Hi, Tony:
Then we can make the following conclusions: 1） There is no algorithm can assure the different headend selects the same sets of links[Let’s call the sleep-able set of links ] to power off, even each headend use the “most-fill” strategy. (such phenomenon can occur in any topology network, regarding less they are in the same continent or not ) 2） There is no way to assure any third headend avoid using the above sleep-able set of links, regarding less of how long they have been idle. 3） There is no way for every headend to exchange their LSP requirements, to coordinate their path calculation results----“node-wide bias” doesn’t lead to “network-wide bias”. Based on the above conclusions, how can the operator power off the idle links? Please state the above constraints in your document, and relevant solutions, before proposing any protocol extensions. To Joel: Please state what state changes can be observed which can assist to solve the above 1)、2)、3) puzzles. Best Regards Aijun Wang China Telecom From: [email protected] [mailto:[email protected]] On Behalf Of Tony Li Sent: Tuesday, September 22, 2026 10:30 AM To: Aijun Wang <[email protected]> Cc: Vishnu Pavan Beeram <[email protected]>; Vishnu Pavan Beeram <[email protected]>; Adrian Farrel <[email protected]>; Barth, Colby <[email protected]>; Robert Raszuk <[email protected]>; John Drake <[email protected]>; John Drake <[email protected]>; WG TEAS <[email protected]>; lsr <[email protected]> Subject: Re: [Lsr] [Teas] Re: Re: Re: Re: Re: Re: Re: Re: [Green] 【Distributed Power-aware TE is Impossilbe】RE: RV: Call for adoption: draft-many-teas-power-steering-01 (Ends 2026-09-10) Hi Aijun, Let me state the logic more clear: 1) One headend(headend A) use the “most-fill” strategy to move the traffic out of a set of links, let’s call it “Set A” 2) Another headend(headend B) use also its “most-fill” strategy to move the traffic out of a set of links, let’s call it “Set B”. 3) According to the previous discussions, we can know there is no theoretical guardedness that can assure the “Set A” is equal to “Set B” , Right? Correct. Of course, given the theoretical foundation of your premise, the two paths might not be on the same continent, not share any links before or after optimization, and thus, could not intersect anyway. This seems like a really contrived example and wholly irrelevant to the case at hand. If luckily, “Set A” is equal “Set B”, the set of these links are idle now, how can you assure there will be no other headend(headend C) will allocate its LSP on such sets of the links later? You cannot. Nor would you want to. Headend C would use the links if there is no better alternative, and thus there is not capacity in the network to shut down those links. If you can’t assure, when will the nodes that connects these idle links power off the these links then? When all of the traffic is off of the links. If you can’t power off the links, even they are idle for a long time, where is the cost saved? Where is the benefits of applying the distributed power-save TE? Asked and answered. If the links are idle for a long time, then they would have been shut down. Tony
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