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

[Carlos Jesús Bernardos Cano <[e-mail]>]

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.

Carlos

> - Jouni
>