[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
RE: comments on draft-shiba-ccamp-gmpls-lambda-labels-00.txt
> -----Original Message-----
> From: Shiba, Sidney [mailto:sidney.shiba@us.fujitsu.com]
> Sent: Monday, October 31, 2005 7:56 AM
> To: Drake, John E; dpapadimitriou@psg.com
> Cc: Adrian Farrel; richard.rabbat@us.fujitsu.com; ccamp@ops.ietf.org
> Subject: RE: comments on draft-shiba-ccamp-gmpls-lambda-labels-00.txt
>
> John,
>
> Comments inline:
>
> > -----Original Message-----
> > From: Drake, John E [mailto:John.E.Drake2@boeing.com]
> > Sent: Monday, October 31, 2005 9:36 AM
> > To: Shiba, Sidney; dpapadimitriou@psg.com
> > Cc: Adrian Farrel; richard.rabbat@us.fujitsu.com; ccamp@ops.ietf.org
> > Subject: RE: comments on
draft-shiba-ccamp-gmpls-lambda-labels-00.txt
> >
> >
> > Sidney,
> >
> > But there's nothing in your picture that requires an absolute
end-end
> > global wavelength. The existing GMPLS solution with relative
> > wavelengths of local significance should work just fine.
>
> [Sidney] Sorry for the missing info. The optical switch is an all
optical
> switch (i.e., no OEO is necessary). The wavelength continuity
constraint
> indicates which wavelength (nominal value) all the optical switches
> traversed by the lightpath needs to cross-connect.
[JD]
I understand all that, but my comment still stands.
>
> > As I said in my previous note, your method precludes combining two
or
> > more parallel WDM links into a single TE link.
>
> [Sidney] Note the Label is complemented by the interface id of the
link.
>
> I think this is the same approach used for parallel SONET OCn
datalinks
> where the label identifies a time-slot and interface id identifies the
> datalink chosen for the connection.
[JD]
That's probably true, but wavelength LSPs don't have that restriction
under the current GMPLS procedures.
>
> >
> > Thanks,
> >
> > John
> >
> > > -----Original Message-----
> > > From: Shiba, Sidney [mailto:sidney.shiba@us.fujitsu.com]
> > > Sent: Monday, October 31, 2005 7:25 AM
> > > To: Drake, John E; dpapadimitriou@psg.com
> > > Cc: Adrian Farrel; richard.rabbat@us.fujitsu.com;
ccamp@ops.ietf.org
> > > Subject: RE: comments on
> > draft-shiba-ccamp-gmpls-lambda-labels-00.txt
> > >
> > > Hi John,
> > >
> > > Optical switches based on Wavelength Selective Switch (WSS)
> > technology
> > > requires the wavelength information for switching. This
> > technology is
> > NOT
> > > wavelength agnostic.
> > >
> > > | |
> > > | wdm | wdm
> > > |2 |2
> > > --------- ---------
> > > wdm 1| optical |3 wdm 1| optical |3 wdm
> > > --------| switch |------------| switch |---------
> > > | (WSS) | | (WSS) |
> > > --------- ---------
> > > |4 |4
> > > | wdm | wdm
> > > | |
> > >
> > > Note that the figure above shows an example of two optical
switches
> > > interconnect
> > > by a single WDM fiber. In this example, each optical switch can be
> > connect
> > > to 4
> > > other optical switches.
> > >
> > > As you can see, the optical ports information do not provide
enough
> > > information
> > > for wavelength switching.
> > >
> > > Hope that clarifies the application requirement.
> > >
> > > Thanks,
> > >
> > > Sidney
> > >
> > > > -----Original Message-----
> > > > From: Drake, John E [mailto:John.E.Drake2@boeing.com]
> > > > Sent: Friday, October 28, 2005 5:33 PM
> > > > To: dpapadimitriou@psg.com; Shiba, Sidney
> > > > Cc: Adrian Farrel; richard.rabbat@us.fujitsu.com;
> > ccamp@ops.ietf.org
> > > > Subject: RE: comments on
> > draft-shiba-ccamp-gmpls-lambda-labels-00.txt
> > > >
> > > >
> > > > Hi,
> > > >
> > > > Below is the text of an e-mail is sent to the
> > Ethernet/GMPLS mailing
> > > > list.
> > > >
> > > > Upon reflection I am not sure using a real wavelength value
makes
> > much
> > > > sense. Between a pair of adjacent nodes, there may be
> > > > multiple pairs of
> > > > switch ports in the same TE link that support a given
> > frequency. If
> > a
> > > > real wavelength value is used, how do the two nodes agree on
> > > > which pair
> > > > of switch ports to use?
> > > >
> > > > Furthermore, the amount of configuration is the same - you
> > > > still need to
> > > > configure the wavelength of each switch port.
> > > >
> > > > Thanks,
> > > >
> > > > John
> > > > ==============================================================
> > > > ==========
> > > > ====
> > > > Adrian,
> > > >
> > > > In the transparent photonic lambda switch case, the
> > labels also have
> > > > only local significance. When an LSP is established, the input
> > ports,
> > > > as identified with local labels, are cross-connected to the
output
> > > > ports, as identified with local labels.
> > > >
> > > > There is just extra configuration to identify, using
> > strictly local
> > > > identifiers, the wavelength associated with the all of
> > the switch's
> > > > ports, and an additional CAC requirement that the
> > wavelengths of the
> > > > input and output ports are the same.
> > > >
> > > > Thanks,
> > > >
> > > > John
> > > >
> > > >
> > > > > -----Original Message-----
> > > > > From: dimitri papadimitriou [mailto:dpapadimitriou@psg.com]
> > > > > Sent: Thursday, October 27, 2005 10:03 AM
> > > > > To: Shiba, Sidney
> > > > > Cc: dimitri.papadimitriou@alcatel.be; Adrian Farrel;
> > > > > richard.rabbat@us.fujitsu.com; ccamp@ops.ietf.org
> > > > > Subject: Re: comments on
> > > > draft-shiba-ccamp-gmpls-lambda-labels-00.txt
> > > > >
> > > > > shiba - see inline for some additional hints:
> > > > >
> > > > > >>Shiba, Sidney wrote:
> > > > > >>
> > > > > >>>Adrian, Dimitri,
> > > > > >>>
> > > > > >>>Thanks for reviewing these I-D.
> > > > > >>>
> > > > > >>>Wavelength continuity constraint does require the use of
> > > > semanticful
> > > > > >>>label whether it is spectral or index.
> > > > > >>
> > > > > >>=> see my reply to adrian on this specific point
> > > > > >>
> > > > > >>>I agree with Dimitri that the
> > > > > >>>wavelength indexing requires document updating each
> > time a new
> > > > > >>>spectrum is introduced.
> > > > > >>
> > > > > >>=> indeed and in addition it requires updating the already
> > > > > >>signaled path
> > > > > >>
> > > > > >>>The use of spectral label provides self maintainance, i.e.,
> > > > > >>>no need to update any document and the use of the
> > nominal value
> > > > > >>>provides a common semantic ground.
> > > > > >>
> > > > > >>=> what do you mean by self-maintenance - would you provide
a
> > > > > >>bit more detail
> > > > > >
> > > > > > [Sidney]What I've meant here was that it was not necessary
to
> > > > > > update any document when new wavelengths are
> > inventoried. In the
> > > > > > case of indexing approach, it would require the
> > > > wavelength indexing
> > > > > > document to be updated with implementation impacts.
> > > > > >
> > > > > > In the case, the nominal value is used, there is no need for
> > > > > > documentation update.
> > > > >
> > > > > ok - what you mean here is that you are going to make use of
the
> > > > already
> > > > > defined C-Type 2 - what about the specific encoding of the
> > > > value space
> > > > ?
> > > > >
> > > > > >>=> now i have a more specific question before being light-up
> > > > > >>how do you know the frequency that you can support ?
> > > > > >
> > > > > > [Sidney] Some new technologies integrate optical switch and
> > > > mux/demux
> > > > > > capabilities, which allows the equipment to know the
> > spectrum it
> > > > > supports.
> > > > >
> > > > > indeed - but the question is what does happen if the
> > > > "detected" values
> > > > > (during initialization) do not match the nominal values ? you
> > don't
> > > > > initialize then ?
> > > > >
> > > > > >>if these differ from the nominal values how are you going to
> > deal
> > > > with
> > > > > these
> > > > > >>discrepancies ?
> > > > > >
> > > > > > [Sidney] These new technologies uses the nominal value as
> > > > reference.
> > > > We
> > > > > can say
> > > > > > that a lightpath wavelength is identified by its
> > nominal value.
> > If
> > > > the
> > > > > equipment
> > > > > > is drifting from this nominal value, it is considered as
> > > > a failure.
> > > > >
> > > > > ok - but if the deviation is such you have overlap - how the
> > control
> > > > > plane is going to be able to detect such failure ?
> > > > >
> > > > > >>this said i am not necessarily sure that having to
> > > > maintain the data
> > > > > plane
> > > > > >>specifics as part of the control plane is really helping
> > > > > >>operations (is this method not just duplicating complexity
?)
> > > > > >
> > > > > > [Sidney] The wavelength is WDM specific as much as the SUKLM
> > label
> > > > > encoding
> > > > > > is for SONET. The wavelegth/frequency nominal value is used
to
> > > > identify
> > > > > the
> > > > > > facilities to cross-connect.
> > > > >
> > > > > there is an equivalence but there is also a major
> > difference, the
> > > > > structure is invariant independently of the state of the
> > > > network, with
> > > > > spectral value space you may have labels that become
unavailable
> > due
> > > > to
> > > > > non-local usage of wavelength in the network
> > > > >
> > > > > hence, there is also no real coupling to the data plane
> > more than
> > > > > knowing the type of interface and some generic capabilities
> > > > >
> > > > > >>>I'm not sure if the draft needs to be updated before the
> > > > > >>>face-to-face meeting or after all comments are collected.
> > Please
> > > > > advise.
> > > > > >>
> > > > > >>=> suggest to keep discussion on - document update can be
> > > > > >>performed at a later stage
> > > > >
> > > > > thanks,
> > > > > - dimitri.
> > > > >
> > > > > >>>>-----Original Message-----
> > > > > >>>>From: owner-ccamp@ops.ietf.org
> > > > [mailto:owner-ccamp@ops.ietf.org]On
> > > > > >>>>Behalf Of Adrian Farrel
> > > > > >>>>Sent: Thursday, October 27, 2005 4:45 AM
> > > > > >>>>To: dpapadimitriou@psg.com;
> > dimitri.papadimitriou@alcatel.be;
> > > > > >>>>ccamp@ops.ietf.org
> > > > > >>>>Subject: Re: comments on
> > > > > >>
> > > > > >>draft-shiba-ccamp-gmpls-lambda-labels-00.txt
> > > > > >>
> > > > > >>>>
> > > > > >>>>Dimitri,
> > > > > >>>>
> > > > > >>>>Thanks for your work reviewing these recent I-Ds. It is
> > > > > >>>>really valuable
> > > > > >>>>and I'd welcome other people doing similar reviews.
> > > > > >>>>
> > > > > >>>>
> > > > > >>>>
> > > > > >>>>>there is a specific point to be clarified in this
document:
> > > > > >>>>>
> > > > > >>>>>semanticless vs semanticful label (even here there is a
> > > > distinction
> > > > > >>>>>between spectral vs indexes i.e. using the
> > wavelength index)
> > > > > >>>>>
> > > > > >>>>>domain-wide vs link local significant label
> > > > > >>>>
> > > > > >>>>Without being too picky, I think all labels are
semanticful
> > > > > >>>>otherwise, we
> > > > > >>>>would not know what resource they refered to.
> > > > > >>>>
> > > > > >>>>So the point reduces to whether the scope of the semantics
> > > > > >>>>are link-local
> > > > > >>>>or wider.
> > > > > >>>>
> > > > > >>>>
> > > > > >>>>
> > > > > >>>>>so, the comparison from this perspective with TDM labels
is
> > > > > >>>>
> > > > > >>>>difficult to
> > > > > >>>>
> > > > > >>>>
> > > > > >>>>>parse, the latter is semanticful but link local
> > > > > >>>>>
> > > > > >>>>>now, i don't specifically see what has changed the
> > late 90's,
> > > > early
> > > > > >>>>>y2k's, to have a change in the wavelength label
definition;
> > > > > >>>>
> > > > > >>>>This is the question I would like to get to the
> > bottom of. In
> > > > > >>>>other words:
> > > > > >>>>do we need this function?
> > > > > >>>>
> > > > > >>>>It seems to me that the question being asked is this:
> > > > > >>>>
> > > > > >>>> If I want to compute a path that has some form of
> > wavelength
> > > > > >>>> constraints, what information do I need access to?
> > > > > >>>>
> > > > > >>>>Another question might be:
> > > > > >>>>
> > > > > >>>> If I want to signal a path with wavelength
> > constraints what
> > > > > >>>> information do I need to include in the signaling
message?
> > > > > >>>>
> > > > > >>>>
> > > > > >>>>I'd suggest that when we started on GMPLS, we were
> > > > > >>
> > > > > >>enthusiastic about
> > > > > >>
> > > > > >>>>transparent optical networks, but we were not properly
> > > > > >>>>focusing wavelength
> > > > > >>>>constraints because lambda-switching PXCs didn't take off.
> > > > > >>>>Therefore we
> > > > > >>>>didn't examine the requirements for wavelength
> > constraints in
> > > > > >>>>routing and
> > > > > >>>>signaling. The authors of this I-D are claiming new
hardware
> > > > > >>>>requirements
> > > > > >>>>for the same function.
> > > > > >>>>
> > > > > >>>>
> > > > > >>>>
> > > > > >>>>>there are
> > > > > >>>>>several solution possible
> > > > > >>>>>
> > > > > >>>>>- absolute values: the freq. of the wavelength:
> > difficult to
> > > > adopt
> > > > > >>>>>because referenced values are nominal and knowing all
> > > > interactions
> > > > > >>>>>between wavelengths this knowledge is at the end of
little
> > > > > >>
> > > > > >>practical
> > > > > >>
> > > > > >>>>>usage; (introduces implicit ordering)
> > > > > >>>>>
> > > > > >>>>>- indexed values: the # of the wavelength: it does not
> > > > > >>
> > > > > >>provide for a
> > > > > >>
> > > > > >>>>>future proof label space for inst. in case new
frequencies
> > > > > >>>>
> > > > > >>>>are inserted
> > > > > >>>>
> > > > > >>>>
> > > > > >>>>>in the grid (introduces explicit ordering)
> > > > > >>>>>
> > > > > >>>>>- diff. values e.g. freq spacing starting from a
reference
> > > > > >>>>
> > > > > >>>>value: pauses
> > > > > >>>>
> > > > > >>>>
> > > > > >>>>>the question of the reference value and does
> > suffer from the
> > > > former
> > > > > >>>>>issue (introduces implicit ordering)
> > > > > >>>>>
> > > > > >>>>>- the solution available today - cumbersome in some
> > > > control plane
> > > > > >>>>>operations (e.g. label set translation) and not easy to
> > > > > >>>>
> > > > > >>>>troubleshoot but
> > > > > >>>>
> > > > > >>>>
> > > > > >>>>>independent of any physical consideration (spectral),
scale
> > to
> > > > any
> > > > > >>>>>number of wavelength per fiber, does not introduce any
> > > > > >>
> > > > > >>ordering, the
> > > > > >>
> > > > > >>>>>most flexible (since allowing each system to maintain its
> > > > specific
> > > > > >>>>>control operations) and the less constraining since
> > maintaining
> > > > the
> > > > > >>>>>control plane operations independent of any data plane
> > > > specifics
> > > > > >>>>>
> > > > > >>>>>
> > > > > >>>>
> > > > >
> > >>>><http://www.ietf.org/internet-drafts/draft-shiba-ccamp-gmpls-l
> > > > > >>>
> > > > > >>>ambda-labels
> > > > > >>>-00.txt>
> > > > > >>>
> > > > > >>>.
> > > > > >>>
> > > > > >>
> > > > > >
> > > > > > .
> > > > > >
> > > >
> >