[Green] Re: [Lsr] Next steps for draft-many-lsr-power-group-02

[Tony Li <[e-mail]>]

Hi Robert,

> > as the traffic demand matrix is not a constant from one day to the next.
> 
> Hmmm that is a pretty bold statement and intuitively hard to argue with. 


Well, Carlos did ask that we be rigorous.  It’s quite clear that the traffic demand is not 100% identical from day to day. The question then is does it change enough to matter

If one wants to be rigorous, one needs to ensure that the traffic matrix between the power save case and the non-power save case is within a delta so small that it doesn’t affect LSP placement. [Fond memories of delta-epsilon proofs come to mind.]


> However maybe you and some of the folks on the list recall Cariden and their tool to build traffic demands in days, weeks and months of the number of tier 1 ISPs. Well the outcome of that was contrary and they found the traffic demand patterns to actually be pretty consistent in a given time deltas. 
> 
> That in turn allowed them to achieve traffic engineering of the relatively large global backbones by only adjusting the link metrics and the proven claim was that it was as good (say - 10%) as compared to the outcome of RSVP-TE. 


I am not arguing that such a delta does not exist.  Certainly it does, however if one wants to make a true apples-to-apples comparison, the delta must be shown to be small enough to not affect the result.


> I am mentioning it here as a potential alternative view on how to shift traffic between selected paths without the need to run full RSVP-TE in the network. Obviously this would rather fall into a controller driven bucket of solutions. 


Let’s not repeat the debate of centralized vs. distributed yet again, please.  It only generates heat and no light.

Cheers,
Tony