Re: [10GMMF] Optical Cable references in LRM Draft
Title: Optical Cable references in LRM Draft
Steve,
thanks for providing us with this information.
At the last meeting, I said that your proposal to
change from "The fiber optic cable shall meet the requirements of IEC 60793-2,
..." to "the fiber optic cable shall meet the requirements of IEC
60794-2-11,..." needed more
study. One reason is that your proposed wording was restrictive rather
than permissive. It wouldn't mean "cable to IEC 60794-2-11 is OK", it
would mean "any other cable is not OK". I do not believe that. For
example, IEC 60794-2-11 specifies "indoor optical fibre cables". We don't
want to forbid people extending Ethernet to outdoor
use!
We are
constrained by the past. The main purpose of the 802.3aq project is
to allow people to re-use existing cable plant, which could be old. IEC
60794-2-11 is very new (published March 2004) and it would be unreasonable to
expect users to consider some kind of qualification after the event. We
are pretty much stuck with using the specifications of 52.14.1 (mentioning IEC 60793-2). We can consider adding a new
permissive statement saying that cable to IEC 60794-2-11 MAY be used - but see
below.
I
notice that IEC 60794-2-11 is a CABLE specification while IEC 60793-2 is a FIBRE
specification. While I could imagine that for electrical cabling, it would
be hard to make such a separation, for us the optical transmission
characteristics are pretty much defined by the (fiber) parameters as e.g. in
table 68-6. I don't think we need to define the cable: we (802.3aq) aren't
defining structured cabling nor attempting to regulate the installation industry
- we let someone else do that e.g. through ISO/IEC 11801.
To
judge the appropriateness of IEC 60794-2-11 you'll have to give us more
information. What does it specify? The weight of a cable?
Color? Strength? Temperature and environmental ratings? This
clause following others (52.11.1) basically mentions "reasonable conditions" and
says that the detail is beyond the scope of this standard. So I don't yet
see what benefit IEC 60794-2-11 brings to this clause.
By the
way, what does the "PAS" in "IEC/PAS 60794-2-11" (from the IEC web site)
mean?
In
your email below you say "two fiber types that we call out, i.e. 60793-2-10 and
60793-2-50". Did you mean -50 "Optical fibres - Part 2-50: Product
specifications - Sectional specification for class B single-mode fibres" or
another part? Anyway, we don't yet have specific references to parts of
60793-2 in the draft, though we mention 60793-2-10 in the objectives. Do
we need to add IEC 60793-2-10 to the list of references or is the reference to
IEC 60793-2 enough? And then would we need to refer to an old version of
IEC 60793-2-10?
Thanks,
Piers
At the meeting in San Antonio, I
agreed to provide additional justification for my comment to replace the title
of 68.9.1 and the reference given from fiber references to cable references
(see Swanson comments 65 and 66). I have copied the scope and Normative
references from the recommended reference - note that this cable document is
intended to ensure compatibility with IS 11801 and references the two fiber
types that we call out, i.e. 60793-2-10 and 60793-2-50.
Cheers,
Steve
IEC 60794-2-11
OPTICAL FIBRE CABLES -
Part 2-11: Indoor optical fibre cables
-
Detailed specification
for simplex and duplex cables for use in premises cabling
1 Scope
This Standard presents the detailed requirements specific to this type
of cable to ensure compatibility with IS 11801 [1], Information technology - Generic cabling for
customers premises. The requirements of the Family Specification IEC
60794-2-10 are applicable to cables covered by this standard.
2 Normative references
The following referenced documents are indispensable for the
application of this document. For dated references, only the edition cited
applies. For undated references, the latest edition of the referenced document
(including any amendments) applies.
IEC 60794-2-10, 2003 : Optical fibre cables - Part 2-10:
Indoor optical fibre cables - Family
Specification for simplex and duplex cables
IEC 60793-2-10, 2002 : Optical fibres - Part 2-10:
Product specification - Sectional
specification for category A1 multimode fibre
IEC 60793-2-50 Ed. 2 : Optical fibres - Part 2-50:
Product specification - Sectional
specification for class B single-mode
fibre