Network Working Group X. Geng Internet-Draft M. Chen Intended status: Experimental Huawei Expires: September 10, 2020 March 09, 2020 SRH Extension for Redundancy Protection draft-geng-spring-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 replicaiton, 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 September 10, 2020. Copyright Notice Copyright (c) 2020 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 Geng & Chen Expires September 10, 2020 [Page 1] Internet-Draft Abbreviated-Title March 2020 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 Requirement Analysis . . . . . . . . . 3 4. SRH Extensions for Redundancy Protection . . . . . . . . . . 3 4.1. Option 1: seperated TLVs for flow identification and sequence number . . . . . . . . . . . . . . . . . . . . . 4 4.2. Option 2 unified TLV for flow identification and sequence number . . . . . . . . . . . . . . . . . . . . . . . . . 4 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 6. Security Considerations . . . . . . . . . . . . . . . . . . . 5 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5 8. Normative References . . . . . . . . . . . . . . . . . . . . 5 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 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 replicaiton, 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 redudancy protection, which is a network device that could implement packet replication. Merging Node: the end point of redudancy protection, which is a network node that could implement packet elimination and ordering(optionally). 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]. Geng & Chen Expires September 10, 2020 [Page 2] Internet-Draft Abbreviated-Title March 2020 3. Redundancy Protection Requirement Analysis The figure shows how to provide redundancy protection over SRv6. | | ----IPv6--->|<---------------SRv6 Domain------------->|<----IPv6--- | | | +------+T2+----+ | +---+ +---+ +-+-+ +-+-+ +---+ +---+ | E1+----| In|--+T1+--+Red| |Mer|--+T4+--| Eg+----+ E2| +---+ +---+ +-+-+ +-+-+ +---+ +---+ +-----+T3+-----+ 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 header+SR of the 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 Rep(Redundancy Node); 2) Tow 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 the current draft[I-D.ietf-6man-segment-routing-header] 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 Extensions for Redundancy Protection Flow Identification and Sequence Number could be defined in SRH optional TLV. Geng & Chen Expires September 10, 2020 [Page 3] Internet-Draft Abbreviated-Title March 2020 4.1. Option 1: seperated TLVs for flow identification and sequence number 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | RESERVED | Flow Identification | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ where: o Type: 8bits, to be assigned by IONA. o Length: 8 octets. o RESERVED: 28 bits, MUST be 0 on transmission and ignored on receipt. o Flow Identification: 20 bits, which is used for identifying redundant protection flow. 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |RESERVED| Sequence Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ where: o Type: 8 bits, to be assigned by IONA. o Length: 8. o RESERVED: 20 bits. MUST be 0 on transmission and ignored on receipt. o Sequence Number: 28 bits, which is used for indicating sequence number of the redundant protection flow. 4.2. Option 2 unified TLV for flow identification and sequence number Geng & Chen Expires September 10, 2020 [Page 4] Internet-Draft Abbreviated-Title March 2020 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 | Flow Identification | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | Sequence Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | RESERVED | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ where: o Type: 8bits, to be assigned by IANA. o Length: 8 octets. o Flow Identification: 20 bits, which is used for identifying the redundant protection flow. o Sequence Number: 28 bits, which is used for indicating sequence number of the redundant protection flow. o Reserved: 32 bits. MUST be 0 on transmission and ignored on receipt. 5. IANA Considerations TBD 6. Security Considerations TBD 7. Acknowledgements Thank you for valuable comments from James Guichard and Andrew Mail 8. Normative References [I-D.ietf-6man-segment-routing-header] Filsfils, C., Dukes, D., Previdi, S., Leddy, J., Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header (SRH)", draft-ietf-6man-segment-routing-header-26 (work in progress), October 2019. Geng & Chen Expires September 10, 2020 [Page 5] Internet-Draft Abbreviated-Title March 2020 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC8655] Finn, N., Thubert, P., Varga, B., and J. Farkas, "Deterministic Networking Architecture", RFC 8655, DOI 10.17487/RFC8655, October 2019, . Authors' Addresses Xuesong Geng Huawei Email: gengxuesong@huawei.com Mach(Guoyi) Chen Huawei Email: mach.chen@huawei.com Geng & Chen Expires September 10, 2020 [Page 6]