Internet-Draft CDNI Additional Footprint Types January 2023
Sopher & Mishra Expires 15 July 2023 [Page]
Workgroup:
Network Working Group
Internet-Draft:
draft-ietf-cdni-additional-footprint-types-10
Updates:
8008 (if approved)
Published:
Intended Status:
Standards Track
Expires:
Authors:
N. Sopher
Qwilt
S. Mishra
Verizon

Content Delivery Network Interconnection (CDNI) Footprint Types: Subdivision Code and Footprint Union

Abstract

Open Caching architecture is a use case of Content Delivery Networks 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). This document supplements the CDNI Metadata Footprint Types defined in RFC 8006. The Footprint Types defined in this document can be used for Footprint objects as part of the Metadata interface (MI) defined in RFC 8006 and for the Footprint & Capabilities Advertisement interface (FCI) defined in RFC 8008. By defining the footprint union Footprint Type, this document updates RFC 8008, allowing an additive semantic over the narrowing semantics defined in Appendix B of RFC 8008. This document also supplements RFC 9241 with relevant ALTO entity domain types. The defined Footprint Types are derived from requirements raised by Open Caching but are also applicable to CDNI use cases in general.

Requirements Language

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174].

Status of This Memo

This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.

Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at https://datatracker.ietf.org/drafts/current/.

Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress."

This Internet-Draft will expire on 15 July 2023.

Table of Contents

1. 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 Networks 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 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 uCDN (upstream CDN) and dCDN (downstream CDN) 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:

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 acronyms:

  • uCDN, dCDN - Upstream CDN and Downstream CDN respectively (see [RFC7336] )

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 CDNI metadata [RFC8006].

2.1. CDNI Metadata Subdivision Code Footprint Type

Section 4.3.8 of [RFC8006] specifies the "Country Code" 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. Herein is defined the subdivisioncode simple data type, as well as a footprint type allowing the dCDN to define constraints matching geographic areas with better granularity, specifically using the [ISO3166-2] Country Subdivision codes.

2.1.1. CDNI Metadata Subdivision Code Data Type

The "subdivisioncode" data type specified in Section 2.1.1.1, describes a country specific subdivision using an [ISO3166-2] code. 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 Subdivision Code 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 Subdivision Codes:
  • "ca-on"
  • "us-ny"

2.1.2. CDNI Metadata Subdivision Code 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].

Below is an example using a footprint object of type "subdivisioncode". The Footprint Object in this example creates a constraint matching clients in the states of New Jersey and 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 subdivision-code footprint advertisement

2.2. CDNI Metadata Footprint Union 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 of a Footprint Objects array as a multiple, additive, footprint constraints. 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 "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 IPv4 or IPv6 clients. However, the described "narrowing" semantic of the Footprint Objects array, as described in Appendix B of [RFC8008], prevents the usage of these objects together to create a footprint constraint that matches IPv4 clients together with IPv6 clients.

Below is an example for an attempt at creating an object matching 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 ipv4cidr together with an ipv6cidr or a countrycode together with a subdivisoncode.

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 Footprint Union 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].

Below is an example using a footprint object of type "footprintunion" 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 CIDR footprint types

The footprint union also enables composing a countrycode and subdivisioncode based footprint objects. In the example below we create a constraint covering autonomous system 64496 within the US (ISO [ISO3166-1] alpha-2 code "US") and the Ontario province of Canada (ISO [ISO3166-2] code "CA-ON").


{
  "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 types

3. 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 defines 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 subdivision codes.

4. IANA Considerations

4.1. 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 requests the registration of the two additional Footprint Types as defined in Section 2.1 and Section 2.2 :

Table 1
Footprint Type Description Reference
subdivisioncode [ISO3166-2] ISO 3166-2 country subdivision 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. RFCthis
footprintunion A combination of other Footprint Objects RFCthis

[RFC Editor: Please replace RFCthis with the published RFC number for this document.]

4.2. ALTO Entity Domain Types

Section 12.3 of [RFC9240] creates the "ALTO Entity Domain Types" registry.

This document requests the registration of an additional ALTO Entity Domain Types:

Table 2
Identifier Entity Identifier Encoding Hierarchy and Inheritance Media Type of Defining Resource Mapping to ALTO Address Type
subdivisioncode See RFCthis, Section 3.1.2 None None false

[RFC Editor: Please replace RFCthis with the published RFC number for this document.]

5. Security Considerations

This specification is in accordance with the CDNI Metadata and the 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. 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.

7. References

7.1. 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, , <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, , <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, , <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, , <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, , <https://www.rfc-editor.org/info/rfc8008>.
[RFC8174]
Leiba, B. and RFC Publisher, "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, , <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, , <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, , <https://www.rfc-editor.org/info/rfc9241>.

7.2. Informative References

[OC-RR]
Finkelman, O., Ed., Hofmann, J., Klein, E., Mishra, S., Ma, K., Sahar, D., and B. Zurat, "Open Caching - Request Routing Functional Specification", Version 2.0, , <https://www.svta.org/product/open-cache-request-routing-functional-specification/>.
[OCWG]
"Open Caching Home Page", <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, , <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, , <https://www.rfc-editor.org/info/rfc7336>.
[SVTA]
"Streaming Video Technology Alliance Home Page", <https://www.svta.org/>.

Authors' Addresses

Nir B. Sopher
Qwilt
6, Ha'harash
Hod HaSharon 4524079
Israel
Sanjay Mishra
Verizon
13100 Columbia Pike
Silver Spring, MD 20904
United States of America