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RE: [EFM] Network timing, ATM, ADSL/VDSL and EFM


Back to Howard's point of a few days ago ..... demarc within a chip.

The demarcation in T1/E1 is somewhere in the middle of the T1/E1 framer/LIU
chip. These chips keep G.821 stats for limited periods and a lot of other
management objects too, for chip set up etc. They have more registers than
you can shake a stick at, read-write and read-only. The remote management
channel (FDL) can be brought out as HDLC or the data from it can be read
from registers, and these chips are very inexpensive.

The FDL based management allows the SP to test the line to within the CPE
(in this case the CSU/DSU or even the T1 interface on a router line card if
it has an integrated CSU/DSU).

This is what the service providers want to do with Gig-E (I had this
re-iterated to me in the UK just yesterday).

	without a security risk from the customer side
		spoofing MAC addresses and VLAN tags drives a coach and horses through the
in-band approach
		you only need one-way traffic for denial of service attack

	without affecting the service offered to the customer
		this is a grey area, but as there is spare bandwidth on the PHY through
the coding
		why bother debating it

Bob Barrett

> -----Original Message-----
> From:
> []On Behalf Of Roy Bynum
> Sent: 03 October 2001 16:08
> To: mattsquire@xxxxxxx
> Cc:
> Subject: Re: [EFM] Network timing, ATM, ADSL/VDSL and EFM
> Matt,
> 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.
> Thank you,
> Roy Bynum
> 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 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.
> > >
> >
> >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.
> >
> >- Matt