Re: [CCAMP] [RTG-DIR] R: RtgDir review: draft-ietf-ccamp-otn-g709-info-model-11.txt

Lou Berger <lberger@labn.net> Mon, 30 September 2013 14:41 UTC

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Date: Mon, 30 Sep 2013 10:40:44 -0400
From: Lou Berger <lberger@labn.net>
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To: Daniele Ceccarelli <daniele.ceccarelli@ericsson.com>, "Joel M. Halpern" <jmh@joelhalpern.com>
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Subject: Re: [CCAMP] [RTG-DIR] R: RtgDir review: draft-ietf-ccamp-otn-g709-info-model-11.txt
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Daniele,

On 09/30/2013 09:59 AM, Daniele Ceccarelli wrote:
> Lou, Joel,
> 
> The text proposed sounds good but it only states the problem without any hint on the solutions (i.e. says there is an inefficiency but doesn’t say that advertising only supported priorities is a way to address such inefficiency).
> There are two options:

Well, there's also the option of dropping the sections.

> 1. Improve the text (the NEW one) saying e.g. only the advertisement of bandwidth for supported priorities is needed

I always find it easier to make a decision when the tradeoffs are
concrete.  Can you (authors) propose revised text?

> 2. Adopt the NEW text as it is and move the remaining part of the text to the OSPF draft (where we say e.g. that only bandwidth for supporter priorities need to be advertised but don't say why).
> 
Doesn't the OSPF draft already already do what you say, i.e., advertise
only used priorities. What specific text are you proposing to add?
>

Thanks,
Lou

> Re all the other comments/suggestion we're ok and will fix them as suggested.
> 
> BR
> Authors
> 
>> -----Original Message-----
>> From: Lou Berger [mailto:lberger@labn.net]
>> Sent: venerdì 27 settembre 2013 21:55
>> To: Joel M. Halpern
>> Cc: rtg-dir@ietf.org; CCAMP WG; draft-ietf-ccamp-otn-g709-info-
>> model.all@tools.ietf.org; BELOTTI, SERGIO \(SERGIO\); rtg-ads@tools.ietf.org
>> Subject: Re: [RTG-DIR] R: [CCAMP] RtgDir review: draft-ietf-ccamp-otn-g709-
>> info-model-11.txt
>>
>> Great. So you and I are in agreement. We'll see what the authors have to
>> say...
>>
>>
>> On 3:26pm, September 27, 2013, Joel M. Halpern wrote:
>>> The proposed alternative text would suffice, although personally I
>>> would just remove the two sections.
>>>
>>> Yours,
>>> Joel
>>>
>>> On 9/27/13 3:00 PM, Lou Berger wrote:
>>>> Joel,
>>>> Does the proposed altnerate text address your comment (assuming the
>>>> author's want to keep the sections)?  If not, can you suggest changes?
>>>>
>>>> Thanks,
>>>> Lou
>>>>
>>>> On 09/27/2013 02:30 PM, Joel M. Halpern wrote:
>>>>> Lou, thanks for stepping in.
>>>>> With your explanation I can live with the LSP text as it is.
>>>>>
>>>>> I look forward to further conversation on the other point.
>>>>>
>>>>> Yours,
>>>>> Joel
>>>>>
>>>>> On 9/27/13 1:37 PM, Lou Berger wrote:
>>>>>> Joel/Authors,
>>>>>>
>>>>>> I thought I might jump in on two points:
>>>>>>
>>>>>>
>>>>>> On 9/26/2013 4:50 AM, BELOTTI, SERGIO (SERGIO) wrote:
>>>>>>> Hello Joel,
>>>>>>>
>>>>>>> thanks for your comments.
>>>>>>> Below in line our reply, marked "authors".
>>>>>>>
>>>>>>
>>>>>> ...
>>>>>>
>>>>>>> Given that this document is about mapping to G.709, it is
>>>>>>> unclear what is intended by the usage of "LSP".  My guess is
>>>>>>> that it is intended to mean Label Switch Paths set up by GMPLS
>>>>>>> to carry OTU/UDU elements.
>>>>>>> It should be stated explicitly.
>>>>>>>
>>>>>>> Authors> We can specify this as you suggest even if we
>>>>>>> Authors> considered not
>>>>>>> necessary to specify the usage of LSP in relation to data
>>>>>>> plane specific. Encoding type should cope with this issue.
>>>>>>>
>>>>>>
>>>>>> Joel,
>>>>>>
>>>>>> I suspect that the usage of LSP in the absence of the MPLS data
>>>>>> plane is what's causing confusion here.  Is this correct?
>>>>>>
>>>>>> If so, I think GMPLS referencing controlled data paths
>>>>>> (circuits) by the common name of Label Switched Path (LSP) is
>>>>>> sufficiently established that this document doesn't need to
>>>>>> revisit it.  In any case, the document already provides context:
>>>>>>
>>>>>> GMPLS routing and signaling, as defined by [RFC4203], [RFC5307],
>>>>>> [RFC3473] and [RFC4328], provides the mechanisms for basic GMPLS
>>>>>> control of OTN networks based on the 2001 revision of the G.709
>>>>>> specification.
>>>>>> and
>>>>>> Background information and a framework for the GMPLS protocol
>>>>>> extensions need to support [G.709-2012] is provided in [OTN-FWK].
>>>>>>
>>>>>> [OTN-FWK] has the often repeated concept:
>>>>>>
>>>>>> GMPLS extends Multi-Protocol Label Switching (MPLS) to encompass
>>>>>> time division multiplexing (TDM) networks (e.g., Synchronous
>>>>>> Optical NETwork (SONET)/ Synchronous Digital Hierarchy (SDH),
>>>>>> Plesiochronous Digital Hierarchy (PDH), and G.709 sub-lambda),
>>>>>> lambda switching optical networks, and spatial switching (e.g.,
>>>>>> incoming port or fiber to outgoing port or fiber).  The GMPLS
>>>>>> architecture is provided in [RFC3945],
>>>>>>
>>>>>> If this doesn't cover the comment, can you elaborate on what you
>>>>>> want explicitly stated?
>>>>>>
>>>>>>> ...
>>>>>>>
>>>>>>> Section 8 on Maximum LSP Bandwdith seems to be objecting to
>>>>>>> too much information leading to a "waste of bits".  While
>>>>>>> possibly of interest to the WG, that does not seem to fit a gap
>> analysis.
>>>>>>> Similarly, section 10 on Priority Support reads as
>>>>>>> implementation advice rather than a gap needing protocol changes.
>>>>>>>
>>>>>>> Authors> The basic scope of the draft is to underline gaps,
>>>>>>> Authors> and even
>>>>>>> if what described in Ch.8 and 10, do not prevent routing to
>>>>>>> work , it is suggested here an requirement for optimization
>>>>>>> based on OTN requirements (e.g. no need to advertise fixed ODU
>>>>>>> container Max LSP BW since implicit in the signal type.)
>>>>>>>
>>>>>>
>>>>>> Authors,
>>>>>> I completely agree with Joel on this point, furthermore sections
>>>>>> 10 and
>>>>>> 8 overlap.  One approach to address his point would be to simply
>>>>>> drop both sections.  An alternative is try to rephrase them to
>>>>>> address Joel's points.  I've taken a pass at the latter below,
>>>>>> but won't object if the authors prefer the former.
>>>>>>
>>>>>> Here's a suggested wording change if you choose to keep the
>> sections:
>>>>>> OLD:
>>>>>> 8. Maximum LSP Bandwidth
>>>>>>
>>>>>> Maximum LSP bandwidth is currently advertised in the common part
>>>>>> of the ISCD and advertised per priority, while in OTN networks
>>>>>> it is only required for ODUflex advertising.  This leads to a
>>>>>> significant waste of bits inside each LSA.
>>>>>> and
>>>>>>
>>>>>> NEW
>>>>>> 8. Maximum LSP Bandwidth
>>>>>>
>>>>>> Maximum LSP bandwidth is currently advertised per priority in
>>>>>> the common part of the ISCD.  Section 5 reviews some of the
>>>>>> implications of advertising OTN network information using
>>>>>> ISCDs, and identifies the need for a more optimized solution.
>>>>>> While strictly not required, such an optimization effort should
>>>>>> also consider the optimization of the per priority maximum LSP
>>>>>> bandwidth advertisement of both fixed and variable ODU types.
>>>>>>
>>>>>> OLD
>>>>>> 10. Priority Support
>>>>>>
>>>>>> [RFC4202] defines 8 priorities for resource availability and usage.
>>>>>> All of them have to be advertised independently on the number of
>>>>>> priorities supported by the implementation.  Considering that
>>>>>> the advertisement of all the different supported signal types
>>>>>> will originate large LSAs, it is advised to advertise only the
>>>>>> information related to the really supported priorities.
>>>>>> NEW
>>>>>> 10. Priority Support
>>>>>>
>>>>>> [RFC4202] defines 8 priorities for resource availability and usage.
>>>>>> As defined, each is advertised independent of the number of
>>>>>> priorities supported by a network.  As is the case in Section 8,
>>>>>> addressing any inefficiency with such advertisements is not
>>>>>> required to support OTN networks.  But any such inefficiency
>>>>>> should also be considered as part of the optimization effort
>>>>>> identified in Section 5.
>>>>>>
>>>>>> Also please replace "Bw" with "Bandwidth" in the document.
>>>>>>
>>>>>> Lou
>>>>>>
>>>>>
>>>>
>>>>
>>>