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RE: [EFM-OAM] RE: [EFM] Re: Loopback and BERT


The honest answer is I don't know enough about GE conformance tests to say
one way or the other. I'll have one of my people look at this and make a
comment later. It looks like a reasonable plan to me, and, as you suggested
it, I would assume that it will meet the service provider requirements.



-----Original Message-----
[]On Behalf Of Roy Bynum
Sent: 25 February 2002 01:50
Subject: Re: [EFM-OAM] RE: [EFM] Re: Loopback and BERT


Wouldn't be easier to just use the conformance test pattern that is already
in the GbE PCS?  The test pattern can be continuously repeated for the
duration of the test.  Invalid code sets can be introduced to verify that
the remote PCS will detect the errors.  Additional OAM physical layer bit
error detection information can be used to detect the errors that might
turn one valid code set into another valid code set.  This can be done by
inserting a bit flip in one of the valid code sets of the conformance
pattern such that it becomes a different valid code set, but not correct
the bit error detection information that would be in the OAM.  This does
not require any new chips to be introduced to the PHY.  It leverages the
existing PCS as much as possible.

Thank you,
Roy Bynum

At 01:35 AM 2/25/2002 +0000, Bob Barrett wrote:

>Correct. The introduction of errors comes from the BERT engine at the POP
>end, and potentially from the BERT engine in the CPE, if the implementer
>chooses to support that in the CPE. The inexpensive BERT chips support all
>of that 'stuff', and one of the BERT chip vendors does a pretty good job on
>10/100 PHY/MAC chips too, so I would hope that they would support this
>-----Original Message-----
>[]On Behalf Of Roy Bynum
>Sent: 24 February 2002 22:07
>Subject: RE: [EFM] Re: Loopback and BERT
>One function that was always part of BERT testing when I was working in
>field operations was the deliberate introduction of errors in the encoded
>data stream to be sure that the customer premise equipment was properly
>able to detect errors.  This is part of the originating conformance
>testing, and part of the conformance testing that was done after a
>repair.  I do not think that your "loop back plug" would qualify for that
>level of conformance BERT testing.
>Thank you,
>Roy Bynum
>At 08:55 PM 2/24/2002 +0000, Bob Barrett wrote:
> >Dear all
> >
> >Rather than put up a presentation on this at the March meeting I have
> >written a white paper expressing what I think are the key issues (and the
> >key reasons and benefits) of including loopback and BERT functions in the
> >EFM subscriber access standard. It can be found at:
> >
> >
> >
> >or from a link at
> >
> >I have written this as an individual, and not included references to my
> >company or products, and I have put it on my personal web site.
> >do mirror my views into the technolgy that my company produces, as do
> >of we equipment vendors.
> >
> >By putting this paper up for discussion now I hope to reach the broad
> >audience of all EFM streams and stimulate debate in advance of the March
> >meeting, to help us to reach consensus.
> >
> >Thanks
> >
> >Bob Barrett