Re: [CCAMP] 答复: R: OSPF OTN considerations post IETF 82 (Issue 1/2)

[John E Drake <[e-mail]>]

Julien,

I would also like to observe that what we are doing in OTN is exactly the same as we did in SDH/SONET, viz, advertising the types of client LSPs a given interface supports.

Thanks,

John

> -----Original Message-----
> From: [e-mail] [mailto:[e-mail]] On Behalf
> Of Julien Meuric
> Sent: Tuesday, December 20, 2011 6:54 AM
> To: Zhangfatai
> Cc: CCAMP
> Subject: Re: [CCAMP] 答复: R: OSPF OTN considerations post IETF 82
> (Issue 1/2)
>
> Hi Fatai.
>
> About the IGP, I believe we agree on several things:
> - we are dealing with the ODUk layers within the OTN
> technology/regions;
> - the ISCD is an appropriate place to put the information on ODUk
> capabilities of nodes.
>
> What we disagree on:
> - using the term "extension" to refer to encoding the hierarchy level
> in
> the SC field: the _fact_ is that PSC-[1~4] are part of existing RFCs
> (e.g. 4203);
> - selecting the SC field as an information on the hierarchy level.
>
> This leaves us with an open discussion on the latter. We already have 2
> options on the table for the ISCD in IGPs:
> a) multiple SC values,
> b)"Switching Cap & Signal Type (& Encoding Type as well)".
>
> First of all, I do not believe the original intend of SC alone was to
> reflect the notion of region: xSC acronyms may map to "regions", but
> from a codepoint perspective we can have several values behind a single
> xSC (e.g. x=P).
>
> Then you propose to use the "[OTN] Signal Type": as opposed to a)
> above,
> this is a new extension, created in
> draft-ietf-ccamp-gmpls-ospf-g709v3-00. As emphasized by Kireeti, the SC
> field should allow to constrain path computation into a range or a
> sub-part of the hierarchy (without necessarily specifying a full list).
> The I-D uses a single SC (OTN-TDM) for the whole OTN, which means the
> SC
> field is useless to prune the network graph when routing an ODUk: even
> for pruning, a CSFP implementation needs to parse some OTN-specific
> sub-TLVs. Hence I prefer the "old-fashion" approach which represent the
> hierarchy information at a higher level in the IGP, like it was done
> for
> PBB-TE (RFC 6060).
>
> Regards,
>
> Julien
>
>
> Le 06/12/2011 20:21, Zhangfatai a écrit :
> >  Hi Julien,
> >
> >  I agree the requirement that you mentioned, but it can be resovled
> >  without extending Switching Cap.
> >
> >  It is known that there are two cases described in RFC5212 and
> >  RFC5339, one is MRN, another one is MLN. In RFC5212, it says:
> >
> =======================================================================
> ========
> >
> >
> Thus, a control plane region, identified by its switching type value
> (e.g., TDM), can be sub-divided into smaller-granularity component
> networks based on "data plane switching layers".  The  Interface
> Switching Capability Descriptor (ISCD) [RFC4202],  identifying the
> interface switching capability (ISC), the encoding type, and the
> switching bandwidth granularity, enables the characterization of the
> associated layers.
> >
> >  In this document, we define a multi-layer network (MLN) to be a
> >  Traffic Engineering (TE) domain comprising multiple data plane
> >  switching layers either of the same ISC (e.g., TDM) or different ISC
> >  (e.g., TDM and PSC) and controlled by a single GMPLS control plane
> >  instance. We further define a particular case of MLNs. A multi-
> >  region network (MRN) is defined as a TE domain supporting at least
> >  two different switching types (e.g., PSC and TDM), either hosted on
> >  the same device or on different ones, and under the control of a
> >  single GMPLS control plane instance.
> >
> =======================================================================
> ==============
> >
> >
> Therefore, for MRN case, we can use Switching Cap to differentiate the
> different "layers"; for MLN case (same ISC with different granularity),
> we can use Switching Cap & Signal Type (& Encoding Type as well) to
> differentiate the different granularity.
> >
> >  So, come back to your question, it can be achived by using Switching
> >  Cap&Encoding Type&Signal Type to identify the granularity requested
> >  in OTN networks(e.g., this information can be carried in
> >  SERVER_LAYER_INFO sub-object) .
> >
> >  Lastly, in my opinion, if there is no issue based on the existing
> >  mechnism or definition without extending Switching Cap, I don't
> think
> >  we need to extend Switching Cap.
> >
> >
> >  Thanks
> >
> >  Fatai
> >
> >
> >
> >  ________________________________________ 发件人: Julien Meuric
> >  [[e-mail]] 发送时间: 2011年12月7日 0:08 到: Zhangfatai
> Cc:
> >  CCAMP; [e-mail] 主题: Re: [CCAMP] R: OSPF OTN considerations
> post
> >  IETF 82 (Issue 1/2)
> >
> >  Hi Fatai.
> >
> >  As co-author of draft-ietf-pce-inter-layer-ext, I believe you will
> >  agree on the fact that having a Switching Capability per ODUk layer
> >  would make the use of objects including a Switching Cap field rather
> >  straightforward and enables a fine-grained resource description,
> e.g.
> >  in: - REQ-ADAP-CAP object, to precisely identify the type of
> >  adaptation requested by a higher layer, or to get a clear feedback
> on
> >  the missing adaptation for unsuccessful path computations; -
> >  SERVER_LAYER_INFO sub-object, to precisely identify the type of
> >  server layer within the ERO.
> >
> >  Do not you think that summarizing G.709 by a single Switching Cap
> >  value would take some capabilities away? What would you suggest so
> as
> >  to achieve the same level of details in that scenario?
> >
> >  Regards,
> >
> >  Julien
> >
> >
> >  Le 02/12/2011 09:51, Zhangfatai a écrit :
> > > Hi all,
> > >
> > > I agree that there is no need to overload Switching Cap.
> > >
> > >
> > >
> > >
> > >
> > > Thanks
> > >
> > > Fatai
> > >
> > >
> > > -----Original Message----- From: [e-mail]
> > > [mailto:[e-mail]] On Behalf Of BELOTTI, SERGIO
> > > (SERGIO)
> > >
> > > John, as co-authors, we shared completely your thoughts.
> > >
> > > Thanks Sergio and Pietro
> > >
> > > SERGIO BELOTTI
> > >
> > > ALCATEL-LUCENT Terrestrial System Architect Optics Portfolio
> > > Evolution
> > >
> > > via Trento 30 , Vimercate(MI) Italy T: [phone]
> > > [e-mail]
> > >
> > >
> > >
> > > -----Messaggio originale----- Da: [e-mail]
> > > [mailto:[e-mail]] Per conto di John E Drake Inviato:
> > > mercoledì 30 novembre 2011 22.37 A: Lou Berger Cc: CCAMP Oggetto:
> > > Re: [CCAMP] OSPF OTN considerations post IETF 82 (Issue 1/2)
> > >
> > > Comments inline. I still think this is a terrible idea and I would
> > > like to see what the rest of the WG thinks.
> > >
> > >> -----Original Message----- From: Lou Berger
> > >> [mailto:[e-mail]] Sent: Wednesday, November 30, 2011
> > >> 1:09 PM To: John E Drake Cc: Daniele Ceccarelli; CCAMP Subject:
> > >> Re: [CCAMP] OSPF OTN considerations post IETF 82 (Issue 1/2)
> > >>
> > >>
> > >> John,
> > >>
> > >> see below
> > >>
> > >>
> > >> On 11/30/2011 2:59 PM, John E Drake wrote:
> > >>> Using Switching Capability to indicate link bandwidth seems
> > >>> ill-considered at best, especially since this information is
> > >>> carried in other fields, and as Daniele noted, it
> > >>> significantly overloads to intended meaning of Switching
> > >>> Capability.
> > >>
> > >> I agree with the point on BW, but my point was related to the
> > >> layer&hierarchy implications of the different ODUk values. I'd
> > >> think that using values that are TDM-1 -> TDM-n should make this
> > >> clear and remove any ambiguity related to bandwidth. It is also
> > >> completely consistent with the base GMPLS definition, i.e.,
> > >> PSC-1 -> PSC-n.
> > >
> > > [JD] You are simply asserting that this is a good idea and further
> > > asserting that there is "ambiguity related to bandwidth', without
> > > providing any evidence.
> > >
> > > To the best of my knowledge no one ever implemented or deployed
> > > the PSC-1 -> PSC-4 hierarchy, simply because no one could figure
> > > out what it meant. To quote from you, below, "Well hopefully we
> > > have a better understanding of the technologies involved than we
> > > had in the past.". I.e., we should all understand that PSC-1 ->
> > > PSC-4 was a bad idea (tm) and move on.
> > >
> > >>
> > >>> It also is inconsistent with the usage of Switching Capability
> > >>> in SDH/SONET.
> > >>
> > >> Well hopefully we have a better understanding of the
> > >> technologies involved than we had in the past.
> > >
> > > [JD] I think we had a very good understanding of SDH/SONET then
> > > and we have a very good understanding of OTN now, and in both cases
> > > the authors saw no requirement to overload switching capability in
> > > the manner you are suggesting.
> > >
> > >>
> > >>>
> > >>> A more extensive quote from RFC4202 is the following, which
> > >>> seems clear enough to me:
> > >>>
> > >>> "In the context of this document we say that a link is
> > >>> connected to a node by an interface. In the context of GMPLS
> > >>> interfaces may have different switching capabilities. For
> > >>> example an interface that connects a given link to a node may
> > >>> not be able to switch individual packets, but it may be able to
> > >>> switch channels within an SDH payload. Interfaces at each end
> > >>> of a link need not have the same switching capabilities.
> > >>> Interfaces on the same node need not have the same switching
> > >>> capabilities."
> > >>
> > >> Not sure how this helps clarify anything...
> > >
> > > [JD] I think it clarifies that switching capabilities is meant to
> > > describe how a given interface switches the information with which
> > > it is provided. This has nothing to do with the interface's
> > > bandwidth.
> > >
> > >>
> > >> Lou
> > >>>
> > >>>> -----Original Message----- From: Lou Berger
> > >>>> [mailto:[e-mail]] Sent: Wednesday, November 30, 2011
> > >>>> 8:43 AM To: John E Drake Cc: Daniele Ceccarelli; CCAMP
> > >>>> Subject: Re: [CCAMP] OSPF OTN considerations post IETF 82
> > >>>> (Issue
> > >> 1/2)
> > >>>>
> > >>>> Great. Care to substantiate your point?
> > >>>>
> > >>>> On 11/30/2011 11:14 AM, John E Drake wrote:
> > >>>>> I completely disagree.
> > >>>>>
> > >>>>>> -----Original Message----- From: [e-mail]
> > >>>>>> [mailto:[e-mail]] On
> > >>>> Behalf
> > >>>>>> Of Lou Berger Sent: Wednesday, November 30, 2011 7:22 AM
> > >>>>>> To: Daniele Ceccarelli Cc: CCAMP Subject: Re: [CCAMP]
> > >>>>>> OSPF OTN considerations post IETF 82 (Issue
> > >>>> 1/2)
> > >>>>>>
> > >>>>>> Hi Daniele, Since I raised the point, I guess I need to
> > >>>>>> champion it! (With chair hat off.)
> > >>>>>>
> > >>>>>> All,
> > >>>>>>
> > >>>>>> Daniele said:
> > >>>>>>> WRT issue 1: the proposal was to indicate the bottom
> > >>>>>>> most ODUk of
> > >>>> the
> > >>>>>>> muxing hiearachy in the Switching Capability field of
> > >>>>>>> the ISCD.
> > >>>> After
> > >>>>>>> a quick talk with the other authors of the ID, the
> > >>>>>>> idea was to
> > >>>> reject
> > >>>>>>> the proposal as it would lead to an overloading of the
> > >>>>>>> meaning of
> > >>>> the
> > >>>>>>> Switching Capability field. (even if the definition of
> > >>>>>>> PSC1-2-3-4 already overloads the meaning of the
> > >>>>>>> switching capability field)
> > >>>>>>
> > >>>>>> This really goes to the interpretation of the intent of
> > >>>>>> Switching Capability Types. So we have a few
> > >>>>>> definitions: 3471 says "the
> > >> type
> > >>>> of
> > >>>>>> switching that should be performed", 4202 says
> > >>>>>> "describes
> > >> switching
> > >>>>>> capability of an interface." 3945 doesn't really define
> > >>>>>> the term
> > >> (it
> > >>>>>> just references 4202), but does equate it with a
> > >>>>>> "layer". While it allows for hierarchy within a "layer"
> > >>>>>> it also says hierarchy
> > >> occurs
> > >>>>>> "between interface types".
> > >>>>>>
> > >>>>>> So I interpret Switching Capability Types to represent
> > >>>>>> (a)
> > >> different
> > >>>>>> switching/technology layers and (b) different levels of
> > >>>>>> hierarchy
> > >> --
> > >>>>>> even within a layer. I think (a) is identifiable in the
> > >> definition
> > >>>> of
> > >>>>>> the original GMPLS supported technologies (i.e., PSC,
> > >>>>>> L2SC, TDM
> > >> LSC,
> > >>>>>> and FSC), and (b) is identifiable in the original types
> > >>>>>> plus the
> > >>>> definition
> > >>>>>> of PSC-1 through PSC-4.
> > >>>>>>
> > >>>>>> So how does this apply to our current OTN work?
> > >>>>>>
> > >>>>>> To me, the first question to ask relates to (a), and is
> > >>>>>> should
> > >> each
> > >>>>>> ODUk be modeled as a separate layer?
> > >>>>>>
> > >>>>>> I know this has been a much debated point, and it seems
> > >>>>>> to me that
> > >>>> they
> > >>>>>> are, but more for the perspective of switching layers
> > >>>>>> than
> > >>>> technology
> > >>>>>> layers (i.e., they are clearly the same technology but
> > >>>>>> are
> > >> different
> > >>>>>> granularity of swicthing.) So this is a yes for me.
> > >>>>>>
> > >>>>>> I think the second question to ask relates to (b), and
> > >>>>>> is does
> > >> each
> > >>>>>> ODUk represent a different level of hierarchy?
> > >>>>>>
> > >>>>>> I see this as simply yes, and no different than what has
> > >>>>>> been done
> > >>>> more
> > >>>>>> recently with Ethernet or, even if we do continue to
> > >>>>>> model OTN as
> > >> a
> > >>>>>> single layer, no different than PSC-1 -> PSC-4.
> > >>>>>>
> > >>>>>> There's also a minor processing efficiency gained by
> > >>>>>> this approach
> > >>>> for
> > >>>>>> nodes that support a smaller set of ODUks than are
> > >>>>>> advertised
> > >> within
> > >>>> an
> > >>>>>> IGP.
> > >>>>>>
> > >>>>>> Based on all this, I believe different ODUk's should use
> > >>>>>> different Switching Types. In particular, I'm proposing:
> > >>>>>> (1) that either the framework or info documents identify
> > >>>>>> that a per-OTUk Switching Capability Types will be used
> > >>>>>> to support G.709v3. (2) that
> > >>>>>> draft-ietf-ccamp-gmpls-ospf-g709v3 define a different
> > >>>>>> Switching Cap field value for each ODUk, and that it
> > >>>>>> state that the value corresponding to the signal type
> > >>>>>> identified in the #stages=0 of the ISCP be set. (Without
> > >>>>>> any other changes to the current definition of ISCD.)
> > >>>>>> (3) that draft-ietf-ccamp-gmpls-signaling-g709v3 be
> > >>>>>> updated to match above.
> > >>>>>>
> > >>>>>> To keep thinks generic, we probably should use TDM-1
> > >>>>>> through TDM-n
> > >>>> as
> > >>>>>> the new Switching Capability Types, but this is a
> > >>>>>> secondary
> > >>>> discussion.
> > >>>>>>
> > >>>>>> Comments?
> > >>>>>>
> > >>>>>> Lou
> > >>>>>>
> > >>>>>> PS While the above is an important change, it doesn't
> > >> significantly
> > >>>>>> impact encoding and won't take much text to make the
> > >>>>>> actual
> > >> change,
> > >>>> so
> > >>>>>> this is a discussion that can continue until Paris if we
> > >>>>>> really
> > >> need
> > >>>> a
> > >>>>>> face to face to resolve the discussion.
> > >>>>>>
> > >>>>>> On 11/23/2011 1:18 PM, Daniele Ceccarelli wrote:
> > >>>>>>> Hi CCAMP,
> > >>>>>>>
> > >>>>>>>
> > >>>>>>>
> > >>>>>>> During the OTN OSPF draft presentation at the IETF
> > >>>>>>> meeting in
> > >>>> Taipei
> > >>>>>> two
> > >>>>>>> comments were raised with respect to the following
> > >>>>>>> issues:
> > >>>>>>>
> > >>>>>>>
> > >>>>>>>
> > >>>>>>> - Issue 1: Using different switching caps for each ODU
> > >>>>>>> type
> > >>>>>>>
> > >>>>>>> - Issue 2: Type 2 (unres bandwidth for variable
> > >>>>>>> containers) and
> > >>>> Type
> > >>>>>> 3
> > >>>>>>> (MAX LSP bandwidth foe variable containers always used
> > >>>>>>> in tandem?
> > >>>>>>>
> > >>>>>>>
> > >>>>>>>
> > >>>>>>> WRT issue 1: the proposal was to indicate the bottom
> > >>>>>>> most ODUk of
> > >>>> the
> > >>>>>>> muxing hiearachy in the Switching Capability field of
> > >>>>>>> the ISCD.
> > >>>> After
> > >>>>>> a
> > >>>>>>> quick talk with the other authors of the ID, the idea
> > >>>>>>> was to
> > >> reject
> > >>>>>> the
> > >>>>>>> proposal as it would lead to an overloading of the
> > >>>>>>> meaning of the Switching Capability field. (even if
> > >>>>>>> the definition of PSC1-2-3-4 already overloads the
> > >>>>>>> meaning of the switching capability field)
> > >>>>>>>
> > >>>>>>>
> > >>>>>>>
> > >>>>>>> WRT issue 2: it is analyzed in section 5.3 of the
> > >>>>>>> draft (version
> > >> -
> > >>>>>> 00).
> > >>>>>>> I'm copying it below for your convenience
> > >>>>>>>
> > >>>>>>>
> > >>>>>>>
> > >>>>>>> In this example the advertisement of an ODUflex->ODU3
> > >> hierarchy
> > >>>> is
> > >>>>>>>
> > >>>>>>> shown. In case of ODUflex advertisement the MAX LSP
> > >>>>>>> bandwidth
> > >>>>>> needs
> > >>>>>>>
> > >>>>>>> to be advertised but in some cases also information
> > >>>>>>> about the
> > >>>>>>>
> > >>>>>>> Unreserved bandwidth could be useful. The amount of
> > >> Unreserved
> > >>>>>>>
> > >>>>>>> bandwidth does not give a clear indication of how many
> > >>>>>>> ODUflex
> > >>>> LSP
> > >>>>>>>
> > >>>>>>> can be set up either at the MAX LSP Bandwidth or at
> > >>>>>>> different
> > >>>>>> rates,
> > >>>>>>>
> > >>>>>>> as it gives no information about the spatial
> > >>>>>>> allocation of the
> > >>>>>> free
> > >>>>>>>
> > >>>>>>> TSs.
> > >>>>>>>
> > >>>>>>>
> > >>>>>>>
> > >>>>>>> An indication of the amount of Unreserved bandwidth
> > >>>>>>> could be
> > >>>>>> useful
> > >>>>>>>
> > >>>>>>> during the path computation process, as shown in the
> > >>>>>>> following
> > >>>>>>>
> > >>>>>>> example. Supposing there are two TE-links (A and B)
> > >>>>>>> with MAX
> > >>>> LSP
> > >>>>>>>
> > >>>>>>> Bandwidth equal to 10 Gbps each. In case 50Gbps of
> > >>>>>>> Unreserved
> > >>>>>>>
> > >>>>>>> Bandwidth are available on Link A, 10Gbps on Link B
> > >>>>>>> and 3
> > >>>> ODUflex
> > >>>>>>>
> > >>>>>>> LSPs of 10 GBps each, have to be restored, for sure
> > >>>>>>> only one
> > >> can
> > >>>>>> be
> > >>>>>>>
> > >>>>>>> restored along Link B and it is probable (but not
> > >>>>>>> sure) that
> > >> two
> > >>>>>> of
> > >>>>>>>
> > >>>>>>> them can be restored along Link A.
> > >>>>>>>
> > >>>>>>>
> > >>>>>>>
> > >>>>>>> Early proposal was to have, in the case of variable
> > >>>>>>> containers advertisements (i.e. ODUflex), the MAX LSP
> > >>>>>>> bandwidth TLV (Type 3)
> > >>>> as
> > >>>>>> a
> > >>>>>>> mandatory piece of information and the Unreserved
> > >>>>>>> bandiwdth TLV
> > >>>> (Type
> > >>>>>> 2)
> > >>>>>>> as an optional piece of information.
> > >>>>>>>
> > >>>>>>> The comment received is that optional information can
> > >>>>>>> lead to interworking issues and the counter proposal
> > >>>>>>> was to have both
> > >>>> pieces
> > >>>>>> of
> > >>>>>>> information as mandatory and, as a consequence, merge
> > >>>>>>> the two
> > >> TLVs
> > >>>>>> into
> > >>>>>>> a single one.
> > >>>>>>>
> > >>>>>>>
> > >>>>>>>
> > >>>>>>> We'd like to hear the opinion of the WG on both issues
> > >>>>>>> before
> > >>>>>> proceeding
> > >>>>>>> with any modification to the document.
> > >>>>>>>
> > >>>>>>>
> > >>>>>>>
> > >>>>>>> Thanks,
> > >>>>>>>
> > >>>>>>> Daniele
> > >>>>>>>
> > >>>>>>>
> > >>>>>>>
> > >>>>>>>
> > >>>>>>>
> > >>>>>>>
> > >>>>>>> *DANIELE CECCARELLI * *System & Technology - DU IP &
> > >>>>>>> Broadband*
> > >>>>>>>
> > >>>>>>>
> > >>>>>>> Via L.Calda, 5 Genova, Italy Phone [phone]
> > >>>>>>> Mobile [phone] [e-mail]
> > >>>>>>> www.ericsson.com
> > >>>>>>>
> > >>>>>>>
> > >>>>>>>
> > >>>>>>> <http://www.ericsson.com/>
> > >>>>>>>
> > >>>>>>>
> > >>>>>>> This Communication is Confidential. We only send and
> > >>>>>>> receive
> > >> email
> > >>>> on
> > >>>>>>> the basis of the term set out at
> > >> www.ericsson.com/email_disclaimer
> > >>>>>>> <http://www.ericsson.com/email_disclaimer>
> > >>>>>>>
> > >>>>>>>
> > >>>>>>>
> > >>>>>>>
> > >>>>>>>
> > >
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