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General GenDispatch Working Group experiment This document describes IETF protocol experiments and provides guidelines for the publication of Experimental RFCs.

Introduction According to , the "Experimental" designation for an RFC typically denotes a specification that is part of a research or development effort. An Experimental RFC may be published for information and as an archival record of the work. An Experimental RFC may be the output of an IRTF Research Group, an IETF Working Group, or it may be an individual contribution that is sponsored by an Area Director or published on the Independent Submission Stream. Experimental RFCs in the IETF Stream describe IETF experiments. IETF process experiments are described in , but this document is concerned with protocol experiments. An IETF protocol experiment is a procedure that is executed on the Internet for a bounded period of time. The experiment can, but does not always, include the deployment of a new protocol or protocol extension. For example, when two protocols are proposed to solve a single problem, the IETF can initiate an experiment in which each protocol is deployed. Operational experience obtained during the experiments can help to determine which, if either, of the protocols should be progressed to the standards track. An IETF protocol experiment must not harm the Internet or interfere with established network operations. It must be conducted in a carefully controlled manner (for example, using a limited domain ). Furthermore, it must use protocol identifiers and code points that do not conflict with deployments of standardized protocols or other experiments. When an IETF protocol experiment concludes, experimental results should be reported to the relevant working group usually via an Internet-Draft, and may be published in an Informational RFCs. This document describes IETF protocol experiments and provides guidelines for the publication of Experimental RFCs. Experimental RFCs in the Independent Submissions Stream or published by the IRTF are out of scope of this document.

Requirements on Experimental RFCs An Experimental RFC must describe the experimental nature of the specification or deployment that it documents. An Experimental RFC should:

• Describe the experiment in detail, so that it can be replicated by non-collaborating parties and recognized when it is seen in deployments.
• Describe how the experiment is safegarded so that it does not harm the Internet or interfere with its established operations.
  • It should indicate how messages or protocol data units are identified and associated with the experiment.
  • It should describe how backward compatability is ensured by non-participating deployments using pre-existing standardized mechanisms to discard or ignore the experiment.
  • It should explain how the experiment is controlled so that it does not "leak out" into the wider Internet.
• List what configuration knobs should be provided on experimental implementations
• Include a date at which the experiment will be terminated.
• Include metrics and observations that will be collected during the experiment.
• Include criteria by which success of the experiment will be determined.
• Explain how reports of the success or failure of the experiment will be brought to the IETF.
• Suggest planned next steps if the experiment is fully or partially successful.

When two protocol mechanisms are proposed to solve a single problem, the IETF can initiate an experiment in which each protocol is deployed. In this case, the same metrics should be collected in each experiment.

Codepoints in Experimental RFCs describes guidelines for writing IANA Considerations sections in RFCs. It lists a number of assignment policies that apply to codepoint registries maintained by IANA. Experimental RFCs cannot obtain codepoints from registries or parts of registries that are managed under the following assignment policies:

• Standards Action
• Hierarchical Allocation

An Experimental RFC may request and be granted codepoints from registries or parts of registries that are managed under the following assignment policies:

• First Come First Served
• Expert Review
• Specification Required
• RFC Required
• IETF Review
• IESG Approval

Consideration must be given to the fact that the experiment may be temporary in nature and the protocol or protocol extensions may be abandoned. If there is a scarcity of available codepoints in a registry, even more caution should be applied to any codepoint assignments. Some registries or parts of registries are marked as "For Experimental Use: Not to be assigned." These ranges are specifically intended for use by protocol experiments, and this may be particularly valuable as described in . But assigments are not made from these codepoint ranges and Experimental RFCs must not document any codepoints from such ranges. Instead, protocol implementations should allow the codepoints to be configured so that all implementations participating in an experiment can interoperate and so that multiple experiments may co-exist in the same network. Experiments may additionally use codepoints from Private Use ranges, but these codepoints are also not recorded Additionally, IANA will not create any new registries or sub-registries as specified in Experimental RFCs. Experimental RFCs that would otherwise ask for the creation of protocol registries can simply enumerate the codepoints within the RFC. [Editors' note: The first sentence in the previous paragraph is to be verified by IANA.]

Requirements Level Language and Keywords An Experimental RFC describing a protocol experiment may use BCP 14 requirements level language and keywords to help clarify the description of the protocol or prtocol extension and the expected behavior of implementations.

Experimental Reports Experimental Reports should include the following information:

• Scale of deployment
• Effort required to deploy
  • Was deployment incremental or network-wide?
  • Was there a need to synchronize configurations at each node or could nodes be configured independently
  • Did the deployment require hardware upgrade?
• Effort required to secure
• Performance impact of risk mitigation
• Effectiveness of risk mitigation
• Cost of risk mitigation
• Interoperability
• Did you deploy two inter-operable implementations?
• Did you experience interoperability problems?
• Effectiveness and sufficiency of OAM mechanism

IANA Considerations This document does not make any requests of IANA, but see for details of the use of codepoints in Experimental RFCs.

Security Considerations As this document does not introduce any new protocols or operational procedures, it does not introduce any new security considerations. Experimental RFCs must include security and privacy considerations as with any other RFC. As well as considering the security and privacy implications of the protocol or protocol extensions, Experimental RFCs should examine the implications for security and privacy of running an experiment on the Internet.

Acknowledgements The authors wish to acknowledge Dhruv Dhody for helpful discussions of experimenal code points.

References Normative References Many protocols make use of points of extensibility that use constants to identify various protocol parameters. To ensure that the values in these fields do not have conflicting uses and to promote interoperability, their allocations are often coordinated by a central record keeper. For IETF protocols, that role is filled by the Internet Assigned Numbers Authority (IANA). To make assignments in a given registry prudently, guidance describing the conditions under which new values should be assigned, as well as when and how modifications to existing values can be made, is needed. This document defines a framework for the documentation of these guidelines by specification authors, in order to assure that the provided guidance for the IANA Considerations is clear and addresses the various issues that are likely in the operation of a registry. This is the third edition of this document; it obsoletes RFC 5226. In many standards track documents several words are used to signify the requirements in the specification. These words are often capitalized. This document defines these words as they should be interpreted in IETF documents. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements. RFC 2119 specifies common key words that may be used in protocol specifications. This document aims to reduce the ambiguity by clarifying that only UPPERCASE usage of the key words have the defined special meanings. Informative References This memo documents the process used by the Internet community for the standardization of protocols and procedures. It defines the stages in the standardization process, the requirements for moving a document between stages and the types of documents used during this process. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements. The IETF has designed process changes over the last ten years in one of two ways: announcement by the IESG, sometimes based on informal agreements with limited community involvement and awareness, and formal use of the same mechanism used for protocol specification. The first mechanism has often proven to be too lightweight, the second too heavyweight. This document specifies a middle-ground approach to the system of making changes to IETF process, one that relies heavily on a "propose and carry out an experiment, evaluate the experiment, and then establish permanent procedures based on operational experience" model rather than those previously attempted. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements. There is a noticeable trend towards network behaviors and semantics that are specific to a particular set of requirements applied within a limited region of the Internet. Policies, default parameters, the options supported, the style of network management, and security requirements may vary between such limited regions. This document reviews examples of such limited domains (also known as controlled environments), notes emerging solutions, and includes a related taxonomy. It then briefly discusses the standardization of protocols for limited domains. Finally, it shows the need for a precise definition of "limited domain membership" and for mechanisms to allow nodes to join a domain securely and to find other members, including boundary nodes. This document is the product of the research of the authors. It has been produced through discussions and consultation within the IETF but is not the product of IETF consensus. When experimenting with or extending protocols, it is often necessary to use some sort of protocol number or constant in order to actually test or experiment with the new function, even when testing in a closed environment. For example, to test a new DHCP option, one needs an option number to identify the new function. This document recommends that when writing IANA Considerations sections, authors should consider assigning a small range of numbers for experimentation purposes that implementers can use when testing protocol extensions or other new features. This document reserves some ranges of numbers for experimentation purposes in specific protocols where the need to support experimentation has been identified.