Network Working Group Y. Liu
Internet Draft China Mobile
Intended status: Standards Track C. Lin
Expires: November 08, 2025 New H3C Technologies
May 06, 2025
SR Policy Extensions for energy efficiency
draft-liu-idr-sr-policy-energy-efficiency-00
Abstract
[draft-liu-spring-sr-energy-efficiency-00] describes the types of
energy consumption information, how to collect energy consumption
information, and the framework for path selection based on energy
consumption information.
This document details the extensions to the BGP SR Policy and BGP-LS
SR Policy to encapsulate the energy consumption information for each
segment list of the SR Policy candidate paths, enabling its
utilization in the route selection process.
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This Internet-Draft will expire on November 08, 2025.
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Table of Contents
1. Introduction...................................................2
1.1. Requirements Language.....................................3
2. BGP SR Policy extension........................................4
3. BGP-LS SR Policy extension.....................................5
4. Metric process of SR Policy segment list.......................6
5. Security Considerations........................................8
6. IANA Considerations............................................8
6.1. BGP Energy Consumption Metric Type........................8
6.2. BGP-LS Energy Consumption Metric Type.....................9
7. References....................................................10
7.1. Normative References.....................................10
7.2. Informational References.................................11
Authors' Addresses...............................................11
1. Introduction
The importance of energy efficiency in modern networks is
increasingly evident. In addition to reducing the power consumption
of devices, network technologies can be leveraged to redirect
traffic towards energy-efficient devices and paths, effectively
lowering the energy consumption of network communications.
[draft-liu-spring-sr-energy-efficiency-00] describes how energy-
consumption information is utilized in SR networks. It elaborates on
the use of energy consumption information for path computation in SR
networks.
The metrics for energy consumption include:
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Maximum Energy Consumption: The power consumption at full load,
measured in watts.
Real-Time Energy Consumption: The real-time power consumption,
measured in watts.
Maximum Unit Energy Consumption: The power consumption at full load
divided by traffic, measured in watts per gigabyte (W/GB).
Real-Time Unit Energy Consumption: The real-time power consumption
divided by real-time traffic, measured in watts per gigabyte (W/GB).
Average Unit Energy Consumption: The change in power consumption
over a measurement period divided by the change in traffic, measured
in watts per gigabyte (W/GB).
In scenarios utilizing SR Policy, after the SR Policy is installed
on the ingress node, packets can be steered into the SR Policy
through route selection. When multiple routes to the same
destination exist, the route selection node may choose a route based
on local policies, which could incorporate the energy consumption
information of the selected path. Therefore, it is necessary to
carry the energy consumption information for each segment list of
the SR Policy candidate paths to facilitate route selection.
Within a domain, SR Policy routing information is disseminated using
BGP UPDATE messages. When collecting SR Policy information using a
controller, BGP-LS messages are typically employed, allowing devices
to convey SR Policy information to the controller. When the
controller distributes SR Policy to the ingress node, the PCEP
protocol is generally used.
This document details the extensions to the BGP SR Policy and BGP-LS
SR Policy to encapsulate the energy consumption information for each
segment list of the SR Policy candidate paths, enabling its
utilization in the route selection process.
1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
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2. BGP SR Policy extension
[draft-ietf-idr-sr-policy-safi] defines how to convey SR Policy
information via BGP<SR Policy SAFI NLRI>.
[draft-ietf-idr-sr-policy-metric-02] introduces a new Metric sub-TLV
to carry Metric information for SR Policy candidate paths, which can
include values for multiple Metric Types. We define energy
consumption information as one of the Metric Types and assign it
several energy-related Metric Type identifiers.
The SR Policy Encoding structure is as follows:
SR Policy SAFI NLRI: <Distinguisher, Policy-Color, Endpoint>
Attributes:
Tunnel Encaps Attribute (23)
Tunnel Type: SR Policy
Binding SID
Preference
Priority
Policy Name
Policy Candidate Path Name
Explicit NULL Label Policy (ENLP)
Segment List
Weight
Metric
Segment
Segment
....
....
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Where metric represents the measurement of the segment list and can
include various types of metrics. This document introduces a new
metric type to carry energy consumption-related measurement
information.
Metric Type for Energy Consumption:
Type1: Maximum Energy Consumption
Type2: Real-Time Energy Consumption
Type3: Maximum Unit Energy Consumption
Type4: Real-Time Unit Energy Consumption
Type5: Average Unit Energy Consumption
3. BGP-LS SR Policy extension
[draft-ietf-idr-bgp-ls-sr-policy-10] describes how to carry SR
Policy information via BGP-LS. The SR Segment List Metric sub-TLV
reports the computed metric of the specific SID-List. The Metric
Type can support various types of metrics, and by including energy
consumption-related metrics, it enables the use of the SR Segment
List Metric sub-TLV to advertise the energy consumption metric of
the Segment List. Note that the metric types here refer to BGP-LS SR
Policy Metric Types, not "IGP Metric."
+-------+--------------------+---------------------------------+
| Code | | |
| Point | Metric Type | Reference |
+-------+--------------------+---------------------------------+
| 0 | IGP | [RFC5305] Section 3 |
| 1 | Min Unidirectional | [RFC8570] Section 4.2 |
| | Delay | |
| 2 | TE | [RFC5305] Section 3.7 |
| 3 | Hop Count | [RFC5440] Section 7.8 |
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| 4 | SID List Length | [RFC8664] Section 4.5 |
| 5 | Bandwidth | [I-D.ietf-lsr-flex-algo-bw-con] |
| 6 | Avg Unidirectional | [RFC8570] Section 4.1 |
| | Delay | |
| 7 | Unidirectional | [RFC8570] Section 4.3 |
| | Delay Variation | |
| 8 | Loss | [RFC8570] Section 4.4 |
|TBD6 | Maximum Energy Consumption(This Document)|
|TBD7 | Real-Time Energy Consumption(This Document)|
|TBD8 | Maximum Unit Energy Consumption(This Document)|
|TBD9 | Real-Time Unit Energy Consumption(This Document)|
|TBD10 | Average Unit Energy Consumption(This Document)|
|128-255| User Defined [I-D.ietf-lsr-flex-algo-bw-con] |
[draft-ietf-idr-bgp-ls-sr-policy] The SR Candidate Path Constraints
TLV is an optional TLV used to report constraints associated with a
candidate path. By including the SR Metric Constraint Sub-TLV, it
can specify metric constraints for the candidate path. By defining
the metric type as energy consumption-related metrics, it enables
the use of energy consumption metrics as constraints for the
candidate path. Note that the metric types here also refer to BGP-LS
SR Policy Metric Types.
4. Metric process of SR Policy segment list
[draft-ietf-idr-sr-policy-metric-02] describes how to handle various
metrics of SR Policy Segment Lists (Seglists). When the local policy
specifies the use of energy consumption-related metrics, these
metrics are utilized for Seglist selection during path
determination.
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When the SR Policy headend node obtains the SR Policy segment list
with the metric field, the metric can be of any defined type (e.g.,
IGP metric, minimum unidirectional link delay, TE metric, hop count,
SID list length, maximum energy consumption per unit, real-time
energy consumption per unit, etc.).
The rules for processing SR Policy metrics are as follows:
The type of metric to be used is determined by the local policy,
which can be configured by the user. For example, the user may
specify the real-time energy consumption per unit as the local
policy.
The metric of the active candidate path is used as the metric of the
SR Policy.
The metric of the active candidate path is determined by the maximum
value of the specified metric type across all segment lists.
Example:
SR Policy: (Headend:1::1, Color: 2, EndPoint: 2::2)
Candidate path preference: 200
Segment list 1: (IGP metric: 20, Link delay: 10, TE metric: 10,
Maximum Unit Energy Consumption: 20, Real-Time Unit Energy
Consumption, 10)
Segment list 2: (IGP metric: 30, Link delay: 20, TE metric: 15,
Maximum Unit Energy Consumption: 40, Real-Time Unit Energy
Consumption, 30)
Candidate Path preference: 100
Segment list 1: (IGP metric: 40, Link delay: 20, TE metric: 20,
Maximum Unit Energy Consumption: 20, Real-Time Unit Energy
Consumption, 10)
Segment list 2: (IGP metric: 30, Link delay: 10, TE metric: 15,
Maximum Unit Energy Consumption: 40, Real-Time Unit Energy
Consumption, 30)
Local policy: Real-Time Unit Energy Consumption
Active candidate path: preference 200
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Active candidate path metric: 10, which is the Real-Time Unit
Energy Consumption of all segment lists in the candidate path.
5. Security Considerations
Procedures and protocol extensions defined in this document do not
affect the BGP security model. See the "Security Considerations"
section of [RFC4271] for a discussion of BGP security.
Security considerations for acquiring and distributing BGP-LS
information are discussed in [RFC7752].
6. IANA Considerations
6.1. BGP Energy Consumption Metric Type
New metric types are requested from "Metric Type" under the "BGP
Tunnel Encapsulation".
+------------+------------------------------------------+
| Code Point | Metric Type |
+------------+------------------------------------------+
| 0 | IGP Metric |
| 1 | Min Unidirectional Link Delay [RFC7471] |
| 2 | TE Metric [RFC3630] |
| 3 | Hop Count (refer [RFC5440]) |
| 4 | SID List Length |
| 5 | Loss Rate |
| TBD1 | Maximum Energy Consumption(This Document)|
| TBD2 | Real-Time Energy Consumption(This Document)|
| TBD3 | Maximum Unit Energy Consumption(This Document)|
| TBD4 | Real-Time Unit Energy Consumption(This Document)|
| TBD5 | Average Unit Energy Consumption(This Document)|
| 251-255 | Private Use (not to be assigned by IANA) |
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+------------+------------------------------------------+
Figure 1: BGP Metric Type Code Point
6.2. BGP-LS Energy Consumption Metric Type
New metric types are requested from "BGP-LS Metric Type".
+-------+--------------------+---------------------------------+
| Code | | |
| Point | Metric Type | Reference |
+-------+--------------------+---------------------------------+
| 0 | IGP | [RFC5305] Section 3 |
| 1 | Min Unidirectional | [RFC8570] Section 4.2 |
| | Delay | |
| 2 | TE | [RFC5305] Section 3.7 |
| 3 | Hop Count | [RFC5440] Section 7.8 |
| 4 | SID List Length | [RFC8664] Section 4.5 |
| 5 | Bandwidth | [I-D.ietf-lsr-flex-algo-bw-con] |
| 6 | Avg Unidirectional | [RFC8570] Section 4.1 |
| | Delay | |
| 7 | Unidirectional | [RFC8570] Section 4.3 |
| | Delay Variation | |
| 8 | Loss | [RFC8570] Section 4.4 |
|TBD6 | Maximum Energy Consumption(This Document)|
|TBD7 | Real-Time Energy Consumption(This Document)|
|TBD8 | Maximum Unit Energy Consumption(This Document)|
|TBD9 | Real-Time Unit Energy Consumption(This Document)|
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|TBD10 | Average Unit Energy Consumption(This Document)|
|128-255| User Defined | [I-D.ietf-lsr-flex-algo-bw-con] |
Figure 2: BGP-LS Metric Type Code Point
7. References
7.1. Normative References
[draft-liu-spring-sr-energy-consumption-00] lin, New H3C
Technologies, "Computing Energy Consumption Path in
Segment Routing Networks", draft-liu-spring-sr-energy-
consumption-00, DOI 10.17487/draft-lin-spring-sr-for-
green-metric-00, Febauary 2025, <https://www.rfc-
editor.org/info/DOI 10.17487/draft-liu-spring-sr-energy-
consumption-00>.
[I-D.ietf-idr-sr-policy-safi]Previdi, S., Filsfils, C., Talaulikar,
K., Mattes, P., and D. Jain, "Advertising Segment Routing
Policies in BGP", Work in Progress, Internet-Draft, draft-
ietf-idr-sr-policy-safi-13, 6 February 2025,
<https://datatracker.ietf.org/doc/html/draft-ietf-idr-sr-
policy-safi-13>.
[I-D.ietf-idr-bgp-ls-sr-policy] Previdi, S., Talaulikar, K., Dong,
J., Gredler, H., and J. Tantsura, "Advertisement of
Segment Routing Policies using BGP Link-State", Work in
Progress, Internet-Draft, draft-ietf-idr-bgp-ls-sr-policy-
10, 9 December 2024,
<https://datatracker.ietf.org/doc/html/draft-ietf-idr-bgp-
ls-sr-policy-10>.
[I-D.draft-ietf-idr-sr-policy-metric-02] K. Zhang, J. Dong, Huawei,
K. Talaulikar, Cisco Systems, "BGP SR Policy Extensions
for metric", Work in Progress, Internet-Draft, draft-ietf-
idr-sr-policy-metric-02, December 2024,
<https://datatracker.ietf.org/doc/html/draft-ietf-idr-sr-
policy-metric-02>.
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7.2. Informational References
TBD
Authors' Addresses
Yisong Liu
China Mobile
China
Email: liuyisong@chinamobile.com
Changwang Lin
New H3C Technologies
China
Email: linchangwang.04414@h3c.com
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