| Internet-Draft | LISP Distinguished Name Encoding | August 2023 |
| Farinacci | Expires 21 February 2024 | [Page] |
This draft defines how to use the AFI=17 Distinguished Names in LISP.¶
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The LISP architecture and protocols [RFC9300] introduces two new numbering spaces, Endpoint Identifiers (EIDs) and Routing Locators (RLOCs) which are intended to replace most use of IP addresses on the Internet. To provide flexibility for current and future applications, these values can be encoded in LISP control messages using a general syntax that includes Address Family Identifier (AFI) [RFC1700].¶
The length of the value field is implicit in the type of address that follows. For AFI 17, a Distinguished Name can be encoded. A name can be a variable length field so the length cannot be determined solely from the AFI value 17. This draft defines a termination character, an 8-bit value of 0 to be used as a string terminator so the length can be determined.¶
LISP Distinguished Names are useful when encoded either in EID-records or RLOC-records in LISP control messages. As EIDs, they can be registered in the mapping system to find resources, services, or simply used as a self-documenting feature that accompany other address specific EIDs. As RLOCs, Distinguished Names, along with RLOC specific addresses and parameters, can be used as labels to identify equipment type, location, or any self-documenting string a registering device desires to convey.¶
An AFI=17 Distinguished Name is encoded as:¶
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 = 17 | ASCII String ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... ASCII String | 0 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+¶
The string of characters are encoded in the ASCII character-set definition [RFC0020].¶
When Distinguished Names are encoded for EIDs, the EID-prefix length of the EIDs as they appear in EID-records for all LISP control messages is the length of the string in bits (include the null 0 byte). Where Distinguished Names are encoded anywhere else (i.e. nested in LCAF encodings), then any length field is the length of the ASCII string including the null 0 byte in units of bytes.¶
When Map-Requests are sent for an EID encoded in Distinguished Name format, an exact match request is performed. So the Map-Server (when configured for proxy-Map-Replying) or the ETR will return a Map-Reply with the same EID-prefix length.¶
This section identifies three specific use-cases for the Distinguished Name format. Two are used for an EID encoding and one for a RLOC-record encoding. When storing public keys in the mapping system, as in [I-D.ietf-lisp-ecdsa-auth], a well known format for a public-key hash can be encoded as a Distinguished Name. When street location to GPS coordinate mappings exist in the mapping system, as in [I-D.farinacci-lisp-geo], the street location can be a free form ascii representation (with whitespace characters) encoded as a Distinguished Name. An RLOC that describes an xTR behind a NAT device can be identified by its router name, as in [I-D.farinacci-lisp-lispers-net-nat], uses a Distinguished Name encoding. As well as identifying the router name (neither an EID or an RLOC) in NAT Info-Request messages uses Distinguished Name encodings.¶
When a Distinguished Name encoding is used to format an EID, the uniqueness and allocation concerns are no different than registering IPv4 or IPv6 EIDs to the mapping system. See [RFC9301] for more details. Also, the use-case documents specified in Section 4 provide allocation recommendations for their specific uses.¶
It is recommended that each use-case register their distinguish-names in a unique VPN according to the encoding procedures in [I-D.ietf-lisp-vpn]. For any use-cases which require different uses for distinguish-names within a VPN MUST define their own structure syntax for the name registered to the mapping system.¶
There are no security considerations.¶
The code-point values in this specification are already allocated in [AFI].¶
The author would like to thank the LISP WG for their review and acceptance of this draft. And a special thank you goes to Marc Portoles for moving this document through the process.¶