Dear all,
As also being
one of the participants directly involved in the SONET/SDH standardization
process from its inception, I would like to echo Andy’s sentiments.
Best regards,
Eve
From:
ietf-bounces@xxxxxxxx [mailto:ietf-bounces@xxxxxxxx] On Behalf Of andy.bd.reid@xxxxxx
Sent: Thursday, September 29, 2011
11:37 AM
To: Malcolm.BETTS@xxxxxxxxxx; huubatwork@xxxxxxxxx
Cc: ietf-bounces@xxxxxxxx; ietf@xxxxxxxx
Subject: RE: Last Call:
<draft-sprecher-mpls-tp-oam-considerations-01.txt> (The Reasons for
Selecting a Single Solution for MPLS-TP OAM) to Informational RFC
All,
First, let me say I
have no absolutely desire to enter into debate into the substantive matter of
this draft.
If the purpose of
the draft is to be ‘Informational’ then the reader would have a reasonable
expectation for the information to be correct, especially if it is referencing
matters beyond its immediate scope. And the section 5.1 is simply factually
wrong.
Huub’s comments on
SONET/SDH give an accurate critique.
If the authors did
want to make meaningful reference to where two separate standards emerged, then
the primary rates (T1 and E1), their associated voice coding (mu-law and
A-law), and PDH multiplexing hierarchies might be a more meaningful place to
start. With a great deal of hard work and good will on all sides, SONET/SDH
achieved an single effective standard bridging these two largely incompatible
worlds.
Andy
From:
ietf-bounces@xxxxxxxx [mailto:ietf-bounces@xxxxxxxx] On Behalf Of Malcolm.BETTS@xxxxxxxxxx
Sent: 29 September 2011 16:10
To: huubatwork@xxxxxxxxx
Cc: ietf-bounces@xxxxxxxx; ietf@xxxxxxxx
Subject: Re: Last Call:
<draft-sprecher-mpls-tp-oam-considerations-01.txt> (The Reasons for
Selecting a Single Solution for MPLS-TP OAM) to Informational RFC
All,
From my personal knowledge, the comments from Huub are
accurate. (I was an active participant at the 1988 ITU meeting in Seoul
where the SDH frame format was agreed).
The IETF should not publish a consensus approved draft that
contains inaccurate information about a standard that was developed outside the
IETF.
The gross inaccuracy in the characterization of SONET/SDH
leads me to question the validity of the document.
Regards,
Malcolm
All,
Why section 5.1 is an author's impression:
Statement:
"SONET and SDH were defined as competing
standards"
Fact:
SONET was developed first by ANSI based on the 24
channel PDH hierarchy
existing in North America and Japan. The
basic rate based on DS3.
Some time later ETSI developed SDH based on the 30
channnel PDH deployed
in Europe. The basic
rate based on E4 (3x DS3).
To be able to deploy SONET and SDH worldwide the
regional SDO experts
came together in ITU-T to define a frame structure and
a frame-rate
that would allow interconnection of SONET and SDH.
A compromise was agreed and approved in an ITU-T
meeting in Seoul
in 1988.
Statement:
"Significant confusion resulted from this
situation."
Fact:
The result of the compromise is documented in ITU-T
recommendation
G.707 which includes the frame definition and
frame-rates, and
documents how SONET and SDH can interconnect.
Statement:
"Equipment manufacturers needed to select the
market segment they
intended to address. The cost of chipsets for a
limited market
increased.
Fact:
Most equipment vendors did/do sell their equipment in
both regions.
I was involved in chip designs for SONET/SDH in
several companies,
they all support SONET and SDH in a single chip, and
the selection
is a matter of provisioning, the addition cost to
support both was
minimal (single chip: higher volume = lower cost)
Statement:
"Service providers needed to consider the merits
of the two standards
and their long-term role in the industry when
examining their
investment options.
Fact:
Because the regions or applicability of SONET and SDH
are well
known SPs do not have to make this consideration.
Statement:
"Only a limited number of equipment manufactures
were available
for selection."
Question:
What do you consider a limited number?
Statement:
"As SONET was considered to be the variant,
interworking had to be
performed before the SDH-based segment was
reached."
Fact:
SONET is *NOT* a variant it is equivalent to SDH.
The reason for placing the interconnection
functionality on the SONET
side was that in a previous agreement on
interconnection the
functionality was placed on the European side.
Conclusion:
There is a single frame structure used by both SONET
and SDH.
This is documented in ITU-T recommendation G.707 (ANSI
and ETSI
still have their SONET resp. SDH standard available in
their
own documentation, but they are aligned with G.707).
It depends on the application of the frame structure
in an environment
with 24 channel legacy PDH to call it SONET and in an
evironment
with 30 channel legacy PDH to call it SDH.
The meeting in Seoul
in 1988 shows that SDOs can compromise to
find a common frame structure that can be used in
different
regions/applications.
Best regards, Huub.
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