| Internet-Draft | ICMP System ID | February 2024 |
| Fenner | Expires 12 August 2024 | [Page] |
RFC5837 describes a mechanism for Extending ICMP for Interface and Next-Hop Identification, which allows providing additional information in an ICMP error that helps identify interfaces participating in the path. This is especially useful in environments where each interface may not have a unique IP address to respond to, e.g., a traceroute.¶
This document introduces a similar ICMP extension for Node identification. It allows providing a unique IP address or a textual name for the node, in the case where each node may not have a unique IP address (e.g., the IPv6 nexthop deployment case described in draft-chroboczek-intarea-v4-via-v6).¶
This note is to be removed before publishing as an RFC.¶
The latest revision of this draft can be found at https://fenner.github.io/icmp-node-id/draft-fenner-intarea-extended-icmp-hostid.html. Status information for this document may be found at https://datatracker.ietf.org/doc/draft-fenner-intarea-extended-icmp-hostid/.¶
Discussion of this document takes place on the Internet Area Working Group Working Group mailing list (mailto:int-area@ietf.org), which is archived at https://mailarchive.ietf.org/arch/browse/int-area/. Subscribe at https://www.ietf.org/mailman/listinfo/int-area/.¶
Source for this draft and an issue tracker can be found at https://github.com/fenner/icmp-node-id.¶
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In addition to adding incoming interface information to a traceroute using the mechanisms described in [RFC5837], a network operator may be interested in adding information to identify nodes themselves. [I-D.chroboczek-intarea-v4-via-v6] describes a scenario in which individual nodes do not have unique IPv4 addresses to use to reply to an IPv4 traceroute, so additional information is needed.¶
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.¶
This section defines the Node Identification Object, an ICMP Extension Object with a Class-Num (Object Class Value) of TBD that can be appended to the following messages:¶
ICMPv4 Time Exceeded¶
ICMPv4 Destination Unreachable¶
ICMPv4 Parameter Problem¶
ICMPv6 Time Exceeded¶
ICMPv6 Destination Unreachable¶
For reasons described in [RFC4884], this extension cannot be appended to any of the currently defined ICMPv4 or ICMPv6 messages other than those listed above.¶
The extension defined herein MAY be appended to any of the above listed messages and SHOULD be appended whenever required to identify the node and when local policy or security considerations do not supersede this requirement.¶
C-Type values in a Node Identification Object include:¶
1: Identifies Node by Name¶
If the Node Identification Object identifies the node by name, the Object Payload contains the configured node name. It is presumed that the operator configures a unique node name for each system that is identified in this manner. If the Object Payload would not otherwise terminate on a 32-bit boundary, it MUST be padded with ASCII NULL characters.¶
2: Identifies Node by Address¶
If the Node Identification Object identifies the node by address, the Object Payload contains an address sufficient to identify the node within the appropriate scope - global or as otherwise configured - as depicted in Figure 1.¶
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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | AFI | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Address...
Payload fields are defined as follows:¶
Address Family Identifier (AFI): This 16-bit field identifies the type of address represented by the Address field. Values for this field represent a subset of values found in the IANA registry of Address Family Numbers (available from [IANA.address-family-numbers]). Valid values are 1 (representing a 32-bit IPv4 address) and 2 (representing a 128-bit IPv6 address).¶
Reserved: This field MUST be set to 0 and ignored upon receipt.¶
Address: This variable-length field represents an address of appropriate scope (global, if none other defined) that can be used to identify the node.¶
It may not be desirable to allow this information to be sent to an arbitrary receiver. The addition of this information SHOULD be configurable, and MUST default to off. An implementation SHOULD determine what objects may be appended to a given message based on the destination IP address of the ICMP message that will contain the objects.¶
The intended field of use for the extensions defined in this document is administrative debugging and troubleshooting. The extensions herein defined supply additional information in ICMP responses. These mechanisms are not intended to be used in non-debugging applications.¶
This document does not specify an authentication mechanism for the extension that it defines. Application developers should be aware that ICMP messages and their contents are easily spoofed.¶
This document will ask IANA to allocate an ICMP Extension Object Class referred to as TBD above. But for now this document is just for discussion.¶
This document derives text heavily from [RFC5837], since the underlying mechanism is identical, and only the content of the messages differ.¶