# ethernet cable

Discussion in 'Archived Threads 2001-2004' started by Anthony Moore, Apr 19, 2002.

1. ### Anthony Moore Supporting Actor

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Does the length of an ethernet cable matter? I was under the impression that as long as it was less than 100 meters, there would be no difference in speed. But after 100 meters, the speed would drop off.

Is this true? If you know of a site that will inform me, please link me.

any help would be appreciated

thanks

2. ### Matt Stryker Screenwriter

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After 300 feet or so, you start to get enough attenuation to affect the signal; it can cause speed loss or complete cable failure.

3. ### Keith Outhouse Stunt Coordinator

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http://www.faqs.org/faqs/LANs/ethernet-faq/index.html
[3.11] What is propagation delay?
The propagation speed of a medium refers to the speed that the data
travels through that medium. Propagation delays differ between
mediums, which affect the maximum possible length of the Ethernet
topology running on that medium.
In the following table, c refers to the speed of light in a vacuum,
or 300,000 kilometers per second.
Medium Propagation Speed
------ -----------------
Thick Coax .77c (231,000 km/sec)
Thin Coax .65c (195,000 km/sec)
Twisted Pair .59c (177,000 km/sec)
Fiber .66c (198,000 km/sec)
AUI Cable .65c (195,000 km/sec)
From these values, the size of a bit on 10BaseT can be calculated.
10BaseT is twisted pair, which has a propagation delay of 177,000
km/sec. 177,000 km/sec divided by 10 million bits per second is
17.7 meters, or the size of a single bit on a 10BaseT network.
The maximum propagation delay through the network can be calculated
by dividing the maximum length by the speed. For 10Base2 thin coax
network, this is 185 meters divided by 195,000 km/sec, or 950
nanoseconds. If the actual propagation delay from one end of the
network to the other is greater than 950 nanoseconds, late
late collisions.

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