Internet Engineering Task Force (IETF)                         N. SopherRequest for Comments: 9388                                         QwiltUpdates: 8008                                                  S. MishraCategory: Standards Track                                        VerizonISSN: 2070-1721                                                July 2023Content Delivery Network Interconnection (CDNI) Footprint Types: Country                  Subdivision Code and Footprint UnionAbstract   Open Caching architecture is a use case of Content Delivery Network   Interconnection (CDNI) in which the commercial Content Delivery   Network (CDN) is the upstream CDN (uCDN) and the ISP caching layer   serves as the downstream CDN (dCDN).  RFC 8006 defines footprint   types that are used for footprint objects as part of the Metadata   interface (MI).  The footprint types are also used for the Footprint   & Capabilities Advertisement interface (FCI) as defined in RFC 8008.   This document defines two new footprint types.  The first footprint   type defined is an ISO 3166-2 country subdivision code.  Defining   this country subdivision code improves granularity for delegation as   compared to the ISO 3166-1 country code footprint type defined in RFC   8006.  The ISO 3166-2 country subdivision code is also added as a new   entity domain type in the "ALTO Entity Domain Types" registry defined   in Section 7.4 of RFC 9241.  The second footprint type defines a   footprint union to aggregate footprint objects.  This allows for   additive semantics over the narrowing semantics defined in Appendix B   of RFC 8008 and therefore updates RFC 8008.  The two new footprint   types are based on the requirements raised by Open Caching but are   also applicable to CDNI use cases in general.Status of This Memo   This is an Internet Standards Track document.   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).  Further information on   Internet Standards is available in 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/rfc9388.Copyright Notice   Copyright (c) 2023 IETF Trust and the persons identified as the   document authors.  All rights reserved.   This document is subject to BCP 78 and the IETF Trust's Legal   Provisions Relating to IETF Documents   (https://trustee.ietf.org/license-info) in effect on the date of   publication of this document.  Please review these documents   carefully, as they describe your rights and restrictions with respect   to this document.  Code Components extracted from this document must   include Revised BSD License text as described in Section 4.e of the   Trust Legal Provisions and are provided without warranty as described   in the Revised BSD License.Table of Contents   1.  Introduction     1.1.  Terminology     1.2.  Requirements Language   2.  CDNI Metadata Additional Footprint Types     2.1.  CDNI Metadata "subdivisioncode" Footprint Type       2.1.1.  CDNI Metadata "subdivisioncode" Data Type         2.1.1.1.  CDNI Metadata "subdivisioncode" Data Type                 Description       2.1.2.  CDNI Metadata "subdivisioncode" Footprint Type               Description     2.2.  CDNI Metadata "footprintunion" Footprint Type       2.2.1.  CDNI Metadata "footprintunion" Data Type       2.2.2.  CDNI Metadata "footprintunion" Footprint Type               Description   3.  ALTO Property Map Service Entity     3.1.  SUBDIVISIONCODE Domain       3.1.1.  Entity Domain Type       3.1.2.  Domain-Specific Entity Identifiers       3.1.3.  Hierarchy and Inheritance   4.  IANA Considerations     4.1.  CDNI Metadata Footprint Types     4.2.  ALTO Entity Domain Types   5.  Security Considerations   6.  References     6.1.  Normative References     6.2.  Informative References   Acknowledgements   Authors' Addresses1.  Introduction   The Streaming Video Technology Alliance [SVTA] is a global   association that works to solve streaming video challenges in an   effort to improve end-user experience and adoption.  The Open Caching   Working Group [OCWG] of the SVTA is focused on the delegation of   video delivery requests from commercial Content Delivery Networks   (CDNs) to a caching layer at the ISP's network.  Open Caching   architecture is a specific use case of Content Delivery Network   Interconnection (CDNI) where the commercial CDN is the upstream CDN   (uCDN) and the ISP caching layer is the downstream CDN (dCDN).  The   "Open Caching Request Routing Functional Specification" [OC-RR]   defines the Request Routing process and the interfaces that are   required for its provisioning.  This document defines and registers   CDNI Footprint and Capabilities objects [RFC8008] that are required   for Open Caching Request Routing.   For consistency with other CDNI documents, this document follows the   CDNI convention of using "uCDN" and "dCDN" to represent the   commercial CDN and ISP caching layer, respectively.   This document registers two CDNI Metadata footprint types   (Section 7.2 of [RFC8006]) for the defined objects:   *  Country subdivision code footprint type (e.g., for a dCDN      advertising a footprint that is specific to a state in the United      States of America)   *  Footprint union footprint type (for a dCDN advertising a footprint      that consists of a group built from multiple footprint types,      e.g., both IPv4 and IPv6 client subnets)1.1.  Terminology   The following terms are used throughout this document:   CDN:  Content Delivery Network   Additionally, this document reuses the terminology defined in   [RFC6707], [RFC7336], [RFC8006], and [RFC8008].  Specifically, we use   the following CDNI abbreviations:   uCDN:  upstream CDN (see [RFC7336])   dCDN:  downstream CDN (see [RFC7336])1.2.  Requirements Language   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.2.  CDNI Metadata Additional Footprint Types   Section 5 of [RFC8008] describes the Footprint & Capabilities   Advertisement interface (FCI) Capability Advertisement object, which   includes an array of CDNI footprint objects.  Each such object has a   footprint type and a footprint value, as described in Section 4.2.2.2   of [RFC8006].  This document defines additional footprint types,   beyond those mentioned in [RFC8006].2.1.  CDNI Metadata "subdivisioncode" Footprint Type   Section 4.3.8 of [RFC8006] specifies the "countrycode" footprint type   for listing [ISO3166-1] alpha-2 codes.  Using footprint objects of   this type, one can define an FCI Capability Advertisement object   footprint constraint that matches a specific country.  This document   defines the "subdivisioncode" simple data type as well as a footprint   type, allowing the dCDN to define constraints that match geographic   areas with better granularity, specifically using the [ISO3166-2]   country subdivision codes.2.1.1.  CDNI Metadata "subdivisioncode" Data Type   The "subdivisioncode" data type specified in Section 2.1.1.1   describes a country-specific subdivision using a code as defined in   [ISO3166-2].  The data type is added to the list of data types   described in Section 4.3 of [RFC8006] that are used as properties of   CDNI Metadata objects.2.1.1.1.  CDNI Metadata "subdivisioncode" Data Type Description   An [ISO3166-2] code in lowercase.  Each code consists of two parts   separated by a hyphen.  As per [ISO3166-2], the first part is the   [ISO3166-1] code of the country and the second part is a string of up   to three alphanumeric characters.   Type:  String   Example country subdivision codes:      *  "ca-on"      *  "us-ny"2.1.2.  CDNI Metadata "subdivisioncode" Footprint Type Description   The "subdivisioncode" simple data type specified in Section 2.1.1 is   added to the data types listed as footprint types in Section 4.2.2.2   of [RFC8006].   Figure 1 is an example using a footprint object of type   "subdivisioncode".  The footprint object in this example creates a   constraint that matches clients in the state of either New Jersey or   New York, USA (ISO [ISO3166-2] codes "US-NJ" and "US-NY",   respectively).   {     "capabilities": [       {         "capability-type": <CDNI capability object type>,         "capability-value": <CDNI capability object>,         "footprints": [             {                 "footprint-type": "subdivisioncode",                 "footprint-value": ["us-nj", "us-ny"]             }         ]       }     ]   }        Figure 1: Illustration of Country Subdivision Code Footprint                               Advertisement2.2.  CDNI Metadata "footprintunion" Footprint Type   As described in Section 5 of [RFC8008], the FCI Capability   Advertisement object includes an array of CDNI footprint objects.   Appendix B of [RFC8008] specifies the semantics for Footprint   Advertisement such that multiple footprint constraints are additive.   This implies that the advertisement of different footprint types   narrows the dCDN's candidacy cumulatively.   Sections 4.3.5 and 4.3.6 of [RFC8006] specify the "ipv4cidr" and the   "ipv6cidr" footprint types, respectively, for listing IP unscoped   address blocks.  Using footprint objects of these types, one can   define FCI Capability Advertisement object footprint constraints that   match either IPv4 or IPv6 clients, but not both.  This is due to the   described "narrowing" semantic of the Footprint Objects array, as   described in Appendix B of [RFC8008], that prevents the usage of   these objects together to create a footprint constraint that matches   IPv4 clients with IPv6 clients.   Figure 2 is an example attempting to create an object that matches   IPv4 clients of subnet "192.0.2.0/24" as well as IPv6 clients of   subnet "2001:db8::/32".  Such a definition results in an empty list   of clients, as the constraints are additives and a client address   cannot be both IPv4 and IPv6.   {     "capabilities": [       {         "capability-type": <CDNI capability object type>,         "capability-value": <CDNI capability object>,         "footprints": [             {                 "footprint-type": "ipv4cidr",                 "footprint-value": ["192.0.2.0/24"]             },             {                 "footprint-type": "ipv6cidr",                 "footprint-value": ["2001:db8::/32"]             }         ]       }     ]   }            Figure 2: Example of Narrowing Semantic Illustrating                     Advertisement of a Null Footprint   To overcome the described limitation and allow a list of footprint   constraints that match both IPv4 and IPv6 client subnets, this   document defines the "footprintunion" footprint type.  This footprint   type allows the collection of multiple footprint-objects into a   unified object.  Therefore, it resolves the above limitation and can   be particularly applicable to unify semantically related objects: for   example, an IPv4 CIDR together with an IPv6 CIDR or a country code   together with a country subdivision code.   Note: to avoid implementation complexity, a "footprintunion" MUST NOT   list any "footprintunion" as a value.  As a union of unions is simply   a union, this syntactic restriction does not result with any semantic   limitation.2.2.1.  CDNI Metadata "footprintunion" Data Type   The "footprintunion" data type is based on the footprint object   already defined in Section 4.2.2.2 of [RFC8006].  The footprint value   for a "footprintunion" object is an array of footprint objects, where   the footprint objects MUST be of any footprint type other than   "footprintunion".2.2.2.  CDNI Metadata "footprintunion" Footprint Type Description   The "footprintunion" data type specified in Section 2.2.1 is added to   the data types listed as footprint types in Section 4.2.2.2 of   [RFC8006].   Figure 3 is an example using a footprint union combining both IPv4   and IPv6 client subnets.   {     "capabilities": [       {         "capability-type": <CDNI capability object type>,         "capability-value": <CDNI capability object>,         "footprints": [           {             "footprint-type": "footprintunion",             "footprint-value": [               {                 "footprint-type": "ipv4cidr",                 "footprint-value": ["192.0.2.0/24"]               },               {                 "footprint-type": "ipv6cidr",                 "footprint-value": ["2001:db8::/32"]               }             ]           }         ]       }     ]   }        Figure 3: Example of an Advertisement of Footprint Union for       Multiple Classless Inter-Domain Routing (CIDR) Footprint Types   The footprint union also enables composing of footprint objects based   on the country code and country subdivision code.  In Figure 4, we   create a constraint covering autonomous system 64496 within the USA   (ISO alpha-2 code "US" as described in [ISO3166-1]) and the Ontario   province of Canada (ISO code "CA-ON" as described in [ISO3166-2]).   {     "capabilities": [       {         "capability-type": <CDNI capability object type>,         "capability-value": <CDNI capability object>,         "footprints": [           {             "footprint-type": "asn",             "footprint-value": ["as64496"]           },           {             "footprint-type": "footprintunion",             "footprint-value": [               {                 "footprint-type": "countrycode",                 "footprint-value": ["us"]               },               {                 "footprint-type": "subdivisioncode",                 "footprint-value": ["ca-on"]               }             ]           }         ]       }     ]   }   Figure 4: Example of an Advertisement of Footprint Union for Multiple                        Geographical Footprint Types3.  ALTO Property Map Service Entity   Section 6 of [RFC9241] describes how to represent footprint objects   as entities in the ALTO property map.  The approach is to represent   the footprint type as an entity domain type of the ALTO entity and   the footprint value as its domain-specific identifier.  [RFC9241]   further refers to the representation of footprint objects of types   "asn" and "countrycode".  Here, we extend this definition to the   "subdivisioncode" footprint type.3.1.  SUBDIVISIONCODE Domain   The SUBDIVISIONCODE domain associates property values that define   codes for the names of the principal subdivisions.3.1.1.  Entity Domain Type   The entity domain type of the SUBDIVISIONCODE domain is   "subdivisioncode" (in lowercase).3.1.2.  Domain-Specific Entity Identifiers   The entity identifier of an entity in a SUBDIVISIONCODE is encoded as   an alpha-2 [ISO3166-1] country code, followed by a separator and up   to three alphanumeric characters.3.1.3.  Hierarchy and Inheritance   There is no hierarchy or inheritance for properties associated with   country subdivision codes.4.  IANA Considerations4.1.  CDNI Metadata Footprint Types   Section 7.2 of [RFC8006] specifies the "CDNI Metadata Footprint   Types" subregistry within the "Content Delivery Network   Interconnection (CDNI) Parameters" registry.   This document registers two footprint types in that subregistry as   defined in Sections 2.1 and 2.2:     +=================+=================================+===========+     | Footprint Type  | Description                     | Reference |     +=================+=================================+===========+     | subdivisioncode | ISO 3166-2 country subdivision  | RFC 9388  |     |                 | code: alpha-2 country code,     |           |     |                 | followed by a hyphen-minus and  |           |     |                 | up to 3 characters from A-Z;0-9 |           |     |                 | as a code within the country    |           |     +-----------------+---------------------------------+-----------+     | footprintunion  | A combination of other          | RFC 9388  |     |                 | footprint objects               |           |     +-----------------+---------------------------------+-----------+          Table 1: Additions to the CDNI Metadata Footprint Types                                Subregistry4.2.  ALTO Entity Domain Types   Section 12.3 of [RFC9240] creates the "ALTO Entity Domain Types"   subregistry within the "Application-Layer Traffic Optimization (ALTO)   Protocol" registry.   This document registers an additional ALTO Entity Domain Type within   that subregistry:    +=================+============+=============+==========+=========+    | Identifier      | Entity     | Hierarchy   | Media    | Mapping |    |                 | Identifier | and         | Type of  | to ALTO |    |                 | Encoding   | Inheritance | Defining | Address |    |                 |            |             | Resource | Type    |    +=================+============+=============+==========+=========+    | subdivisioncode | See RFC    | None        | None     | false   |    |                 | 9388,      |             |          |         |    |                 | Section    |             |          |         |    |                 | 3.1.2      |             |          |         |    +-----------------+------------+-------------+----------+---------+       Table 2: Addition to the ALTO Entity Domain Types Subregistry5.  Security Considerations   This specification is in accordance with "Content Delivery Network   Interconnection (CDNI) Metadata" and "Content Delivery Network   Interconnection (CDNI) Request Routing: Footprint and Capabilities   Semantics".  As such, it is subject to the security and   confidentiality considerations as defined in Section 8 of [RFC8006]   and in Section 7 of [RFC8008], respectively.6.  References6.1.  Normative References   [ISO3166-1]              ISO, "Codes for the representation of names of countries              and their subdivisions -- Part 1: Country code",              ISO 3166-1:2020, Edition 4, August 2020,              <https://www.iso.org/standard/72482.html>.   [ISO3166-2]              ISO, "Codes for the representation of names of countries              and their subdivisions -- Part 2: Country subdivision              code", ISO 3166-2:2020, Edition 4, August 2020,              <https://www.iso.org/standard/72483.html>.   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate              Requirement Levels", BCP 14, RFC 2119,              DOI 10.17487/RFC2119, March 1997,              <https://www.rfc-editor.org/info/rfc2119>.   [RFC8006]  Niven-Jenkins, B., Murray, R., Caulfield, M., and K. Ma,              "Content Delivery Network Interconnection (CDNI)              Metadata", RFC 8006, DOI 10.17487/RFC8006, December 2016,              <https://www.rfc-editor.org/info/rfc8006>.   [RFC8008]  Seedorf, J., Peterson, J., Previdi, S., van Brandenburg,              R., and K. Ma, "Content Delivery Network Interconnection              (CDNI) Request Routing: Footprint and Capabilities              Semantics", RFC 8008, DOI 10.17487/RFC8008, December 2016,              <https://www.rfc-editor.org/info/rfc8008>.   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,              May 2017, <https://www.rfc-editor.org/info/rfc8174>.   [RFC9240]  Roome, W., Randriamasy, S., Yang, Y., Zhang, J., and K.              Gao, "An Extension for Application-Layer Traffic              Optimization (ALTO): Entity Property Maps", RFC 9240,              DOI 10.17487/RFC9240, July 2022,              <https://www.rfc-editor.org/info/rfc9240>.   [RFC9241]  Seedorf, J., Yang, Y., Ma, K., Peterson, J., and J. Zhang,              "Content Delivery Network Interconnection (CDNI) Footprint              and Capabilities Advertisement Using Application-Layer              Traffic Optimization (ALTO)", RFC 9241,              DOI 10.17487/RFC9241, July 2022,              <https://www.rfc-editor.org/info/rfc9241>.6.2.  Informative References   [OC-RR]    Finkelman, O., Ed., Zurat, B., Sahar, D., Klein, E.,              Hofmann, J., Ma, K.J., Stock, M., Mishra, S., and Y.              Gressel, "Open Caching - Request Routing Functional              Specification", Version 2.0, 15 January 2021,              <https://www.svta.org/product/open-cache-request-routing-              functional-specification/>.   [OCWG]     SVTA, "Open Caching", <https://opencaching.svta.org/>.   [RFC6707]  Niven-Jenkins, B., Le Faucheur, F., and N. Bitar, "Content              Distribution Network Interconnection (CDNI) Problem              Statement", RFC 6707, DOI 10.17487/RFC6707, September              2012, <https://www.rfc-editor.org/info/rfc6707>.   [RFC7336]  Peterson, L., Davie, B., and R. van Brandenburg, Ed.,              "Framework for Content Distribution Network              Interconnection (CDNI)", RFC 7336, DOI 10.17487/RFC7336,              August 2014, <https://www.rfc-editor.org/info/rfc7336>.   [SVTA]     SVTA, "Streaming Video Technology Alliance",              <https://www.svta.org/>.Acknowledgements   The authors would like to express their gratitude to Ori Finkelman   and Kevin J. Ma for their guidance and reviews throughout the   development of this document.  We would also like to thank all the   Area Directors for their review and feedback in improving this   document.Authors' Addresses   Nir B. Sopher   Qwilt   6, Ha'harash   Hod HaSharon 4524079   Israel   Email: nir@apache.org   Sanjay Mishra   Verizon   13100 Columbia Pike   Silver Spring, MD 20904   United States of America   Email: sanjay.mishra@verizon.com