Re: [RE] Latencies through RE cables
Geoff,
Thanks for the detailed numbers.
I guess it doesn't hurt to use actual numbers, to validate
the following statement.
>> (This number is much more than the speed of light, ...
I suppose an illustration of conflicting traffic, which
can oftentimes be the cause of conflicts, would also
be helpful. I believe Pioneer had a slide presentation
on this topic, and that had been overlooked in the
writeup.
Thanks again,
DVJ
David V. James
>> -----Original Message-----
>> From: Geoff Thompson [mailto:gthompso@nortel.com]
>> Sent: Tuesday, April 26, 2005 1:45 PM
>> To: David V James
>> Cc: STDS-802-3-RE@LISTSERV.IEEE.ORG
>> Subject: Re: [RE] Latencies through RE cables
>>
>>
>> David-
>>
>> The cable latency is less than or equal to 570 ns/100 meter link
>> (one way).
>> This is a well established number within 802.3 and cabling standards.
>>
>> This is based on the 5.7 ns/m figure that is in 10BASE-T (ref: 14.4.2.4)
>> The higher speed links are slightly faster.
>>
>> Geoff
>>
>>
>> At 12:14 PM 4/26/2005 -0800, David V James wrote:
>> >All,
>> >
>> >Things seem to have been quiet for the last week.
>> >Perhaps I could stimulate some discussions on
>> >cable latencies?
>> >
>> >I believe Alexei's presentations have claimed that
>> >interactive latencies of 15ms are nearly audible.
>> >
>> >Since the link delays are only part of the delay
>> >equation, this has led some of us to believe that
>> >(worst case) per-hop latencies should not exceed
>> >0.5ms. (This number is much more than the speed
>> >of light, since it includes buffer and conflict
>> >delays.)
>> >
>> >Is there any controversy with using this as a
>> >working per-hop maximum delay number?
>> >
>> >For background material on this topic, please
>> >reference pages 15-17 of the following
>> >working paper:
>> >
>> > http://groups.yahoo.com/group/REInterestGroup/files/
>> > The paper is listed as dvjRePaper2005Apr26.pdf
>> >
>> >I have spent the last week accumulating content
>> >of various slide presentations into the above
>> >listed working paper. Hopefully this will be helpful
>> >when considering this and other issues.
>> >
>> >DVJ
>> >David V. James
>> >
>>
>>