why can a t1 go further than ethernet

Unanswered Question
Feb 26th, 2008

Just a general question that I never understood.

My guess is because a T1 goes over a pots line that has multiple repeaters to keep the signal alive.

I know you can run phone over ethernet and ethernet over phone line so they are interchangable.

Any answers would be appreciated.

I have this problem too.
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Edison Ortiz Tue, 02/26/2008 - 10:21

You need the necessary equipment (like the Telco) to extend the WAN media. T1 infrastructure was built on routers, now that switches provide features comparable to routers, WAN ethernet is growing dramatically.

MetroEthernet deployment has jumped exponentially over the past 5 years.

T1 is not longer the WAN connectivity of choice (at least in the USA).




jenderlin Tue, 02/26/2008 - 11:03


but generally speaking, why can a T1 circuit go further than ethernet cable? Ethernet can go what 300ft before you lose a lot of signal, yet T1 line (pots) can go a lot further. Its hard to believe just because of the type of wiring in the cable.

I believe it is because there are repeaters on the phone pole lines to re-boost the signal to keep the signal alive. Yes?

Edison Ortiz Tue, 02/26/2008 - 11:14

Are you referring Ethernet solely on copper connection? If so, yes - the number you've mentioned is the limitation.

When I think of Ethernet in the WAN, I'm mostly referring to Fiber which can run for miles and miles...



jenderlin Tue, 02/26/2008 - 11:35


here is the exact question i want to know.

why can a t1 circuit go further than an ethernet run? is it the wiring in the line or?

i know fiber can go for a long time. we run all single and multimode fiber here at the county. It is just a general question that one of my friends had and I have no real answer.

so again, why can a t1 circuit (that is over a pots line) go further than an ethernet cable? Why not just use t1 (phone lines) to desktops and such if it can go much futher than ethernet at 300ft limit??

Edison Ortiz Tue, 02/26/2008 - 11:44

why can a t1 circuit (that is over a pots line)

Sorry but that's not the case T1s do not run over pots line, here is a good bit of history and information about T-Carriers.


As for Ethernet, it has its limitations on distance. That's the spec. However, if you want distance and Ethernet, there is an answer and the answer is Fiber, not phones lines.




Hi, just thought I would provide you with the simple answer, T1 circuits do not travel over Cat5e or Cat6 UTP cables, Cat5 and Cat6 cable sufer from attenuation at the 100 meter mark. The signal will be degraded in these cables past the rated distance physical they cant transmit a signal past 100 meters no matter what signal is on the wire. HTH

lamav Tue, 02/26/2008 - 15:02


Let me offer some info from an electrical theory perspective, which is what I think you are searching for.

Electrical signals that travel over copper wires are susceptible to distortion and attenuation as a result of EMI, electromagnetic interference.

As electrical current flows in the wire, a magnetic field builds around it. This is known as electromagnetism, of course. As the intensity of the current changes -- as the signal's amplitude changes -- so, too, does the force and intensity of the resulting magnetic field.

The magnetic field's lines of flux collapse and induces an electromotive force (EMF - voltage) in the adjacent wire as the data signal's amplitude returns to zero.

So, what you have are electrical currents flowing through a wire, changing in intensity and polarity, thereby inducing magnetic fields of varying intensity, which then collapse and create an EMF around the adjacent wire.

The EMF that is produced interferes with the flow of the data signal on the adjacent wire. The more rapid the bit rate of the signal, and the more amplitude and polarity changes that occur, the greater the interference on the neighboring wire's data flow.

Moreover, according to the Nyquist theorem, a synchronous data stream requires a certain number of "ones" bits to be used as synchronization bits. This is called Ones Density. The theorem states that no more than 15 consecutive zero bits can occur before the end systems lose synchronization. That is the whole reason for Bit 7 stuffing and B8ZS encoding.

A T1 has a bit rate of 1.544 Mbps while Ethernet is anywhere form 10 Mbps to 1Gbps and up. The faster bit rate of ethernet and its requirement for a greater one's density makes it more susecptible to the effects of EMI and induction. This is, by the way, why an Ethernet cable's wires are so tightly wound -- a lot more than a T1 cable. It is meant to cancel out the magnetic fields that are produced as the current flows through the wire, thereby minimizing interference.

Lastly, the length of the cable has a direct bearing on the capacitance. As the capacitance changes, so, too, does the impedance and the ability for the data to flow without experiencing significant attenuation. Cable length effects T1 curcuits as well as Ethernet links, but again, the greater demands of maintaining the integrity of an Ethernet signal's current flow make Ethernet more vulnerable to long cable lengths.


If so, please rate post.



Joseph W. Doherty Tue, 02/26/2008 - 17:36

Simple answer, slower baud (signal transition) rate usually allows additional distance, everything else being equal.

lamav Tue, 02/26/2008 - 17:50

Hi, Joseph:

Read my explanation and you will see that 1.) You have restated what I said already, and 2.) Why it is the case that a slower bit rate can tolerate longer distances. :-)




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