| Internet-Draft | IS-IS PG | June 2026 |
| Barth, et al. | Expires 24 December 2026 | [Page] |
Many networks have a daily utilization pattern. For example, a network might be busy during the day and less busy at night.¶
If the network is robust, it has enough capacity to satisfy demand during peak hours and excess capacity during non-peak hours. That excess capacity increases energy costs and environmental impact.¶
[I-D.many-teas-power-steering] introduces a Power Conserving Path Placement Strategy (PCPPS). When possible, PCPPS concentrates traffic onto a small set of network resources. When traffic is concentrated onto a small set of network resources, other network resources become idle and can be powered down until they are needed again. This solves the problem of excess capacity during non-peak hours.¶
PCPPS uses information that is distributed by an IGP. This document specifies the IS-IS encoding for that information.¶
This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.¶
Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at https://datatracker.ietf.org/drafts/current/.¶
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This Internet-Draft will expire on 24 December 2026.¶
Copyright (c) 2026 IETF Trust and the persons identified as the document authors. All rights reserved.¶
This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License.¶
Many networks have a daily utilization pattern. For example, a network might be busy during the day and less busy at night.¶
If the network is robust, it has enough capacity to satisfy demand during peak hours and excess capacity during non-peak hours. That excess capacity increases energy costs and environmental impact.¶
[I-D.many-teas-power-steering] introduces a Power Conserving Path Placement Strategy (PCPPS). When possible, PCPPS concentrates traffic onto a small set of network resources. When traffic is concentrated onto a small set of network resources, other network resources become idle and can be powered down until they are needed again. This solves the problem of excess capacity during non-peak hours.¶
PCPPS uses information that is distributed by an IGP. This document specifies the IS-IS encoding for that information.¶
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 BCP14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.¶
The following terms are used as defined in [I-D.many-teas-power-steering]:¶
The Power Group TLV is a top level TLV. If a Power Group is sleep-capable, it is advertised by IS-IS and appears in the LSDB. Otherwise, it is not advertised by IS-IS and it does not appear in the LSDB.¶
Where:¶
Type: 1 octet, value TBD1¶
Length: 1 octet, unsigned integer. Value 12.¶
Power Group Identifier: 4 octets, selector. MUST NOT be equal to 0.¶
PSP: 4 octets, unsigned integer. The Power Group's PSP, in milliwatts.¶
Parent Identifier: 4 octets, selector.¶
The Power Group Identifier has node-local significance. If the Parent Identifier is equal to 0, the Power Group has no parent (i.e., it is the root of a Power Group hierarchy). Otherwise, the Parent Identifier MUST NOT be set to 0.¶
The Sleeping Adjacencies TLV is a top level TLV. An adjacency is sleeping if it satisfies the following criteria:¶
It has been UP in the past¶
It is not currently UP¶
All of the interfaces that supports it are ASLEEP.¶
The Sleeping Adjacencies TLV can include TLVs 22, 23, 141, 222 and 223.¶
Where:¶
This sub-TLV is found in TLVs for advertising neighbor information.¶
This sub-TLV advertises a Power Group to which the interface belongs. Because a LAG interface can belong to many Power Groups, many instances of this sub-TLV may be advertised.¶
Where:¶
This sub-TLV is found in TLVs for advertising neighbor information.¶
This sub-TLV advertises an interface's PSP.¶
Where:¶
This sub-TLV is found in TLVs for advertising neighbor information.¶
This sub-TLV advertises the sleeping bandwidth. The sleeping bandwidth advertised by this sub-TLV MUST be the sleeping bandwidth from the system originating the Link State Advertisement (LSA) to its neighbor.¶
Where:¶
Type: 1 octet, value TBD5¶
Length: 1 octet, unsigned integer. Value 4.¶
Sleeping Bandwidth: 4 octets, IEEE floating-point format measured in bytes per second.¶
The Sleeping bandwidth field carries the sleeping bandwidth on a link, forwarding adjacency [RFC4206], or bundled link. For a link or forwarding adjacency, sleeping bandwidth is defined as the maximum bandwidth [RFC5305] minus the bandwidth currently allocated to RSVP-TE label switched paths that was transitioned to power-sleep. For a bundled link, sleeping bandwidth is defined to be the sum of the component link sleeping bandwidths.¶
This is a bit in the Link Attribute Sub-TLV (19). Presence of this bit indicates that the link may be put into power-sleep mode. The position of this bit is TBD5.¶
IANA is requested to add the following entries to the IS-IS Top-Level TLV Codepoints registry (https://www.iana.org/assignments/isis-tlv-codepoints/isis-tlv-codepoints.xhtml#tlv-codepoints):¶
| Value | Name | IIH | LSP | SNP | Purge | MP | Status Reference |
|---|---|---|---|---|---|---|---|
| TBD1 | Power Group | N | Y | N | N | N | This document |
| TBD2 | Sleeping Adjacencies | N | Y | N | N | N | This document |
IANA is also requested to add the following entries to the IS-IS Sub-TLVs for TLVs Advertising Neighbor Information registry (https://www.iana.org/assignments/isis-tlv-codepoints/isis-tlv-codepoints.xhtml#isis-tlv-codepoints-advertising-neighbor-information):¶
| Type | Description | 22 | 23 | 25 | 141 | 222 | 223 | MP | Reference |
|---|---|---|---|---|---|---|---|---|---|
| TBD3 | Power Group Member | Y | Y | Y(s) | Y | Y | Y | N | This document |
| TBD4 | Interface PSP | Y | Y | Y(s) | Y | Y | Y | N | This document |
| TBD5 | Unidirectional Sleeping Bandwith | Y | Y | Y(s) | Y | Y | Y | N | This document |
IANA is also requested to add the following entry to the IS-IS Neighbor Link-Attribute Bit Values registry (https://www.iana.org/assignments/isis-tlv-codepoints/isis-tlv-codepoints.xhtml#isis-tlv-codepoints-19of22):¶
| Value | Name | L2BM | Reference |
|---|---|---|---|
| TBD5 | Power-Sleep Capable | N | This document |
Thanks to Les Ginsberg for his review and comments.¶