Network Working Group W. Cheng Internet-Draft W. Jiang Intended status: Standards Track China Mobile Expires: March 30, 2022 C. Lin New H3C Technologies September 30, 2021 Encapsulation and Processing of Network Slice Selector in IPv6 Data Plane draft-cheng-teas-ipv6-network-slice-selector-00 Abstract Packets belong to a network slice need to be forwarded using the specific network resources. A network slice selector is carried in each packet to identify the network slice that it belongs to. This document proposes a new Network Slice Selector Option, and describes the encapsulation and processing of network slice selector in IPv6 data plane using the proposed option. 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 March 30, 2022. 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 (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents Cheng, et al. Expires March 30, 2022 [Page 1] Internet-Draft Ipv6 Network Slice Selector September 2021 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 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 2 1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 2. Carrying Network Slice Selector in IPv6 Data Plane . . . . . 3 3. Definition of Network Slice Selector Option . . . . . . . . . 3 4. Processing of Network Slice Selector Option . . . . . . . . . 4 5. Usage of Network Slice Selector Option . . . . . . . . . . . 5 5.1. IP Backbone of Network Slice . . . . . . . . . . . . . . 5 5.2. IP Fast-Reroute of Network Slice . . . . . . . . . . . . 7 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 7. Security Considerations . . . . . . . . . . . . . . . . . . . 8 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 8 8.1. Normative References . . . . . . . . . . . . . . . . . . 8 8.2. Informative References . . . . . . . . . . . . . . . . . 8 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9 1. Introduction Network slicing provides the ability to partition a physical network into multiple isolated logical networks of varying sizes, structures, and functions so that each slice can be dedicated to specific services or customers. [I-D.ietf-teas-ietf-network-slices] defines the term "IETF Network Slice" and establishes the general principles of network slicing in the IETF context. [I-D.cheng-teas-network-slice-usecase] describes several use cases of IETF Network Slice. [I-D.bestbar-teas-ns-packet] proposes a solution to realize network slicing in IP/MPLS networks. Network nodes need to identify a packet belonging to a network slice before it can apply the proper forwarding treatment, so a Network Slice Selector must be carried in each packet. This document proposes a new Network Slice Selector Option, and describes the encapsulation and processing of the network slice selector in IPv6 data plane using the proposed option. 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 Cheng, et al. Expires March 30, 2022 [Page 2] Internet-Draft Ipv6 Network Slice Selector September 2021 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here. 1.2. Terminology IETF Network Slice: An IETF Network Slice is a logical network topology connecting a number of endpoints using a set of shared or dedicated network resources that are used to satisfy specific Service Level Objectives. See [I-D.ietf-teas-ietf-network-slices]. Service Level Objectives (SLO): Define a set of measurable network attributes and characteristics that describe an IETF Network Slice service. See [I-D.ietf-teas-ietf-network-slices]. Network Slice Selector (NSS): An identifier carried in each packet to indicate the network slice that it belongs to. 2. Carrying Network Slice Selector in IPv6 Data Plane As specified in [RFC8200], the Hop-by-Hop Options header is used to carry optional information that may be examined and processed by every node along a packet's delivery path. Therefore, in IPv6 data plane, the Network Slice Selector can be carried as a Hop-by-Hop option in the Hop-by-Hop options header. Each node along the path will process the IPv6 Hop-by-Hop options header and apply the specific Per Hop Behavior (PHB) that is associated with the network slice. 3. Definition of Network Slice Selector Option A new Network Slice Selector Option is defined to encapsulate the network slice selector in IPv6 data plane. It identifies the network slice which the packet belongs to. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Option Type | Opt Data Len | Flags | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Network Slice Selector | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ o Option Type: 8-bit identifier of the type of option. The value is to be assigned by IANA. The highest-order 2 bits are set to 00 to indicate that a node which does not recognize the option type will skip over this option and continue processing the header. The Cheng, et al. Expires March 30, 2022 [Page 3] Internet-Draft Ipv6 Network Slice Selector September 2021 third highest-order bit is set to 0 to indicate the option data does not change en route. o Opt Data Len: 8-bit unsigned integer. Length of the Option Data field of this option, in octets. The Value is 6. o Flags: 16 bits of flags. The following flags are defined: 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |B U U U U U U U U U U U U U U U| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * B: Best-effort. When the forwarding behavior of the specific network slice identified by the Network Slice Selector filed is not configured or available, if B-Flag is set, the packet should be transmitted ignoring the Network Slice Selector Option, otherwise it should be discarded. * U: Unused and for future use. MUST be 0 on transmission and ignored on receipt. o Network Slice Selector: 32-bit identifier of the network slice which the packet belongs to. 4. Processing of Network Slice Selector Option In an IPv6 network which deploys network slicing, the ingress node encapsulates an outer IPv6 Header with the Network Slice Selector Option into each packet that belongs to a certain network slice. The Network Slice Selector is carried in the Hop-by-Hop Options Header, and needs to be processed by each node along the delivery path. Nodes should be able to process the Network Slice Selector Option in the forwarding plane. When forwarding a packet with the Network Slice Selector Option, a node performs an IPv6 fib lookup on the Destination Address in IPv6 Header, and determines the next hop to the destination. Then it processes the Network Slice Selector Option in the Hop-by-Hop Options Header with the following logic: Cheng, et al. Expires March 30, 2022 [Page 4] Internet-Draft Ipv6 Network Slice Selector September 2021 Perform network slice lookup using the Network Slice Selector and determine the forwarding behavior IF (the network slice or the forwarding behavior is not configured or available) { IF (B-Flag is set) { Transmit the packet to next hop indicated by Destination Address, ignoring the Network Slice Selector Option } ELSE { Discard the packet } } ELSE { Transmit the packet to next hop indicated by Destination Address, using the forwarding behavior for the specific network slice } Nodes which do not recognize the Network Slice Selector Option should ignore the Network Slice Selector Option and continue to forward the packet. The egress node decapsulates the outer IPv6 Header carrying the Network Slice Selector Option. 5. Usage of Network Slice Selector Option 5.1. IP Backbone of Network Slice In Figure 1, the network operator has created two network slices in the IP Backbone for IETF network slices, which are NS1 and NS2. The SLO of NS1 is guaranteed bandwidth of 100Mbps, and the SLO of NS2 is guaranteed bandwidth of 200Mbps. Two network slice selectors, NSS1 and NSS2, are assigned for NS1 and NS2 respectively. SRv6 is applied in the IP Backbone. Along with the forwarding path , dedicated queues with guaranteed bandwidth for NS1 and NS2 are configured at corresponding interfaces of each router. Taking the interface P1-P2 of router P1 as an example, which is shown in Figure 2, Queue 1 is configured with network slice selector NSS1 and guaranteed bandwidth of 100Mbps, and Queue 2 is configured with NSS2 and 200Mbps. When P1 transmits a packet through interface P1-P2, the network slice selector carried in the packet header is checked. If NSS1 appears in Hop-by-Hop Options Header, P1 uses Queue 1 to transmit the packet. If NSS2 appears in Hop-by-Hop Options Header, P1 uses Queue 2 to transmit the packet. Cheng, et al. Expires March 30, 2022 [Page 5] Internet-Draft Ipv6 Network Slice Selector September 2021 When the traffic flows of NS1 or NS2 enter the IP Backbone, PE1 and PE2 encapsulate the received packet with an outer IPv6 header. The outer IPv6 header has a Hop-by-Hop Options Header which contains a Network Slice Selector Option carrying NSS1 or NSS2, along with a SRH header which contains the SIDs of path . In packet forwarding, P1 and P2 use the SID in IPv6 destination address and SRH to determine the next-hop and the outgoing interface, and then, according to the Hop-by-Hop Options Header, use the dedicated queue related with NSS1 or NSS2 to transmit the packet. ................................. : IP Backbone : CPE PE1 P1 P2 PE2 ...... |----| |---| NS1 |---| NS1 |---| NS1 |---| : DC : | o---|o-o|-----|o-o|-----|o-o|-----|o-o|--o : | o---|o-o|-----|o-o|-----|o-o|-----|o-o|--o : |----| |---| NS2 |---| NS2 |---| NS2 |---| :....: : : :...............................: +-------+ +-------+ | IPv6 | | IPv6 | +-------+ +-------+ | HBH | | HBH | +-------+ +-------+ | SRH | | SRH | +-------+ +-------+ +-------+ +-------+ | IPv6 | | IPv6 | | IPv6 | | IPv6 | +-------+ <-> +-------+ <...> +-------+ <-> +-------+ |Payload| |Payload| |Payload| |Payload| +-------+ +-------+ +-------+ +-------+ Figure 1 |----| Interface: P1-P2 | | ---------------------------------- | | >>>>>>Queue 1: NSS1, 100Mbps>>>>>> | P1 | >>>>>>Queue 2: NSS2, 200Mbps>>>>>> | | >>>>>> ... >>>>>> | | ---------------------------------- |----| Figure 2 Cheng, et al. Expires March 30, 2022 [Page 6] Internet-Draft Ipv6 Network Slice Selector September 2021 5.2. IP Fast-Reroute of Network Slice In Figure 3, the network operator has created a network slice NS1. A forwarding path is selected to transmit the traffic flows of NS1. On the links of PE1-P1, P1-P2 and P2-PE2, dedicated resources are allocated for NS1. When the traffic flows of NS1 enter the network via PE1, PE1 encapsulates the received packet with an outer IPv6 header. The outer IPv6 header has a Hop-by-Hop Options Header which contains a Network Slice Selector Option carrying NSS1, along with a SRH header which contains the SIDs of path . The B-Flag in the Network Slice Selector Option is set. The packets are forwarded along the selected path, using the dedicated resources. Then, a failure occurs on P2. The fast re-route technology on P1 works, and P1 will send the packets to P3 and make the packet forwarding along the path . However, on the links of P1-P3, P3-P4 and P4-PE2, there is no dedicated resource allocated for NS1. The B-Flag in the Network Slice Selector Option indicates the routers to transmit the packets with best-effort service rather than discard them. Since the lack of dedicated resource along the new path, the SLO of NS1 may not be satisfied during the failure, but NS1 remains available. |---| |---| |---| |---| --|PE1|*****|P1 |*****|P2 |*****|PE2|-- |---| |---| |---| |---| | | | | | | | | | | | | | |---| |---| | +-------|P3 |-----|P4 |-------+ |---| |---| *****: links with dedicated resource for NS1 -----: links without dedicated resource for NS1 Figure 3 For another example as shown in Figure 4, the network operator has assigned a main path and a hot-standby backup path for NS1. Dedicated resources are allocated both on the main and backup paths. In this case, the B-Flag in the Network Slice Selector Option can be unset. When PE1 detects a failure on the main path, the traffic flows of NS1 will be steered to the backup path and forwarded with dedicated resource. Cheng, et al. Expires March 30, 2022 [Page 7] Internet-Draft Ipv6 Network Slice Selector September 2021 |---| |---| |---| |---| --|PE1|*****|P1 |*****|P2 |*****|PE2|-- |---| |---| |---| |---| * | | * * | | * * | | * * |---| |---| * ********|P3 |*****|P4 |******** |---| |---| *****: links with dedicated resource for NS1 -----: links without dedicated resource for NS1 Figure 4 6. IANA Considerations This document requests IANA to assign a new option type for Network Slice Selector Option. 7. Security Considerations TBD. 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, . [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 (IPv6) Specification", STD 86, RFC 8200, DOI 10.17487/RFC8200, July 2017, . 8.2. Informative References Cheng, et al. Expires March 30, 2022 [Page 8] Internet-Draft Ipv6 Network Slice Selector September 2021 [I-D.bestbar-teas-ns-packet] Saad, T., Beeram, V. P., Wen, B., Ceccarelli, D., Halpern, J., Peng, S., Chen, R., Liu, X., Contreras, L. M., and R. Rokui, "Realizing Network Slices in IP/MPLS Networks", draft-bestbar-teas-ns-packet-03 (work in progress), July 2021. [I-D.cheng-teas-network-slice-usecase] Cheng, W., Jiang, W., Chen, R., Gong, L., and S. Peng, "IETF Network Slice use cases", draft-cheng-teas-network- slice-usecase-01 (work in progress), August 2021. [I-D.ietf-teas-ietf-network-slices] Farrel, A., Gray, E., Drake, J., Rokui, R., Homma, S., Makhijani, K., Contreras, L., and J. Tantsura, "Framework for IETF Network Slices", draft-ietf-teas-ietf-network- slices-04 (work in progress), August 2021. Authors' Addresses Weiqiang Cheng China Mobile Email: chengweiqiang@chinamobile.com Wenying Jiang China Mobile Email: jiangwenying@chinamobile.com Changwang Lin New H3C Technologies Email: linchangwang.04414@h3c.com Cheng, et al. Expires March 30, 2022 [Page 9]