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Hi
Greg,
Responses.
Snigdho
Hi Snigdho,
responses below.
--Snip--
-----> What is a "WSON
signal" is a key question we are trying to nail down hear and with the
framework draft. Sorry to lead you astray with the "wireless" backhaul
application. We are primarily concerned with digital signals as is
the case for G.872 and G.709. However specification of the signal
type such as STM-256 is not sufficient anymore since the same signal type
may employ different modulations. In ITU-T G.959.1 (March 2006) they
introduce general signal classes to differentiate this, i.e., NRZ 40G and
RZ 40G. This ITU-T spec and many others including G.872 lay the foundation
for what we need to characterize a "WSON signal" for our
purposes...
[Bardalai, Snigdho] Is
specification of the STM-256 modulation scheme a WSON specific
issue? Should this not be addressed generally from a GMPLS
perspective?
--->
GMPLS is a general approach that includes a base set of protocols plus
extensions. STM-256's are handled with the SONET/SDH extensions detailed in
RFC4606. From a layering perspective I'd argue against modifying RFC4606 since
that document and its predecessor dealt with the digital (TDM) signals and
their multiplexing structure. Hence I'd think it more prudent to model the
fact that a given digital signal (STM, or Ethernet say) can have more than
optical modulation or FEC schemes at an appropriate "optical layer".
[Bardalai,
Snigdho] Why not extend RFC4328? G.709 allows STMx over
OCh.
------>
Let me clarify this a bit. GMPLS signaling utilizing the "label set"
feature already supports distributed wavelength assignment. However this
technique encounters a problem when we attempt to use it for
bi-directional signals per current GMPLS standards. See the Framework
document for more details. Hence this requirement is really a request to
fix something that is broken not add a whole new class of
functionality.
[Bardalai, Snigdho] This seems to an general GMPLS
issue wrt specifying the "label set" for the reverse
direction traffic. Again, why is this specific to
WSON?
---> Extensions to
GMPLS protocols may or may not be specific to a technology or an application
area. However the demand for an extension to GMPLS must stem from some
concrete requirement. Hence when we look at GMPLS RSVP-TE signaling as
specified in RFC3473 you see that it is updated by RFC 4003,RFC 4201,RFC 4420,RFC 4783,RFC 4873,RFC 4874,RFC
4974,RFC 5063,RFC 5151. And these are all the extensions available for
use in "GMPLS RSVP-TE". You'll see another example of this in Dublin
where the VCAT/LCAS draft needed some kind of call object, similarly for some
Ethernet service stuff and it turns out that the MRN draft has a CALL_OPS
defined which the other drafts will use.
[Bardalai,
Snigdho] Could this be part of an extension of RFC4328
???
------->
"bit rate" is a standard GMPLS/MPLS-TE signaling parameter, though it is
actually specified in bytes per second and specified as a 32 bit IEEE
floating point number so this isn't a new parameter for GMPLS. I'm
looking at "necessary" "optical/physical" parameters since we know the
signal types such as OTUk, STM-x, GigE, etc... When we encounter OEO
devices such as wavelength converters or regenerators many of these can
accomodate multiple signal types but need this basic low level information
to determine compatibility. ITU-T G.872 Annex A tells us what information
we must have to determine compatibility with a particular level of
regenerator (and hence we can use this for OEO based wavelength converters
too).
[Bardalai, Snigdho] Why is it
necessary to encode additional "optical/physical" parameters for O-E-O
regeneration? What is the basis of your
assumption?
--->
Hmm, I thought this was clear from the above: "When we encounter OEO devices
such as wavelength converters or regenerators many of these can accomodate
multiple signal types but need this basic low level information to determine
compatibility." By including such information as modulation type,
modulation parameters, and bit rate in signaling we can configure the devices
along the path. For example a 3R regenerator or OEO based wavelength
converter is needs timing (bit rate) information (see ITU-T G.872 Annex
A).
[Bardalai, Snigdho] Sorry, my question was not clear. What is
preventing us from using the "signal type" for this
purpose?
--
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Dr Greg Bernstein, Grotto Networking (510) 573-2237
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Dr Greg Bernstein, Grotto Networking (510) 573-2237
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