Connecting two wireless routers together

Hi,

As posted before, we are trying to set up a test bed with a bunch of
Linksys WRT54GL routers. I would like to be able to cable the routers
together so that they are not using OTA to communicate. Ideally, there
would be an adjustable attenuator in the cable as well so we could
simulate distance.

In a naive attempt at doing this we tried wrapping the routers in
tinfoil (after removing the antennae) to isolate them. This worked
pretty well. Then we tried wrapping a cardboard tube in tinfoil and
connecting the routers by placing the tube over the antennae RP-TNC
connectors on the routers. (the naive part!) This didn't work at all -
no signals got through.

More research on the internet found me at this site: http://
www.wirelessdesignmag.com/ShowPR.aspx?
PUBCODE=055&ACCT=0031546&ISSUE=0610&RELTYPE=PR&ORI GRELTYPE=FE&PRODCODE=W0240&PRODLETT=A
which shows a test setup of wireless nodes connected with 'RF cable'.
My questions are:

Would this actually work? Assuming it does:
Are attenuators required so that the output from one router doesn't
damage the other router? What cable is best to use for this
application? Any other advice (note - we don't have any experience in
this field)?

thanks,
charlie

"Charlie" <(E-Mail Removed)> hath wroth:

>As posted before, we are trying to set up a test bed with a bunch of
>Linksys WRT54GL routers. I would like to be able to cable the routers
>together so that they are not using OTA to communicate. Ideally, there
>would be an adjustable attenuator in the cable as well so we could
>simulate distance.

Yep. Been there and done that. What you want is a portable RF screen
room or shielded box. Since you're only trying to block a small range
of frequencies, this should be easy. See:
<http://www.smallnetbuilder.com/content/view/26746/100/>
<http://www.azimuthsystems.com/index.asp?p=198>
<http://www.ramseyelectronics.com/te/default.asp?page=rften>
<http://www.saelig.com/miva/merchant.mvc?Screen=PROD&Product_Code=TE001&Catego ry_Code=TE>
for examples. I'll spare you my photograph of the mylar foil and
aluminum duct tape "tent" that I constructed for my first attempt at
shielding. Search Google for "RF test enclosure".

>In a naive attempt at doing this we tried wrapping the routers in
>tinfoil (after removing the antennae) to isolate them. This worked
>pretty well.

Until they overheated. That's why I gave up on foil. Also, there was
considerable leakage from the CAT5 cables on some routers.

>Then we tried wrapping a cardboard tube in tinfoil and
>connecting the routers by placing the tube over the antennae RP-TNC
>connectors on the routers. (the naive part!) This didn't work at all -
>no signals got through.

Chuckle.

>More research on the internet found me at this site: http://
>www.wirelessdesignmag.com/ShowPR.aspx?
>PUBCODE=055&ACCT=0031546&ISSUE=0610&RELTYPE=PR&OR IGRELTYPE=FE&PRODCODE=W0240&PRODLETT=A
>which shows a test setup of wireless nodes connected with 'RF cable'.

In the future, please wrap your URL's with <> so that they don't wrap.
<http://www.wirelessdesignmag.com/ShowPR.aspx?CommonCount=0PUBCODE=055&ACCT=0031546& ISSUE=0610&RELTYPE=PR&ORIGRELTYPE=FE&PRODCODE=W024 0&PRODLETT=A>

>Would this actually work?

Sure. However, there's quite a bit of detail missing. There are no
combiners shown in the picture. You need some what to linearly
combine all the tx and rx signals. A simple resistive combiner will
do, or you can use a power splitter.
<http://www.hyperlinktech.com/web/signal_splitters.php>
Be sure to terminate any unused ports. I use an 8 port device.

Getting attenuators that don't leak and are accurate is more of a
challenge. You'll need to attentuate the maximum tx power down to the
baseline noise level. That's about:
+20dBm - -90dBm = 110dBm
range. That's much more than can be easily found with the common
switchable attenuator that might have perhaps 60dB of adjustable
range. Fortunately, you only need half the 110dBm of each leg of the
power splitter so a mess of common 60dB switchable attenuators will
barely work. However, I suggest also buying a mess of fixed
attenuators to make life easy on the attenuator.

One big problem will be calibration. You're going to have quite a bit
of hardware floating around that may not necessarily be accurate at
2.4GHz. I strongly suggest you spend the time calibrating the
attenuation of the various components at 2.4/5.7Ghz before you
discover that your switchable attenuators were previously used as
someone's dummy load.

>Assuming it does:
>Are attenuators required so that the output from one router doesn't
>damage the other router?

Oh yes. LOTS of attenuators. The typical wi-fi receiver has a very
limited dynamic range. My guess(tm) is that they can't really handle
signals much stronger than perhaps -20dBm before blocking, saturating,
or overloading. You might damage the receiver with anything over
perhaps +30dBm (1 watt), but that's not possible. I've done some
crude damage testing and found that most access points can handle at
least +20dBm before doing any damage. However, that's because the
diversity switch PIN diodes effectively limit the input power. I
don't know what will happen is the PIN switch wasn't there.

>What cable is best to use for this application?

Well, for TNC and SMA connectors, I use RG-400 and LMR-240.
For N connectors, it's all LMR-400 or LMR-400 ultraflex. The stuff is
really stiff. Make sure you use decent crimp connectors.

>Any other advice (note - we don't have any experience in
>this field)?

Yes. Find someone with microwave experience to help. Be prepared to
buy some rather expensive RF test equipment.

--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Wed, 31 Jan 2007 09:56:11 -0800, Jeff Liebermann
<(E-Mail Removed)> wrote in
<(E-Mail Removed)>:

>>More research on the internet found me at this site: http://
>>www.wirelessdesignmag.com/ShowPR.aspx?
>>PUBCODE=055&ACCT=0031546&ISSUE=0610&RELTYPE=PR&O RIGRELTYPE=FE&PRODCODE=W0240&PRODLETT=A
>>which shows a test setup of wireless nodes connected with 'RF cable'.
>
>In the future, please wrap your URL's with <> so that they don't wrap.
><http://www.wirelessdesignmag.com/ShowPR.aspx?CommonCount=0PUBCODE=055&ACCT=0031546& ISSUE=0610&RELTYPE=PR&ORIGRELTYPE=FE&PRODCODE=W024 0&PRODLETT=A>

That's recommended practice, but _won't_ necessarily stop the unwanted
wrapping. It notably doesn't help in Forte Agent.

--
Best regards, FAQ for Wireless Internet: <http://Wireless.wikia.com>
John Navas FAQ for Wi-Fi: <http://wireless.wikia.com/wiki/Wi-Fi>
Wi-Fi How To: <http://wireless.wikia.com/wiki/Wi-Fi_HowTo>
Fixes to Wi-Fi Problems: <http://wireless.wikia.com/wiki/Wi-Fi_Fixes>

John Navas <(E-Mail Removed)> hath wroth:

>On Wed, 31 Jan 2007 09:56:11 -0800, Jeff Liebermann
><(E-Mail Removed)> wrote in
><(E-Mail Removed)>:
>
>>>More research on the internet found me at this site: http://
>>>www.wirelessdesignmag.com/ShowPR.aspx?
>>>PUBCODE=055&ACCT=0031546&ISSUE=0610&RELTYPE=PR& ORIGRELTYPE=FE&PRODCODE=W0240&PRODLETT=A
>>>which shows a test setup of wireless nodes connected with 'RF cable'.
>>
>>In the future, please wrap your URL's with <> so that they don't wrap.
>><http://www.wirelessdesignmag.com/ShowPR.aspx?CommonCount=0PUBCODE=055&ACCT=0031546& ISSUE=0610&RELTYPE=PR&ORIGRELTYPE=FE&PRODCODE=W024 0&PRODLETT=A>
>
>That's recommended practice, but _won't_ necessarily stop the unwanted
>wrapping. It notably doesn't help in Forte Agent.

Wrong. I use Forte Agent 4.1/32.1088 for most of postings and have
found that wrapping URL's in <> now prevents wrapping. Earlier
versions just made a mess. If you look at any of my posting that
include URL's, they don't wrap or do weird things to the line spacing.
Version 4.2 just was released, and I have no idea what it does.

--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Jeff Liebermann <(E-Mail Removed)> hath wroth:

>>>In the future, please wrap your URL's with <> so that they don't wrap.
>>><http://www.wirelessdesignmag.com/ShowPR.aspx?CommonCount=0PUBCODE=055&ACCT=0031546& ISSUE=0610&RELTYPE=PR&ORIGRELTYPE=FE&PRODCODE=W024 0&PRODLETT=A>
>>
>>That's recommended practice, but _won't_ necessarily stop the unwanted
>>wrapping. It notably doesn't help in Forte Agent.

>Wrong. I use Forte Agent 4.1/32.1088 for most of postings and have
>found that wrapping URL's in <> now prevents wrapping. Earlier
>versions just made a mess. If you look at any of my posting that
>include URL's, they don't wrap or do weird things to the line spacing.
>Version 4.2 just was released, and I have no idea what it does.

I just installed Forte Agent 4.2/32.1177. No URL wrapping using the
same URL as before:
<http://www.wirelessdesignmag.com/ShowPR.aspx?CommonCount=0PUBCODE=055&ACCT=0031546& ISSUE=0610&RELTYPE=PR&ORIGRELTYPE=FE&PRODCODE=W024 0&PRODLETT=A>


--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Thu, 01 Feb 2007 08:41:28 -0800, Jeff Liebermann
<(E-Mail Removed)> wrote in
<(E-Mail Removed)>:

>John Navas <(E-Mail Removed)> hath wroth:
>
>>On Wed, 31 Jan 2007 09:56:11 -0800, Jeff Liebermann
>><(E-Mail Removed)> wrote in
>><(E-Mail Removed)>:
>>
>>>>More research on the internet found me at this site: http://
>>>>www.wirelessdesignmag.com/ShowPR.aspx?
>>>>PUBCODE=055&ACCT=0031546&ISSUE=0610&RELTYPE=PR &ORIGRELTYPE=FE&PRODCODE=W0240&PRODLETT=A
>>>>which shows a test setup of wireless nodes connected with 'RF cable'.
>>>
>>>In the future, please wrap your URL's with <> so that they don't wrap.
>>><http://www.wirelessdesignmag.com/ShowPR.aspx?CommonCount=0PUBCODE=055&ACCT=0031546& ISSUE=0610&RELTYPE=PR&ORIGRELTYPE=FE&PRODCODE=W024 0&PRODLETT=A>
>>
>>That's recommended practice, but _won't_ necessarily stop the unwanted
>>wrapping. It notably doesn't help in Forte Agent.
>
>Wrong.

No, just different versions.

> use Forte Agent 4.1/32.1088 for most of postings and have
>found that wrapping URL's in <> now prevents wrapping. Earlier
>versions just made a mess.

True. Which is what I meant. Agent lost its way IMnsHO with its change
in basic architecture after version 1.93, which I still use, turning a
lean mean fighting machine into sluggish bugware. (FYI, I dutifully
reported some of those bugs, but failed to generate any real interest in
fixing them.)

My original point remains: Wrapping URLs in <>, while a good standards
compliant idea in general, _won't_ necessarily eliminate bad wrapping.
That it works for you is great, but it won't work for lots of others,
including me.

--
Best regards, FAQ for Wireless Internet: <http://Wireless.wikia.com>
John Navas FAQ for Wi-Fi: <http://wireless.wikia.com/wiki/Wi-Fi>
Wi-Fi How To: <http://wireless.wikia.com/wiki/Wi-Fi_HowTo>
Fixes to Wi-Fi Problems: <http://wireless.wikia.com/wiki/Wi-Fi_Fixes>

On Thu, 01 Feb 2007 21:49:11 GMT, John Navas
<(E-Mail Removed)> wrote:

>True. Which is what I meant. Agent lost its way IMnsHO with its change
>in basic architecture after version 1.93, which I still use, turning a
>lean mean fighting machine into sluggish bugware. (FYI, I dutifully
>reported some of those bugs, but failed to generate any real interest in
>fixing them.)

You might want to try again. The original writers of Forte Agent
bought the company back from the clueless previous buyers and are
again scribbling code.
<http://www.forteinc.com/main/who.php>
I haven't seen much in the way of bugs lately. There have been 8
releases since 1.92.
<http://www.forteinc.com/release/index.php>

>My original point remains: Wrapping URLs in <>, while a good standards
>compliant idea in general, _won't_ necessarily eliminate bad wrapping.

Works for me in Forte 4.2. Also seems to work with Outlook and
Outlook Express. However, Thunderbird 1.5.0.9 seems to word wrap.

>That it works for you is great, but it won't work for lots of others,
>including me.

All things come to he who upgrades.

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558 (E-Mail Removed)
# http://802.11junk.com (E-Mail Removed)
# http://www.LearnByDestroying.com AE6KS

On Fri, 02 Feb 2007 01:46:42 GMT, Jeff Liebermann
<(E-Mail Removed)> wrote in
<(E-Mail Removed)>:

>On Thu, 01 Feb 2007 21:49:11 GMT, John Navas
><(E-Mail Removed)> wrote:
>
>>True. Which is what I meant. Agent lost its way IMnsHO with its change
>>in basic architecture after version 1.93, which I still use, turning a
>>lean mean fighting machine into sluggish bugware. (FYI, I dutifully
>>reported some of those bugs, but failed to generate any real interest in
>>fixing them.)
>
>You might want to try again. The original writers of Forte Agent
>bought the company back from the clueless previous buyers and are
>again scribbling code.
><http://www.forteinc.com/main/who.php>

I know that. I'm talking about their new versions of Agent.

>I haven't seen much in the way of bugs lately. There have been 8
>releases since 1.92.
><http://www.forteinc.com/release/index.php>

My bugs still exist as of the last time I tested.
Likewise the sluggish performance.

>>My original point remains: Wrapping URLs in <>, while a good standards
>>compliant idea in general, _won't_ necessarily eliminate bad wrapping.
>
>Works for me in Forte 4.2. Also seems to work with Outlook and
>Outlook Express. However, Thunderbird 1.5.0.9 seems to word wrap.

The point is that framing in <>, while a good idea in general, is not
any sort of assurance that bad wrapping won't occur.

>>That it works for you is great, but it won't work for lots of others,
>>including me.
>
>All things come to he who upgrades.

Really?! Whatever happened to:


The effect is also self-perpetuating. Features get added faster than
bugs get fixed. It's a natural law or something. This effect
eventually results in a bloated monster ...


So, there we have the logic:
In order to sell upgrades, it has to be noticeably buggy.
In order to be sufficiently buggy, it has to be big and bloated.
In order to look like an improvement, it has to have new features.


Software tends to grow faster than the bugs can be fixed. Bloat is
in, quality is out. Eventually, reliability and scaleability will
suffer. Bigger is better or at least sells better.


Few users would upgrade to the latest version just for the new and
wonderful features that nobody really needs. They upgrade because
there's a small hope that the new and improved release will have
fewer bugs. This never really happens because features and functions
get added faster than bugs get fixed resulting in a bloated
application that's full of known bugs.


My conspiracy theory is that all software manufactories,
intentionally leave bugs unfixed, so that the customer has an
incentive to purchase upgrades and support. If the stuff actually
worked out of the box, people would simply use the last version
forever, and the software manufactory will go otto biz. Therefore,
bugs are permanent and a good thing.

On a similar note, if some company accidentally produces something
that actually works, an incentive to upgrade must be found.
Manufacturing groups, consortia, and industry committees, meet in the
inevitable smoke filled room, and conspire to introduce new
technology, new acronyms, and standards in copious quantities. Soon,
everything you own that actually works, is obsolete, incompatible, or
unsupported. This is called progress.

Since the sales of MS NT4 have shown that the customers are
unconcerned about reliability, stability, and performance, companies
are forced to sell their products on the basis of features and
support acronyms. Unfortunately, acronyms an features are added
faster than bugs get fixed, resulting in bloated, oversided, feature
infested, and buggy software. When the feature bloat grows to the
point of non-functionality, a totally new product is invented to fill
the product niche.


I've got a lean mean stable release with very few bugs. Tell me again
why I should upgrade?

--
Best regards, FAQ for Wireless Internet: <http://Wireless.wikia.com>
John Navas FAQ for Wi-Fi: <http://wireless.wikia.com/wiki/Wi-Fi>
Wi-Fi How To: <http://wireless.wikia.com/wiki/Wi-Fi_HowTo>
Fixes to Wi-Fi Problems: <http://wireless.wikia.com/wiki/Wi-Fi_Fixes>

On Sat, 03 Feb 2007 00:04:20 GMT, John Navas
<(E-Mail Removed)> wrote:

>I know that. I'm talking about their new versions of Agent.

Well, I must admit that I don't use every single feature in Forte
Agent. Still, what I use works well enough.

>My bugs still exist as of the last time I tested.
>Likewise the sluggish performance.

Well, ok. I don't notice any sluggish performance on my systems which
are certainly not state-o-de-art.

>The point is that framing in <>, while a good idea in general, is not
>any sort of assurance that bad wrapping won't occur.

There is a line length limit where things autowrap. I don't mean the
configurable limit that's usually set to 75 characters. I mean the
255 or so character limit probably caused by a fixed length buffer
somewhere in Agent. That is sometimes a problem with Linksys URL's,
which tend to be rediculously long. Otherwise, <> non-wrapping has
worked just fine when I've used it in the last 3 or so versions.

>>All things come to he who upgrades.
>
>Really?! Whatever happened to:
>
> The effect is also self-perpetuating. Features get added faster than
> bugs get fixed. It's a natural law or something. This effect
> eventually results in a bloated monster ...

Yep. I said that, I believe that, I even practice that. Give me
features or give me death (of the product). Does the world really
need MS Vista?

> So, there we have the logic:
> In order to sell upgrades, it has to be noticeably buggy.
> In order to be sufficiently buggy, it has to be big and bloated.
> In order to look like an improvement, it has to have new features.

Yep. I said that. I won't go so far as to suggest that vendors
intentionally introduce bugs in order to sell future upgrades.
However, I will suggest that bugs are often ignored in favor of adding
features, where time is limited. I gave up joining beta test ordeals
after my bug reports were ignored, but my feature requests got their
attention.

> Software tends to grow faster than the bugs can be fixed. Bloat is
> in, quality is out. Eventually, reliability and scaleability will
> suffer. Bigger is better or at least sells better.

Yep. I said that. I don't think Forte Agent qualifies. There have
been features added, but there have also be releases that are
overwhelmingly bug fixes (i.e. version 4.1). There was a big leap in
code size from 1.9x to 2.x, which I guess qualifies. However, as I
understand it, the changes in architecture and design were required to
supply new added features.

> Few users would upgrade to the latest version just for the new and
> wonderful features that nobody really needs. They upgrade because
> there's a small hope that the new and improved release will have
> fewer bugs. This never really happens because features and functions
> get added faster than bugs get fixed resulting in a bloated
> application that's full of known bugs.

Yep. I said that. I think Vista might become a good example of this.
Lots of features that nobody wants or is willing to pay for. Most of
the customers that are bugging me about Vista are the ones that are
having reliability problems with some part of Vista.

> My conspiracy theory is that all software manufactories,
> intentionally leave bugs unfixed, so that the customer has an
> incentive to purchase upgrades and support. If the stuff actually
> worked out of the box, people would simply use the last version
> forever, and the software manufactory will go otto biz. Therefore,
> bugs are permanent and a good thing.

Yep. I said that. If the stuff worked, nobody would be asking
questions in the newsgroups, nobody would need to read the manual,
nobody would be upgrading to later firmware, and few would upgrade to
the latest versions unless they needed the features.

> On a similar note, if some company accidentally produces something
> that actually works, an incentive to upgrade must be found.
> Manufacturing groups, consortia, and industry committees, meet in the
> inevitable smoke filled room, and conspire to introduce new
> technology, new acronyms, and standards in copious quantities. Soon,
> everything you own that actually works, is obsolete, incompatible, or
> unsupported. This is called progress.

Yep. I said that. Progress is measured in sales and stock prices.
Those don't go up unless the company releases new products or upgrades
on an almost continuous basis. Want to pump up the stock price? Just
issue a press release announcing something new and/or improved. Know
any company that has been selling the same version for a long time?

> Since the sales of MS NT4 have shown that the customers are
> unconcerned about reliability, stability, and performance, companies
> are forced to sell their products on the basis of features and
> support acronyms. Unfortunately, acronyms an features are added
> faster than bugs get fixed, resulting in bloated, oversided, feature
> infested, and buggy software. When the feature bloat grows to the
> point of non-functionality, a totally new product is invented to fill
> the product niche.

Yep. I said that. It's evolution in action. There's a good reason
that the dinosaurs tended toward titanic growth. Being big is very
defensible. Same with software. Want to avoid being eaten by the
competition? Easy, grow big.

>I've got a lean mean stable release with very few bugs. Tell me again
>why I should upgrade?

So you can have <> quoted URL's that don't wrap.

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558 (E-Mail Removed)
# http://802.11junk.com (E-Mail Removed)
# http://www.LearnByDestroying.com AE6KS

On Sat, 03 Feb 2007 00:04:20 GMT, in alt.internet.wireless , John
Navas <(E-Mail Removed)> wrote:

>My bugs still exist as of the last time I tested.

If you can identify them, I might be able to test again.

>Likewise the sluggish performance.

YMMV. I use Agent 3.3 and its far from sluggish. Considerably more
nippy than the other newsreaders I tried, in point offact. Maybe it
was a h/w issue.

>The point is that framing in <>, while a good idea in general, is not
>any sort of assurance that bad wrapping won't occur.

Sure. but Jeff's point is that it _does_ remove instances of bad
wrapping the readers he tried.

>I've got a lean mean stable release with very few bugs. Tell me again
>why I should upgrade?

V3 had enough new features, and no bugs that affected me, to make it
worthwhile. YMMV of course.
--
Mark McIntyre