Hi Colby, I am not sure John is suggesting GCO. I think he as few other folks on this list are simply puzzled to how your proposal works in practice.
I voice my questions few time - but did not get any clear answer. Namely my doubt comes down to the below question (maybe John and few others are also wondering about this too) Assume there is set of links and there are network resources which would have sufficient capacity to carry traffic from those links. Of course assume 100% TE. The question is how would you assume that few hundreds of headends will at their time to reoptimize LSPs act in concert that the same set of links is being dried out ? Well I have had a nice chat with Tony on the side and he revealed one subtle but vastly important point. The capability that given link can be put to sleep is not really a constant capability of that link. The same applies to Power Group. So such "capability" is advertised when some oracle thinks it makes sense. It is not described in ISIS draft like this. I guess all we are asking here is to learn if this advertisement (via IGP flooding) at specific time intervals of the network is what makes the hope that even 100s of headends will notice that and will start their own attempt to shift the traffic on links not painted as sleep capable. It may actually work at scale it is just that current version of the draft is not make it clear. Cheers, R. On Fri, Sep 4, 2026 at 6:03 PM Barth, Colby <jonathan.barth= [email protected]> wrote: > Hi John, > > I assume you’re making the case for Global Concurrent Optimization (once > again)? Sure, that would provide better results than distributed TE. This > is not a new argument, we already discussed it in this thread (and for many > years, for that matter). As we’ve stated many times already, if you want a > “Controller” to consume the power-group info (and all the associated per > interface, per tunnel, power telemetry streaming) and perform GCO, this > solution does not prohibit you. > > However, not all operators leverage a central Controller and GCO comes > with its own ‘costs’ (also already highlighted in this thread by Tony) nor > should we require it. Therefore, this proposal caters to both centralize > and distributed TE to facilitate power savings. > > It would be nice if we could just discuss the specific IS-IS extensions we > proposed and not continue this circular argument. > > Thanks, > > -- Colby > > *From: *John Drake <[email protected]> > *Date: *Friday, September 4, 2026 at 8:29 AM > *To: *Barth, Colby <[email protected]> > *Cc: *John Drake <[email protected]>; Aijun Wang < > [email protected]>; Tony Li <[email protected]>; WG TEAS < > [email protected]>; lsr <[email protected]> > *Subject: *Re: [Lsr] Re: [Teas] Re: Re: [Green] 【Distributed Power-aware > TE is Impossilbe】RE: RV: Call for adoption: > draft-many-teas-power-steering-01 (Ends 2026-09-10) > > Colby, > > Your statement is incorrect. > > Because your proposal is distributed, there is always the possibility that > links that should have been put to sleep are not, because the > re-distribution of LSPs in order to put links to sleep is not co-ordinated > in order to provide global co-ordination of that re-distribution. > > John > > Sent from my iPhone > > On Sep 4, 2026, at 11:07 AM, Barth, Colby <jonathan.barth= > [email protected]> wrote: > > > John, > > It only results in no links being put to sleep IF there are insufficient > resources to consolidate traffic. That’s a feature, not a limitation. > > -- Colby > > *From: *John Drake <[email protected]> > *Date: *Friday, September 4, 2026 at 7:14 AM > *To: *Barth, Colby <[email protected]> > *Cc: *Aijun Wang <[email protected]>; Tony Li < > [email protected]>; WG TEAS <[email protected]>; lsr <[email protected]> > *Subject: *Re: [Teas] Re: [Lsr] Re: [Green] 【Distributed Power-aware TE > is Impossilbe】RE: RV: Call for adoption: draft-many-teas-power-steering-01 > (Ends 2026-09-10) > > Colby, > > Path placement in this proposal is indeed deterministic. However, its > effects are not; i.e., even though it may be possible to put some links > to sleep, this proposal will not do that deterministically. In > particular, this proposal may not put any links to sleep. > > I don’t think that’s acceptable. > > John > Sent from my iPhone > > On Sep 4, 2026, at 9:47 AM, Barth, Colby <jonathan.barth= > [email protected]> wrote: > > > Aijin, > > Distributed TE path placement is deterministic. Tony’s example is about > placing TE tunnels on paths with sufficient resources. > > You are criticizing many other solutions with your example. The PCE > architecture follows the same model. > > -- Colby > > *From: *Aijun Wang <[email protected]> > *Date: *Thursday, September 3, 2026 at 6:23 PM > *To: *'Tony Li' <[email protected]> > *Cc: *'TEAS WG' <[email protected]>; 'lsr' <[email protected]> > *Subject: *[Teas] Re: [Lsr] Re: [Green] 【Distributed Power-aware TE is > Impossilbe】RE: RV: Call for adoption: draft-many-teas-power-steering-01 > (Ends 2026-09-10) > > Hi, Tony: > > Then, there will be no deterministic effect for the distributed > power-aware TE, Right? > Why the operator will deploy such proposal that has the unknown > probability of success? > > And, for the power group related information, since they are static, and > will almost never to be changed, even the controller based approaches need > them, it is not the IGP's role to flooding them. > > Let's image the possible scenario: > NMS configure the power group information on each device---->IGP flood > such information among all the nodes---->BGP-LS collect such information to > the Controller > Why don’t we let the NMS synchronize such information to the Controller? > In most of the real deployment, NMS is almost the same, or collocate with > SDN controller. > > So, what's the usage of the distributed power-aware TE proposal? > > Best Regards > > Aijun Wang > China Telecom > > -----Original Message----- > From: [email protected] [mailto:[email protected] > <[email protected]>] On Behalf Of Tony Li > Sent: Friday, September 4, 2026 3:18 AM > To: Aijun Wang <[email protected]> > Cc: TEAS WG <[email protected]>; lsr <[email protected]> > Subject: [Lsr] Re: [Teas] [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's trim the discussions within TEAS only. > > > No, let’s not. > > > > "the relevant nodes can then detect that the link is idle and can put it > into power-sleep." via the "reserved bandwidth"? > > Then the proposal depends solely on RSVP style TE. > > > No. Other proposals are free to use the information as well. If you have > a controller-based approach and want PSP information on the network, here’s > one way. > > > > Even so, how you assure all the ingress node will select to avoid the > same link along the e2e path that is determined by its own? Only behave in > such manner, can you move out of the traffic from one link step by step. > > > There is no guarantee that all headends will be able to consolidate > traffic. If the traffic levels are sufficiently low and the relevant > headends compute paths that do consolidate traffic, then links can > transition to power-sleep. If traffic levels are not sufficiently low and > one headend cannot find a path that avoids the link, well, the the link > cannot be put into power sleep. This is not a bug, this is a feature. > > > > Changing the link metric can get the effect of " in the middle of a > flock of birds and clap your hands, they will fly away ". > > But for the distributed TE proposal, the effect will be the birds fly > from east to west, and then from north to south, or, fly around within the > forest, because every edge router direct them to avoid some different tree. > > > We are not changing the link metric. We are adding a penalty to the path > for the link in question. There may be many links on a path that are > capable of power-sleep, so there may be many penalties. Those penalties do > not have to be the same from LSP to LSP, nor from head-end to head-end, nor > from link to link to have an effect on path computation. As long as each > headend finds a path with sufficient capacity, then the network is in an > acceptable state. > > Tony > > _______________________________________________ > Lsr mailing list -- [email protected] > To unsubscribe send an email to [email protected] > > _______________________________________________ > Teas mailing list -- [email protected] > To unsubscribe send an email to [email protected] > _______________________________________________ > Teas mailing list -- [email protected] > To unsubscribe send an email to [email protected] > > _______________________________________________ > Lsr mailing list -- [email protected] > To unsubscribe send an email to [email protected] > > _______________________________________________ > Teas mailing list -- [email protected] > To unsubscribe send an email to [email protected] >
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