[CQ-Contest] FW: Ethernet Cable Length

[n1cc at jlaporta.com]

Jim - Here is my try at posting on CQ-Contest... de N1CC

Jim, N1CC
Contesting and DX
http://www.jlaporta.com/N1CC 


-----Original Message-----
From: Jim Brown [mailto:k9yc at audiosystemsgroup.com] 
Sent: Saturday, October 08, 2016 12:23 PM
To: n1cc at jlaporta.com
Subject: Re: [CQ-Contest] Ethernet Cable Length

Thanks for the excellent and detailed response. You should post this to the
reflector. It only came to me.

73, Jim

On Sat,10/8/2016 8:57 AM, n1cc at jlaporta.com wrote:
> Jim:  Timing is one issue with 10BaseT, 100BaseTX and Gigabit-E (1000 
> still not fully defined).  When these modes are used over UTP, and 
> that includes CAT5e, the longer the cable the more likely that additional
"collisions"
> will occur.  That's because the sending station does not get the reply 
> back in time and sends the original packet again. (The physical layer 
> protocol is
> CSMA/CD)
>
> Most use 100BaseTX (100 Mbps) today, although both CAT5(*) and CAT6(*) 
> can be used up to 100m without excessive delay producing more 
> collisions than acceptable, it is usually shorter than that and more 
> often over 100' the use of Shielded Twisted Pair is preferred.
>
> All "Ethernet" is only capable of 30% loading of the speed supported.  
> Once you put 30% and above on the segment you get excessive collisions 
> and the throughput begins to fail.  At 50% load you have zero 
> throughput ... only collisions.
>
> Here is a write-up from one of my pre-retirement companies:
> http://www.cisco.com/c/en/us/support/docs/routers/10000-series-routers
> /46792 -ethbase.html that pretty well tells a technical person the 
> limitations.
> And although some use UTP because it is cheap, I wouldn't ever use it 
> for audio runs.  There's cable made for that, costs more, however does 
> the job right as you know.
>
>
> 73, Jim
>
> Jim, N1CC
> Contesting and DX
> http://www.jlaporta.com/N1CC
>
>
> -----Original Message-----
> From: CQ-Contest [mailto:cq-contest-bounces at contesting.com] On Behalf 
> Of Jim Brown
> Sent: Saturday, October 08, 2016 1:05 AM
> To: cq-contest at contesting.com
> Subject: [CQ-Contest] Ethernet Cable Length
>
> On Fri,10/7/2016 7:22 PM, Mike Smith VE9AA wrote:
>> I am not a N+ (Network) guy, so I wouldn't really want to make an 
>> educated statement and any advice I would give would only be a  guess.
>> I know often I hear they don't like running network cables like Cat5E 
>> or
>> Cat6 more than 100m (321').
> The issue with cable length is timing. I'm not the expert, but we ran 
> into this 20+ years ago using Ethernet to carry audio in large pro
systems.
>
> 73, Jim K9YC
>
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