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

There are barriers that are related to other issues, not only power.
More speed means higher signal frequency and copper starts behaving less
and less a good conductor. Someone has to pick a limit for the standard,
and it happens to be 100m.

-Carlos

Marko Milivojevic @ 15/06/2013 00:15 -0300 dixit:
> Technically, yes. As long as you can guarantee it will be full-duplex. I've
> had cables linger than 100m work fine.
>
> Of course, at some point, the transmitter strength becomes and issue.
>
> --
> Marko Milivojevic - CCIE #18427 (SP R&S)
> Senior CCIE Instructor / Managing Partner - IPexpert
>
>
> On Fri, Jun 14, 2013 at 3:01 PM, John Neiberger <jneiberger_at_gmail.com>wrote:
>
>> That's a good point. If we're running full duplex and collision detection
>> is disabled, does that eliminate the 100m restriction since the limiting
>> timing factor no longer applies?
>>
>>
>> On Fri, Jun 14, 2013 at 3:51 PM, Carlos G Mendioroz <tron_at_huapi.ba.ar
>>> wrote:
>>
>>> I beg your pardon ?
>>> I have not seen any implementation of multiaccess 1G ethernet,
>>> and it's ages since I last saw a 100 Mb hub.
>>>
>>> What's the point of half duplex and colission detection nowadays ?
>>>
>>> -Carlos
>>>
>>> John Neiberger @ 14/06/2013 16:03 -0300 dixit:
>>>> 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 ?
>>>>>>>
>>>>>>>
>>>>>>> Blogs and organic groups at http://www.ccie.net
>>>>>>>
>>>>>>>
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>>>>
>>>>
>>>>
>>>
>>> --
>>> Carlos G Mendioroz <tron_at_huapi.ba.ar> LW7 EQI Argentina
>>
>>
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-- 
Carlos G Mendioroz  <tron_at_huapi.ba.ar>  LW7 EQI  Argentina
Blogs and organic groups at http://www.ccie.net