Re: [EFM] Network timing, ATM, ADSL/VDSL and EFM
Fletcher,
I and my customers would prefer "smart pipes" to either "fat pipes" or
"smart switches". One of the problems that the transmission service
providers have created is a level of support transparentcy that most people
are unaware of. On of the reasons that ATM is so complex is that trys to
emulate the functionality that is inherent in the service provider Tx
framing. Like 802.3, most people take it for granted that transmission
"circuits" are "plug and play" at the physical connectivity level. They do
not know that the vast majority of that plug and play functionality is
because of the physical coding and signal standards. T1/E1 etc, have a
coding similar to what was done for 64/66 in 10GbE. Every x number of bits
"revenue traffic", an additional bit is added. Unlike 10GbE, the
additional bits in T1/E1 coding are also used to carry
information. Network "timing" synchronization, customer service
labels, remote problem resolution, and a low bandwidth comm function are
embedded in the T1/E1 "out-of-band" overhead created by those bits. This
works so well and so transparently, that even the shared service people
such as the ISPs are unaware of how the physical connectivity is maintained
and supported.
It is also inexpensive. A T!/E1 CSU today costs less that what a GbE SMF
PCI card does. If it had the commodity market that 10/100Mb Ethernet does,
it would probably have much the same pricing, or lower.
Thank you,
Roy Bynum
At 08:53 PM 9/30/01 -0400, Fletcher E Kittredge wrote:
>On Fri, 28 Sep 2001 15:58:14 -0700 Moshe Oron wrote:
> > I agree to what Matt wrote about QoS mechanisms being crucial mostly when
> > resources get congested. This is why the argument that ATM is
> inefficient as
> > it involves the cell tax is not a good one. Over-engineering the link
> to the
> > extent that prevents congestion and thus eliminates the need for QoS might
> > involve a much higher tax.
>
>Correct! The key question is which is cheaper: fat pipes or smart
>switches and CPEs? This would be a question for the market-place.
>
>regards,
>fletcher