote:

> My current config consist of four 3COM 3CRW554G72T (A-D below), and A
> is the base router. They connect to each other by 3Com WDS now, as
> cabling is not feasible for us.
>
> A <---> B <---> C <---> D <<->> X <<->> Y
> _____________________________^_______^
> _____________________________| _______|
> _____________________________V_______ V
> _____________________________W <<->> Z

Forgive me, but I don't understand your diagram.
Do you really have 3 wireless hops between WDS bridge "D"
and the router "A"? That's a huge performance hit.
Max speed drops by at least 50% for each hop.
Normally the various workgroup bridges connect
directly via wireless to the central router.

Incidentally, what's the model number of the base
router?

Perhaps it would be best if you scribble a drawing,
labeling the wired and wireless hops individually,
and post the JPG or PDF to some public web site.

> My office will be extended to a new zone beyond the AP D. By the size
> of current coverage, I estimate four new AP are required (W-Z). Anyone
> has experience with such large WDS configuration? Will it have any
> limitation / trouble for these long chains?

Hell yes. They barely work. As I mentioned, max speed
drops in half for every hop. A typical "good" wireless
connection will connect at 25Mbits/sec. That yields a
maximum TCP thruput of about 12Mbit/sec. Add another
repeater hop, and your maximum goes down to 6Mbits/sec.
Yet another hop is 3Mbits/sec max. If you've only got a
1.5Mbit/sec DSL connection, this may actually work.
However my experience indicates that this is the theoretical
best case. Reality is far worse. I've given demos of WDS
bridges all running in the same room. After about 4 hops,
traffic just simply stops and dies from all the packet
collisions and retransmissions in the same airspace.

> In other ways, I have also try to look for alternate methods. A
> promising one is the wireless repeater/extender from Linksys(WRE54G) or
> Belkin(F5D7132). But someone told me that only one could be used per
> wlan, so I won't be able to setup the config by extender.

The WRE54G can also operate as a WDS bridge. I think what
they meant is that you can't use more than one in the same
airspace without seeing excessive collisions and retransmissions.
I've used two of these to cover two sides of a building, where
both repeaters could see the central wireless router, but could
not see each other. That also required some rather exotic sector
antennas. I would not recommend such a system for your
office application.

Are you *SURE* that CAT5 and other wiring options are not
available. Workgroup bridges work well for single hops, but
I wouldn't try it for more than one.

> Any comments on the repeaters / range extenders? or any other
> suggestion for my situtation? Thanks

I don't know anything about your situation except a diagram
that I don't understand and an office application without any
data. Some details would be helpful, but offhand, methinks
you've already built what amounts to an indoor mesh network,
which does not scale very well. Run the wires.

>
> Patrick
>
> ------------------------------------------------------------------------
> View this thread:http://www.wirelessforums.org/showthread.php?t=26585http://www.wirelessforums.org


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