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]] 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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