SFC Yuehua. Wei, Ed. Internet-Draft ZTE Corporation Intended status: Standards Track U. Elzur Expires: 16 July 2022 Intel S. Majee Individual contributor C. Pignataro Cisco D. Eastlake Futurewei Technologies 12 January 2022 Network Service Header Metadata Type 2 Variable-Length Context Headers draft-ietf-sfc-nsh-tlv-11 Abstract Service Function Chaining (SFC) uses the Network Service Header (NSH) (RFC 8300) to steer and provide context Metadata (MD) with each packet. Such Metadata can be of various Types including MD Type 2 variable length context headers. This document specifies several such context headers that can be used within a service function path. 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 16 July 2022. Copyright Notice Copyright (c) 2022 IETF Trust and the persons identified as the document authors. All rights reserved. Wei, et al. Expires 16 July 2022 [Page 1] Internet-Draft NSH MD2 Context Headers January 2022 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 Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Conventions used in this document . . . . . . . . . . . . . . 3 2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 2.2. Requirements Language . . . . . . . . . . . . . . . . . . 3 3. NSH MD Type 2 format . . . . . . . . . . . . . . . . . . . . 3 4. NSH MD Type 2 Context Headers . . . . . . . . . . . . . . . . 4 4.1. Forwarding Context . . . . . . . . . . . . . . . . . . . 4 4.2. Tenant Identifier . . . . . . . . . . . . . . . . . . . . 6 4.3. Ingress Network Node Information . . . . . . . . . . . . 6 4.4. Ingress Network Source Interface . . . . . . . . . . . . 7 4.5. Flow ID . . . . . . . . . . . . . . . . . . . . . . . . . 8 4.6. Source and/or Destination Groups . . . . . . . . . . . . 8 4.7. Policy Identifier . . . . . . . . . . . . . . . . . . . . 9 5. Security Considerations . . . . . . . . . . . . . . . . . . . 9 6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 10 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 7.1. MD Type 2 Context Types . . . . . . . . . . . . . . . . . 10 7.2. Forwarding Context Types . . . . . . . . . . . . . . . . 10 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 11 8.1. Normative References . . . . . . . . . . . . . . . . . . 11 8.2. Informative References . . . . . . . . . . . . . . . . . 12 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13 1. Introduction The Network Service Header (NSH) [RFC8300] is the Service Function Chaining (SFC) encapsulation that supports the SFC architecture [RFC7665]. As such, the NSH provides following key elements: 1. Service Function Path (SFP) identification. 2. Indication of location within a Service Function Path. 3. Optional, per-packet metadata (fixed-length or variable-length). Wei, et al. Expires 16 July 2022 [Page 2] Internet-Draft NSH MD2 Context Headers January 2022 [RFC8300] further defines two metadata formats (MD Types): 1 and 2. MD Type 1 defines the fixed-length, 16-octet long metadata, whereas MD Type 2 defines a variable-length context format for metadata. This document defines several common metadata context headers for use with NSH MD Type 2. These supplement the Subscriber Identity and Performance Policy MD Type 2 metadata context headers specified in [RFC8979]. This document does not address metadata usage, updating/chaining of metadata, or other SFP functions. Those topics are described in [RFC8300]. 2. Conventions used in this document 2.1. Terminology This document uses the terminology defined in the SFC Architecture [RFC7665] and the Network Service Header [RFC8300]. 2.2. 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 BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here. 3. NSH MD Type 2 format An NSH is composed of a 4-octet Base Header, a 4-octet Service Path Header and optional Context Headers. The Base Header identifies the MD-Type in use: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Ver|O|U| TTL | Length |U|U|U|U|MD Type| Next Protocol | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 1: NSH Base Header Please refer to NSH [RFC8300] for a detailed header description. When the base header specifies MD Type = 0x2, zero or more Variable Length Context Headers MAY be added, immediately following the Service Path Header. Figure 2 below depicts the format of the Context Header as defined in Section 2.5.1 of [RFC8300]. Wei, et al. Expires 16 July 2022 [Page 3] Internet-Draft NSH MD2 Context Headers January 2022 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Metadata Class | Type |U| Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Variable-Length Metadata | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 2: NSH Variable-Length Context Headers 4. NSH MD Type 2 Context Headers [RFC8300] specifies Metadata Class 0x0000 as IETF Base NSH MD Class. In this document, metadata types are defined for the IETF Base NSH MD Class. 4.1. Forwarding Context This metadata context carries a network forwarding context, used for segregation and forwarding scope. Forwarding context can take several forms depending on the network environment. For example, VXLAN/VXLAN-GPE VNID, VRF identification, or VLAN. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Metadata Class = 0x0000 | Type = TBA1 |U| Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |CT=0x0 | Reserved | VLAN ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 3: Forwarding Context - 1(VLAN) 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Metadata Class = 0x0000 | Type = TBA1 |U| Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |CT=0x1 |Resv | Service VLAN ID | Customer VLAN ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 4: Forwarding Context - 2(QinQ) Wei, et al. Expires 16 July 2022 [Page 4] Internet-Draft NSH MD2 Context Headers January 2022 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Metadata Class = 0x0000 | Type = TBA1 |U| Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |CT=0x2 | Reserved | MPLS VPN Label | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 5: Forwarding Context - 3(MPLS VPN) 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Metadata Class = 0x0000 | Type = TBA1 |U| Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |CT=0x3 | Resv | Virtual Network Identifier | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 6: Forwarding Context - 4(VNI) 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Metadata Class = 0x0000 | Type = TBA1 |U| Length = 8 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |CT=0x4 | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Session ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 7: Forwarding Context - 5(Session ID) where: Context Type (CT) is four bits-long field that defines the length and the interpretation of the Forwarding Context field. Please see the IANA Considerations in Section 7. This document defines these CT values: - 0x0 - 12 bits VLAN identifier. See Figure 3. Reserved bits MUST be sent as zero and ignored on receipt Wei, et al. Expires 16 July 2022 [Page 5] Internet-Draft NSH MD2 Context Headers January 2022 - 0x1 - 24 bits double tagging identifiers. A service VLAN tag followed by a customer VLAN tag [IEEE.802.1Q_2018]. The two VLAN IDs are concatenated and appear in the same order that they appeared in the payload. See Figure 4. Reserved bits MUST be sent as zero and ignored on receipt - 0x2 - 20 bits MPLS VPN label. See Figure 5. Reserved bits MUST be sent as zero and ignored on receipt - 0x3 - 24 bits virtual network identifier (VNI). See Figure 6. Reserved bits MUST be sent as zero and ignored on receipt - 0x4 - 32 bits Session ID ([RFC3931]). This is called Key in GRE [RFC2890]. See Figure 7. 4.2. Tenant Identifier Tenant identification is often used for segregation within a multi- tenant environment. Orchestration system-generated tenant IDs are an example of such data. This context header carries the value of the Tenant identifier. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Metadata Class = 0x0000 | Type = TBA2 |U| Length = var| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ Tenant ID ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 8: Tenant Identifier List The fields are described as follows: Length: Indicates the length of the Tenant ID in octets (see Section 2.5.1 of [RFC8300]). Tenant ID: Represents an opaque value pointing to Orchestration system-generated tenant identifier. The structure and semantics of this field are deployment specific. 4.3. Ingress Network Node Information This context header carries a Node ID of the ingress network node. Wei, et al. Expires 16 July 2022 [Page 6] Internet-Draft NSH MD2 Context Headers January 2022 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Metadata Class = 0x0000 | Type = TBA3 |U| Length = var| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ Node ID ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 9: Ingress Network Node ID The fields are described as follows: Length: Indicates the length of the Node ID in octets (see Section 2.5.1 of [RFC8300]). Node ID: Represents an opaque value of the ingress network node ID. The structure and semantics of this field are deployment specific. For example, Node ID may be a 4 octets IPv4 address Node ID, or a 16 octets IPv6 address Node ID, or a 6 octets MAC address, or 8 octets MAC address (EUI-64), etc. 4.4. Ingress Network Source Interface This context identifies the ingress interface of the ingress network node. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Metadata Class = 0x0000 | Type = TBA4 |U| Length = var| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ Source Interface ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 10: Ingress Network Source Interface The fields are described as follows: Length: Indicates the length of the Source Interface in octets (see Section 2.5.1 of [RFC8300]). Source Interface: Represents an opaque value of identifier of the ingress interface of the ingress network node. Wei, et al. Expires 16 July 2022 [Page 7] Internet-Draft NSH MD2 Context Headers January 2022 4.5. Flow ID Flow ID provides a field in the NSH MD Type 2 to label packets belonging to the same flow. Absence of this field, or a value of zero denotes that packets have not been labeled. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Metadata Class = 0x0000 | Type = TBA5 |U| Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Flow ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 11: Flow ID The fields are described as follows: Length: Indicates the length of the Flow ID in octets (see Section 2.5.1 of [RFC8300]). [RFC8200] defined IPv6 Flow Label as a 20-bit long unsigned integer. Also, [RFC6790], which defined the use of an entropy label in the MPLS network, is 20-bit long. Flow ID: Represents an opaque value of the Flow ID. The Flow ID is right justified (appears in the least significant bits of the Flow ID word) and is padded on the left with bits which MUST be sent as zero and ignored on receipt. 4.6. Source and/or Destination Groups Intent-based systems can use this data to express the logical grouping of source and/or destination objects. [OpenStack] and [OpenDaylight] provide examples of such a system. Each is expressed as a 32-bit opaque object. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Metadata Class = 0x0000 | Type = TBA6 |U| Length=8 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Source Group | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Dest Group | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 12: Source/Dest Groups Wei, et al. Expires 16 July 2022 [Page 8] Internet-Draft NSH MD2 Context Headers January 2022 4.7. Policy Identifier Traffic handling policies are often referred to by a system-generated identifier, which is then used by the devices to look up the policy's content locally. For example, this identifier could be an index to an array, a lookup key, a database Id. The identifier allows enforcement agents or services to look up the content of their part of the policy. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Metadata Class = 0x0000 | Type = TBA7 |U| Length=var | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ Policy ID ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 13: Policy ID The fields are described as follows: Length: Indicates the length of the Policy ID in octets (see Section 2.5.1 of [RFC8300]). Policy ID: Represents an opaque value of the Policy ID. This policy identifier is a general policy ID, essentially a key to allow Service Functions to know which policies to apply to packets. Those policies generally will not have much to do with performance, but rather with what specific treatment to apply. It may for example select a URL filter data set for a URL filter, or select a video transcoding policy in a transcoding SF. The Performance Policy Identifier in [RFC8979] is described there as having very specific use, and for example says that fully controlled SFPs would not use it. The Policy ID in this document is for cases not covered by [RFC8979]. 5. Security Considerations A misbehaving node from within the SFC-enabled domain may alter the content of the Context Headers, which may lead to service disruption. Such an attack is not unique to the Context Headers defined in this document. Measures discussed in Section 8 of [RFC8300] describes the general security considerations for protecting NSH. [I-D.ietf-sfc-nsh-integrity] specifies methods of protecting the integrity of the NSH metadata. If the NSH includes the MAC Context Header, the authentication of the packet MUST be verified before Wei, et al. Expires 16 July 2022 [Page 9] Internet-Draft NSH MD2 Context Headers January 2022 using any data. If the verification fails, the receiver MUST stop processing the variable length context headers and notify an operator. 6. Acknowledgments The authors would like to thank Paul Quinn, Behcet Sarikaya, Dirk von Hugo, Mohamed Boucadair, Gregory Mirsky, and Joel Halpern for providing invaluable concepts and content for this document. 7. IANA Considerations 7.1. MD Type 2 Context Types IANA is requested to assign the following types (Table 1) from the "NSH IETF- Assigned Optional Variable-Length Metadata Types" registry available at [IANA-NSH-MD2].These Metadata Types only apply when the Metadata Class is 0x000 (IETF Base NSH MD Class) +=======+==================================+===============+ | Value | Description | Reference | +=======+==================================+===============+ | TBA1 | Forwarding Context | This document | +-------+----------------------------------+---------------+ | TBA2 | Tenant Identifier | This document | +-------+----------------------------------+---------------+ | TBA3 | Ingress Network NodeID | This document | +-------+----------------------------------+---------------+ | TBA4 | Ingress Network Interface | This document | +-------+----------------------------------+---------------+ | TBA5 | Flow ID | This document | +-------+----------------------------------+---------------+ | TBA6 | Source and/or Destination Groups | This document | +-------+----------------------------------+---------------+ | TBA7 | Policy Identifier | This document | +-------+----------------------------------+---------------+ Table 1: Type Values 7.2. Forwarding Context Types IANA is requested to create a new sub-registry for "Forwarding Context" context types at [IANA-NSH-MD2] as follows: The Registration Policy is IETF Review Wei, et al. Expires 16 July 2022 [Page 10] Internet-Draft NSH MD2 Context Headers January 2022 +=========+=========================================+===============+ | Value | Forwarding Context Header Types | Reference | +=========+=========================================+===============+ | 0x0 | 12-bit VLAN identifier | This document | +---------+-----------------------------------------+---------------+ | 0x1 | 24-bit double tagging identifiers | This document | +---------+-----------------------------------------+---------------+ | 0x2 | 20-bit MPLS VPN label | This document | +---------+-----------------------------------------+---------------+ | 0x3 | 24-bit virtual network identifier | This document | | | (VNI) | | +---------+-----------------------------------------+---------------+ | 0x4 | 32-bit Session ID | This document | +---------+-----------------------------------------+---------------+ | 0x5-0xE | Unassigned | | +---------+-----------------------------------------+---------------+ | 0xF | Reserved | This document | +---------+-----------------------------------------+---------------+ Table 2: Forwarding Context Types 8. References 8.1. Normative References [I-D.ietf-sfc-nsh-integrity] Boucadair, M., Reddy, T., and D. Wing, "Integrity Protection for the Network Service Header (NSH) and Encryption of Sensitive Context Headers", Work in Progress, Internet-Draft, draft-ietf-sfc-nsh-integrity-09, 20 September 2021, . [IANA-NSH-MD2] IANA, "NSH IETF-Assigned Optional Variable-Length Metadata Types", . [IEEE.802.1Q_2018] IEEE, "IEEE Standard for Local and Metropolitan Area Networks--Bridges and Bridged Networks", July 2018, . [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . Wei, et al. Expires 16 July 2022 [Page 11] Internet-Draft NSH MD2 Context Headers January 2022 [RFC3931] Lau, J., Ed., Townsley, M., Ed., and I. Goyret, Ed., "Layer Two Tunneling Protocol - Version 3 (L2TPv3)", RFC 3931, DOI 10.17487/RFC3931, March 2005, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [RFC8300] Quinn, P., Ed., Elzur, U., Ed., and C. Pignataro, Ed., "Network Service Header (NSH)", RFC 8300, DOI 10.17487/RFC8300, January 2018, . 8.2. Informative References [OpenDaylight] OpenDaylight, "Group Based Policy", 2021, . [OpenStack] OpenStack, "Group Based Policy", 2021, . [RFC2890] Dommety, G., "Key and Sequence Number Extensions to GRE", RFC 2890, DOI 10.17487/RFC2890, September 2000, . [RFC6790] Kompella, K., Drake, J., Amante, S., Henderickx, W., and L. Yong, "The Use of Entropy Labels in MPLS Forwarding", RFC 6790, DOI 10.17487/RFC6790, November 2012, . [RFC7665] Halpern, J., Ed. and C. Pignataro, Ed., "Service Function Chaining (SFC) Architecture", RFC 7665, DOI 10.17487/RFC7665, October 2015, . [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 (IPv6) Specification", STD 86, RFC 8200, DOI 10.17487/RFC8200, July 2017, . Wei, et al. Expires 16 July 2022 [Page 12] Internet-Draft NSH MD2 Context Headers January 2022 [RFC8979] Sarikaya, B., von Hugo, D., and M. Boucadair, "Subscriber and Performance Policy Identifier Context Headers in the Network Service Header (NSH)", RFC 8979, DOI 10.17487/RFC8979, February 2021, . Authors' Addresses Yuehua Wei (editor) ZTE Corporation No.50, Software Avenue Nanjing 210012 China Email: wei.yuehua@zte.com.cn Uri Elzur Intel Email: uri.elzur@intel.com Sumandra Majee Individual contributor Email: Sum.majee@gmail.com Carlos Pignataro Cisco Email: cpignata@cisco.com Donald E. Eastlake Futurewei Technologies Email: d3e3e3@gmail.com Wei, et al. Expires 16 July 2022 [Page 13]