6MAN Working Group X. He Internet-Draft China Telecom Intended status: Standards Track X. Min Expires: 22 December 2024 ZTE Corp. C. Xie China Telecom T. Mizrahi Huawei Z. Li China Mobile 20 June 2024 ICMPv6 Extensions for Reflecting IPv6 Extension Header draft-he-6man-icmpv6-extensions-ipv6-ext-header-00 Abstract This document defines a generic ICMPv6 extensions for carrying and reflecting IPv6 extension header, using two extended ICMPv6 message types: Echo Request and Echo Reply, for diagnostic purposes. Also, an example of leveraging the ICMPv6 extensions for carrying and reflecting IPv6 option header, which contains the IOAM Trace Option, is presented. 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 22 December 2024. Copyright Notice Copyright (c) 2024 IETF Trust and the persons identified as the document authors. All rights reserved. He, et al. Expires 22 December 2024 [Page 1] Internet-Draft ICMPv6 Extensions for Reflecting IPv6 Ex June 2024 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 . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.1. Requirements Language . . . . . . . . . . . . . . . . . . 4 2.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4 3. The extended ICMPv6 Messages . . . . . . . . . . . . . . . . 4 3.1. The extended Echo Request Message . . . . . . . . . . . . 4 3.1.1. ICMP Extension Objects . . . . . . . . . . . . . . . 5 3.1.2. Examples of Echo Request . . . . . . . . . . . . . . 6 3.2. The extended Echo Reply Message . . . . . . . . . . . . . 7 3.2.1. ICMP Extension Objects . . . . . . . . . . . . . . . 8 3.2.2. Examples of Echo Reply . . . . . . . . . . . . . . . 8 4. The Extended Echo Request/Reply Operation . . . . . . . . . . 10 5. Example of Reflecting IOAM Trace Information . . . . . . . . 10 5.1. Operation of the Extended ICMPv6 Messages . . . . . . . . 12 6. Updates to RFC 4884 . . . . . . . . . . . . . . . . . . . . . 13 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13 7.1. ICMPv6 Type . . . . . . . . . . . . . . . . . . . . . . . 13 7.2. ICMP Extension Object Class . . . . . . . . . . . . . . . 14 8. Security Considerations . . . . . . . . . . . . . . . . . . . 14 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 14 9.1. Normative References . . . . . . . . . . . . . . . . . . 14 9.2. Informative References . . . . . . . . . . . . . . . . . 15 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16 1. Introduction As specified in [RFC4443], the Internet Control Message Protocol for IPv6 (ICMPv6) is an integral part of IPv6, and the base protocol MUST be fully implemented by every IPv6 node. ICMPv6 messages include error messages and informational messages, and the latter are referred to as ICMPv6 Echo Request/Reply messages. ICMPv6 Echo request/reply message is very commonly used for diagnostic purposes, such as PING [RFC2151], to test bidirectional connectivity between two nodes: the source node sends an Echo Request to the destination node, and the destination node responds with an Echo Reply to the source node. The data (payload) received in the ICMPv6 Echo Request message MUST be returned entirely and unmodified in the ICMPv6 Echo He, et al. Expires 22 December 2024 [Page 2] Internet-Draft ICMPv6 Extensions for Reflecting IPv6 Ex June 2024 Reply message. [RFC4884] defines ICMPv6 Extension Structure by which multi-part ICMPv6 error messages are supported. [RFC8335] defines ICMPv6 Extended Echo Request/Reply messages, containing an ICMPv6 Extension Structure customized for this message. Both [RFC4884] and [RFC8335] provide sound principles and examples on how to extend ICMPv6 messages. IPv6 encapsulation for In-situ OAM (IOAM) data is defined in RFC9486], which uses the IPv6 Hop-by-Hop and Destination options header to carry IOAM data fields ([RFC9197], [RFC9326]). [I-D. shi- ippm-congestion-measurement-data] also adopts Hop-by-hop Option Header and Destination option header to collect the congestion information data along the path. [draft-filsfils-ippm-path-tracing] provides a record of the packet path as a sequence of interface ids by adopting Hop-by-hop Option Header and Destination option header. These two extension option headers are used for collecting information along the path a packet traverses. It is expected that there are more requirements that need to use IPv6 options header for carrying path information in the future. The collected information is then exported to a central collector or controller for further process. However, clearly in some cases, the sender is more concerned about these trace information. Currently there are some RFCs and ongoing drafts in IETF that describe methods for sending this tracking information back to the sender. [RFC9322] defines two new flags in the IOAM Trace Option headers: the Loopback and Active flags. The Loopback flag is used to request that each transit device along the path loops back a truncated copy of the data packet to the sender. The Active flag indicates that a packet is used for active measurement. [I-D. ippm-stamp-ext-hdr-00] extends Simple Two-Way Active Measurement Protocol (STAMP) to carry and reflect any type of IPv6 option that carries IOAM data fields. This document defines a generic ICMPv6 extensions for carrying and reflecting IPv6 extension headers, using two extended ICMPv6 message types: Echo Request and Echo Reply. Also, an example of leveraging the ICMPv6 extensions for carrying and reflecting IPv6 option header, which contains the IOAM Trace Option, is presented. 2. Conventions He, et al. Expires 22 December 2024 [Page 3] Internet-Draft ICMPv6 Extensions for Reflecting IPv6 Ex June 2024 2.1. 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. 2.2. Terminology Abbreviations used in this document: ICMPv6: Internet Control Message Protocol for IPv6 IOAM: In situ Operation, Administration, and Maintenance ECMP: Equal-Cost Multipath 3. The extended ICMPv6 Messages This document defines two extended ICMPv6 types: the extended Echo Request and the extended Echo Reply. 3.1. The extended Echo Request Message 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Code | Checksum | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Identifier | Sequence Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ICMP Extension Structure | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 1: The Extended Echo Request ICMPv6 Fields: Type: TDB, defined in this document. Code: MUST be set to 0. Identifier: As defined in [RFC4443], the identifier to aid in matching Echo Replies to this Echo Request. May be zero. Sequence Number: As defined in [RFC4443], the sequence number to aid in matching Echo Replies to this Echo Request. May be zero. He, et al. Expires 22 December 2024 [Page 4] Internet-Draft ICMPv6 Extensions for Reflecting IPv6 Ex June 2024 ICMP Extension Structure: As defined in [RFC4884], it contains exactly one Extension Header followed by one or more extension objects. Description Every node MUST implement an ICMPv6 Echo responder function that receives ICMPv6 Echo Requests and originates corresponding Echo Replies. A node SHOULD also implement an application-layer interface for originating ICMPv6 Echo Requests and receiving ICMPv6 Echo Replies, for diagnostic purposes. Upper Layer Notification Echo Request messages MAY be passed to processes receiving ICMP messages. 3.1.1. ICMP Extension Objects Each extension object contains one 32-bit word, representing an object header without any payload. All object headers share a common format. Figure 2 depicts the object header. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Length | Class-Num | C-Type | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 2: Object header without any Payload AS defined in [RFC4884], an object header has the following fields: Length: 16 bits, length of the object, measured in octets, including the object header. Class-Num: 8 bits, identifies object class. C-Type: 8 bits, identifies object sub-type. This document defines the values of Class-Num and C-Type as follows: * Class-Num: IPv6 extension header Object. The values are listed as the following: He, et al. Expires 22 December 2024 [Page 5] Internet-Draft ICMPv6 Extensions for Reflecting IPv6 Ex June 2024 Value Object Name ----- ----------- TBD1 the Hop-by-Hop Options header TBD2 the Destination Options header TBD3 the Routing header * C-Type: Values are listed as the following: Class-Num C-Type C-Type Name --------- ------ ----------- TBD1 0 Reserved TBD2 0 Reserved TBD3 0 Reserved 3.1.2. Examples of Echo Request In some use cases where only one object is used, which instructs the destination node (Echo responder) to copy the corresponding IPv6 extension header into the Object payload in the extended Echo Reply packet,, the Echo Request is depicted as follows: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Code | Checksum | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Identifier | Sequence Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ICMP Extension Header | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Length | Class-Num1 | C-Type(0) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 3: Echo Request of ICMP extension structure including one object In another use cases where multiple objects may be used, which instruct the destination node to copy the multiple corresponding IPv6 extension headers into the Object payload respectively, the Echo Request with two objects is depicted as follows: He, et al. Expires 22 December 2024 [Page 6] Internet-Draft ICMPv6 Extensions for Reflecting IPv6 Ex June 2024 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Code | Checksum | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Identifier | Sequence Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ICMP Extension Header | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Length | Class-Num1 | C-Type(0) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Length | Class-Num2 | C-Type(0) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 4: Echo Request of ICMP extension header including two object 3.2. The extended Echo Reply Message 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Code | Checksum | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Identifier | Sequence Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ICMP Extension Structure | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 5: The Extended Echo Reqply ICMPv6 Fields: Type: TDB, defined in this document. Code: MUST be set to 0. Identifier: As defined in [RFC4443], the identifier from the invoking Echo Request message. Sequence Number: As defined in [RFC4443], the sequence number from the invoking Echo Request message. ICMP Extension Structure: As defined in [RFC4884], it contains exactly one Extension Header followed by one or more extension objects. Description He, et al. Expires 22 December 2024 [Page 7] Internet-Draft ICMPv6 Extensions for Reflecting IPv6 Ex June 2024 Every node MUST implement an ICMPv6 Echo responder function that receives ICMPv6 Echo Requests and originates corresponding Echo Replies. A node SHOULD also implement an application-layer interface for originating ICMPv6 Echo Requests and receiving ICMPv6 Echo Replies, for diagnostic purposes. Upper Layer Notification Echo Reply messages MUST be passed to the process that originated an Echo Request message. 3.2.1. ICMP Extension Objects Each extension object contains one or more 32-bit words, including an object header and payload. All object headers share a common format. Figure 6 depicts the object header and payload. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Length | Class-Num | C-Type | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | // (Object payload) // | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 6: Object header and payload AS defined in [RFC4884], an object header has the following fields: Length: 16 bits, length of the object, measured in octets, including the object header. Class-Num: 8 bits, and its values are defined in Section 3.1.1. C-Type: 8 bits, and its values are defined in Section 3.1.1. Object payload: n*32 bits, MUST contain the integral IPv6 extension header, including Next Header field, Hdr Ext Len field and Options field, defined in RFC8200. Echo Reply packet MUST copy the entire IPv6 extension header into the Object payload. 3.2.2. Examples of Echo Reply In some use cases where only one object is used, the Echo Reply, with an Object payload containing the corresponding IPv6 extension header, is depicted as follows: He, et al. Expires 22 December 2024 [Page 8] Internet-Draft ICMPv6 Extensions for Reflecting IPv6 Ex June 2024 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Code | Checksum | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Identifier | Sequence Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ICMP Extension Header | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Length | Class-Num1 | C-Type (0) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | Object payload containing IPv6 Hop-by-Hop Options Header | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 7: The extended Echo Reply including an object carrying the corresponding IPv6 extension header In another use cases where two objects may be used, the Echo Reply, with two Object payloads containing the IPv6 extension header respectively, is depicted as follows: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Code | Checksum | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Identifier | Sequence Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ICMP Extension Header | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Length | Class-Num1 | C-Type (0) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | Object payload containing IPv6 Hop-by-Hop Options Header | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Length | Class-Num2 | C-Type (0) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | Object payload containing IPv6 Destination Options Header | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 8: The extended Echo Reply including two objects He, et al. Expires 22 December 2024 [Page 9] Internet-Draft ICMPv6 Extensions for Reflecting IPv6 Ex June 2024 4. The Extended Echo Request/Reply Operation When the source node adds an IPv6 extension header to be reflected, it also MUST add one object contained in ICMP extension structure in the extended ICMPv6 Echo Request packet, which instructs the destination node to copy the corresponding IPv6 extension header into the Object payload in the extended Echo Reply packet. When adding multiple IPv6 extension headers, one or multiple objects MUST be added, each one with matching IPv6 extension header object class. When the extended Echo Request packet carries an IPv6 extension header that it does not require Echo responder to reflect in the Echo Reply packet, it SHOULD not add the matching object class in ICMP extension structure in the extended Echo Request packet. When the Echo responder receives the extended Echo Request packet with IPv6 extension header and ICMP extension structure, the responder that supports this extended Echo, MUST copy the entire IPv6 extension header into the Object payload in the extended Echo Reply packet. When the Echo responder receives the extended Echo Request packet with IPv6 extension header but it does not carry any object in ICMP extension structure, the responder SHOULD not copy the entire IPv6 extension header into the Object payload. When the Echo responder receives the extended Echo Request packet with IPv6 extension header and ICMP extension structure carrying any unrecognized object class, the responder SHOULD skip this object and only copy the entire IPv6 extension header with recognized object class into the Object payload. 5. Example of Reflecting IOAM Trace Information In situ Operations, Administration, and Maintenance (IOAM) collects operational and telemetry information in packets while they traverse a path between two points in the network. The IOAM data fields are defined in [RFC9197]. This document presents an example of leveraging the ICMPv6 extensions for carrying and reflecting IPv6 options header, which contains the IOAM Trace Option. IPv6 encapsulation for IOAM data is defined in RFC9486], which uses the IPv6 Hop-by-Hop option header to collect information along the path a packet traverses. Clearly in some cases, the sender is more concerned about these trace information. Some possible needs are listed as follows: * Which nodes and links does the specified traffic flow traverse? He, et al. Expires 22 December 2024 [Page 10] Internet-Draft ICMPv6 Extensions for Reflecting IPv6 Ex June 2024 * In an Equal-Cost Multipath (ECMP) scenario, which ECMP path does a specified N-tuple of flow pass through? * Is the specified traffic flow forwarding path consistent on both forward and reverse path? An integral extended Echo Request packet includes IPv6 header, Hop- by-Hop option header, ICMPv6 header and ICMP extension structure that contains one object, instructing the Echo responder to reflect IOAM trace information. This extended Echo Request packet is depicted as follows: +----------------------------+ | IPv6 Header | +----------------------------+ | Hop-by-Hop Option Header | +----------------------------+ | ICMPv6 Header | +----------------------------+--+ | ICMP Extension Header | | +----------------------------+ ICMP Extension Structure | Object Header | | +----------------------------+--+ Figure 9: An integral extended Echo Request packet Similarly, an integral extended Echo Reply packet also includes IPv6 header, Hop-by-Hop option header, ICMPv6 header and ICMP extension structure that contains one object with object payload field filled with Hop-by-Hop option header. This extended Echo Reply packet is depicted as follows: +----------------------------------+ | IPv6 Header | +----------------------------------+ | Hop-by-Hop Options Header | +----------------------------------+ | ICMPv6 Header | +----------------------------------+--+ | ICMP Extension Header | | +----------------------------------+ | | Object Header |ICMP Extension Structure +----------------------------------+ | | Object payload | | | (IPv6 Hop-by-Hop Options Header) | | +----------------------------------+--+ He, et al. Expires 22 December 2024 [Page 11] Internet-Draft ICMPv6 Extensions for Reflecting IPv6 Ex June 2024 Figure 10: An integral extended Echo Reply packet 5.1. Operation of the Extended ICMPv6 Messages An IOAM network can be depicted as follows. +--------+ +-----------+ +-----------+ +-----------+ +--------+ | Host |=====| IOAM node |=====| IOAM node |=====| IOAM node |=====| Host | +--------+ +-----------+ +-----------+ +-----------+ +--------+ Encapsulating Transit Decapsulating Node Node Node |------------------ IOAM-Domain ---------------| Figure 11: IOAM network The sender (source) of the Echo request messages can be a host or network device. When a host or a network device sends an Echo request message, if it acts as an IOAM encapsulating node, it MUST perform the operation of IOAM Data-Fields encapsulation, i.e., it MUST place the IOAM Data-Fields directly in the IPv6 Hop-by-Hop Option Header. To accurately retrieve the trace information the Echo request packet traverses, including all nodes and links it passes through, the IOAM encapsulating node MUST set both the Most significant bit (Bit 0) and Bit 1 of the IOAM Trace-Type value to "1". Therefore, when processing this trace option, every transit node (including encapsulating node) in IOAM-Domain MUST populates its IOAM data with two data fields, namely, the Hop_Lim and node_id data field and ingress_if_id and egress_if_id data field. The rest of the bits of IOAM-Trace-Type MAY be set "1" or "0" depending on implementation. Similarly, the responder (destination) of the Echo request messages can also be a host or network device. When a host or a network device receives an Echo request message, if it acts as an IOAM node, no matter what node (encapsulating node, transit node or decapsulating node) it is, it MUST originate an Echo reply message, copying the entire IPv6 Hop-by-Hop Option Header with IOAM Data into the Object payload of ICMP Extension Structure. He, et al. Expires 22 December 2024 [Page 12] Internet-Draft ICMPv6 Extensions for Reflecting IPv6 Ex June 2024 In reverse path, to accurately retrieve the trace information the Echo reply packet traverses, similarly, when processing this trace option, every transit node in IOAM-Domain MUST populates IOAM Data with two data fields, namely, the Hop_Lim and node_id data field and ingress_if_id and egress_if_id data field. The sender can determine the consistence of the forward and reverse path by comparing the Object payload of ICMP Extension Structure with the IPv6 Hop-by-Hop Options Header carrying IOAM data in the received Echo reply packet. Notably, to simulate the real path the specified traffic flow traverses, especially in ECMP scenario, the same value or values in any ECMP affecting fields (e.g., the 3-tuple of the Flow Label, Source Address, and Destination Address fields [RFC6437]) MUST be populated in Echo request packets, ensuring the fate sharing between the Echo request/reply packets and the specified traffic flow packets. 6. Updates to RFC 4884 Section 4.6 of [RFC4884] provides a list of extensible ICMP messages (i.e., messages that can carry the ICMP Extension Structure). This document adds the ICMPv6 Extended Echo Request message and the ICMPv6 Extended Echo Reply message to that list. 7. IANA Considerations 7.1. ICMPv6 Type IANA is requested to allocate the following values in the "Internet Control Message Protocol version 6 (ICMPv6) Parameters" registry. Two values are to be allocated from the "ICMPv6 type Numbers" range: +---------+------------------+--------+-------------+------------------+ | Type | Name | Code | Name | Reference | +---------+------------------+--------+-------------+------------------+ | TBD | Echo Request | 0 | Reserved | [This document] | +---------+---------------------------+-------------+------------------+ | TBD | Echo Reply | 0 | Reserved | [This document] | +---------+------------------+--------+-------------+------------------+ Figure 12: The extended ICMPv6 Type Numbers The two type values should be allocated from one of the unassigned values greater than 127. He, et al. Expires 22 December 2024 [Page 13] Internet-Draft ICMPv6 Extensions for Reflecting IPv6 Ex June 2024 IANA is requested to define a code registry for each of the two new types. The registration procedure for these registries is First Come First Served. In each of these new registries, a single code value is assigned by this document: Code 0. 7.2. ICMP Extension Object Class IANA is requested to allocate the following values in the "ICMP Extension Object Classes and Class Sub-types" registry. +--------------+----------------------------+----------+---------------+-----------------+ | Class-Num | Object Name | C-Type | C-Type Name | Reference | +--------------+------------------+---------+---------------+----------------------------+ | TBD1 | Hop-by-Hop Options Header | 0 | Reserved | [This document] | +--------------+----------------------------+----------+---------------+-----------------+ | TBD2 | Destination Options Header | 0 | Reserved | [This document] | +--------------+----------------------------+----------+---------------+-----------------+ | TBD3 | Routing Header | 0 | Reserved | [This document] | +--------------+----------------------------+----------+---------------+-----------------+ Figure 13: ICMP Extension Object Classes and Class Sub-types values 8. Security Considerations From a security perspective this document does not introduce new security threats beyond the threats that are already applicable for existing ICMPv6 messages, and are described in [RFC4443]. The extended ICMPv6 Echo Reply message can be longer than the extended Echo Request message, since the Extension Structure of the extended Echo Reply includes one or more objects containing the respective IPv6 options header. Thus, an Echo Reply message is slightly amplified compared to an Echo Request message. However, the amplification effect is minor, as an IPv6 options can have a maximum length of 255 octets. 9. References 9.1. 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, . He, et al. Expires 22 December 2024 [Page 14] Internet-Draft ICMPv6 Extensions for Reflecting IPv6 Ex June 2024 [RFC2151] Kessler, G. and S. Shepard, "A Primer On Internet and TCP/ IP Tools and Utilities", FYI 30, RFC 2151, DOI 10.17487/RFC2151, June 1997, . [RFC4443] Conta, A., Deering, S., and M. Gupta, Ed., "Internet Control Message Protocol (ICMPv6) for the Internet Protocol Version 6 (IPv6) Specification", STD 89, RFC 4443, DOI 10.17487/RFC4443, March 2006, . [RFC4884] Bonica, R., Gan, D., Tappan, D., and C. Pignataro, "Extended ICMP to Support Multi-Part Messages", RFC 4884, DOI 10.17487/RFC4884, April 2007, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [RFC8335] Bonica, R., Thomas, R., Linkova, J., Lenart, C., and M. Boucadair, "PROBE: A Utility for Probing Interfaces", RFC 8335, DOI 10.17487/RFC8335, February 2018, . [RFC9197] Brockners, F., Ed., Bhandari, S., Ed., and T. Mizrahi, Ed., "Data Fields for In Situ Operations, Administration, and Maintenance (IOAM)", RFC 9197, DOI 10.17487/RFC9197, May 2022, . [RFC9486] Bhandari, S., Ed. and F. Brockners, Ed., "IPv6 Options for In Situ Operations, Administration, and Maintenance (IOAM)", RFC 9486, DOI 10.17487/RFC9486, September 2023, . 9.2. Informative References [I-D.filsfils-ippm-path-tracing] Filsfils, C., Abdelsalam, A., Camarillo, P., Yufit, M., Graf, T., Su, Y., Matsushima, S., Valentine, M., and Dhamija, "Path Tracing in SRv6 networks", Work in Progress, Internet-Draft, draft-filsfils-ippm-path- tracing-01, 2 June 2024, . He, et al. Expires 22 December 2024 [Page 15] Internet-Draft ICMPv6 Extensions for Reflecting IPv6 Ex June 2024 [I-D.ietf-ippm-stamp-ext-hdr] Gandhi, R. and T. Zhou, "Simple Two-Way Active Measurement Protocol (STAMP) Extensions for Reflecting STAMP Packet Extension Headers", Work in Progress, Internet-Draft, draft-ietf-ippm-stamp-ext-hdr-00, 30 May 2024, . [I-D.shi-ippm-congestion-measurement-data] Shi, H., Zhou, T., and Z. Li, "Data Fields for Congestion Measurement", Work in Progress, Internet-Draft, draft-shi- ippm-congestion-measurement-data-00, 3 March 2024, . [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 8126, DOI 10.17487/RFC8126, June 2017, . [RFC9322] Mizrahi, T., Brockners, F., Bhandari, S., Gafni, B., and M. Spiegel, "In Situ Operations, Administration, and Maintenance (IOAM) Loopback and Active Flags", RFC 9322, DOI 10.17487/RFC9322, November 2022, . [RFC9343] Fioccola, G., Zhou, T., Cociglio, M., Qin, F., and R. Pang, "IPv6 Application of the Alternate-Marking Method", RFC 9343, DOI 10.17487/RFC9343, December 2022, . Authors' Addresses Xiaoming He China Telecom Email: hexm4@chinatelecom.cn Xiao Min ZTE Corp. Email: xiao.min2@zte.com.cn Chongfeng Xie China Telecom Email: xiechf@chinatelecom.cn He, et al. Expires 22 December 2024 [Page 16] Internet-Draft ICMPv6 Extensions for Reflecting IPv6 Ex June 2024 Tal Mizrahi Huawei Email: tal.mizrahi.phd@gmail.com Zhenqiang Li China Mobile Email: li_zhenqiang@hotmail.com He, et al. Expires 22 December 2024 [Page 17]