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RE: Final draft of response to the OIF
Hi Richard,
A long time ago an agreement was reached to unify
the SDH and SONET encodings, since carriers did not
want to manage unnecessary differences.
What implementations have done as a result of the
bad example in RFC 3946 is unfortunate, and leads to
interop problems -- and thus the item from the OIF.
This is our opportunity to fix the example and
removed the problem (and then folks can simplify
their implementations). If the difference remains,
there will be opportunity for creating more interop
problems (if implementations behave differently for
the different encodings).
So, rather than make things more complicated by
modifying an accepted rule (RCC=1 requires NCC>1),
retaining two encodings for the same signal, and
adding notes to attempt to explain the interworking
options, it is much easier to correct the example.
This is good engineering practice, in my view.
Regards,
Ben
> -----Original Message-----
> From: Richard Rabbat [mailto:richard@us.fujitsu.com]
> Sent: Tuesday, August 30, 2005 3:58 PM
> To: Mack-Crane, T. Benjamin
> Cc: Huub van Helvoort; Adrian Farrel; ccamp@ops.ietf.org
> Subject: Re: Final draft of response to the OIF
>
> Ben,
> Adrian's final draft of the response is most inclusive. From what you
> said earlier, it seems that you've already coded it in one way
> (whichever) but are accepting both sets of values for NCC &
> RCC (both 1
> or 0).
> Is there an engineering problem with the text of the response besides
> that you would be able to remove those couple of lines of
> code? if so,
> we should solve it.
> Richard.
>
>
> Mack-Crane, T. Benjamin wrote:
>
> >Hi Huub,
> >
> >See in-line below.
> >
> >Regards,
> >Ben
> >
> >
> >
> >>-----Original Message-----
> >>From: Huub van Helvoort [mailto:hhelvoort@chello.nl]
> >>Sent: Friday, August 26, 2005 10:56 AM
> >>To: Mack-Crane, T. Benjamin
> >>Cc: Adrian Farrel; ccamp@ops.ietf.org
> >>Subject: Re: Final draft of response to the OIF
> >>
> >>Hello Ben,
> >>
> >>You wrote:
> >>
> >>
> >>
> >>>I proposed a simple (and I think technically sound) solution to
> >>>item #1 and saw no objections, however the answer has not changed.
> >>>
> >>>I do not understand the reason for different encodings for
> >>>VC-4 and STS-3c SPE. I think they should be the same, unless
> >>>there is a technical need to distinguish them.
> >>>
> >>>
> >>If there is agreement that they should be the same, we should
> >>also look at higher order contiguous concatenated signals:
> >>i.e. STS-12c == VC-4-4c, STS-48c == VC-4-16c, STS-192c == VC-4-64c
> >>STS-768c == VC-4-256c
> >>
> >>
> >
> >These signals are already encoded the same way (for instance see
> >examples 3 and 9 in RFC 3946).
> >
> >
> >
> >>>I also do not understand the RCC=1 NCC=1 encoding, since the rule
> >>>contained in the current RFC actually makes more sense.
> >>>
> >>>
> >>However indicating the number of signals concatenated in NCC
> >>makes your first objective impossible: STS-3Xc == VC-4-Xc
> >>so there will always be a difference of a factor 3 between
> >>STS and VC-4 encoding
> >>
> >>
> >
> >All the encodings of contiguous concatenated signals use VC-4
> >(STS-3c SPE) as the base, so the NCC values are the same. This
> >was done to align SONET and SDH encodings.
> >
> >
> >
> >>>If there is
> >>>only
> >>>one signal element, there is no contiguous concatenation,
> >>>
> >>>
> >>by definition.
> >>
> >>In fact a single signal is always contiguous concatenated ;-)
> >>
> >>
> >>
> >>>So I fail to see the usefulness of these encodings.
> >>>
> >>>
> >>NCC = 1 would normally not occur, so it could be used for
> >>this specific case of SONET signals transported in an
> >>SDH world, or SDH signals transported in SONET land.
> >>And if these signals would not cross borders the value
> >>NCC > 1 can be used.
> >>
> >>
> >
> >The SDH and SONET encodings have been aligned in all cases
> >except this one (VC-4, STS-3c SPE). So these should also
> >be aligned.
> >
> >
> >
> >>>Regards,
> >>>Ben
> >>>
> >>>
> >>Cheers, Huub.
> >>
> >>--
> >>================================================================
> >> http://members.chello.nl/hhelvoort/
> >>================================================================
> >>Always remember that you are unique...just like everyone else...
> >>
> >>
> >>
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The information contained in this message may be privileged
and confidential and protected from disclosure. If the reader
of this message is not the intended recipient, or an employee
or agent responsible for delivering this message to the
intended recipient, you are hereby notified that any reproduction,
dissemination or distribution of this communication is strictly
prohibited. If you have received this communication in error,
please notify us immediately by replying to the message and
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