RE: [EFM] Network timing, ATM, ADSL/VDSL and EFM
It's interesting that you mention T1/E1 framing for OAM.
In previous mailings you mentioned the need not to damage the revenue
T1 framing is an example of just the opposite!
E1 framers use Time-Slot-16 as the OAM channel and Time-Slot-0 for
synchronization, while T1 uses a bit-stealing mechanism for both. This is
why you receive 56K links in T1 while E1 gives you 64K links.
Food for thought...
[mailto:email@example.com]On Behalf Of Roy Bynum
Sent: Wednesday, October 03, 2001 5:08 PM
Subject: Re: [EFM] Network timing, ATM, ADSL/VDSL and EFM
What I am looking at are several separate factors. The existing T1/E1
CSU/DSU logic is provided as a single "chip" from vendors, which means that
technology can be further reduced in price by the increased production and
yield of a more commodity market. T1/E1 framing is old technology that
already provides some of the OAM requirements for supporting the physical
infrastructure of an extensive diversity of services offerings. ( Where I
am, I can get T1 bandwidths over DSL into my home from my DSL ISP, but
today I have to run ATM to do it. ) This means that the PHY level framing
technology can be adopted to new applications, particularly when used over
the new copper and optical signaling technologies. For those silicon
device vendors that are used to supporting the "service provider" market,
this is not new "stuff". Adding some functionality for supporting minimal
additional requirements over the higher bandwidth technologies should not
be that difficult either. Once the PHYs are defined properly, how the
different "box" vendors use that functionality will depend on the market
sector that each will be targeting.
Borrowing functionality from technology that already supports the require
At 11:09 PM 10/2/01 -0400, Matt Squire wrote:
> > It is also inexpensive. A T!/E1 CSU today costs less that what a GbE
> > PCI card does. If it had the commodity market that 10/100Mb Ethernet
> > it would probably have much the same pricing, or lower.
>I have to question this expense argument. You're saying that a 1.5Mbps
>copper T1 device costs less then a 1Gps fiber/optical component. Fine,
>but I'm not sure why that's compelling. If we tried to make that same
>device run 650 times faster and use optical components as a GbE SMF,
>would that price comparison would hold up? I don't have any hard data
>to pull out, but I'm guessing it wouldn't.