Re: OT Why Ethernet cannot still cross the 10m barrier ?

Exactly what I was thinking. The 100m limit is there because longer cables
mess with synchronization and timing. Here's a snippet I found that
explains it for the OP:

On 10-Mbps Ethernet one bit at the MAC layer requires 100 nanoseconds (ns)
to transmit. At 100 Mbps that same bit requires 10 ns to transmit and at
1000 Mbps only takes 1 ns. As a rough estimate, 20.3 cm (8 in) per
nanosecond is often used for calculating propagation delay down a UTP
cable. For 100 meters of UTP, this means that it takes just under 5
bit-times for a 10BASE-T signal to travel the length the cable.

For CSMA/CD Ethernet to operate, the sending station must become aware of a
collision before it has completed transmission of a minimum-sized frame. At
100 Mbps the system timing is barely able to accommodate 100 meter cables.
At 1000 Mbps special adjustments are required as nearly an entire
minimum-sized frame would be transmitted before the first bit reached the
end of the first 100 meters of UTP cable. For this reason half duplex is
not permitted in 10-Gigabit Ethernet.

http://ethernettiming.blogspot.com/

On Fri, Jun 14, 2013 at 11:58 AM, Joe Sanchez <marco207p_at_gmail.com> wrote:

> Preamble , Preamble
>
> Regards,
> Joe Sanchez
>
> ( please excuse the brevity of this email as it was sent via a mobile
> device. Please excuse misspelled words or sentence structure.)
>
> On Jun 14, 2013, at 4:23 AM, marc edwards <renorider_at_gmail.com> wrote:
>
> > This isn't distance limitation of Ethernet. Instead this is physical
> > limitation of Ethernet over copper cabling.
> > Law's of Physic's . The signal degrades over length and also you have
> issue
> > with the time the signal takes to both ends. You can push ethernet pass
> > 100m, i have personally seen 160m for a connection between console server
> > and device but i would not advise it.
> >
> >
> > On Wed, Jun 12, 2013 at 11:32 PM, Ahmed <ahmedsalim_at_gmail.com> wrote:
> >
> >> Is there a history for this 100m barrier ? Even with the modern
> switches ,
> >> cannot this be overcome ?
> >>
> >>
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Received on Fri Jun 14 2013 - 13:03:15 ART