SPRING Working Group W. Jiang Internet Draft China Mobile Intended status: Standards Track C. Lin Expires: December 20, 2024 New H3C Technologies R. Chen ZTE Corporation June 21, 2024 Segment Routing Policy Extension for NRP draft-jiang-spring-sr-policy-nrp-01 Abstract Network Resource Partition (NRP), which is a subset of the resources and associated policies in the underlay network. In networks with multiple NRPs, an SR Policy can be associated with a particular NRP. This document describes how the SR Policy extension for associated NRP and the operational mechanisms function together. 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 December 20, 2024. Copyright Notice Copyright (c) 2024 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 (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents Jiang, et al. Expire December 20, 2024 [Page 1] Internet-Draft Segment Routing Policy Extension for NRP June 2024 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...................................................3 1.1. Requirements Language.....................................3 2. Solution.......................................................4 3. SR Policy Extension for NRP....................................5 3.1. NRP ID of a Candidate Path................................5 3.2. Candidate Path Validity Verification......................6 3.3. Summary...................................................7 4. Steering into an SR Policy with NRP............................8 5. Manageability Considerations...................................8 6. Security Considerations........................................8 7. IANA Considerations............................................8 8. References.....................................................8 8.1. Normative References......................................8 8.2. Informative References....................................9 Acknowledgements.................................................10 Authors' Addresses...............................................11 Jiang, et al. Expires December 20, 2024 [Page 2] Internet-Draft Segment Routing Policy Extension for NRP June 2024 1. Introduction A Segment Routing Policy (SR Policy) [RFC9256] is an ordered list of segments (i.e., instructions) that represent a source-routed policy. The headend node is said to steer a flow into an SR Policy. The packets steered into an SR Policy have an ordered list of segments associated with that SR Policy written into them. [RFC8660] describes the representation and processing of this ordered list of segments as an MPLS label stack for SR-MPLS, while [RFC8754] and [RFC8986] describe the same for Segment Routing over IPv6 (SRv6) with the use of the Segment Routing Header (SRH). [RFC9543] provides the definition of IETF network slice for use within the IETF and discusses the general framework for requesting and operating IETF Network Slices, their characteristics, and the necessary system components and interfaces.It also introduces the concept Network Resource Partition (NRP), which is a subset of the resources and associated policies in the underlay network. As described in [I-D.ietf-teas-nrp-scalability], one scalable data plane approach to support network slicing is to carry a dedicated NRP ID in the data packet to identify the NRP the packet belongs to, so that the packet can be processed and forwarded using the subset of network resources allocated to the NRP. In networks with multiple NRPs, an SR Policy can be associated with a particular NRP. This document describes how the SR Policy extension for associated NRP and the operational mechanisms function together. 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. Jiang, et al. Expires December 20, 2024 [Page 3] Internet-Draft Segment Routing Policy Extension for NRP June 2024 2. Solution ---------------------------------------- ( |PE|.............|PE|.............|PE| ) ( -- SR Policy-1 -- SR Policy-1 -- )<---------+ ---------------------------------------- | SR Policy-1 with NRP 1 | | ---------------------------------------- | ( |PE|..............................|PE| ) | ( -- SR Policy-2 -- )<-------+ ---------------------------------------- | SR Policy-2 with NRP 2 | | ---------------------------------------------- | ( |PE|.....-.....|PE|...... |PE|.......|PE| ) | ( -- |P| -- :-...:-- -..:-- ) | ( : -:.............|P|.........|P| )--+ ( -......................:-:..- - ) ( |P|.........................|P|......: ) ( - - ) ---------------------------------------------- Underlay Network Figure 1: Solution of SR Policy Extension for NRP In each NRP for network slices, the connectivity among PEs is achieved by SR Policies. The segment lists of these SR Policies composed with segments associated with the corresponding NRPs. Traffics are steered into the SR Policies, so that the corresponding NRPs will be used for forwarding. Jiang, et al. Expires December 20, 2024 [Page 4] Internet-Draft Segment Routing Policy Extension for NRP June 2024 Physical Interface 1 +---------------------------------------+ | | | Layer-3 Sub-interface 1-1: 1Gbps | |=======================================| |>>>>>> Queue 1-1: NRP-1, 100Mbps >>>>>>| |>>>>>> Queue 1-2: NRP-2, 200Mbps >>>>>>| |>>>>>> ... >>>>>>| |=======================================| | | | Layer-3 Sub-interface 1-2: 2Gbps | |====================================== | |>>>>>> Queue 1-1: NRP-1, 100Mbps >>>>>>| |>>>>>> Queue 1-2: NRP-2, 200Mbps >>>>>>| |>>>>>> ... >>>>>>| |=======================================| | | +---------------------------------------+ Figure 2: Network Resource Partition As shown in Figure 2, the bandwidth resource of a physical interface is partitioned in two NRPs. The NRPs are sliced by HQoS queues with dedicated bandwidth under the layer-3 sub-interface. NRP needs to be identified by using an extra dimension. On both MPLS-SR and SRv6 data plane, there are several options for realizing NRP-ID, such as [I-D.ietf-6man- enhanced-vpn-vtn-id], [I-D.cheng-spring-srv6-encoding-network- sliceid], [I-D.decraene-mpls-slid-encoded-entropy-label-id], and [I- D.li-mpls-enhanced-vpn-vtn-id]. As mentioned above, the traffics of network slice are forwarded according to the segment list of SR Policy. Firstly, the outgoing interface associated segment will be the layer-3 sub-interface. Then, the HQoS queue will be selected according to the NRP-ID carried in the packets, and the bandwidth resource of NRP will be used. 3. SR Policy Extension for NRP The SR Policy determines the path that packets will traverse, while NRP reserves resources along the path designated by the SR Policy. Through the integration of SR Policy and NRP, it ensures both the forwarding path and resource reservation along the path. 3.1. NRP ID of a Candidate Path The NRP ID of a candidate path is utilized to identify the resources corresponding to the forwarding paths of all segment lists within an Jiang, et al. Expires December 20, 2024 [Page 5] Internet-Draft Segment Routing Policy Extension for NRP June 2024 SR Policy. It is a 32-bit value serving as an identifier for the Network Resource Partition. The NRP ID associated with a candidate path of an SR Policy from a specific Protocol-Origin as specified below: o When provisioning is via configuration, it is specific to the implementation's configuration model. o When signaling is via PCEP, the method to uniquely signal an individual candidate path along with its NRP ID is described in [I-D.draft-dong-pce-pcep-nrp]. o When signaling is via BGP SR Policy, the method to uniquely signal an individual candidate path along with its NRP ID is described in [I-D.ietf-idr-sr-policy-nrp].It can be collected via BGP-LS [I-D.draft-chen-idr-bgp-ls-sr-policy-nrp]. Under the same Candidate Path, all segment lists must share the same NRP ID. While different Candidate Paths can have identical NRP IDs, it is advisable for each candidate path within an SR Policy to possess a unique NRP ID. By associating NRP IDs with Candidate Paths, the assurance of both the SR Policy's path and its resources is achieved. The process involves the following steps: o Planning the network topology resources and assigning NRP IDs. o At the headend node, performing path arrangement. During the path planning process of the SR Policy, resources are considered for different candidate paths, and NRP IDs are configured under each Candidate path to establish the association between the path and resources. 3.2. Candidate Path Validity Verification A candidate path is considered usable when it is valid, with the validation rules outlined in Section 5 of [RFC9256]. When a Candidate Path contains an NRP ID, a segment list of a candidate path may be declared invalid if the resources corresponding to the NRP ID on the segment list path do not exist. Additionally, if the head-end is unable to perform path resolution for the first SID into one or more outgoing interfaces and next-hops, along with the corresponding NRP ID resources, the status of that segment list is set to invalid. When running fast detection protocols, such as Bidirectional Forwarding Detection (BFD), the headend may compute and validate Jiang, et al. Expires December 20, 2024 [Page 6] Internet-Draft Segment Routing Policy Extension for NRP June 2024 backup candidate paths and provision them into the forwarding plane as a backup for the active path. In such cases, it is necessary to include NRP encapsulation to detect the NRP resources along the path, ensuring the availability of both the path and resources. 3.3. Summary In summary, the information model is the following: SR Policy POL1 Candidate Path CP1 Preference 200 NRP-ID 100 Segment List 1 , Weight 1 Segment List 2 , Weight 1 Segment List 3 , Weight 1 Candidate Path CP2 Preference 100 NRP-ID 200 Segment List 4 , Weight 1 Segment List 5 , Weight 1 Segment List 6 , Weight 1 SR Policy POL1 has two Candidate Paths, CP1 and CP2. CP1 is the active candidate path (valid and with the highest Preference). NRP- ID 100 is configured under CP1, while NRP-ID 200 is configured under CP2. The three segment lists of CP1 with NRP-ID 100 are installed as the forwarding instantiation of SR Policy POL1. NRP-ID 100 needs to be configured and resources reserved on the paths traversed by segment list 1, segment list 2, and segment list 3. When traffic is steered on POL1 and flow-based hashed on segment list , NRP-100 is added, and forwarding is based on the resources pointed to by NRP-100. Jiang, et al. Expires December 20, 2024 [Page 7] Internet-Draft Segment Routing Policy Extension for NRP June 2024 4. Steering into an SR Policy with NRP The method of traffic steering aligns with the description in Section 8 of [RFC9256]. When an SR policy's active path contains an NRP ID, specific handling is necessary, as follows: o when steering traffic to the SR policy through Per-Destination Steering or Policy-Based Routing, after adding the corresponding segment list encapsulation for the SR policy, NRP encapsulation is also required. The specific NRP encapsulation details are outside the scope of this document. o Similarly, When steering traffic to the SR policy via the BindingSID, after adding the segment list encapsulation for the SR policy, NRP encapsulation is required. The specific NRP encapsulation details are outside the scope of this document. 5. Manageability Considerations This document specifies the detailed construction of the SR Policy with NRP-ID and its operational mechanisms. Therefore, the manageability considerations of [RFC9256] apply. 6. Security Considerations The security considerations described in [RFC9256] also apply to this document. This document does not introduce any new security consideration. 7. IANA Considerations This document has no IANA actions. 8. References 8.1. 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, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . Jiang, et al. Expires December 20, 2024 [Page 8] Internet-Draft Segment Routing Policy Extension for NRP June 2024 [RFC9256] Filsfils, C., Talaulikar, K., Voyer, D., Bogdanov, A., and P. Mattes, "Segment Routing Policy Architecture", BCP 14, RFC 9256, DOI 10.17487/RFC9256, July 2022, < https://www.rfc-editor.org/info/rfc9256 >. [I-D.ietf-teas-nrp-scalability]Dong, J., Li, Z., Gong, L., Yang, G., Mishra, G. S., and F. Qin, "Scalability Considerations for Network Resource Partition", Work in Progress, Internet-Draft, draft-ietf-teas-nrp-scalability-03, 21 October 2023,. 8.2. Informative References [I-D.ietf-teas-nrp-scalability] Dong, J., Li, Z., Gong, L., Yang, G., Mishra, G. S., and F. Qin, "Scalability Considerations for Network Resource Partition", Work in Progress, Internet-Draft, draft-ietf-teas-nrp-scalability-03, 21 October 2023,. [I-D.ietf-6man-enhanced-vpn-vtn-id] Dong, J., Li, Z., Xie, C., Ma, C., and G. Mishra, "Carrying Virtual Transport Network (VTN) Identifier in IPv6 Extension Header", Work in Progress, Internet-Draft, draft-ietf-6man-enhanced-vpn- vtn-id-00, 5 March 2022, . [I-D.cheng-spring-srv6-encoding-network-sliceid] Cheng, W., Lin, C., Gong, L., Zadok, S., and X. Wang, "Encoding Network Slice Identification for SRv6", Work in Progress, Internet- Draft, draft-cheng-spring-srv6-encoding-network-sliceid- 04, 8 July 2022, . [I-D.decraene-mpls-slid-encoded-entropy-label-id] Decraene B., Filsfils, C., Henderickx W., Saad T., Beeram V., "Using Entropy Label for Network Slice Identification in MPLS networks", Work in Progress, Internet-Draft, draft- decraene-mpls-slid-encoded-entropy-label-id-04, 14 June 2022, . Jiang, et al. Expires December 20, 2024 [Page 9] Internet-Draft Segment Routing Policy Extension for NRP June 2024 [I-D.li-mpls-enhanced-vpn-vtn-id] Li, Z. and J. Dong, "Carrying Virtual Transport Network Identifier in MPLS Packet", Work in Progress, Internet-Draft, draft-li-mpls-enhanced-vpn- vtn-id-02, 7 March 2022, . [I-D. draft-dong-pce-pcep-nrp] Dong, J.,S. Fang,Q. Xiong,S. Peng,L. Han, "Path Computation Element Communication Protocol (PCEP) Extensions for Network Resource Partition (NRP)", Work in Progress, Internet-Draft, draft-dong-pce-pcep-nrp- 01, 23 October 2023, . [I-D.ietf-idr-sr-policy-nrp] Dong, J., Hu, Z., and R. Pang, "BGP SR Policy Extensions for Network Resource Partition", Work in Progress,Internet-Draft, draft-ietf-idr-sr-policy-nrp-00, 17 December 2023, . [I-D.draft-chen-idr-bgp-ls-sr-policy-nrp] R. Chen, J. Dong, D. Zhao, L. Gong, Y. Zhu and R. Pang, "SR Policies Extensions for Network Resource Partition in BGP-LS", Work in Progress,Internet-Draft, draft-chen-idr-bgp-ls-sr-policy- nrp-08,18 May 2024,. Acknowledgements TBD Jiang, et al. Expires December 20, 2024 [Page 10] Internet-Draft Segment Routing Policy Extension for NRP June 2024 Authors' Addresses Wenying Jiang China Mobile Beijing China Email: jiangwenying@chinamobile.com Changwang Lin New H3C Technologies Beijing China Email: linchangwang.04414@h3c.com Ran Chen ZTE Corporation Email: chen.ran@zte.com.cn Jiang, et al. Expires December 20, 2024 [Page 11]