Hi Robert,
> But you did not comment on the question how PCPPS would relate to RFC7810 > constraints if at all. As we have said repeatedly, PCPPS is only a modification to the metric. CSPF still respects all constraints. > In respect to power groups you said: > > Power groups allow vendors and operators to advertise the power consumption > of NPUs and other silicon components and the relationships between those > components so that external devices can make good decisions about path > computation. > > Excellent I fully get the desire to shut NPU not just bunch of lasers. But > now you are really asking for ingress nodes to understand that per node > groupings in their path calculations. Which is exactly why this information is advertised in the IGP. > And here I must say that I share the concern of others that selecting the > same set of power groups (not only interfaces) by independent ingress nodes > may be a matter of luck then heuristics. And needless to say that needs to be > done bidirectionally which by itself argues against the nature of power > groups. > > Why ? It is neither a matter of luck nor heuristics. It is a matter of metric. Larger metrics drive traffic away. PCPPS increases the metric on interfaces where there are power-saving opportunities. If symmetrically configured (which is NOT a given, due to asymmetric metrics because the two ends of the link are not symmetric with respect to router architecture), then the PCPPS addition would be symmetric and drive traffic to alternate paths. > NPUs serving east ingress nodes (east-headends) may be part of completely > disjoined power groups from NPUs serving traffic coming from west ingress > nodes (west-headends). Correct. In fact, power-groups are node-local. > With staying on a per link granularity the likehood of success (moving LSPs > to other paths) IMO is much bigger then if adding to the mix the concept of > power groups (which again brings the question of how CSPF actually is > supposed to use them). Well, I completely disagree with you. NPUs will likely have much larger contribution to PCPPS due to its higher power consumption, so I see no clear reason why it would not have an effect. Cheers, Tony
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