Question about extenders

I'm doing some computer upgrades at home, the end result of the trickledown
will be a dual processer that used to be my server getting rebuilt for my
neighbor who's on a very old Windows 98 computer.

I'd like to get him onto my network at home, so I can set him up on my
exchange server there and let him start using email.

I've got several access points throughout the house, since I have several
wireless devices.

My newest addition was a 3com officeconnect wireless router. Works great, and
I noted that it has the repeater mode option.

From what I've gleaned in here and elsewhere, the bandwidth is halved when
you use this option, due to the wrapping of the packets to get repeated.

Before I look at this as an option, I just wanted to make sure that the only
effective slowing is between the two repeater points, that the rest of the
network and access points would still operate normally, correct? I don't see
why they wouldn't, but figured I'll double check first since this will be a
new infrastructure implementation for me.

Thanks for any info.


--
John

On Thu, 14 Oct 2004 12:01:28 GMT, "John" <(E-Mail Removed)> wrote:

>I'm doing some computer upgrades at home, the end result of the trickledown
>will be a dual processer that used to be my server getting rebuilt for my
>neighbor who's on a very old Windows 98 computer.
>
>I'd like to get him onto my network at home, so I can set him up on my
>exchange server there and let him start using email.
>
>I've got several access points throughout the house, since I have several
>wireless devices.
>
>My newest addition was a 3com officeconnect wireless router. Works great, and
>I noted that it has the repeater mode option.
>
>From what I've gleaned in here and elsewhere, the bandwidth is halved when
>you use this option, due to the wrapping of the packets to get repeated.

Sorta. Every packet that goes *THROUGH* the repeater is effectively
sent twice. Once by the originator, and again by the repeater.
Because the repeater is half-duplex (can't transmit and receive
simultaneously), each packet consumes twice as much "air time" as with
a direct connection.

>Before I look at this as an option, I just wanted to make sure that the only
>effective slowing is between the two repeater points, that the rest of the
>network and access points would still operate normally, correct?

Nope. Since everything has to be on one channel for a repeater to
work, the doubling of the "air time" used by the repeater will appear
as interference to other client radios. This will give them less time
to talk, while waiting for the repeater to shut up. Since the access
point only arbitrates its own client connections and has no control
over the other the radios connected to/thru the repeater, the repeater
and its users will appear as if they were co-channel users, or
neighbors with wireless networks, otherwise known as interference.
(Incidentally, this effect is what's wrong with single radio mesh
networks).

Anything that transmits extraneous packets in the same airspace (can
be heard by your client radios) and on the same frequency will result
in a slowdown. Think of airspace or air time as a shared party line
or network bus, where excess traffic slows everyone down. The
resultant slowdown to the rest of your wireless network will not be
huge, but it will be noticeable.

It will also have the "hidden" transmitter problem, where collisions
between two widely spaced radios that cannot hear each other, will
some slowdown. The usual fix is to enable CTS/RTS flow control. For
a network the size of yours, this is a wasted effort, as it will slow
things down to about half for every radio.

The easiest fix is to turn the repeater back into an access point, but
it it on a different non-overlapping channel as your house access
point. Your neighbors wireless traffic isn't heard by your wireless
network and therefore doesn't affect your performance. However, you
will need to run a CAT5 cable between the two access points.

If you absolutely must play repeater, I suggest using two radios, on
different channels, back to back, as a repeater. Since they are on
different channels, they don't interfere with each other. Since there
are two radio sections, it can transmit and receive simultaneously.
There is still a slight slowdown due to accumulated delays (latency)
but no way near half your bandwidth.

Wired LAN connections are unaffected.

>I don't see
>why they wouldn't, but figured I'll double check first since this will be a
>new infrastructure implementation for me.

I usually recommend repeaters and WDS only as the last restort to
maintain connectivity.

>Thanks for any info.


--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 AE6KS 831-336-2558