Joel –

There are multiple examples in the comments I have made that – if agreed to – 
would result in non-backwards compatible changes.
In addition, there are areas which have only been mentioned in passing (e.g., 
extending to support SR and/or multicast and/or other non-TE traffic) in the WG 
discussion that might result in changes to how things are advertised.

I do not have to come up with a definition of how to address these unexplored 
areas in order to be concerned.

   Les

From: Joel Halpern <[email protected]>
Sent: Wednesday, August 19, 2026 10:51 AM
To: Les Ginsberg (ginsberg) <[email protected]>; Christian Hopps 
<[email protected]>; [email protected]
Cc: [email protected]; [email protected]; [email protected]
Subject: Re: [Lsr] Re: WG adoption call for draft-many-lsr-power-group-03 (Ends 
2026-08-30)


Les, I am trying to understand your primary concern.  Can you give an example 
of what you would like this TLV to be able to handle so others can evaluate 
whether there is indeed a shortfall?  Preferably with some indication of what 
sort of information would be needed to handle the case?

Yours,

Joel
On 8/19/2026 1:43 PM, Les Ginsberg (ginsberg) wrote:

Regarding WG adoption...



This draft is certainly relevant to the WG.

But the current definition addresses the needs of only one type of traffic - TE 
unicast traffic (as has been pointed out by others). I think the solution has 
the potential to be applicable to other types of traffic. But the current TLV 
definitions are so TE focused that extending the solution to other scenarios 
would be likely to require non-backwards compatible changes.  WG adoption makes 
it more likely that early implementations will be deployed - as reinforced by 
the authors' publicly stated intent to "ship this version".  Which means that 
introduction of non-backwards compatible changes as work continues will meet 
resistance (for practical reasons).

If the draft were in a more mature state, the risks would be less.



Which is why I would prefer that the document remain an individual contribution 
until it becomes more encompassing.



Putting that aside, here are some comments on the current content of the 
document.



Section 3.1

Defines a new Power Group TLV.

As defined it allows for only a single power group to be defined/TLV - not the 
most efficient encoding. Also, given that Power Groups can be defined in a 
hierarchy (see draft-many-teas-power-steering) it suggests that the Power Group 
TLV could define a (sub)tree of the power group hierarchy. Whether this change 
is made or not, there are potential ambiguities:



  o the same child power group might be advertised referencing multiple parents

  o a child group might be advertised referencing a non-existent parent



Handling of these cases is not discussed.



Section 3.2

Defines a new Sleeping Adjacencies TLV



The very cryptic definition suggests that it is simply a wrapper which contains 
potentially multiple (previously) non-sleeping adjacencies. Which raises 
multiple questions/concerns.



Is the format of the contained "TLVs" simply a copy of the TLV as it was 
previously advertised when it was non-sleeping?

If so, how can the MP flag be defined as "N" (as it is in the IANA section)?



The encoding, if it is indeed just a copy of the non-sleeping state, results in 
considerable unnecessary duplication e.g., the link endpoints are independent 
of the MTID.

While it is understandable that it may be desirable/necessary for some link 
attributes to be advertised in the sleeping state, there are a number of link 
attributes for which advertisement while in the sleeping state is unnecessary.

For example, advertisements of dynamic performance measurements (Unidirectional 
Link Delay, Min/Max Unidirectional Link Delay, Unidirectional Delay Variation, 
Unidirectional Link Loss) have no real meaning in the powered off state.



There is also no discussion as to how the identity of the neighbor on a 
sleeping link remains valid across events such as reloads - when post reload 
the neighbor link might still be in a sleeping state and so not discoverable.



Presumably Sleeping Adjacency TLVs are ignored when a matching non-sleeping 
adjacency is also advertised?? There is no discussion of this.



Section 3.3

Defines a Power Group Member sub-TLV - and allows multiple such TLVs to account 
for LAGs. But in the absence of information identifying which LAG member is 
associated with which power group, it seems difficult to use this at Layer 3 
interface level in other than an all or nothing manner - which suggests a 
single sub-TLV with a list of Power Group Identifiers is more appropriate.



Power Group Identifiers advertised in TLV 25 (L2 bundle members) naturally 
associate the bundle member with the Power Group. Which suggests that the Power 
Group advertised at Layer 3 would be the parent of all the Layer 2 member power 
groups - and that would be expressed in the Power Group TLV (Section 3.1).



Section 3.3.3

Defines a new Unidirectional Sleeping Bandwidth sub-TLV.

I would assume that this sub-TLV should be ignored if sent in a non-sleeping 
Neighbor TLV advertisement?? (Text does not say)

Which is related to the earlier discussion about the Sleeping Adjacencies TLV 
as to what link attribute information is actually required when advertising a 
sleeping adjacency.



And given that a link cannot be "partially asleep", why wouldn't the bandwidth 
sub-TLVs defined in RFC 8570 which indicate how much bandwidth is utilized be 
sufficient to indicate "sleeping bandwith" when advertised in a sleeping 
adjacency TLV.



References

The reference section is missing many needed entries.



   Les



>-----Original Message-----

>From: Christian Hopps via Datatracker 
><[email protected]><mailto:[email protected]>

>Sent: Sunday, August 16, 2026 5:57 PM

>To: [email protected]<mailto:[email protected]>

>Cc: [email protected]<mailto:[email protected]>; 
>[email protected]<mailto:[email protected]>; 
>[email protected]<mailto:[email protected]>

>Subject: [Lsr] WG adoption call for draft-many-lsr-power-group-03 (Ends

>2026-08-30)

>

>Hi Folks,

>

>This begins a 2 week WG Adoption Call for the following draft:

>

>  https://datatracker.ietf.org/doc/draft-many-lsr-power-group/

>

>Please indicate your support or objections by August 30th, 2026.

>

>An IPR declaration has been made

>

>  
> https://datatracker.ietf.org/ipr/search/?submit=draft&id=draft-many-lsr-<https://datatracker.ietf.org/ipr/search/?submit=draft&id=draft-many-lsr-power-group>

>power-group<https://datatracker.ietf.org/ipr/search/?submit=draft&id=draft-many-lsr-power-group>

>

>Authors, please respond to the list indicating whether you are aware of any

>other IPR that applies to this draft.

>

>Thanks,

>Chris.

>

>[Call for adoption end date (2026-08-30)]

>

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