]> 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 This document defines how DetNet data fields are encapsulated as part of the Segment Routing with IPv6 data plane (SRv6) header [RFC8754].

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. has proposed the overall framework of DetNet enhancements for large-scale deterministic 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 Action (DLA) 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

DLA:

Deterministic Latency Action

DetNet Data Fields Encapsulation in SRH The DetNet data fields such as DLA 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 Action 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. The SRH segment list extensions for DetNet DLA Option is as follows.

SRH Segment List Extensions for DLA Option

D (Deterministic Flag) : when it is set, indicates the SRH extension for DLA Option Data. DLA Q-Type (8bits): as defined by the DLA Option Header field, and is defined in Section 4.2.1.2 of . DLA Option Data List (variable): as defined by the DLA Option Data field, and is defined in Section 4.2.2 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 DLA Option is as follows.

SRH TLV Extensions for DLA 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: DetNet-Length (8 bits): indicates the DetNet option length. DetNet-Type (8 bits): indicates the DetNet option type. DLA Type (16 bits): as defined by the Option Type field, and is defined in Section 4.1 of . Data Len (8 bits): unsigned integer. This field specifies the length of DLA option data added by each node. Ancillary Len (8 bits): unsigned integer. This field specifies the length of DLA ancillary data added by each node. DLA Data List(variable): as defined by the Data field including option data and ancillary data, and is defined in Section 4.2 of . The DLA Option Data can be carried one time or in list.

SRH DetNet Segment Extensions The DetNet data field can be carried in SRH segment called DetNet Segment when a particular option data is processed within each node. The mapping from DLA data of current node to DLA data of next node SHOULD be provided in the control plane. It SHOULD swap and encapsulate the DetNet Segment at each forwarding node. The SRH segment extensions for DetNet DLA Option is as follows.

SRH DetNet Segment Extensions for DLA Option

D (Deterministic Flag) : when it is set, indicates the SRH extension for DLA Option Data. The SRv6 DetNet Segment format is as follows.

DetNet Segment Format for DLA Option

The definition of the value can be referred as .

Security Considerations TBA

IANA Considerations TBA

Acknowledgements TBA

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. 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. ZTE Corporation China Mobile CAICT Beijing Jiaotong University From charter and milestones, the enhanced Deterministic Networking (DetNet) is required to provide the enhancement of flow identification and packet treatment for data plane to achieve the DetNet QoS in large-scale networks. This document analyzes the gaps of the existing technologies especially applying the DetNet data plane as per RFC8938 and proposes the enhancement of packet treatment to support the functions and metadata for enhanced DetNet data plane. It describes related enhanced controller plane considerations as well. This document discusses the specific metadata which should be carried in Enhanced Data plane (EDP), proposes the DetNet data fields and option types for EDP such as Deterministic Latency Action Option. DetNet Data-Fields for EDP can be encapsulated into a variety of protocols such as MPLS, IPv6 and SRv6 networks.