Network Working Group J. Dong Internet-Draft Z. Li Intended status: Standards Track Huawei Technologies Expires: May 6, 2021 C. Xie C. Ma China Telecom November 2, 2020 Carrying Virtual Transport Network Identifier in IPv6 Extension Header draft-dong-6man-enhanced-vpn-vtn-id-02 Abstract A Virtual Transport Network (VTN) is a virtual network which has a customized network topology and a set of dedicated or shared network resources allocated from the network infrastructure. A VTN can be used as the underlay for one or a group of VPNs to provide enhanced VPN (VPN+) services. In packet forwarding, some fields in data packet needs to be used to identify the VTN the packet belongs to, so that the VTN-specific processing can be performed. This document proposes a new option type to carry VTN ID in an IPv6 extension headers to identify the Virtual Transport Network (VTN) the packet belongs to. The procedure for processing of the VTN option is also specified. 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 May 6, 2021. Dong, et al. Expires May 6, 2021 [Page 1] Internet-Draft IPv6 VTN Option November 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 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. Requirements Language . . . . . . . . . . . . . . . . . . . . 3 3. New IPv6 Extension Header Option for VTN . . . . . . . . . . 3 4. Procedures . . . . . . . . . . . . . . . . . . . . . . . . . 4 4.1. VTN Option Insertion . . . . . . . . . . . . . . . . . . 4 4.2. VTN based Packet Forwarding . . . . . . . . . . . . . . . 4 5. Operational Considerations . . . . . . . . . . . . . . . . . 5 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 7. Security Considerations . . . . . . . . . . . . . . . . . . . 5 8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 6 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 10.1. Normative References . . . . . . . . . . . . . . . . . . 6 10.2. Informative References . . . . . . . . . . . . . . . . . 6 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7 1. Introduction Virtual Private Networks (VPNs) provide different groups of users with logically isolated connectivity over a common shared network infrastructure. With the introduction of 5G, new service types may require connectivity services with advanced characteristics comparing to traditional VPNs, such as strict isolation from other services or guaranteed performance. These services are refered to as "enhanced VPNs" (VPN+). [I-D.ietf-teas-enhanced-vpn] describes a framework and candidate component technologies for providing VPN+ services. The enhanced properties of VPN+ require tighter coordination and integration between the underlay network resources and the overlay network. VPN+ service can be built on a Virtual Transport Network (VTN) which has a customized network topology and a set of dedicated Dong, et al. Expires May 6, 2021 [Page 2] Internet-Draft IPv6 VTN Option November 2020 or shared network resources allocated from the underlay network. The overlay VPN together with the corresponding VTN in the underlay provide the VPN+ service. In the network, traffic of different VPN+ services need to be processed separately based on the topology and the network resources associated with the corresponding VTN. [I-D.dong-teas-enhanced-vpn-vtn-scalability] describes the scalability considerations for VPN+, one of which is to improve the data plane scalability through the introduction of a dedicated identifier in data packets that is used to identify the VTN the packets belong to, so that VTN-specific packet processing can be performed. This is called Resource Independent (RI) VTN. This document proposes a mechanism to carry the VTN ID in an IPv6 extension header [RFC8200] of a packet, so that the packet will be processed by network nodes using the network resources allocated to the corresponding VTN. The procedure for processing the VTN ID is also specified. This provides a scalable solution for enhanced VPN data plane, so that it may be used to support a large number of VTNs in an IPv6 network. 2. 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 BCP14 RFC 2119 [RFC2119] RFC 8174 [RFC8174] when, and only when, they appear in all capitals, as shown here. 3. New IPv6 Extension Header Option for VTN A new option type "VTN" is defined to carry the Virtual Transport Network Identifier (VTN ID) in an IPv6 packet header. Its format is shown as below: Option Option Option Type Data Len Data +--------+--------+--------+--------+ |BBCTTTTT|00000100| 4-octet VTN ID | +--------+--------+--------+--------+ Figure 1. The format of VTN Option Option Type: 8-bit identifier of the type of option. The type of VTN option is to be assigned by IANA. The highest-order bits of the type field are defined as below: Dong, et al. Expires May 6, 2021 [Page 3] Internet-Draft IPv6 VTN Option November 2020 o BB 00 The highest-order 2 bits are set to 00 to indicate that a node which does not recognize this type will skip over it and continue processing the header. o C 0 The third highest-order bit are set to 0 to indicate this option does not change en route. Opt Data Len: 8-bit unsigned integer indicates the length of the option Data field of this option, in octets. The value of Opt Data Len of VTN option SHOULD be set to 4. Option Data: 4-octet identifier which uniquely identifies a VTN. Editor's note: The length of the VTN ID is defined as 4-octet for the matching with the 4-octet Single Network Slice Selection Assistance Information (S-NSSAI) defined in 3GPP [TS23501]. 8-bit 24-bit +------------+-------------------------+ | SST | Slice Differentiator | +------------+-------------------------+ Figure 2. The format of S-NSSAI 4. Procedures As the VTN option needs to be processed by each node along the path for VTN-specific forwarding, it SHOULD be carried in IPv6 Hop-by-Hop options header when the Hop-by-Hop options header can be processed in forwarding plane by all the nodes along the path. 4.1. VTN Option Insertion When an ingress node of an IPv6 domain receives a packet, according to traffic classification or mapping policy, the packet is steered into one of the VTNs in the network, then packet SHOULD be encapsulated in an outer IPv6 header, and the VTN-ID of the VTN which the packet is mapped to SHOULD be carried in the Hop-by-Hop options header associated with the outer IPv6 header. 4.2. VTN based Packet Forwarding On receipt of a packet with the VTN option, each network node which can parse the VTN option SHOULD use the VTN ID to identify the VTN the packet belongs to. This means the forwarding behavior is based on both the destination IP address and the VTN option. The destination IP address is used for the lookup of the next-hop node, and VTN-ID can be used to determine the set of network resources reserved for processing and sending the packet to the next-hop node. Dong, et al. Expires May 6, 2021 [Page 4] Internet-Draft IPv6 VTN Option November 2020 The egress node of the IPv6 domain SHOULD decapsulate the outer IPv6 header. There can be different implementations for reserving local network resources to the VTNs. For example, on one interface, a subset of forwarding plane resource allocated to a particular VTN can be considered as a virtual sub-interface with dedicated bandwidth and other associated resources. In packet forwarding, the IPv6 destination address of the received packet is used to identify the next-hop and the outgoing interface, and the VTN ID is used to further identify the virtual sub-interface which is associated with the VTN on the outgoing interface. Routers which do not support Hop-by-Hop options header SHOULD ignore the Hop-by-Hop options header and forward the packet only based on the destination IP address. Routers which support Hop-by-Hop Options header, but do not support the VTN option SHOULD ignore the Hop-by- Hop option and continue to forward the packet only based on the destination IP address. 5. Operational Considerations As described in [RFC8200], nodes may be configured to ignore the Hop- by-Hop Options header, and in some implementations a packet containing a Hop-by-Hop Options header may be dropped or assigned to a slow processing path. This needs to be taken into consideration when VTN option is introduced to a network. The operator needs to make sure that all the network nodes in a VTN can either process Hop- by-Hop Options header in packet forwarding, or ignore the Hop-by-Hop Option header. In other word, packets steered into a VTN MUST NOT be dropped due to the existence of the Hop-by-Hop Options header. It is RECOMMENDED to configure all the nodes in a VTN to process the Hop- by-Hop Options header if there is a nob for this. 6. IANA Considerations This document requests IANA to assign a new option type from "Destination Options and Hop-by-Hop Options" registry. Value Description Reference -------------------------------------- TBD VTN Option this document 7. Security Considerations TBD Dong, et al. Expires May 6, 2021 [Page 5] Internet-Draft IPv6 VTN Option November 2020 8. Contributors Zhibo Hu Email: huzhibo@huawei.com Lei Bao Email: baolei7@huawei.com 9. Acknowledgements The authors would like to thank Juhua Xu and James Guichard for their review and valuable comments. 10. References 10.1. 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, . 10.2. Informative References [I-D.dong-teas-enhanced-vpn-vtn-scalability] Dong, J., Li, Z., and F. Qin, "Virtual Transport Network (VTN) Scalability Considerations for Enhanced VPN", draft- dong-teas-enhanced-vpn-vtn-scalability-00 (work in progress), February 2020. [I-D.ietf-teas-enhanced-vpn] Dong, J., Bryant, S., Li, Z., Miyasaka, T., and Y. Lee, "A Framework for Enhanced Virtual Private Networks (VPN+) Service", draft-ietf-teas-enhanced-vpn-06 (work in progress), July 2020. Dong, et al. Expires May 6, 2021 [Page 6] Internet-Draft IPv6 VTN Option November 2020 [RFC8754] Filsfils, C., Ed., Dukes, D., Ed., Previdi, S., Leddy, J., Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header (SRH)", RFC 8754, DOI 10.17487/RFC8754, March 2020, . [TS23501] "3GPP TS23.501", 2016, . Authors' Addresses Jie Dong Huawei Technologies Huawei Campus, No. 156 Beiqing Road Beijing 100095 China Email: jie.dong@huawei.com Zhenbin Li Huawei Technologies Huawei Campus, No. 156 Beiqing Road Beijing 100095 China Email: lizhenbin@huawei.com Chongfeng Xie China Telecom China Telecom Beijing Information Science & Technology, Beiqijia Beijing 102209 China Email: xiechf@chinatelecom.cn Chenhao Ma China Telecom China Telecom Beijing Information Science & Technology, Beiqijia Beijing 102209 China Email: machh@chinatelecom.cn Dong, et al. Expires May 6, 2021 [Page 7]