MPLS Working Group T. Li Internet-Draft Juniper Networks Intended status: Informational J. Drake Expires: 1 March 2025 28 August 2024 MPLS Network Action for Entropy draft-li-mpls-mna-entropy-03 Abstract Load balancing is a powerful tool for engineering traffic across a network and has been successfully used in MPLS as described in RFC 6790, "The Use of Entropy Labels in MPLS Forwarding". With the emergence of MPLS Network Actions (MNA), there is signficant benefit in being able to invoke the same load balancing capabilities within the more general MNA infrastructure. This document describes a network action for entropy to be used in conjunction with "MPLS Network Action (MNA) Sub-Stack Solution". Status of This Memo 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/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on 1 March 2025. Copyright Notice Copyright (c) 2024 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 Li & Drake Expires 1 March 2025 [Page 1] Internet-Draft MNA Entropy August 2024 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. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Requirement Language . . . . . . . . . . . . . . . . . . 3 2. The Entropy Action . . . . . . . . . . . . . . . . . . . . . 3 3. Security Considerations . . . . . . . . . . . . . . . . . . . 4 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 5. References . . . . . . . . . . . . . . . . . . . . . . . . . 4 5.1. Normative References . . . . . . . . . . . . . . . . . . 4 5.2. Informative References . . . . . . . . . . . . . . . . . 5 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5 1. Introduction Load balancing is a powerful tool for engineering traffic across a network. The use of entropy labels within MPLS was first described in [RFC6790] and [RFC6391] and has been deployed succesfully in multiple MPLS networks. With the emergence of MPLS Network Actions [I-D.ietf-mpls-mna-requirements] [I-D.ietf-mpls-mna-fwk] [I-D.ietf-mpls-mna-hdr], there is a benefit to being able to describe entropy as a network action. Without this, a packet that required load balancing and network actions would need to deal with the overhead of having both MNA and an Entropy Label in the label stack. By defining an action for Entropy within the MNA infrastructure, overhead and complexity can be reduced. It is RECOMMENDED that MNA and the Entropy Label not be used in the same packet, but if they are, the Entropy Label and Entropy Value do not need to be the same as consistency for the flow suffices. Given that [RFC6790] is widely deployed, it is expected that that will continue to be a common mechanism for encoding an Entropy Label. This document adds an alternative encoding that may be more efficient if other MNA actions are in use. The two encodings can co-exist in the same network. Li & Drake Expires 1 March 2025 [Page 2] Internet-Draft MNA Entropy August 2024 1.1. Requirement 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. These words may also appear in this document in lower case as plain English words, absent their normative meanings. 2. The Entropy Action This section describes the details of how the Entropy Action is encoded, per Section 5 of [I-D.ietf-mpls-mna-fwk]. * Name: Entropy Action * Network Action Indication: The Entropy Action is opcode TBA1. * Scope: The Entropy Action is valid in Hop-by-Hop (HBH) and Select scopes and SHOULD be processed as discussed below. The Entropy Action is not valid in I2E scope and SHOULD be ignored if found in I2E scope. * In-Stack Data: The Entropy Action carries 20 bits of ancillary data, known as the Entropy Value. * Processing: The semantics of the Entropy Value are identical to the semantics of the Entropy Label as found in [RFC6790], [RFC8012], and [RFC8662], except that the Entropy Value is not found in the Label field of the Label Stack Entry (LSE). While the RFC 6790 Entropy Label has some restrictions to avoid collisions with the reserved label space (0-15) [RFC3032], those restrictions are not necessary for the Entropy Value and do not apply. A forwarding node SHOULD incorporate the Entropy Value into its forwarding decision when the Entropy Action is evaluated. Not using the Entropy Value may result in unintended forwarding consequences, possibly resulting in unnecessary congestion and packet loss. * LSE Format: C. There is no additional data. The Network Action Length (NAL) field MUST be sent as zero. The U bit in the Format C LSE may be set at the discretion of the implementation and network operator. If there are no further actions to be included in the Network Action Sub-Stack (NAS), then the Entropy Action must follow an opcode 2 (NOP) Format B LSE. * Interactions: None Li & Drake Expires 1 March 2025 [Page 3] Internet-Draft MNA Entropy August 2024 3. Security Considerations The forwarding plane is insecure. If an adversary can affect the forwarding plane, then they can inject data, remove data, corrupt data, or modify data. MNA additionally allows an adversary to make packets perform arbitrary network actions. Link-level security mechanisms can help mitigate some on-link attacks, but does nothing to preclude hostile nodes. 4. IANA Considerations This document requests that IANA allocate a codepoint (TBA1) from the "Multiprotocol Label Switching Architecture (MPLS)"/"MPLS Network Actions Parameters"/"Network Action Opcodes Registry" registry for the Entropy Action. The allocation should reference this document. 5. References 5.1. Normative References [I-D.ietf-mpls-mna-fwk] Andersson, L., Bryant, S., Bocci, M., and T. Li, "MPLS Network Actions (MNA) Framework", Work in Progress, Internet-Draft, draft-ietf-mpls-mna-fwk-10, 6 August 2024, . [I-D.ietf-mpls-mna-hdr] Rajamanickam, J., Gandhi, R., Zigler, R., Song, H., and K. Kompella, "MPLS Network Action (MNA) Sub-Stack Solution", Work in Progress, Internet-Draft, draft-ietf-mpls-mna-hdr- 07, 17 June 2024, . [I-D.ietf-mpls-mna-requirements] Bocci, M., Bryant, S., and J. Drake, "Requirements for Solutions that Support MPLS Network Actions (MNA)", Work in Progress, Internet-Draft, draft-ietf-mpls-mna- requirements-16, 30 May 2024, . [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . Li & Drake Expires 1 March 2025 [Page 4] Internet-Draft MNA Entropy August 2024 [RFC3032] Rosen, E., Tappan, D., Fedorkow, G., Rekhter, Y., Farinacci, D., Li, T., and A. Conta, "MPLS Label Stack Encoding", RFC 3032, DOI 10.17487/RFC3032, January 2001, . [RFC6790] Kompella, K., Drake, J., Amante, S., Henderickx, W., and L. Yong, "The Use of Entropy Labels in MPLS Forwarding", RFC 6790, DOI 10.17487/RFC6790, November 2012, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . 5.2. Informative References [RFC6391] Bryant, S., Ed., Filsfils, C., Drafz, U., Kompella, V., Regan, J., and S. Amante, "Flow-Aware Transport of Pseudowires over an MPLS Packet Switched Network", RFC 6391, DOI 10.17487/RFC6391, November 2011, . [RFC8012] Akiya, N., Swallow, G., Pignataro, C., Malis, A., and S. Aldrin, "Label Switched Path (LSP) and Pseudowire (PW) Ping/Trace over MPLS Networks Using Entropy Labels (ELs)", RFC 8012, DOI 10.17487/RFC8012, November 2016, . [RFC8662] Kini, S., Kompella, K., Sivabalan, S., Litkowski, S., Shakir, R., and J. Tantsura, "Entropy Label for Source Packet Routing in Networking (SPRING) Tunnels", RFC 8662, DOI 10.17487/RFC8662, December 2019, . Authors' Addresses Tony Li Juniper Networks Email: tony.li@tony.li John Drake Email: je_drake@yahoo.com Li & Drake Expires 1 March 2025 [Page 5]