MPLS Working Group J. Dong Internet-Draft T. Zhou Intended status: Standards Track Huawei Technologies Expires: 25 January 2023 24 July 2022 Encapsulation of MPLS Network Actions and associated Data draft-dong-mpls-mna-encaps-00 Abstract This document specifies a solution for carrying MPLS network actions and the associated data either in the MPLS label stack or after the MPLS label stack. 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 25 January 2023. Copyright Notice Copyright (c) 2022 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. Dong & Zhou Expires 25 January 2023 [Page 1] Internet-Draft MNA Solution July 2022 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 2 2. Design Principles . . . . . . . . . . . . . . . . . . . . . . 3 3. MNA Indicator . . . . . . . . . . . . . . . . . . . . . . . . 3 4. In-stack Network Actions without Data . . . . . . . . . . . . 4 5. In-stack Network Actions Identifier . . . . . . . . . . . . . 5 6. Post-stack Network Actions with Data . . . . . . . . . . . . 6 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 8. Security Considerations . . . . . . . . . . . . . . . . . . . 6 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 10.1. Normative References . . . . . . . . . . . . . . . . . . 6 10.2. Informative References . . . . . . . . . . . . . . . . . 7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7 1. Introduction The use cases and requirements to carry additional network instructions and the associated data in data packets in MPLS networks, i.e., MPLS Network Actions (MNA), are described in [I-D.ietf-mpls-mna-usecases] and [I-D.ietf-mpls-mna-requirements] respectively. [I-D.andersson-mpls-mna-fwk] introduces a framework of MNA, in which the In-stack Data (ISD) and Post-Stack Data (PSD) are considered as two possible mechanisms to carry the MPLS network actions and the optional data associated with the actions. This document specifies a general solution for carrying MPLS network actions and the optional data associated with the network actions either in the MPLS label stack or after the MPLS label stack. The specification of specific type of network action and the associated data is out of the scope of this document. 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. Dong & Zhou Expires 25 January 2023 [Page 2] Internet-Draft MNA Solution July 2022 2. Design Principles The MPLS architecture as specified in [RFC3031] provides a mechanism for forwarding packets through a network without requiring any analysis of the packet payload's network layer header by intermediate nodes (Label Switching Routers - LSRs). The encoding of MPLS label stack is specified in [RFC3032]. Section 3.1 of [I-D.ietf-mpls-mna-requirements] provides the general requirements on the MNA solution. Specifically, it is required that any solution must maintain the properties of MPLS: extensibility, flexibility and efficiency by using control plane context combined with a simple data plane mechanism to allow the network to make forwarding decisions about a packet. The proposed solution in this document aims to meet the requirements in [I-D.ietf-mpls-mna-requirements] with the following design principles: * Minimize the length of MNA information carried as ISD in the MPLS label stack. When ISD is needed, an ISD design with fixed length is RECOMMENDED. * Carry the MNA information with large and/or variable length and possibly flexible structure as PSD in the post-stack extension headers as defined in [I-D.song-mpls-extension-header]. 3. MNA Indicator The MNA Indicator is introduced to indicate the presence of any MNA information in the packet. It can be used to indicate the existence of MNA actions and the optional associated data in the ISD, or the PSD or both. Since this indicator is generic for all types of MPLS network actions, it is reasonable to allocate a basic Special Purpose MPLS label (bSPL) for it. The TC and TTL fields of the MNA Indicator are redefined as flags. The format of the MNA Indicator is shown as below: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | MNA Indicator=SPL (TBA) |H|I|P|S|ISF| RSV | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 1. The format of MNA Indicator Where: Dong & Zhou Expires 25 January 2023 [Page 3] Internet-Draft MNA Solution July 2022 * MNA Indicator label: A new bSPL, the value is TBA by IANA. * H (Hop-by-Hop processing) flag: When set, it indicates that the MNA information in the packet needs to be processed hop-by-hop. * I (In-stack MNA information) flag: When set, it indicates the next label entry is used to carry the MNA information. * P (Post-stack MNA information) flag: When set, it indicates there is post-stack data following the MPLS label stack. * S: Bottom of Stack. The value of the S bit depends on the position of the MNA indicator in the label stack. * ISF (In-stack data Format): The first 2-bit of the original TTL field. When the I bit is set, the ISF field is used to indicate the format of the in-stack MNA information in the following label stack.The following ISF values are defined in this document. - ISF = 00: There is no in-stack MNA information. When the I flag is 0, the value of the ISF field MUST be set to 0 on transmit and MUST be ignored on receipt. - ISF = 01: The following label stack entry is used to carry a list of network actions without any associated data. - ISF = 10: The following label stack entry is used to carry a domain significant label value which could be used by the network nodes to determine the set of network actions based on local policy. - ISF = 11: Reserved. It could be used to indicate other format of the in-stack MNA information. * RSV: The rest 6 bits in the original TTL field are reserved for future use. They MUST be set to 0 on transmit and MUST be ignored on receipt. 4. In-stack Network Actions without Data When the I flag in the MNA Indicator is set, and the ISF field is set to 01, the MPLS label stack entry which follows the MNA indicator is encoded as a list of flags of network actions which do not require any associated action data to be carried in the packet. The format of the In-stack network actions without data is shown as below: Dong & Zhou Expires 25 January 2023 [Page 4] Internet-Draft MNA Solution July 2022 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | In-stack action flags w/o data | TC |S| TTL | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 2. The format of In-stack action flags without Data Where: * Label field: The 20-bit label field is used to encode the in-stack network actions which do not require any associated data. * TC field: The value of the TC field SHOULD be set to zero. It be may be redefined for future use. * TTL field: The value of TTL field SHOULD be set to 0. This is to ensure that it is not used inadvertently for forwarding. It may be redefined for future use. 5. In-stack Network Actions Identifier When the I flag in the MNA Indicator is set, and the ISF field is set to 10, the MPLS label stack entry which follows the MNA indicator is encoded as a domain significant label value which could be used by the network nodes to determine the set of network actions to be performed based on local policy. This label serves as an implicit identifier of the in-stack network actions. The encoding and functionality is the same as the Reference Forwarding Value (RFV) as defined in[I-D.raszuk-mpls-raf-fwk]. The format of in-stack network actions identifier is shown as below: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | RFV | TC |S| TTL=0 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 3. The format of In-stack Network Actions Identifier Where: * RFV (Referenced Forwarding Value), this is defined in [I-D.raszuk-mpls-raf-fwk]. * TC: The value of the TC field SHOULD be set to zero. It be may be redefined for future use. * S: Bottom of Stack. Dong & Zhou Expires 25 January 2023 [Page 5] Internet-Draft MNA Solution July 2022 * TTL: The value of the TTL field SHOULD be set to 0. It may be redefined for future use. 6. Post-stack Network Actions with Data When the P flag in the MNA Indicator is set, it indicates there is post-stack data (PSD) carried after the MPLS label stack. The encoding of post-stack network actions and the optional associated data is based on the MPLS post-stack extension headers as defined in [I-D.song-mpls-extension-header]. 7. IANA Considerations IANA is requested to allocate a new value for the MNA Indicator label from the "Base Special-Purpose MPLS Label Values" registry. IANA is requested to create a new registry for the bit positions of the In-stack network action flags without data. 8. Security Considerations TBD 9. Acknowledgements The authors would like to thank XXX for the review and discussion. 10. References 10.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol Label Switching Architecture", DOI 10.17487/RFC3031, RFC 3031, January 2001, . [RFC3032] Rosen, E., Tappan, D., Fedorkow, G., Rekhter, Y., Farinacci, D., Li, T., and A. Conta, "MPLS Label Stack Encoding", DOI 10.17487/RFC3032, RFC 3032, January 2001, . Dong & Zhou Expires 25 January 2023 [Page 6] Internet-Draft MNA Solution July 2022 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . 10.2. Informative References [I-D.andersson-mpls-mna-fwk] Andersson, L., Bryant, S., Bocci, M., and T. Li, "MPLS Network Actions Framework", Work in Progress, Internet- Draft, draft-andersson-mpls-mna-fwk-04, 27 June 2022, . [I-D.ietf-mpls-mna-requirements] Bocci, M., Bryant, S., and J. Drake, "Requirements for MPLS Network Action Indicators and MPLS Ancillary Data", Work in Progress, Internet-Draft, draft-ietf-mpls-mna- requirements-01, 21 June 2022, . [I-D.ietf-mpls-mna-usecases] Saad, T., Makhijani, K., Song, H., and G. Mirsky, "Use Cases for MPLS Network Action Indicators and MPLS Ancillary Data", Work in Progress, Internet-Draft, draft- ietf-mpls-mna-usecases-00, 19 May 2022, . [I-D.raszuk-mpls-raf-fwk] Raszuk, R., "Framework of MPLS Reference Augmented Forwarding", Work in Progress, Internet-Draft, draft- raszuk-mpls-raf-fwk-00, 25 April 2022, . [I-D.song-mpls-extension-header] Song, H., Li, Z., Zhou, T., Andersson, L., Zhang, Z., Gandhi, R., Rajamanickam, J., and J. Bhattacharya, "MPLS Post-Stack Extension Header", Work in Progress, Internet- Draft, draft-song-mpls-extension-header-07, July 2022, . Authors' Addresses Dong & Zhou Expires 25 January 2023 [Page 7] Internet-Draft MNA Solution July 2022 Jie Dong Huawei Technologies Beijing China Email: jie.dong@huawei.com Tianran Zhou Huawei Technologies Beijing China Email: zhoutianran@huawei.com Dong & Zhou Expires 25 January 2023 [Page 8]