]> ZTE Corporation

No.6 Huashi Park Rd Wuhan Hubei 430223 China xiong.quan@zte.com.cn

ZTE Corporation

Nanjing Jiangsu China wu.haisheng@zte.com.cn

Beijing Jiaotong University

Beijing China dyang@bjtu.edu.cn

Routing DETNET The DetNet data fields such as the Deterministic Latency Option can be used in enhanced Deterministic Networking (DetNet) to provide QoS treatment to achieve deterministic latency. This document defines how DetNet data fields are encapsulated as part of the Segment Routing with IPv6 data plane (SRv6) header.

Introduction According to , Deterministic Networking (DetNet) operates at the IP layer and delivers service which provides extremely low data loss rates and bounded latency within a network domain. DetNet data planes has been specified in . has described the enhancement requirements for DetNet enhanced data plane in large-scale networks. The packet treatment should schedule the resources and indicate the behaviour to ensure the deterministic latency. Moreover, new functions and related metadata should be supported in DetNet enhanced data plane. has proposed a common DetNet data fields and option types for enhanced DetNet data plane and defined a Deterministic Latency Option to carry queuing-based metadata. This document defines how DetNet data fields are encapsulated as part of the Segment Routing with IPv6 data plane (SRv6) header .

Conventions used in this document

Terminology The terminology is defined as , and .

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 when, and only when, they appear in all capitals, as shown here. Abbreviations and definitions used in this document:

EDP:

Enhanced Data plane

SRH:

Segment Routing Header

SRv6:

Segment Routing for IPv6 forwarding plane

DL:

Deterministic Latency

DetNet Data Fields Encapsulation in SRH The DetNet data fields such as deterministic latency option are defined in , and can be used for ensuring deterministic latency in enhanced DetNet data plane. The SRv6 encapsulation header (SRH) is defined in and DetNet data fields can be encapsulated in the SRH. The DetNet data fields can be divided into option header and data. And it can be carried in SRH extensions including the options such as SRH header field, segment List, TLV and the last segment. This enables the DetNet enhanced functions to build on the network programmability capability of SRv6. The following sections discuss the optional SRH extensions for enhanced DetNet data plane in encapsulating the Deterministic Latency Option.

SRH Segment List Extensions The DetNet data field can be carried in SRH segment list. This enables the ability of SRv6 networks to forward a DetNet flow per segment list. This document defines a new SRv6 Endpoint behavior which can be used to indicate the Deterministic Forwarding (DF) function, called End.DF. The End.DF is a variant of the End.X behavior defined in . The End.DF SID SHOULD support the SRH processing of Penultimate Segment Pop (PSP), Ultimate Segment Pop (USP), and Ultimate Segment Decapsulation (USD) flavors as defined in . The End.DF SIDs can be allocated by a centralized network controller and advertized by IGP or BGP-LS. The SRH segment list extensions for Deterministic Latency Option is as follows.

SRH Segment List Extensions for Deterministic Latency Option

D (Deterministic Flag): when it is set, indicates the SRH extension for Deterministic Latency Option Data. DL (Deterministic Latency) Type (8bits): as defined by the Deterministic Latency Option Header field, and is defined in Section 6.1 of . Deterministic Latency Option Data List (variable): as defined by the Deterministic Latency Option data field, and is defined in Section 6.2 of .

SRH TLV Extensions The DetNet data field can be carried in SRH TLV. This enables the ability for an SRv6 node to determine whether to process or ignore some specific SRH TLVs is based on the SID function. The nodes which support the enhanced DetNet functionality can process the SRH TLV and the others can ignore the SRH DetNet TLV. The SRH TLV for DetNet Deterministic Latency Option is as follows.

SRH TLV Extensions for Deterministic Latency Option

SRH-TLV-Type/SRH-TLV-Length (8 bits): DetNet TLV Type for SRH is defined as TBA1. Length of the SRH TLV in 4-octet units. The fields related to the encapsulation of DetNet data fields in the SRH are defined as follows: DL Type (8 bits): as defined by the Option Type field, and is defined in Section 6.1 of . Data Len (8 bits): unsigned integer. This field specifies the length of option data added by each node. Deterministic Latency Data List(variable): as defined by the Deterministic Latency Option data field, and is defined in Section 6.2 of . The Option Data can be carried one time or in list.

Security Considerations As this document describes new options for IPv6, it can apply the security considerations of . Security considerations for DetNet are covered in the DetNet Architecture and DetNet data plane , , and DetNet security considerations . The security considerations specified in are also applicable to the procedures defined in this document.

IANA Considerations TBA

Acknowledgements The authors would like to thank Rakesh Gandhi, Aihua Liu, Peng Liu, Bin Tan and Shaofu Peng for their review, suggestions and comments to this document.

Normative References In many standards track documents several words are used to signify the requirements in the specification. These words are often capitalized. This document defines these words as they should be interpreted in IETF documents. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements. RFC 2119 specifies common key words that may be used in protocol specifications. This document aims to reduce the ambiguity by clarifying that only UPPERCASE usage of the key words have the defined special meanings. This document provides the overall architecture for Deterministic Networking (DetNet), which provides a capability to carry specified unicast or multicast data flows for real-time applications with extremely low data loss rates and bounded latency within a network domain. Techniques used include 1) reserving data-plane resources for individual (or aggregated) DetNet flows in some or all of the intermediate nodes along the path of the flow, 2) providing explicit routes for DetNet flows that do not immediately change with the network topology, and 3) distributing data from DetNet flow packets over time and/or space to ensure delivery of each packet's data in spite of the loss of a path. DetNet operates at the IP layer and delivers service over lower-layer technologies such as MPLS and Time- Sensitive Networking (TSN) as defined by IEEE 802.1. This document provides an overall framework for the Deterministic Networking (DetNet) data plane. It covers concepts and considerations that are generally common to any DetNet data plane specification. It describes related Controller Plane considerations as well. Segment Routing can be applied to the IPv6 data plane using a new type of Routing Extension Header called the Segment Routing Header (SRH). This document describes the SRH and how it is used by nodes that are Segment Routing (SR) capable. This document presents a timing model for sources, destinations, and Deterministic Networking (DetNet) transit nodes. Using the model, it provides a methodology to compute end-to-end latency and backlog bounds for various queuing methods. The methodology can be used by the management and control planes and by resource reservation algorithms to provide bounded latency and zero congestion loss for the DetNet service. A DetNet (deterministic network) provides specific performance guarantees to its data flows, such as extremely low data loss rates and bounded latency (including bounded latency variation, i.e., "jitter"). As a result, securing a DetNet requires that in addition to the best practice security measures taken for any mission-critical network, additional security measures may be needed to secure the intended operation of these novel service properties. This document addresses DetNet-specific security considerations from the perspectives of both the DetNet system-level designer and component designer. System considerations include a taxonomy of relevant threats and attacks, and associations of threats versus use cases and service properties. Component-level considerations include ingress filtering and packet arrival-time violation detection. This document also addresses security considerations specific to the IP and MPLS data plane technologies, thereby complementing the Security Considerations sections of those documents. This document specifies the Deterministic Networking (DetNet) data plane operation for IP hosts and routers that provide DetNet service to IP-encapsulated data. No DetNet-specific encapsulation is defined to support IP flows; instead, the existing IP-layer and higher-layer protocol header information is used to support flow identification and DetNet service delivery. This document builds on the DetNet architecture (RFC 8655) and data plane framework (RFC 8938). This document specifies the Deterministic Networking (DetNet) data plane when operating over an MPLS Packet Switched Network. It leverages existing pseudowire (PW) encapsulations and MPLS Traffic Engineering (MPLS-TE) encapsulations and mechanisms. This document builds on the DetNet architecture and data plane framework. The Segment Routing over IPv6 (SRv6) Network Programming framework enables a network operator or an application to specify a packet processing program by encoding a sequence of instructions in the IPv6 packet header. Each instruction is implemented on one or several nodes in the network and identified by an SRv6 Segment Identifier in the packet. This document defines the SRv6 Network Programming concept and specifies the base set of SRv6 behaviors that enables the creation of interoperable overlays with underlay optimization. China Mobile Huawei Futurewei Technologies USA ZTE Corporation ETRI New H3C Technologies Huawei Aiming at scaling deterministic networks, this document describes the technical and operational requirements when the network has large variation in latency among hops, great number of flows and/or multiple domains without the same time source. Different deterministic levels of applications co-exist and are transported in such a network. This document also describes the corresponding Deterministic Networking (DetNet) data plane enhancement requirements. The DetNet-specific metadata should be carried in enhanced data plane based on the enhancement requirements. This document proposes the common DetNet data fields and option types such as Aggregation Option and Deterministic Latency Option. The common DetNet Data-Fields can be encapsulated into a variety of protocols such as MPLS, IPv6 and SRv6 networks.