Internet Engineering Task Force (IETF) A. Baber
Request for Comments: 9371
Category: Informational P. Hoffman
ISSN: 2070-1721 ICANN
Registration Procedures for Private Enterprise Numbers (PENs)
This document describes how Private Enterprise Numbers (PENs) are
registered by IANA. It shows how to request a new PEN and how to
modify a current PEN. It also gives a brief overview of PEN uses.
Status of This Memo
This document is not an Internet Standards Track specification; it is
published for informational purposes.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Not all documents
approved by the IESG are candidates for any level of Internet
Standard; see Section 2 of RFC 7841
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at https://www.rfc-editor.org/info/rfc9371
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Table of Contents 1.
Uses of PENs 2.
PEN Assignment 2.1.
Requesting a PEN Assignment 2.2.
Modifying an Existing Record 2.3.
Deleting a PEN Record 3.
PEN Registry Specifics 4.
IANA Considerations 5.
Security Considerations 6.
Normative References 6.2.
Private Enterprise Numbers (PENs) are identifiers that can be used
anywhere that an ASN.1 object identifier (OID) [ASN1] can be used.
Originally, PENs were developed so that organizations that needed to
identify themselves in Simple Network Management Protocol (SNMP)
] Management Information Base (MIB) configurations could do
so easily. PENs are also useful in any application or configuration
language that needs OIDs to identify organizations.
The IANA Functions Operator, referred to in this document as "IANA",
manages and maintains the PEN registry in consultation with the IESG.
PENs are issued from an OID prefix that was assigned to IANA. That
OID prefix is 126.96.36.199.4.1. Using the (now archaic) notation of
ownership names in the OID tree, that corresponds to: 1
3 6 1 4 1
A PEN is an OID that begins with the PEN prefix. Thus, the OID
188.8.131.52.4.1.32473 is a PEN.
1.1. Uses of PENs
Once a PEN has been assigned to an organization, individual, or other
entity, that assignee can use the PEN by itself (possibly to
represent the assignee) or as the root of other OIDs associated with
the assignee. For example, if an assignee is assigned the PEN
184.108.40.206.4.1.32473, it might use 220.127.116.11.4.1.32473.7 to identify a
protocol extension and use 18.104.22.168.4.1.32473.12.3 to identify a set
of algorithms that it supports in a protocol.
Neither IANA nor the IETF can control how an assignee uses its PEN.
In fact, no one can exert such control: that is the meaning of
"private" in "private enterprise number". Similarly, no one can
prevent an assignee that is not the registered owner of a PEN from
using that PEN, or any PEN, however they want.
A very common use of PENs is to give unique identifiers in IETF
protocols. SNMP MIB configuration files use PENs for identifying the
origin of values. Protocols that use PENs as identifiers of
extension mechanisms include RADIUS [RFC2865
], Diameter [RFC6733
], RSVP [RFC5284
], and vCard [RFC6350
2. PEN Assignment
PENs are assigned by IANA. The registry is located at
>, and requests
for new assignments or the modification of existing assignments can
also be submitted at that URL.
IANA maintains the PEN registry in accordance with the "First Come
First Served" registration policy described in [RFC8126
]. Values are
2.1. Requesting a PEN Assignment
Requests for assignment must provide the name of the assignee, the
name of a public contact who can respond to questions about the
assignment, and contact information that can be used to verify change
requests. The contact's name and email address will be included in
the public registry.
A prospective assignee may request multiple PENs, but obtaining one
PEN and making internal sub-assignments is typically more
appropriate. (Sub-assignments should not be reported to IANA.)
IANA may refuse to process abusive requests.
2.2. Modifying an Existing Record
Any of the information associated with a registered value can be
modified, including the name of the assignee.
Modification requests require authorization by a representative of
the assignee. Authorization will be validated either with
information kept on file with IANA or with other identifying
documentation, if necessary.
2.3. Deleting a PEN Record
Although such requests are rare, registrations can be deleted. When
a registration is deleted, all identifying information is removed
from the registry, and the value is marked as "returned." Returned
values will not be made available for reassignment until all other
unassigned values have been exhausted; as can be seen in Section 3
the unassigned values are unlikely to ever run out.
3. PEN Registry Specifics
The range for values after the PEN prefix is 0 to 2**32-1. The
values 0 and 4294967295 (2**32-1) are reserved. Note that while the
original PEN definition had no upper bound for the value after the
PEN prefix, there is now an upper bound due to some IETF protocols
limiting the size of that value. For example, Diameter [RFC6733
limits the value to 2**32-1.
There is a PEN number, 32473, reserved for use as an example in
documentation. This reservation is described in [RFC5612
Values in the registry that have unclear ownership are marked
"Reserved". These values will not be reassigned to a new company or
individual without consulting the IESG.
4. IANA Considerations
Per this document, IANA has made the following changes to the PEN
* Values 2187, 2188, 3513, 4164, 4565, 4600, 4913, 4999, 5099, 5144,
5201, 5683, 5777, 6260, 6619, 14827, 16739, 26975, and the range
from 11670 to 11769, which had been missing from the registry,
have been listed as "Reserved." As described in [RFC8126
reserved values can be released by the IESG.
* This document has been listed in the registry's "Reference" field.
* "First Come First Served" has been listed as its registration
5. Security Considerations
Registering PENs does not introduce any significant security
There is no cryptographic binding of a registrant in the PEN registry
and the PEN(s) assigned to them. Thus, the entries in the PEN
registry cannot be used to validate the ownership of a PEN in use.
For example, if the PEN 22.214.171.124.4.1.32473 is seen in a protocol as
indicating the owner of some data, there is no way to securely
correlate that use with the name and assignee of the owner listed in
the PEN registry.
6.1. Normative References
] 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,
6.2. Informative References
[ASN1] ITU-T, "Information technology - ASN.1 encoding rules:
Specification of Basic Encoding Rules (BER), Canonical
Encoding Rules (CER) and Distinguished Encoding Rules
(DER)", ITU-T Recommendation X.690, February 2021,
] Rigney, C., Willens, S., Rubens, A., and W. Simpson,
"Remote Authentication Dial In User Service (RADIUS)", RFC 2865
, DOI 10.17487/RFC2865
, June 2000,
] Harrington, D., Presuhn, R., and B. Wijnen, "An
Architecture for Describing Simple Network Management
Protocol (SNMP) Management Frameworks", STD 62, RFC 3411
, December 2002,
] Swallow, G. and A. Farrel, "User-Defined Errors for RSVP", RFC 5284
, DOI 10.17487/RFC5284
, August 2008,
] Gerhards, R., "The Syslog Protocol", RFC 5424
, March 2009,
] Eronen, P. and D. Harrington, "Enterprise Number for
Documentation Use", RFC 5612
, DOI 10.17487/RFC5612
] Perreault, S., "vCard Format Specification", RFC 6350
, August 2011,
] Fajardo, V., Ed., Arkko, J., Loughney, J., and G. Zorn,
Ed., "Diameter Base Protocol", RFC 6733
, October 2012,
An earlier draft version of this document was authored by Pearl Liang
and Alexey Melnikov. Additional significant contributions have come
from Dan Romascanu, Bert Wijnen, David Conrad, Michelle Cotton, and
Internet Assigned Numbers Authority
12025 Waterfront Drive
Los Angeles, 90094
United States of America
12025 Waterfront Drive
Los Angeles, 90094
United States of America