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Perhaps the question I want to ask is not directly related to discussion subjects over here, but I couldn't find better place to ask.

I wanna know how does internet connection speed depend on distance while connecting with different cables. For example, if a connection made with optical fiber cable and the distance it follows is 1(one) mile, would it get a down speed for some reason? And what if the distance is 10 or a 100 etc? Same goes for a DSL connection type.

Also, If there is some down speed because of the distance, how does it actually happens and why? Is it because as the distance higher - then weaker the signal is?

  • In any wire, the normal flow of electrical power is about 2/3 the speed of light. Ethernet was designed by Metcalf to be 100 meters per cable to avoid timeouts due to that latency. So if you need to go further than that you need a bridge. It is not a matter of signal strength - just time. – SDsolar Mar 1 '17 at 20:33
  • Did any answer help you? if so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you could provide and accept your own answer. – Ron Maupin Aug 12 '17 at 21:40
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The answer to your question depends completely on the technology used. The complete answer to your question is far too broad, covering many different technologies, to answer here. Any distance will add to latency which can affect perceived speed, depending on the upper layer protocol used.

Fiber (there are multiple standards with various fiber types and bandwidths) will either work at the bandwidths for the standard used, or it won't work.

Some copper based technologies will either work (up to the distance limitation), or they will not work. Some (DSL comes to mind) will degrade to lower bandwidth because some of the frequency channels will not work over a certain distance while others still do.

  • Does latency affect speed in that context? I thought it's more a delay, but the transmitted data eventually will get to the point and it won't affect dramatically speed. Of course, I understand the general question is kind of broad, but perhaps speaking generally it may get a partly answer of what kind of things may cause to low speed due to distance. Like you said(about dsl). I just think in world of today the infrastructure of EU or NA allow to transmit data without significant lose of speed. Perhaps it will be affected by distance from NA to EU or EU to NA due the distance? Is that possible – Mike Nov 11 '15 at 21:07
  • It really depends on what you mean by speed. Latency will affect how fast something gets from one end to the other (speed), and there are other factors besides distance that affect latency. If by speed, you mean bandwidth (not really speed) then the bandwidth on something like fiber is not affected by distance, but it can be on some technologies. – Ron Maupin Nov 11 '15 at 21:13
  • By speed I meant how fast something actually gets from one side to another, yes. I actually didn't find any material about latency affecting speed, perhaps you may refer me to something related(google didn't help)? I always thought that latency in fair range(less than 300ms) has no real affect on speed. For instance, it won't reduce your speed by 50%+ if you connection is 100mbps. – Mike Nov 11 '15 at 21:29
  • T=S/V. Is there any way to calculate(approximately at least) the influence on speed by latency? – Mike Nov 11 '15 at 21:52
  • The impact of latency on data transfer time depends heavilly on how much data you are transferring. TCP works by gradually increasing data rate until it detects congestion. – Peter Green Aug 5 '16 at 15:32
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There are two aspects to speed, data rate (often called bandwidth though that is confusing) and latency. Both can have an impact on the time taken to complete actions (viewing webpagages, typing characters in a remote terminal, downloading files etc).

Data rate is how much traffic the connection can carry per unit of time. Latency is how long it takes a packet of data to get from one end to the other. Normally we measure latency in the form of round trip time since measuring one-way latency is tricky and usually fairly irrelevent.

As a rule of thumb latency will dominate the performance for actions that only involve a small ammount of data while bandwidth will dominate the performance for actions that involve a large ammount of data.

Latency can roughly speaking be divided down into processing delays, queueing delays and cable delays. Cable delays do increase with distance but the delay from the cable that forms your "internet connection" is likely to be small compared to delays further back in the network. Processing delays on some forms of DSL can be significant due to interleaving. Processing also tend to be higher on low-datarate links as often a complete packet must be received byfore it can be forwarded.

The achiveable data rate depends on the Characteristics of the cable. As a cable gets longer the signal integrity (for a given signal launch power) will get worse and so the achivable data rate will go down.

Some technologies (notablly modern DSL) are rate-adapative. They will tailor the charateristics of their signal to match the observed performance on the line. Other technologies use fixed modulation parameters and will start dropping large numbers of packets and then fail completely if the signal integrity is too poor.

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This is the most powerful assertion - "As a rule of thumb latency will dominate the performance for actions that only involve a small ammount of data while bandwidth will dominate the performance for actions that involve a large ammount of data."

Rephrasing this, every packet that leaves the source will arrive late at the destination owing to whatever latency. However, at the destination, the inflow of data will be at the specified speed of the medium (for example 1 GPS). Even So, the speed for each packet is lower (if the cable length is large) yet the information (bits) influx is (nearly) same as that is specified independent of the length.

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