Aijun, GenChen, Benoit, JinMing
Each of you have expressed concern regarding a distributed approach to the
Power Conserving Path Placement Strategy (PCPPS). The following is a response.
A Power Conservation Strategy includes many components. First among them is the
Path Placement Component. The Path Placement Component concentrates traffic
onto relatively few network resources during periods of low demand and
redistributes traffic during periods of high demand. It *does not* power
interfaces up and down. Its only function is path computation. When it computes
paths, it optimizes for energy efficiency, leaving some network resources idle
or nearly idle.
Another component is the Sleep Management Component. The Sleep Management
Component is configured with criteria that must be satisfied before a network
resource is powered down. It monitors network resources and powers them down
when they satisfy the configured criteria. It also powers them up again when
the power up criteria are satisfied.
The Power Placement Component and Sleep Management Component are decoupled from
one another. In the simplest case, one could run a Path Placement Component
without a Sleep Management Component. (Although I can't imagine why). One could
also run a Sleep Management Component without a Path Placement Component. In
some networks, and for some power down criteria, this makes sense.
In a more complex case, the Sleep Management component may require information
from the Path Placement component to determine if an interface satisfies the
power-up/power-down criteria. For example, the Sleep Management algorithm may
prevent interfaces that support LSPs from being powered down.
Draft-many-teas-power-steering and draft-many-lsr-power-groups describe the
Path Placement Component. They *do not* describe the Sleep Management function.
This is beyond their scope.
Many of your comments address the Sleep Management function. For example:
*
You will not find an instruction to power an interface up or down in either of
the current drafts
*
The problem of oscillation due to frequent power-up/power-down events is beyond
the scope of the current documents, because they do not power network resources
up or down.
Finally, regarding the question of distributed versus centralized
implementation.....
Path Placement Strategies rely on CSPF and the CSPF relies on the LSDB/TED.
Each node must maintain an identical LSDB copy.
In the past, we have populated the LSDB/TED in a distributed manner, using an
IGP, or in a centralized manner, using a PCE and BGP-LS. Both approaches work.
Some customers prefer one while other customers prefer the other. The Power
Conserving Path Placement Strategy is no different from legacy path placement
strategies. There is no reason why it should be limited to one approach or the
other.
Ron
________________________________
From: Aijun Wang <[email protected]>
Sent: Tuesday, August 25, 2026 11:09 PM
To: 'Bonica, Ron' <[email protected]>; 'Christian Hopps'
<[email protected]>; [email protected] <[email protected]>
Cc: [email protected] <[email protected]>; [email protected]
<[email protected]>; [email protected]
<[email protected]>
Subject: RE: [Lsr] Re: WG adoption call for draft-many-lsr-power-group-03 (Ends
2026-08-30)
Hi, Ron:
Since the TEAS WG has yet start the adoption call of
draft-many-teas-power-group.(They are preparing for it now/IPR call), I would
still suggest that we wait the conclusion of adoption call of the base document.
And I think you have noticed, there is argument for the necessary of the
distributed solution, given it can’t finish the overall power save aim
itself(need information or control capabilities from the management plane), and
overlap with the capabilities of management plane.
Until now, I don’t see the promise of the distributed solution, only the
confusion of these newly introduced capricious TLVs and their usages.
Or, would you like to introduce the necessary, indispensable or even the
benefits of the distributed solution?
Some detail replies inline below.
Best Regards
Aijun Wang
China Telecom
From: [email protected] [mailto:[email protected]] On
Behalf Of Bonica, Ron
Sent: Wednesday, August 26, 2026 8:07 AM
To: Aijun Wang <[email protected]>; 'Christian Hopps'
<[email protected]>; [email protected]
Cc: [email protected]; [email protected]; [email protected]
Subject: [Lsr] Re: WG adoption call for draft-many-lsr-power-group-03 (Ends
2026-08-30)
Hi Ajun,
Thanks for the review. Response inline See [rb]
Ron
________________________________
From: Aijun Wang <[email protected]<mailto:[email protected]>>
Sent: Monday, August 24, 2026 10:23 PM
To: 'Christian Hopps' <[email protected]<mailto:[email protected]>>;
[email protected]<mailto:[email protected]> <[email protected]<mailto:[email protected]>>
Cc: [email protected]<mailto:[email protected]>
<[email protected]<mailto:[email protected]>>;
[email protected]<mailto:[email protected]>
<[email protected]<mailto:[email protected]>>;
[email protected]<mailto:[email protected]>
<[email protected]<mailto:[email protected]>>
Subject: RE: [Lsr] Re: WG adoption call for draft-many-lsr-power-group-03 (Ends
2026-08-30)
【Correct one typo: 】
I do not support its adoption.
-----Original Message-----
From: [email protected]<mailto:[email protected]>
[mailto:[email protected]] On Behalf Of Aijun Wang
Sent: Tuesday, August 25, 2026 10:19 AM
To: 'Christian Hopps' <[email protected]<mailto:[email protected]>>;
[email protected]<mailto:[email protected]>
Cc: [email protected]<mailto:[email protected]>;
[email protected]<mailto:[email protected]>;
[email protected]<mailto:[email protected]>
Subject: [Lsr] Re: WG adoption call for draft-many-lsr-power-group-03 (Ends
2026-08-30)
Hi, All:
I do not support is adoption.
The reason are the followings:
1) The base document,
https://urldefense.com/v3/__https://datatracker.ietf.org/doc/draft-many-teas-power-steering/__;!!NpxR!iPWTa_HdgTs4cfKq-wRonK1P2gTSQHdnS6G14eA4oW_y_OIb6VUvnFZwy4DJlK0_xuExEoZ2KnHSBwyHIjSsao3c$<https://urldefense.com/v3/__https:/datatracker.ietf.org/doc/draft-many-teas-power-steering/__;!!NpxR!iPWTa_HdgTs4cfKq-wRonK1P2gTSQHdnS6G14eA4oW_y_OIb6VUvnFZwy4DJlK0_xuExEoZ2KnHSBwyHIjSsao3c$>
, has not been adopted as the TEAS WG document, it is too early to determine
whether the IGP protocol extension is necessary or not.
[rb] I think that Gunther addressed this issue. In any event, the TEAS WG is
currently having a call for adoption on draft-many-teas-power-group.
[WAJ] Let’s wait the conclusion of the adoption call of the base document, then
the necessary of this distributed solution.
2) There is no any description, or argument to describe the reason that
accomplish the power saving via the distributed IGP protocol and the challenge
for the network operation etc. when comparing with the solution solely via the
management plane(NETCONT/YANG etc.)
[rb] The current drafts describe a distributed Power Conserving Path Placement
Solution. They do not preclude a centralized solution. Because we do not
preclude a centralized solution, we don't feel the need to argue against one.
[WAJ] I don’t see the benefits, or the indispensable necessary of such
distributed solution.
3) Considering the mentioned interfaces can only be switched on/off via the
management, I am wondering why bother IGP to accomplish the path calculation
work then?
[rb] Are you sure that interfaces can only be switched on/off via a network
management interface? Is it possible that the platform might offer an API
through which an interface can be switched on/off? Might that API be made
available to multiple network management applications (e.g., CLI, NETCONF)?
Might that API also be made available to a local application that monitors
interface utilization and powers interface on/off as needed?
[WAJ] These are all possible, but currently there are no on/off signal
communicated via the IGP protocol, then it must depend on other ways to
accomplish the power save aim. Or, will you add some mechanism in your
proposal later?
Are you sure that the IGP does the path calculation work? According to
draft-many-teas-power-steering, CSPF does the path calculation work. It uses
the PCPPS metric to do so. It uses the TLVs described in
draft-many-lsr-power-group to calculate the PCPPS metric.
[WAJ] If the flooding of these TLVs is not let IGP does the path calculation
work, then the necessary of such flooding became more unnecessary:
The PCE know the services requirements, the PCE can collect the network
conditions, the PCE can calculate the necessary topology/bandwidth/interfaces
on/off, then why let the IGP do extraordinary work?
4) Given the discussions for the encoding of proposed TLVs, and the authors'
responses for the updating them later, which are all non-trivial modifications,
it's better to postpone to its adoption.
[rb] This is a procedural issue, to be addressed by the chairs. Typically, at
the end of a call for adoption, authors are given a chance to produce a new
version of the draft that addresses issues raided during the call for adoption.
[WAJ] The core contents of this LSR draft are the definition of these TLVs, If
they have not been solid, what’s the value, and legitimacy of the adoption call?
5) The document defines only some TLVs and there is no any procedures to
describe how to utilize them, how to coordinate with other existing
TLVs/sub-TLVs/Flooding mechanism etc., it will be difficult for other vendors
to implement and will influence future interoperability.
[rb] Which TLVs are missing? As per draft-many-teas-power-steering, these TLVs
are used as inputs to the PCPPS metric calculation. Which interactions are
missing? Should the addition of any TLV or sub-TLV change the flooding
mechanism?
[WAJ] In the base document, it mentioned there may be centralized, or
distributed.
If PCPPS is centralized, as I mentioned above, there is no necessary for the
IGP to participate in
If PCPPS is distributed, the procedure for consuming such newly defined TLVs
should be described.
Ron
Best Regards
Aijun Wang
China Telecom
-----Original Message-----
From: [email protected]<mailto:[email protected]>
[mailto:[email protected]] On Behalf Of Christian Hopps via
Datatracker
Sent: Monday, August 17, 2026 8:57 AM
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://urldefense.com/v3/__https://datatracker.ietf.org/doc/draft-many-lsr-power-group/__;!!NpxR!iPWTa_HdgTs4cfKq-wRonK1P2gTSQHdnS6G14eA4oW_y_OIb6VUvnFZwy4DJlK0_xuExEoZ2KnHSBwyHIv92BtCB$<https://urldefense.com/v3/__https:/datatracker.ietf.org/doc/draft-many-lsr-power-group/__;!!NpxR!iPWTa_HdgTs4cfKq-wRonK1P2gTSQHdnS6G14eA4oW_y_OIb6VUvnFZwy4DJlK0_xuExEoZ2KnHSBwyHIv92BtCB$>
Please indicate your support or objections by August 30th, 2026.
An IPR declaration has been made
https://urldefense.com/v3/__https://datatracker.ietf.org/ipr/search/?submit=draft&id=draft-many-lsr-power-group__;!!NpxR!iPWTa_HdgTs4cfKq-wRonK1P2gTSQHdnS6G14eA4oW_y_OIb6VUvnFZwy4DJlK0_xuExEoZ2KnHSBwyHIpbPHXJm$<https://urldefense.com/v3/__https:/datatracker.ietf.org/ipr/search/?submit=draft&id=draft-many-lsr-power-group__;!!NpxR!iPWTa_HdgTs4cfKq-wRonK1P2gTSQHdnS6G14eA4oW_y_OIb6VUvnFZwy4DJlK0_xuExEoZ2KnHSBwyHIpbPHXJm$>
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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