[Asterisk-Users] phones with two ethernet ports

Mon Jan 3 16:08:19 MST 2005

Each 4-pair wire has 8 wires in the "blue wrapper" cable.

You only need 2 pairs, 4 of the wires, for 100MB Ethernet.

You could split the wire at the wall jack and at the switch end where it
goes through the punch down thingy (the name escapes me at the moment.)

You only need to run 1 blue/4 pair wire cable to each desk. You could
put a small hub on each desk to split our more sockets.

For the life of me I will never understand why people believe that each
cubical/desk needs it own 4-pair cable, CAT5 cable connect back to the
server.

Normally cubes are arranged so that at least 4 are connecting to the
electric lines via one feeder line. Every house in the city does not
have a private electrical feed back to the power plant.

With a network you bring one, 1, une, uno, eine, CAT5 Cable to an area,
then you place hub or a switch. Then you connect each user to this
hub/switch.

Stop screaming. What does a hub cost compared having to wait for the
CAT5 Cable guy to drag a new wire each time and the he has to bring your
network up and down several times because none of the wires are labeled
correctly and they are all blue. Eventually the conduit fills up and you
have to put in another 8 inch conduit, but the elevator shaft is
full,...

Yes, go on, tell me that each user requires 100 Mbps to their desk on a
continuous basis or they will not get any work done (the phone sucks
about 100 kilo-bits, BITS! Per second. 100kps or less.)

They don't. Unless of course they are running an older Microsoft version
of the Enterprise's Transporters with Scotty at the other end.

Look folks, in your house there is a phone line that connects you, not
all the way back to the phone company, but a green box in your
neighborhood. This little box has about 1 line back to another box for
every 10 phones in your neighborhood and so on to larger boxes until you
hit the telephone company. (1:10 1:8 1:6, whatever, lets go with the
easy math here.)

The telephone works all the time except when everyone tries to make a
call at the same time. You don't need to drag wires so every phone in
the country connects directly to a switch. Yes, a switch!

The calls all branch together up stream to the switch through a set of
switches/hubs and then connect to the DS3 in the cloud.

They can do this cause some guy name A.K. Erlang,
http://pass.maths.org.uk/issue2/erlang/, spawned the erlang, "A
measurement unit of the average traffic usage of a telecommunications
facility during a period of time (normally a busy hour) with reference
to one hour of continuous use. The capacity of Erlangs is the ratio of
time during which a facility is occupied to the time the facility is
available for occupancy with reference to one hour. For example, a 12
minute call is 0.2 Erlangs. 1 Erlang equals 36 centum call seconds
(CCS)."

Or simply put:

"In 1917, he looked at a village telephone exchange. He supposed that
the village has a certain number of telephone lines going from it to the
outside world. 

We'll call the number of lines C. People in the village want to make
calls to the outside world. We don't know when they will want to call or
how long their calls will last, but let's suppose that there are on
average v calls starting per minute, and that the average length of a
call is one minute. Erlang wanted to know what fraction of callers would
find that all the C lines leading out of the village were already full,
and so would not be able to make their call until later. He worked out
this formula, which gives the answer: 

This is called Erlang's formula. The left hand side, E(v,C), represents
the proportion of callers that find all the lines already full, and the
right hand side gives an equation for that quantity. If you know how big
v and C are, you can work out what proportion of calls cannot get out of
the village. "

Face it 95% of the time the wires are idle. If your network seems slow
it is because you have a pig sitting on a bottle neck somewhere in the
network.

Please, stop dragging wires everywhere, learn how to use a switch. Can
anyone say "hub and spoke"?

Race "The Tyrant" Vanderdecken

Yes, you can use one pair for data and one pair for voice to keep the
networks separate if you like to do that type of thing.

Yes, splitting the pair at the wall jack and that thingy on the other
end is work, but wait till your boss finds out that you have twice as
many CAT5 runs as you will every need or that you are wasting have the
wire.

-----Original Message-----
From: asterisk-users-bounces at lists.digium.com
[mailto:asterisk-users-bounces at lists.digium.com] On Behalf Of Harry
McGregor
Sent: 03 January 2005 16:34
To: Asterisk Users Mailing List - Non-Commercial Discussion
Subject: Re: [Asterisk-Users] phones with two ethernet ports

Personally I would run the two Cat5 runs.

I am in a situation where we "only" have two cat 5 cables into each
office.  Once (if) we start our VOIP deployment we will be using Zultys
4x4 phones with 3 10/100 ports (802.1q capable switch built in) on one
office port, and the other will be for the researcher's "main" desktop
on our gigabit switches.  I would love to be able to connect more
systems at Gig, but putting a small gig switch in each office is cost
prohibitive, and a management nightmare.

Try finding a VOIP Phone that does gigabit... Won't happen for a while.
Cable is cheap when you look at the cost of running the cable.  If you
use two boxes, it will take virtually the same amount of time to run two
as it does to run one.

			Harry

On Sun, 2005-01-02 at 16:35 -0500, Erick Perez wrote:
> Hi there, what phones are available that have two ethernet ports?
> I want to do some cabling at a new installation and i heard there are
> such phones (SIP i guess) out there. That way i dont have to run two
> cat5 to the user desktop.
> I think 3COM had one but can't find the web site reference for the two
> port phone
> 
> thanks,
> 
> erick
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-- 
Harry McGregor, Computing Manager
Tucson Support Group - U.S. Geological Survey
University of Arizona - Environment and Natural Resource Building
520-670-5574 (office) - hmcgregor at espri.arizona.edu
520-661-7875 (Cell) - hmcgregor at usgs.gov

The opinions/statements expressed herein are my own and should
not be taken as a position, opinion, or endorsement of the
University of Arizona or the U.S. Geological Survey.

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