IPv6 Maintenance Working Group X. Geng Internet-Draft M. Chen Intended status: Standards Track F. Yang Expires: August 24, 2021 Huawei Technologies February 20, 2021 SRH Extension for Redundancy Protection draft-geng-6man-redundancy-protection-srh-00 Abstract Redundancy protection is a method of service protection by sending copies of the same packets of one flow over multiple paths, which includes packet replication, elimination and ordering. This document defines SRv6 header (SRH) extensions to support redundancy protection. Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in . 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 August 24, 2021. Copyright Notice Copyright (c) 2021 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 Geng, et al. Expires August 24, 2021 [Page 1] Internet-Draft draft-geng-6man-redundancy-protection-srh February 2021 (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 Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Terminology and Conventions . . . . . . . . . . . . . . . . . 2 3. Redundancy Protection over SRv6 Scenario . . . . . . . . . . 3 4. SRH Extension for Redundancy Protection . . . . . . . . . . . 3 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 6. Security Considerations . . . . . . . . . . . . . . . . . . . 4 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4 8. Normative References . . . . . . . . . . . . . . . . . . . . 4 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5 1. Introduction Redundancy protection is a method of providing 1+1 protection by sending copies of the same packets of one flow over multiple paths, which includes packet replication, elimination and ordering. This document defines SRv6 header (SRH) extensions to support redundancy protection. 2. Terminology and Conventions The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. Redundancy Node: the start point of redundancy protection, which is a network device that could implement packet replication. Merging Node: the end point of redundancy protection, which is a network node that could implement packet elimination and ordering (optionally). Flow Identification: information in SR data service to indicate one flow. Sequence Number: information in SR data service to indicate the packet sequence of one flow. Geng, et al. Expires August 24, 2021 [Page 2] Internet-Draft draft-geng-6man-redundancy-protection-srh February 2021 Editor's Note: Similar mechanism is defined as "Service Protection" in the [RFC8655]. In this document, we define a new term "Redundancy Protection" to distinguish with other service protection method. Some of the terms are the similar as [RFC8655]. 3. Redundancy Protection over SRv6 Scenario The figure shows how to provide redundancy protection over SRv6. | | ----IPv6--->|<---------------SRv6 Domain------------>|<----IPv6--- | | | +------+R1+----+ | +---+ +---+ +-+-+ +-+-+ +---+ +---+ |E1 +----+In +-------+Red| |Mer+--------+Eg +----+E2 | +---+ +---+ +-+-+ +-+-+ +---+ +---+ +------+R2+----+ As the figure shows, an IPv6 flow is sent out from the end station E1. The packet of the flow is encapsulated in an outer IPv6+SRH header in the Ingress(In) and transported through an SRv6 domain. In the Egress(Eg), the outer IPv6+SRH header of packet is popped, and the packet is sent to the destination E2. The process of redundancy protection is as follows: 1) The flow is replicated in Red (Redundancy Node); 2) Two replicated flows go through different paths till Mer (Merging Node); When there is any failures happened in one the path, the service continues to deliver through the other path without break; 3) The first received packet of the flow is transmitted from Mer (Merging Node) to Eg(Egress), and the redundant packets are eliminated; 4) Sometimes, the packet will arrive out of order because of redundancy protection, the function of reordering may be necessary in the Merging Node. This document defines Flow Identification and Sequence Number in Segment Routing Header(SRH) as an extension of [RFC8754] to support redundancy protection. Flow Identification is used to distinguish flows, and Sequence Number is used to distinguish packets in the same flow when doing packet merging and ordering. 4. SRH Extension for Redundancy Protection Flow Identification and Sequence Number could be defined in SRH optional TLV. Geng, et al. Expires August 24, 2021 [Page 3] Internet-Draft draft-geng-6man-redundancy-protection-srh February 2021 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | RESERVED | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Flow Identification | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Sequence Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ where: o Type: 8 bits, indicates the use of redundancy protection, to be assigned by IANA. o Length: 8 bits. o Reserved: 16 bits. MUST be 0 on transmission and ignored on receipt. o Flow Identification: 32 bits, which is used for identifying the redundant protection flow. o Sequence Number: 32 bits, which is used for indicating sequence number of the redundant protection flow. 5. IANA Considerations This document requires registration of a specific type of TLV used for redundancy protection in "Segment Routing Header TLVs" registry. 6. Security Considerations TBD 7. Acknowledgements Thanks for the valuable comments from James Guichard and Andrew Malis. 8. 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, . Geng, et al. Expires August 24, 2021 [Page 4] Internet-Draft draft-geng-6man-redundancy-protection-srh February 2021 [RFC8655] Finn, N., Thubert, P., Varga, B., and J. Farkas, "Deterministic Networking Architecture", RFC 8655, DOI 10.17487/RFC8655, October 2019, . [RFC8754] Filsfils, C., Ed., Dukes, D., Ed., Previdi, S., Leddy, J., Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header (SRH)", RFC 8754, DOI 10.17487/RFC8754, March 2020, . Authors' Addresses Xuesong Geng Huawei Technologies Beijing China Email: gengxuesong@huawei.com Mach(Guoyi) Chen Huawei Technologies Beijing China Email: mach.chen@huawei.com Fan Yang Huawei Technologies Beijing China Email: shirley.yangfan@huawei.com Geng, et al. Expires August 24, 2021 [Page 5]