Re: [CCAMP] WG Last Call comments on draft-ietf-ccamp-gmpls-signaling-g709v3-04

Daniele Ceccarelli <> Mon, 28 January 2013 10:08 UTC

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From: Daniele Ceccarelli <>
To: "Zafar Ali (zali)" <>, Lou Berger <>
Thread-Topic: [CCAMP] WG Last Call comments on draft-ietf-ccamp-gmpls-signaling-g709v3-04
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Date: Mon, 28 Jan 2013 10:08:19 +0000
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Subject: Re: [CCAMP] WG Last Call comments on draft-ietf-ccamp-gmpls-signaling-g709v3-04
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I think the changes proposed are meaningful and would support them in an individual or early WG draft, but they don't seem to provide significative advantages to risk interworking issues with early implementations.
Moreover the changes don't allow us getting totally rid of of the bit_rate field as it is still needed for ODUflex (CBR).

My 2c

>-----Original Message-----
>From: Zafar Ali (zali) [] 
>Sent: lunedì 28 gennaio 2013 4.47
>To: Lou Berger
>Cc: Gruman, Fred; Fatai Zhang; Daniele Ceccarelli; CCAMP; 
>Subject: Re: [CCAMP] WG Last Call comments on 
>Hi Lou- 
>Please see in-line.
>On 1/27/13 9:46 PM, "Lou Berger" <> wrote:
>>	Is your comment with respect to just routing or both 
>signaling and 
>Both, including consistency between signaling and routing attributes.
>>Also, when you say "implementations based on draft versions", 
>do these 
>>implementations include support for ODUflex?  (Which has really been 
>>the focus of the discussion.)
>Yes, I was referring to ODUFlex. As you know, fixed ODU is 
>signaled via level (0 BW) so its not an issue.
>>BTW I took Fred's comments as related to just the new 
>OTN-specific ISCD 
>>definitions (section 4.1.2 of ospf-g709v3-05, in particular).  Note 
>>that section 4.1.1 already carries N (number of ODUs) not 
>IEEE floating 
>>point representations of available bandwidth.
>What I meant is Unreserved Bandwidth at priority x and Max LSP 
>Bandwidth at priority x. 
>>Much thanks,
>>On 1/27/2013 7:46 PM, Zafar Ali (zali) wrote:
>>> All-
>>> This impacts existing implementations based on draft versions (and 
>>> hence interop with these implementations moving forward). 
>IMO this is 
>>> a bigger change for us to assume at the last call stage. 
>>> we have been using IEEE floating point format for Unreserved 
>>> Bandwidth/ Max LSP BW in IEEE floating point format for other 
>>> technologies. Overall, I think this change suffers from the 
>"law of diminishing returns".
>>> Thanks
>>> Regards Š Zafar
>>> On 1/27/13 10:28 AM, "Gruman, Fred" 
><> wrote:
>>>> Hi Lou, Fatai, Daniele,
>>>> I understand the latest change to the way bandwidth is 
>signaled for  
>>>>ODUflex(GFP), i.e., signaling the number of tributary slots 
>N instead 
>>>>of  the bandwidth rate in bps.  I believe that this simplifies the 
>>>>signaling  and interoperability so I'm in agreement with 
>this change.
>>>> However, it seems we are now inconsistent between how we 
>>>>bandwidth in routing and signaling for ODUflex(GFP).  Routing 
>>>>advertises  the bandwidth using a floating point representation of 
>>>>bandwidth, while  signaling is using the number of tributary slots. 
>>>>It seems the same  benefits would be obtained by 
>advertising the max 
>>>>LSP bandwidth and  unreserved bandwidth for ODUflex(GFP) in 
>terms of 
>>>>the number of tributary  slots.
>>>> Fred
>>>> -----Original Message-----
>>>> From: [] On 
>>>>Behalf Of  Lou Berger
>>>> Sent: Wednesday, January 23, 2013 9:08 AM
>>>> To: Fatai Zhang
>>>> Cc: CCAMP;
>>>> Subject: Re: [CCAMP] WG Last Call comments on
>>>> draft-ietf-ccamp-gmpls-signaling-g709v3-04
>>>> Fatai,
>>>> On 1/23/2013 6:49 AM, Fatai Zhang wrote:
>>>>> Hi Lou,
>>>>> For ODUflex(CBR), the formula is from [G.709-2012] and it 
>has been 
>>>>> discussed before, so please trust that there is no 
>opportunity for 
>>>>> misinterpretation. (Note that there are two cases, one is
>>>>> ODUflex(CBR) and another one is ODUflex(GFP)).
>>>>> In addtion, ODUflex cannot be concatenated by [G.709-2012].
>>>> Thanks for confirming my understanding.  This raises the 
>question of 
>>>> if the new traffic should just apply to ODUFlex?  Correct 
>me if I'm 
>>>> wrong, but I believe the [RFC4328] is sufficient in all 
>other cases.  
>>>> This may also make it easier for early implementations of 
>the draft 
>>>> as then they can limit code changes from the (-03) rev to 
>only ODUflex LSPs.
>>>> Just to be clear, I'm really just *asking* about this.  As I said 
>>>> before, I'm open on specifics...
>>>> Any thoughts/comments? Authors?  Implementors?
>>>> Thanks,
>>>> Lou
>>>>> I will issue a new version tomorrow to capture all your comments.
>>>>> Best Regards
>>>>> Fatai
>>>>> -----Original Message-----
>>>>> From: Lou Berger []
>>>>> Sent: Wednesday, January 23, 2013 2:11 AM
>>>>> To: Fatai Zhang
>>>>> Cc: CCAMP;
>>>>> Subject: Re: [CCAMP] WG Last Call comments on
>>>>> draft-ietf-ccamp-gmpls-signaling-g709v3-04
>>>>> Fatai,
>>>>> On 1/20/2013 9:43 PM, Fatai Zhang wrote:
>>>>>> Hi Lou,
>>>>>> You said:
>>>>>>> but you're says encoded as (N*Nominal Rate) right? Wat's the 
>>>>>>>value of  this vs just carrying N?
>>>>>> [Fatai] The original way (in version 04&05) is putting 
>(N* Nominal
>>>>>> Rate) in "Bit_Rate" field for ODUflex(GFP), the value is that we 
>>>>>> can generalize to just use one single "Bit_Rate" field to carry 
>>>>>> IEEE float number for both cases, it seems that you 
>don't agree on 
>>>>>> this value, :-)
>>>>> I've seen differences in calculated floating point values from 
>>>>>different  implementations, so I just want to ensure that 
>such cases 
>>>>>are avoided.
>>>>> I'm open to specific solutions and certainly will deffer on the  
>>>>>specifics assuming there is no opportunity for 
>>>>>misinterpretation/interop  issues. I don't think the 
>original passed 
>>>>>this threshold, i.e.,:
>>>>>          N = Ceiling of
>>>>>    ODUflex(CBR) nominal bit rate * (1 + ODUflex(CBR) bit rate
>>>>>        ODTUk.ts nominal bit rate * (1 - HO OPUk bit rate 
>>>>>> . Therefore, I (was) am saying that I am going to accept your 
>>>>>> suggestion to carry N for ODUflex(GFP). We are 
>discussing where to 
>>>>>> put N for ODUflex(GFP).
>>>>>> You said:
>>>>>>> bits in the control plane are generally cheap, IMO it's 
>better to  
>>>>>>>have simpler encoding than to optimize every bit (or 8 in this 
>>>>>> [Fatai] OK, I will add a new field (to occupy the reserved bits) 
>>>>>> to carry N.
>>>>> As you see fit.
>>>>> Just to clarify my understanding, ODUflex and Virtual 
>>>>>can  never be combined for the same signal type/level, right? 
>>>>>(Although an  ODUflex client signal could be carried over 
>a virtual 
>>>>>concatenated  ODUk).  Is this correct or did I miss something in 
>>>>> Thanks,
>>>>> Lou
>>>>>> Best Regards
>>>>>> Fatai
>>>>>> -----Original Message-----
>>>>>> From: Lou Berger []
>>>>>> Sent: Friday, January 18, 2013 1:42 AM
>>>>>> To: Fatai Zhang
>>>>>> Cc: CCAMP;
>>>>>> Subject: Re: [CCAMP] WG Last Call comments on
>>>>>> draft-ietf-ccamp-gmpls-signaling-g709v3-04
>>>>>> On 1/15/2013 10:16 PM, Fatai Zhang wrote:
>>>>>>> Hi Lou,
>>>>>>> To avoid misunderstanding, I would like to clarify more on the 
>>>>>>> following point.
>>>>>>>>>>> It is better to have consistent format and the same meaning 
>>>>>>>>>>>of one
>>>>>> field for both ODUflex(CBR) and GFP. This is why we have section 
>>>>>> 5.1
>>>>>> &5.2 to describe the complex stuff.
>>>>>>>>>> I actually wasn't suggesting that N be carried in 
>the bit rate  
>>>>>>>>>> The bit rate field can either be set as described or to zero 
>>>>>>>>>>(i.e.,  ignored).  At the time, I was thinking about 
>carrying N 
>>>>>>>>>>in the  reserved  field. But perhaps the right place 
>is MT, if 
>>>>>>>>>>my understanding is  right  (would always be 1 
>otherwise). I'm 
>>>>>>>>>>open to either...
>>>>>>>>> [Fatai] Why not just use "bit rate"field to carry 
>"N"because "N"
>>>>>>>>> implies bit rate?  I am OK if you like to use a new 
>filed (like 
>>>>>>>>> Number") to occupy the reserved field even though 
>that I prefer 
>>>>>>>>>the  original approach (ie., use "bit rate"field to carry "N").
>>>>>>>> Are you proposing dropping carrying bit rates 
>represented as an 
>>>>>>>>IEEE  floating point and just carrying N for ODUflex? 
>This seems 
>>>>>>>>workable  to  me, but we should ensure that there are no 
>>>>>>>>significant objections.
>>>>>>> [Fatai] There are two usages for " Bit_Rate " field as 
>>>>>>> in the lines 287-310.
>>>>>>> (1)    For ODUflex(CBR), the Bit_Rate field indicates 
>the nominal
>>>>>>> rate of ODUflex(CBR) expressed in bytes per second, 
>encoded as a  
>>>>>>>32-bit  IEEE single precision floating-point number. For this 
>>>>>>>case, we MUST  use  32-bit IEEE floating point instead of 
>>>>>>>"N"(Please see more in section  5.1).
>>>>>> I guess you really still need (to be based on) the client signal 
>>>>>> rate at the edges.
>>>>>>> (2)    For ODUflex(GFP), we can change the text (the 
>lines from 305
>>>>>>> 310) based on your suggestion, ie., the Bit_Rate field 
>is used to  
>>>>>>>carry  "N"to indicate the nominal bit rate of the  ODUflex(GFP).
>>>>>> but you're says encoded as (N*Nominal Rate) right?  Wat's the 
>>>>>>value of  this vs just carrying N?
>>>>>>> Therefore, I am proposing using one single filed ("Bit_Rate ") 
>>>>>>> for these two cases, in this way, we can leave the "Reserved" 
>>>>>>> bits for future.
>>>>>> bits in the control plane are generally cheap, IMO it's 
>better to 
>>>>>>have  simpler encoding than to optimize every bit (or 8 in this 
>>>>>> Lou
>>>>>>> Hope we are now at the same page.
>>>>>>> Best Regards
>>>>>>> Fatai
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