Re: Cohousing-L digest, ethernet
From: sleonard (sslahsc.arizona.edu)
Date: Sat, 9 Jun 2001 01:38:12 -0600 (MDT)
Ok, I'm mostly a lurker, cause I'm not associated w/ a cohousing group yet,  
just been
very interested for 4 years or so... but I wanted to address a message which 
pertains
to an area I have some knowledge in (cause it's part of what I do everyday)

I am not a wiring expert however, though I'm fairly good with most other 
aspects of
Lans.  I think that it would be a good idea to have an expert at least look 
over your
plans.  If  this is too costly for you, there are lots of good resources 
on-line...

Here is the site I went to for help when I was overhauling the building LAN at 
my job:

http://www.allexperts.com/getExpert.asp?Category=1049

I got some useful responses, and some not.

and here is charles spurgeon on100-Mbps ethernet.  he is, afaik a guru on this
subject:
http://www.ots.utexas.edu/ethernet/100quickref/ch14qr_3.html
http://www.ots.utexas.edu/ethernet/100quickref/ch14qr_5.html

good luck!  feel free to send me off-list email. I have included other comments
in-line.

cohousing-l-request [at] cohousing.org wrote:

>
> --__--__--
>
> Message: 8
> From: "Alex G" <striker222 [at] hotmail.com>
> To: cohousing-l [at] cohousing.org
> Subject: [C-L]_Ethernet and intra-networking for cohousing
> Date: Wed, 06 Jun 2001 15:23:04 -0700
> Reply-To: cohousing-l [at] cohousing.org
>
> >>Ethernet uses 3 pairs, I think (1 through 6)
>
> Standard "ethernet" can use 2 pairs, or 4, depending on the mode it is
> running.
>
> In Tierra Nueva many houses have 2 pairs for two phone lines, and 2 pairs
> for thier data. This allows 10 megabits a second.

I think this was on splitting voice and data in a single cat-5 run.  I  
personally
would recommend not doing this, as its "penny-wise and pound foolish"  wire is
relatively cheap, its the labor to pull it and terminate it that's more 
expensive. You
dont have to terminate everything you pull, if you want to save a few $.  the
difference in labor between running one wire and two is small.  And it's also a 
lot
harder and more expensive to retrofit and put more wire in later.

>
>
>
> >>Note that 3 levels of hub are allowed
>
> You can have as many levels of hubs as you want, well, within reason.

hmm. you "can" do whatever you like.  However the question is if  its going to 
work.
You can break the ethernet rules, but if you have more than minimal traffic 
you'll
probably get errors, which is a bad thing, cause to many of these can make 
things
slow, and even stop working.

In my opinion, it is really not advisable to push the standard limits.  
Especially
since there is less leeway in the specs if you upgrade from 10bT to  faster 
100bT
equipment.

> A lan
> is no different than the internet, there are broadcast stations and media.
> As long as there is not too much media inbetween 2 broadcast routers (hubs,
> computers, routers, switches, etc)

Leaving routers out of it, there are  differences between stringing a bunch of 
hubs
and stringing a bunch of switches.   the short answer is that if you use some
switches, instead of all hubs, you can have more cable runs "end-to-end" . (and 
more
levels of depth).

The long answer is that "hubs" are repeaters and "switches" are bridges. 
switches
segment the ethernet collision domain. introducing a  switch creates separate
collision domains. Therefore the rules of thumb such as "3-4-5" are applied to 
each
collsion domain, instead of your entire lan. and so, you can safely have a 
greater
length end-to-end.

> the signal will perpetuate forever, its
> like a long chain.  Just reading your email you probly went through anywhere
> between 5 and 15.

maybe 5-15 "pieces of net equipment"  but I seriously doubt it went thru 15 
hubs.

>
>
> You MAY be thinking of various LAN standards and measurments, there are IEEE
> standards, and 802.xx standards, for example. They are just
> guidelines.
>
>
>
> >>I discovered that if you are running 10baseT over cat5 cable, it >>works
> >>if the blue & white pair has a phone line on it.
>
> A wire is a wire is a wire. Color is merely for your own organization, in
> your case, the other end of the line must have been configured in a way that
> made blue the correct choice.
>
> >>I'm not competent to answer that.  But note that cat5 is by definition
> >>unshielded.
>
> There are different kinds of cat5-UTP (unshielded twisted pair), strait cat
> 5 relies on twisted pairs to cancle out interference.  Cat5-STP, or
> something, is shieled, heavy, thick, and expensive. Note that tierra nueva
> uses Cat5-E, for extended, increases the range a bit.
>
> -Tierra Nueva lan guy

>
>    8. Ethernet and intra-networking for cohousing (Alex G)
>
> --__--__--
>
> Message: 8
> From: "Alex G" <striker222 [at] hotmail.com>
> To: cohousing-l [at] cohousing.org
> Subject: [C-L]_Ethernet and intra-networking for cohousing
> Date: Wed, 06 Jun 2001 15:23:04 -0700
> Reply-To: cohousing-l [at] cohousing.org
>
> >>Ethernet uses 3 pairs, I think (1 through 6)
>
> Standard "ethernet" can use 2 pairs, or 4, depending on the mode it is
> running.
>
> In Tierra Nueva many houses have 2 pairs for two phone lines, and 2 pairs
> for thier data. This allows 10 megabits a second.
>
> >>Note that 3 levels of hub are allowed
>
> You can have as many levels of hubs as you want, well, within reason. A lan
> is no different than the internet, there are broadcast stations and media.
> As long as there is not too much media inbetween 2 broadcast routers (hubs,
> computers, routers, switches, etc) the signal will perpetuate forever, its
> like a long chain.  Just reading your email you probly went through anywhere
> between 5 and 15.
>
> You MAY be thinking of various LAN standards and measurments, there are IEEE
> standards, and 802.xx standards, for example. They are just
> guidelines.
>
> >>I discovered that if you are running 10baseT over cat5 cable, it >>works
> >>if the blue & white pair has a phone line on it.
>
> A wire is a wire is a wire. Color is merely for your own organization, in
> your case, the other end of the line must have been configured in a way that
> made blue the correct choice.
>
> >>I'm not competent to answer that.  But note that cat5 is by definition
> >>unshielded.
>
> There are different kinds of cat5-UTP (unshielded twisted pair), strait cat
> 5 relies on twisted pairs to cancle out interference.  Cat5-STP, or
> something, is shieled, heavy, thick, and expensive. Note that tierra nueva
> uses Cat5-E, for extended, increases the range a bit.
>
> -Tierra Nueva lan guy
>
> __
>
> --__--__--
>
> >
> >
> > -
>
> End of Cohousing-L Digest

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