Re: [Detnet-dp-dt] about identity labels.. was Re: new versions of my slides

[Loa Andersson <[e-mail]>]

Jouni and Carlos,

I see that this could work, but we need to go over how this will be
established for every signaling protocol we think in scope.

Please see inline.

On 2017-03-04 18:01, Carlos Jesús Bernardos Cano wrote:
> Hi Jouni,
>
> On Wed, 2017-03-01 at 18:51 -0800, Jouni Korhonen wrote:
>> Folks,
>>
>> Back to d-id.. I understand the intent and need for the d-id label.
>> What I cannot immediately see it is going to help the FRER
>> implementation. Using Loa’s slides as a reference: assume G and D
>> both assign the same d-pw1 label values to F and A. Fortunately the
>> combination of d-id+d-pw is unique. However, when packets arrive at
>> B, the seqnum+history lookup would need to use both d-id+d-pw as a
>> combined key. This is getting cumbersome. One would need to map d-
>> id+d-pw to something that is locally unique in LFIB or use d-id as an
>> indirect index to separate LFIB tables holding d-pw associated
>> information. Since d-id and d-pw are separate labels this ends up
>> two-three lookups and carrying along the history metadata. Depending
>> on the flexibility of the memory sub-system one might face
>> interesting restrictions, for example on the size of the LFIB tables
>> first indexed by d-id.
>>
>> I know this was very implementation dependent rant, but how I
>> currently see d-id, it has made life easier for a control plane and a
>> provisioning. At the same time it seems to make the life of the hw
>> and data structure design hard.
>>
>> So far the “cleanest” solution for me has been the one with d-pw
>> ranges configured into T-DetNet-PE devices - to prevent collisions.
>> That one had the downside of fixed allocations put into nodes by the
>> network administrator.
>>
>
> I share your view. I like more the approach in which we avoid having
> the additional d-id (and we use globally unique d-pw labels). I
> acknowledge see all the advantages it brings, but I also share the
> concerns about the extra label layer and the potentially cumbersome
> processing. There have been also some discussions about the size of the
> label pool if they need to be globally unique. I think we need to have
> some discussion documented in the draft about this if we go in this
> direction.

This begs the question of what "globally unique d-pw labels" means above

Is it

- global as the special purpose labels, seems unlikely
- global as unique with in the domain, though we know there is a scaling
   problem
- global for one sender, not that different from d-id, other that the
   placment in the stack

???

/Loa
>
> Carlos
>
>> - Jouni
>>
>
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-- 


Loa Andersson                        email: [e-mail]
Senior MPLS Expert                          [e-mail]
Huawei Technologies (consultant)     phone: [phone]