Re: [CCAMP] [RTG-DIR] RtgDir review: draft-ietf-ccamp-general-constraint-encode-16.txt

[Lou Berger <[e-mail]>]

Young,

I guess I didn't see the new text as substantively different or more
informative than preceding text:

   ... There may be more than one matrix associated with
   a node as the node can partition the switch matrix into several sub-
   matrices for various reasons such as incremental updates, etc. When
   the matrix is partitioned into sub-matrices, it is envisioned that
   they are mutually exclusive to one another in representing which
   ports/labels are associated with each sub-matrix. This implies that
   two matrices will not have the same {src port, src label, dst port,
   dst label}.

I'd suggest directly addressing the ambiguity by revising the first
sentence and "for various reasons such as incremental updates, etc. " in
particular.  Perhaps "primarily to limit the size of any individual
information element used to represent the matrix."  or however else
you'd like to capture the intent.

Lou

On 2/2/2015 5:15 PM, Leeyoung wrote:
> Hi Lou,
>
> The original question Tomonori raised was if sub-matrices are like virtual nodes attached to connectivity matrix. The answer was no, and sub-matrix is simply a partition of connectivity matrix into smaller pieces. To that end, I added the following text in Section 2.1
>
>    Each sub-matrix is assigned a unique Matrix ID to represent a 
>    mutually exclusive set of {src port, src label, dst port, dst label} 
>    from other sub-matrices. 
>
> Let me know what you think.
>
> Thanks,
> Young
>
> -----Original Message-----
> From: Lou Berger [mailto:[e-mail]] 
> Sent: Monday, February 02, 2015 3:29 PM
> To: Leeyoung
> Cc: Tomonori Takeda; [e-mail]; '[e-mail]'; '[e-mail]'; '[e-mail]'
> Subject: Re: [RTG-DIR] RtgDir review: draft-ietf-ccamp-general-constraint-encode-16.txt
>
> Hi Young,
>
> I see you just published an update.  I have one question below.
>
> On 1/23/2015 3:01 AM, Tomonori Takeda wrote:
>> Hi Young,
>>
>> OK, thanks,
>>
>> Tomonori
>>
>> -----Original Message-----
>> From: Leeyoung [mailto:[e-mail]] 
>> Sent: Thursday, January 22, 2015 2:44 AM
>> To: Tomonori Takeda（武田知典）; Leeyoung; [e-mail]
>> Cc: '[e-mail]'; '[e-mail]'; '[e-mail]'
>> Subject: RE: [RTG-DIR] RtgDir review: draft-ietf-ccamp-general-constraint-encode-16.txt
>>
>> Hi Tomonori,
>>
>> Thanks for your comment. Please see in-line for my response. Please let me know if the response would satisfy you. 
>>
>> Best regards,
>> Young
>>
>> -----Original Message-----
>> From: Tomonori Takeda [mailto:[e-mail]] 
>> Sent: Wednesday, January 21, 2015 12:48 AM
>> To: Leeyoung; [e-mail]
>> Cc: '[e-mail]'; '[e-mail]'; '[e-mail]'; Tomonori Takeda
>> Subject: RE: [RTG-DIR] RtgDir review: draft-ietf-ccamp-general-constraint-encode-16.txt
>>
>> Hi Young,
>>
>> Thanks.
>>
>> Two follow-up questions/comments.
>> (I am fine with other points, which you already addressed in the updated draft.)
>>
>>> 2) In section 2.1, it says "two matrices will not have the same {src port, src label, dst port, dst label}". To be precise, I guess this should be > "two matrices will not have the same {src port, src label}, and two matrices will not have the same {dst port, dst label}"?
>>>
>>> YOUNG>> I think your suggestion may be too restrictive. For instance, if we have one source (port 1) and one destination (port 2) with two labels > each. Then we would have: {(1,1,2,1), (1,1,2,2), (1,2,2,1), (1,2,2,2)} I think with the current statement, we can send this info in any combination > of multiple matrices, which I think perfectly fine. With your suggestion, I would not be able send (1,1,2,1) and (1,1,2,2) together. Why would this > not be made possible? My take is as long as each submatrix represents a set of disjoint quadruples, that should be allowed.
>> My reading of "two matrices will not have the same {src port, src label, dst port, dst label}" is as follows.
>>
>> <Example A>
>>
>>   input port=1  --> Submatrix#1 --> output port=2
>>   input label=1                     output label=1
>>
>>   input port=1  --> Submatrix#2 --> output port=2
>>   input label=1                     output label=2
>>
>>   This is allowed.
>>
>> <Example B>
>>
>>   input port=1  --> Submatrix#1 --> output port=2
>>   input label=1                     output label=1
>>
>>   input port=1  --> Submatrix#2 --> output port=2
>>   input label=1                     output label=1
>>
>>   This is not allowed.
>>
>> <Example C>
>>
>>   input port=1  --> Submatrix#1 --> output port=2
>>   input label=1                     output label=1
>>
>>   input port=1  --> Submatrix#2 --> output port=2
>>   input label=2                     output label=2
>>
>>   This is allowed.
>>
>> Is above understanding correct?
>> If so, I am not sure how example A works, since I am not sure what is the indentifier to direct from input to each submatrix.
>>
>> Maybe I am mis-understanding what sub-matrix is. I thought sub-matrix is a sort of virtual node, splitting the single matrix (or switch) into smaller pieces.
> Can you explain how the revised text clarifies this point?
>
> Thanks,
> Lou
>
>> ....