Hi David, Please see inline.
On Mon, Nov 3, 2025 at 10:57 AM David 'equinox' Lamparter - equinox at diac24.net <[email protected]> wrote: > - is it really a good idea to assume power usage is hierarchical? > We didn't get into it in the presentation, but we are not assuming that power usage is a single hierarchy. In fact, for the cases of LAGs, we need multiple hierarchies, as a LAG can span multiple line cards and NPUs. I'm not a low-level hardware person, but to my knowledge there are e.g. > platforms that have crosspoint switches between their front panel ports and > the forwarding engines. AIUI this is more of a reliability/redundancy > thing, but that doesn't preclude its use for optimizing power usage. Such > a platform might have, say, 4 pairs of interfaces that can each be swapped > between 2 forwarding engines. (There are probably more complicated setups > too, but AIUI this is a realistic example.) > We have not gotten into the situation where an interface can swap between forwarding engines, but you could easily model any single configuration hierarchically. A power group can represent the entire crosspoint switch, with each forwarding engine as a power-group with the crosspoint switch as a parent. - how much of this is dynamic/worth putting into IS-IS, vs. how much of > this would be better served getting pulled from the routers via > netconf/inventory? > We have been trying for years to get the appropriate YANG model standardized. The GREEN WG is still discussing terminology. We are not young enough to take that path. (And, just to point out, the usage of live/actual power data is somewhat > limited by the fact that it won't be available for sleeping interfaces, and > you can probably get some very ugly oscillations if you have live data from > running interfaces competing with stale or theoretical data for sleeping > interfaces. Even freezing the last known is finnicky if the entire system > then heats up and everything uses 25% more power.) > In most cases, getting live/actual power is very hard. Most devices don't have a built-in power meter. As I said at the mic, we are hoping for best effort numbers, which in many cases, will be a static average-case number. T
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