ICMP Extensions for Environmental Impact

IP devices use the Internet Control Message Protocol ICMPv4 and ICMPv6 to convey control information to source hosts. In particular, when an IP device receives a datagram that it cannot process, it may send an ICMP message to the datagram's originator or source. Network operators and higher-level protocols use these ICMP messages to detect and diagnose network issues. As the world transitions towards sustainability in technology, the focus is shifting not only on creating modern technologies infused with sustainability but also on bridging gaps in the tools that are already available, to enhance visibility, measurement, and quantification of their impact. Consequently, tools which have been foundational for control and management for decades now encounter new requirements including enhancing them to cater to a significantly increasing demand for monitoring the sustainability and environmental impact. This document serves that need by defining an ICMP extension object that appends environmental impact information to ICMP messages. Using the extension defined herein, a device can explicitly append these exemplary environmental impact metrics: Power metrics (e.g., time average, min/max) Electrical Energy Provider or Zone Geolocation Future sustainability metrics

This document uses the following terms:
Generically referring to ICMPv4 and ICMPv6 messages.
Extended ICMP to support multi-part messages through an ICMP extension structure, as defined in .

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 when, and only when, they appear in all capitals, as shown here.

The IAB held a workshop on "Environmental Impact of Internet Applications and Systems (eimpactws)" , in which the need for visibility into environmental impact metrics within traditional Internet tools such as traceroute was highlighted (see WebVTT cue identifiers 139 and 140 of .) The Environmental Impact ICMP Extensions defined in this document allow for augmenting the traceroute output with environmental metrics from each reported node.

This section defines the Environmental Impact Object, an ICMP extension object with a Class-Num (Object Class Value) of TBA that can be appended to the following messages, as per and : ICMPv4 Time Exceeded ICMPv4 Destination Unreachable ICMPv4 Parameter Problem ICMPv4 Extended Echo Reply ICMPv6 Time Exceeded ICMPv6 Destination Unreachable ICMPv6 Extended Echo Reply The ICMP extension defined in this document MAY be appended to any of the above listed messages based on policy and following security considerations. These extensions are preceded by an ICMP Extension Structure Header, and include an ICMP Object Header. Both are defined in . The same backward compatibility issues that apply to apply to this extension. A single ICMP message can contain zero, one, or multiple instances of the Environmental Impact Object. The C-Type further identifies the information fields carried. A single instance of the Environmental Impact Object can convey the following information from each reporting node: TODO FROM C-TYPE DEFINITION.

The ICMP Environmental Impact Extension has the following format.

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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+... |Version| Reserved | Checksum |(1) +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+... | Length | Class-Num | C-Type | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+(2) ~ Object payload ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+...
2 .
0 .
The one's complement checksum of the ICMP extension .
Length of the object, including header and payload, in octets.
TBA (Environmental Impact)
C-Type as explained in .

The 8-bit C-Type defined in the Section 8 of allows to carry different information elements within this Class-Num (TBA). The techniques herein defined can be used with any specific e-impact metric in use, current or future.

The ICMP Environmental Impact Extension Object header has the following format: 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=TBA | C-Type=1-255 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ The following C-Type values are currently defined. Power Consumption Sub-Object

A Class-Num of TBA and a C-Type of 1 are specified. The returned power metric is a magnitude that may be directly displayed, and is expressed in Watts; one of the uses is having a traceroute or ping facility that shows per-hop power metrics. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Power (32-bit unsigned word) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Other metrics to be provided in subsequent revisions.

The security considerations of and of apply to these extensions. Upon receipt of an ICMP message, application software must check it for syntactic correctness. The extension checksum MUST be verified. Care should be taken, as improperly specified length attributes and other syntax problems may result in buffer overruns. This document does not define the conditions under which a router sends an ICMP message. Therefore, it does not expose routers to any new denial-of-service attacks. Routers may need to limit the rate at which ICMP messages are sent. This document defines an extension that allows a router to append environmental impact information to multi-part ICMP messages, and therefore can provide the user of the traceroute and ping applications with additional metrics. The intended field of use for the extensions defined in this document is administrative debugging and troubleshooting and operational facilities. The extensions herein defined supply additional information in ICMP responses. These mechanisms are not initially intended for other uses. Some of the additional metrics provided, as e.g., power draw information, have privacy considerations. For example, behavioral considerations of the devices, or estimating other node and network attributes from the power or energy data. This document does not specify an authentication mechanism for the extension that it defines. Application developers should be aware of various ICMP attacks .

IANA is requested to assign the following object Class-num in the ICMP Extension Object Classes and Class Sub-types registry : Class Value Class name Reference TBA Environmental Impact Object This document IANA is requested to establish a registry for the corresponding class sub-type (C-Type) space, as follows: C-Type Value Description Reference 0 Reserved This document 1 Power This document 2-246 Unassigned 247-255 Reserved for Experimentation This document C-Type values are assignable on a first-come-first-serve (FCFS) basis.

We are very grateful to Michael Welzl for his thorough review and most useful set of comments and suggestions.