Aijun,

The behavior you are questioning is already a standard outcome of
distributed bandwidth-engineered networks when ingress nodes independently
apply the same path-selection policy.

For example, Junos most-fill behavior is documented in the MPLS
path-selection documentation [1]: “Prefer the path with the least available
bandwidth (with the minimum available bandwidth ratio) when several
equal-cost candidate paths to a destination exist.” The minimum available
bandwidth ratio of a path is the smallest available bandwidth ratio among
the links in that path.

When each ingress node independently uses this same technique, network
traffic gradually polarizes onto a preferred set of resources. This is not
theoretical; it is exactly how distributed TE path placement works in
practice today. There is nothing especially complex here: local
path-selection bias, combined with independent path resizing, causes
traffic to converge onto a preferred subset of resources over time.

This does not mean that distributed TE is globally optimal in all cases,
but it does show that meaningful, practical network-wide steering effects
are already achieved without a centralized optimization loop.

I think we have reached the point where the underlying question has been
addressed repeatedly, and I will leave it there.

Regards,
-Pavan

[1]
https://www.juniper.net/documentation/us/en/software/junos/cli-reference/topics/ref/statement/label-switched-path-edit-protocols-mpls.html

On Thu, Sep 17, 2026 at 12:11 AM Aijun Wang <[email protected]>
wrote:

> Hi, Vishnu:
>
>
>
> I reviewed the document(
> https://www.juniper.net/documentation/us/en/software/junos/mpls/topics/topic-map/lsp-computation.html?utm_source=chatgpt.com#id-computing-cspf-paths-offline)
> from Juniper, and it states clearly:
>
>
>
> The Junos OS provides online, real-time CSPF computation only;* each
> router performs CSPF calculations independent of the other routers in the
> network.* These calculations are based on currently available topology
> information—information that is usually recent, but not completely
> accurate. *LSP placements are locally optimized*, based on current
> network status.
>
> *To optimize links globally across the network, you can use an offline
> tool* to perform the CSPF calculations and determine the paths for the
> LSPs. You can create such a tool yourself, or you can modify an existing
> network design tool to perform these calculations. You should run the tool
> periodically (daily or weekly) and *download the results into the router*.
> An offline tool should take the following into account when performing the
> optimized calculations:
>
> ·       *All the LSP’s requirements*
>
> ·       *All link attributes*
>
> ·       *Complete network topology*
>
>
>
> I would like to know where is the reference document for distributed
> ”network-wide polarization”?
>
>
>
> As shown by the above text, to achieve the “network-wide polarization”, we
> need “all the LSP’s requirements”, “all link attributes” and “complete
> network topology”, how each headend can get the first of these three
> information? (“all the LSP’s requirements”)?
>
>
>
> My suggestion for this document is, REMOVE the distributed power TE part,
> it is not practical.
>
>
>
> Best Regards
>
>
>
> Aijun Wang
>
> China Telecom
>
>
>
>
>
>
>
> *From:* [email protected] [mailto:teas-bounces=
> [email protected]] *On Behalf Of *Vishnu Pavan Beeram
> *Sent:* Thursday, September 17, 2026 12:28 PM
> *To:* Aijun Wang <[email protected]>
> *Cc:* [email protected]; Barth, Colby <jonathan.barth=
> [email protected]>; Robert Raszuk <[email protected]>; John Drake
> <[email protected]>; John Drake <[email protected]>;
> Tony Li <[email protected]>; WG TEAS <[email protected]>; lsr <
> [email protected]>
> *Subject:* [Teas] Re: [Lsr] 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)
>
>
>
> Aijun,
>
> I’m not sure I understand what you mean by “node-wide polarization.”
>
> In bandwidth-engineered networks where paths are automatically resized
> independently at each ingress node based on the amount of traffic being
> placed on them, traffic in the network can be made to gradually become
> polarized onto a preferred set of network resources. This is not
> theoretical; it is already a well-established operational pattern in
> distributed bandwidth-engineered networks and is supported by most vendor
> implementations that use most-fill path selection.
>
> I would encourage you to consult with operators who run such networks and
> to review vendor documentation describing most-fill path selection, in
> order to understand how distributed TE path placement becomes intentionally
> biased toward a subset of links without requiring a global synchronized
> optimization loop. In fact, this is already a common way in which
> distributed TE achieves a meaningful network-wide steering effect (maybe it
> is time we published a BCP). This is a broader topic, but it is worth
> keeping in mind as we discuss the scope of the draft.
>
> The key point is that distributed TE already has mechanisms that can
> produce a meaningful network-wide steering effect. It does so in practice
> today, and the same principles can be built on and extended to power-aware
> TE.
>
> Regards,
> -Pavan
>
>
>
> On Wed, Sep 16, 2026 at 8:59 PM Aijun Wang <[email protected]>
> wrote:
>
> Hi, Vishnu:
>
>
>
> Power-aware TE requires network-wide polarize, it is more strict than 
> “distributed
> bandwidth-engineered networks”, which is node-wide polarize.
>
>
>
> Image one simple example:
>
> Let’s assume the each headend synchronizes their necessary information,
> and the network utilization is almost same in two links.
>
> To *achieve **“network-wide” polarize effect*,  we need to assure each
> headend calculate its CSPF computation in sequence, or there will be no
> deterministic results that they will select the same sleepable link.
>
>
>
> For some more complex network, it will be more challenge to achieve such 
> *“network-wide”
> polarize effect”.*
>
>
>
> In order to close the argument, similar with the comments from Adrian, I
> think the document should provide:
>
> 1)    Either the limited scope of distributed power-aware TE can be
> applied.
>
> 2)    Or, detail algorithm that it can apply in most of the network real
> network.
>
>
>
> Given the network has enough capacity to concentric traffic.
>
>
>
>
>
> Best Regards
>
>
>
> Aijun Wang
>
> China Telecom
>
>
>
>
>
> *From:* [email protected] [mailto:lsr-bounces=
> [email protected]] *On Behalf Of *Vishnu Pavan Beeram
> *Sent:* Thursday, September 17, 2026 6:54 AM
> *To:* [email protected]
> *Cc:* Barth, Colby <[email protected]>; Aijun Wang <
> [email protected]>; Robert Raszuk <[email protected]>; John Drake
> <[email protected]>; John Drake <[email protected]>;
> Tony Li <[email protected]>; WG TEAS <[email protected]>; lsr <
> [email protected]>
> *Subject:* [Lsr] Re: [Teas] 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 Adrian,
>
> I just realized that this email had not yet received a response. Thank you
> for your thoughtful comments.
>
> Regarding applicable topologies, I believe any topology in which
> distributed TE, or distributed bandwidth engineering, is deployed today
> could also be relevant for distributed power-aware TE. As you noted,
> distributed TE may not achieve a globally optimal network-wide outcome.
> However, this has not prevented operators from deploying it successfully
> across a variety of topologies and operating conditions. Mechanisms such as
> most-fill tie-breakers are widely used to polarize traffic in distributed
> bandwidth-engineered networks. The same principle applies to power-aware TE.
>
> The draft also notes that PCPPS can be applied when CSPF is performed
> centrally or in a distributed manner. Nothing in the draft precludes a
> centralized computation function from using the PCPPS metric and associated
> power-awareness information.
>
> More generally, power-aware TE is most likely to be effective in networks
> with sufficient spare capacity and enough path diversity or mesh
> connectivity to consolidate traffic without violating bandwidth,
> redundancy, or other constraints. These conditions apply to both
> centralized and distributed computation, although centralized computation
> can typically achieve better consolidation more quickly.
>
> The intent of the draft is not to claim that distributed PCPPS provides
> global optimization. Rather, it extends the CSPF model by adding power
> awareness, allowing the computation function, whether centralized or
> distributed, to bias path placement toward appropriate resources when
> topology, traffic, and capacity permit. If consolidation cannot be achieved
> without compromising capacity, redundancy, or other constraints, the
> relevant resources should remain active.
>
> Best regards,
> Pavan
>
>
>
> On Tue, Sep 8, 2026 at 3:49 PM Adrian Farrel <[email protected]> wrote:
>
> Hello all,
>
>
>
> Colby said “TE solutions aren’t required to be globally optimal to be
> effective.”
>
> And he is right, and this is possibly one of the messages of RFC 9522.
>
>
>
> However, the perils of non-centralised systems are also well-known. As the
> network resources get more contested (i.e., as the traffic load approaches
> network capacity), distributed TE is increasingly likely to cause blocked
> contention. And, of course, it is always possible to derive degenerate
> examples where even simple networks and loads will fail in the distributed
> case, but can be solved with a centralised view. None of this is new or
> shocking.
>
>
>
> Practically, if the sizes of flows are small relative to the capacity of
> links, distributed TE works well until the links are almost full. In fact,
> when the sizes of the flows are quite a bit smaller than the unused link
> bandwidths and/or when the network is very meshy, distributed TE will be
> fine.
>
>
>
> Curiously, one of the early motivations for PCE was distributed 
> **re**-optimisation
> which tended (in the way of all things) to converge on a synchronous moment
> which increased the chances of contention.
>
>
>
> But, to cut back to this conversation, it may be helpful to describe the
> types of network where distributed power-aware TE is
> applicable/satisfactory and contrast with the types of network where
> centralisation is to be preferred.
>
>
>
> Adrian
>
>
>
> *From:* Barth, Colby <[email protected]>
> *Sent:* 08 September 2026 14:08
> *To:* Aijun Wang <[email protected]>; 'Robert Raszuk' <
> [email protected]>
> *Cc:* 'Vishnu Pavan Beeram' <[email protected]>; 'Barth, Colby'
> <[email protected]>; 'John Drake' <je_drake=
> [email protected]>; 'John Drake' <[email protected]>; 'Tony Li'
> <[email protected]>; 'WG TEAS' <[email protected]>; 'lsr' <[email protected]>
> *Subject:* [Teas] Re: [Lsr] 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,
>
>
>
> I’ll try to repeat what Robert said in a different way.  TE solutions aren
> ’t required to be globally optimal to be effective.
>
>
>
> Consider BW optimization as an example; there is no debate that a
> centralized computation may result in a more optimal state (at least on
> paper) than a fully distributed solution but a distributed solution still
> produces better BW optimization than doing nothing at all.
>
>
>
> If you are arguing that path computation MUST be centralized, that is
> incorrect.  Evidence by the very, very big networks out there operating
> successfully using distributed TE.
>
>
>
> -- Colby
>
>
>
> *From: *Aijun Wang <[email protected]>
> *Date: *Monday, September 7, 2026 at 9:28 PM
> *To: *'Robert Raszuk' <[email protected]>
> *Cc: *'Vishnu Pavan Beeram' <[email protected]>; 'Barth, Colby' <
> [email protected]>; 'John Drake' <
> [email protected]>; 'John Drake' <[email protected]>;
> 'Tony Li' <[email protected]>; 'WG TEAS' <[email protected]>; 'lsr' <
> [email protected]>
> *Subject: *[Teas] Re: [Lsr] 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, Robert:
>
>
>
> If the network are composed by some power aware links, and also some power
> unaware links, the traffic may be converged into the power unaware links,
> but such effects can be achieved only under some specific network topology.
>
> That is to say, such solution is not one generalize solution, and can’t
> get the deterministic effect.
>
>
>
> And, if the network evolved to the state that links are all power aware,
> it is impossible to find some special links, penalize them at the same time
> by every headend, and then move the traffic out of these Oracle-selected
> links.
>
>
>
> To Tony’s example of “Nash Equilibrium”, we should know “Nash Equilibrium”
> is not equal “Global Optimum”(POA=1).
>
>
>
> If you want to prove you have the mechanism to overwritten the above
> conclusion, please state clearly your mechanism, and then the necessary
> extension of the IGP protocol.
>
>
>
> Until now, we can still make the following conclusions:
>
> 1)    The proposal has no deterministic global effect, that can assure
> the traffic being centralized successfully on some limited links, in any
> arbitrary topology.
>
> 2)    The proposal can only apply to the 100% TE controlled network,
> which is rarely in real network.
>
> 3)    There is no detail mechanism description in the current document,
> or in other references documents that can achieve the power saving goal aim.
>
>
>
>
>
> Best Regards
>
>
>
> Aijun Wang
>
> China Telecom
>
>
>
> *From:* [email protected] [mailto:[email protected]
> <[email protected]>] *On Behalf Of *Robert Raszuk
> *Sent:* Monday, September 7, 2026 6:29 PM
> *To:* Aijun Wang <[email protected]>
> *Cc:* Vishnu Pavan Beeram <[email protected]>; Barth, Colby <
> [email protected]>; John Drake <
> [email protected]>; John Drake <[email protected]>;
> Tony Li <[email protected]>; WG TEAS <[email protected]>; lsr <
> [email protected]>
> *Subject:* [Lsr] Re: [Teas] 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 Ajiun,
>
>
>
> Actually if you zoom into how CSPF really works what the draft assumes
> (distributed TE computation) and shifting paths onto non power saving
> designated links is very much possible.
>
>
>
> To understand it just forget about all of the power stuff. Imagine you are
> running a vanilla TE with ISIS extensions as described in RFC5305
>
>
>
> So here you already have number of ways to discourage CSPF on all headends
> to keep using link which you would advertise using sub-TLV 18  (Traffic
> Engineering Default Metric) and apply there for example MAX_PATH_METRIC.
>
>
>
> I see no reason why this would not result in all headends running their
> independent CSFP to avoid such link. I also see no oscillation affecting
> the subject link. Of course when more then one ingress node will start
> compete for the TE bw of some non power aware link there could be
> collisions - but those are normal in TE world and most robust TE
> implementations know how to handle it.
>
>
>
> Cheers,
>
> R.
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> On Mon, Sep 7, 2026 at 2:45 AM Aijun Wang <[email protected]>
> wrote:
>
> Hi, Vishnu(and also Barth, Tony, or other experts who support such
> proposal)
>
>
>
> We are arguing that, even in 100% TE environment, “Distributed
> Power-aware TE” is impossible, if the headend routers don’t exchange
> their path calculation results.
>
>
>
> Let’s make the analogy as “the WG document adoption call”-----each expert
> make the judgement based on his/her own knowledge. Even we exchange
> intensely our thoughts on the mail list, there are difficulties to make the
> consensus---how can you expect each headend can coordinate with each other,
> or, without coordinating with each other, to make the same decision, to put
> out of their own traffic out of one specific link?
>
>
>
> Some detail replies for your arguments are inline below.
>
>
>
>
>
> Best Regards
>
>
>
> Aijun Wang
>
> China Telecom
>
>
>
>
>
> *From:* [email protected] [mailto:[email protected]]
> *On Behalf Of *Vishnu Pavan Beeram
> *Sent:* Saturday, September 5, 2026 4:48 AM
> *To:* Robert Raszuk <[email protected]>
> *Cc:* Barth, Colby <[email protected]>; John Drake
> <[email protected]>; John Drake <[email protected]>;
> Aijun Wang <[email protected]>; Tony Li <[email protected]>;
> WG TEAS <[email protected]>; lsr <[email protected]>
> *Subject:* [Lsr] Re: [Teas] 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)
>
>
>
> {as a WG participant}
>
>
>
> The key issue here is not whether global centralized coordination is
> valuable — clearly it is — but whether it is the only viable way to
> achieve meaningful network-wide efficiency. The argument in favor of
> distributed TE is that it can still steer traffic in a globally useful
> direction without the operational cost and complexity of a centralized
> optimization loop.
>
> [WAJ] Each headend make the decisions themselves,  How can you get the 
> “globally
> useful direction”? please explain this conclusion in detail.
>
>
> I doubt there would be any dispute with the argument that global
> centralized coordination offers the best way to maximize network-wide
> efficiency. However, it is not the only viable model, and it is not always
> the operationally preferred one.
>
> In practice, many deployments already rely on the “most-fill” local path
> selection tie-breaker to bias TE path computation toward a preferred subset
> of links, and this knob is available across major vendor implementations.
> When such a tie-breaker is incorporated into a network-wide distributed TE
> profile, the resulting path placement, computed independently by different
> ingress nodes, is not arbitrary; it becomes intentionally polarized onto a
> narrower set of links. Over time, as tunnel bandwidth is resized and
> re-optimized, this polarization naturally converges toward the most
> efficient set of links, while leaving other links unused.
>
> [WAJ] “Such polarized effect” is your aim, but you don’t describe how to
> achieve it. This is key argument points. Would you elaborate it in more
> detail?
>
> The mechanism proposed in draft-many-teas-power-steering is conceptually
> no different. By carrying power-group information in the TED, distributed
> TE path computation gains the same kind of local biasing capability:
> ingress nodes can optimally place paths by taking power-group information
> into account, thereby consolidating traffic and increasing the number of
> links that may be eligible for power-sleep. In other words, the goal is not
> to compete with global coordination, but to make distributed TE path
> placement more effective overall without requiring a controller-based
> optimization loop for every case.
>
> [WAJ] If the aim can’t be achieved, we will not evaluate whether it is
> efficient or not.
>
>
> The key point is that path selection can be made “network-aware” — and
> this is where the IGP extensions come into play — even without full
> centralized coordination. The effect may be more gradual than a
> controller-based optimization, but it is still a real and effective
> mechanism for driving traffic onto a preferred subset of links and creating
> power-sleep opportunities in a scalable manner.
>
> [WAJ] Path selection can be made “network-aware”, but can’t achieve the “
> network-wide” effect.  Because each headend determine the “network-aware” path
> itself.
>
> It will make the traffic oscillation, not concentrated.
>
>
>
> Regards,
>
> -Pavan
>
>
>
> On Fri, Sep 4, 2026 at 12:13 PM Robert Raszuk <[email protected]> wrote:
>
> 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
>
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