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Versions: (draft-seedorf-cdni-request-routing-alto) 00 01 02 03 04 05 06 07 08

CDNI                                                          J. Seedorf
Internet-Draft                 HFT Stuttgart - Univ. of Applied Sciences
Intended status: Standards Track                                 Y. Yang
Expires: September 12, 2019                                  Tongji/Yale
                                                                   K. Ma
                                                                Ericsson
                                                             J. Peterson
                                                                 Neustar
                                                                  X. Lin
                                                                  Tongji
                                                          March 11, 2019


 Content Delivery Network Interconnection (CDNI) Request Routing: CDNI
          Footprint and Capabilities Advertisement using ALTO
              draft-ietf-alto-cdni-request-routing-alto-05

Abstract

   The Content Delivery Networks Interconnection (CDNI) framework
   [RFC6707] defines a set of protocols to interconnect CDNs, to achieve
   multiple goals such as extending the reach of a given CDN to areas
   that are not covered by that particular CDN.  One component that is
   needed to achieve the goal of CDNI described in [RFC7336] is the CDNI
   Request Routing Footprint & Capabilities Advertisement interface
   (FCI).  [RFC8008] defines precisely the semantics of FCI and provides
   guidelines on the FCI protocol, but the exact protocol is explicitly
   outside the scope of that document.  In this document, we follow the
   guidelines to define an FCI protocol using the Application-Layer
   Traffic Optimization (ALTO) protocol.

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 September 12, 2019.




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Copyright Notice

   Copyright (c) 2019 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 Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Background  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     2.1.  Semantics of FCI Advertisement  . . . . . . . . . . . . .   5
     2.2.  ALTO Background and Benefits  . . . . . . . . . . . . . .   6
   3.  CDNI FCI Map  . . . . . . . . . . . . . . . . . . . . . . . .   8
     3.1.  Media Type  . . . . . . . . . . . . . . . . . . . . . . .   8
     3.2.  HTTP Method . . . . . . . . . . . . . . . . . . . . . . .   9
     3.3.  Accept Input Parameters . . . . . . . . . . . . . . . . .   9
     3.4.  Capabilities  . . . . . . . . . . . . . . . . . . . . . .   9
     3.5.  Uses  . . . . . . . . . . . . . . . . . . . . . . . . . .   9
     3.6.  Response  . . . . . . . . . . . . . . . . . . . . . . . .   9
     3.7.  Examples  . . . . . . . . . . . . . . . . . . . . . . . .  11
       3.7.1.  IRD Example . . . . . . . . . . . . . . . . . . . . .  12
       3.7.2.  Basic Example . . . . . . . . . . . . . . . . . . . .  14
       3.7.3.  Incremental Updates Example . . . . . . . . . . . . .  15
   4.  CDNI FCI Map using ALTO Network Map . . . . . . . . . . . . .  17
     4.1.  Network Map Footprint Type: altonetworkmap  . . . . . . .  17
     4.2.  Examples  . . . . . . . . . . . . . . . . . . . . . . . .  17
       4.2.1.  IRD Example . . . . . . . . . . . . . . . . . . . . .  17
       4.2.2.  ALTO Network Map for CDNI FCI Footprints Example  . .  17
       4.2.3.  ALTO Network Map Footprints in CDNI FCI Map . . . . .  18
       4.2.4.  Incremental Updates Example . . . . . . . . . . . . .  19
   5.  Filtered CDNI FCI Map using Capabilities  . . . . . . . . . .  21
     5.1.  Media Type  . . . . . . . . . . . . . . . . . . . . . . .  21
     5.2.  HTTP Method . . . . . . . . . . . . . . . . . . . . . . .  21
     5.3.  Accept Input Parameters . . . . . . . . . . . . . . . . .  21
     5.4.  Capabilities  . . . . . . . . . . . . . . . . . . . . . .  22
     5.5.  Uses  . . . . . . . . . . . . . . . . . . . . . . . . . .  22
     5.6.  Response  . . . . . . . . . . . . . . . . . . . . . . . .  22
     5.7.  Examples  . . . . . . . . . . . . . . . . . . . . . . . .  23
       5.7.1.  IRD Example . . . . . . . . . . . . . . . . . . . . .  23



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       5.7.2.  Basic Example . . . . . . . . . . . . . . . . . . . .  23
       5.7.3.  Incremental Updates Example . . . . . . . . . . . . .  25
   6.  Query Footprint Properties using ALTO Unified Property
       Service . . . . . . . . . . . . . . . . . . . . . . . . . . .  26
     6.1.  Representing Footprint Objects as Unified Property Map
           Entities  . . . . . . . . . . . . . . . . . . . . . . . .  27
       6.1.1.  ASN Domain  . . . . . . . . . . . . . . . . . . . . .  27
       6.1.2.  COUNTRYCODE Domain  . . . . . . . . . . . . . . . . .  27
     6.2.  Examples  . . . . . . . . . . . . . . . . . . . . . . . .  28
       6.2.1.  IRD Example . . . . . . . . . . . . . . . . . . . . .  28
       6.2.2.  Property Map Example  . . . . . . . . . . . . . . . .  28
       6.2.3.  Filtered Property Map Example . . . . . . . . . . . .  30
       6.2.4.  Incremental Updates Example . . . . . . . . . . . . .  31
   7.  Design Decisions and Discussions  . . . . . . . . . . . . . .  32
     7.1.  Table versus Map  . . . . . . . . . . . . . . . . . . . .  32
     7.2.  Filter-based Query versus Test-based Query  . . . . . . .  33
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  33
     8.1.  CDNI Metadata Footprint Type Registry . . . . . . . . . .  33
     8.2.  ALTO Entity Domain Registry . . . . . . . . . . . . . . .  33
     8.3.  ALTO CDNI FCI Property Type Registry  . . . . . . . . . .  34
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .  34
   10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  35
   11. References  . . . . . . . . . . . . . . . . . . . . . . . . .  35
     11.1.  Normative References . . . . . . . . . . . . . . . . . .  36
     11.2.  Informative References . . . . . . . . . . . . . . . . .  37
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  37

1.  Introduction

   The ability to interconnect multiple content delivery networks (CDNs)
   has many benefits, including increased coverage, capability, and
   reliability.  The Content Delivery Networks Interconnection (CDNI)
   framework [RFC6707] defines four interfaces to achieve
   interconnection of CDNs: (1) the CDNI Request Routing Interface; (2)
   the CDNI Metadata Interface; (3) the CDNI Logging Interface; and (4)
   the CDNI Control Interface.

   Among the four interfaces, the CDNI Request Routing Interface
   provides key functions, as specified in [RFC6707]: "The CDNI Request
   Routing interface enables a Request Routing function in an Upstream
   CDN to query a Request Routing function in a Downstream CDN to
   determine if the Downstream CDN is able (and willing) to accept the
   delegated Content Request.  It also allows the Downstream CDN to
   control what should be returned to the User Agent in the redirection
   message by the upstream Request Routing function."  On a high level,
   the scope of the CDNI Request Routing Interface, therefore, contains
   two main tasks: (1) determining if the downstream CDN (dCDN) is
   willing to accept a delegated content request; (2) redirecting the



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   content request coming from an upstream CDN (uCDN) to the proper
   entry point or entity in the downstream CDN.

   Correspondingly, the request routing interface is broadly divided
   into two functionalities: (1) CDNI Footprint & Capabilities
   Advertisement interface (FCI); (2) CDNI Request Routing Redirection
   interface (RI).  Since this document focuses on the first
   functionality, CDNI FCI, we will describe it in a more detailed way.
   CDNI FCI is an advertisement from a dCDN to a uCDN (push) or a query
   from a uCDN to a dCDN (pull) so that the uCDN knows whether it can
   redirect a particular user request to that dCDN.

   A key component in defining CDNI FCI is defining objects describing
   the footprints and capabilities of a dCDN.  Such objects are already
   in [RFC8008].  A protocol to transport and update such objects
   between a uCDN and a dCDN, however, is not defined.  Hence, the scope
   of this document is to define such a protocol by introducing a new
   Application-Layer Traffic Optimization (ALTO) [RFC7285] service
   called "CDNI FCI Map Service".

   There are multiple benefits in using ALTO as a transport protocol, as
   we discuss in Section 2.2.

   The rest of this document is organized as follows.  Section 2
   provides non-normative background on both CDNI FCI and ALTO.
   Section 3 introduces the most basic service, called CDNI FCI Map, to
   realize CDNI FCI using ALTO.  Section 4 demonstrates a key benefit of
   using ALTO: the ability to integrate CDNI FCI with ALTO network maps.
   Such integration provides a new granularity to describe footprints.
   Section 5 builds on filtered ALTO maps to introduce filtered CDNI FCI
   maps using capabilities so that a uCDN can get footprints with given
   capabilities instead of getting the full map which can be huge.
   Section 6 further shows a benefit of using ALTO: the ability to query
   footprint properties using ALTO unified properties.  In this way, a
   uCDN can effectively fetch capabilities of some footprints in which
   it is interested.  IANA and security considerations are discussed in
   Section 8 and Section 9 respectively.

   Throughout this document, we use the terminology for CDNI defined in
   [RFC6707], [RFC8006], [RFC8008] and we use the terminology for ALTO
   defined in [RFC7285], [I-D.ietf-alto-unified-props-new].

2.  Background

   The design of CDNI FCI transport using ALTO depends on the
   understanding of both FCI semantics and ALTO.  Hence, we start with a
   review of both.




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2.1.  Semantics of FCI Advertisement

   The CDNI document on "Footprint and Capabilities Semantics" [RFC8008]
   defines the semantics of CDNI FCI, and provides guidance on what
   Footprint and Capabilities mean in a CDNI context and how a protocol
   solution should in principle look like.  The definitions in [RFC8008]
   depend on [RFC8006].  Here we briefly summarize key related points of
   [RFC8008] and [RFC8006].  For a detailed discussion, the reader is
   referred to the RFCs.

   o  Footprint and capabilities are tied together and cannot be
      interpreted independently from each other.  Hence, capabilities
      must be expressed on a per footprint basis.  [RFC8008] integrates
      footprint and capabilities with an approach of "capabilities with
      footprint restrictions".

   o  Given that a large part of Footprint and Capabilities
      Advertisement will actually happen in contractual agreements, the
      semantics of CDNI Footprint and Capabilities advertisement refers
      to answering the following question: what exactly still needs to
      be advertised by the CDNI FCI?  For instance, updates about
      temporal failures of part of a footprint can be useful information
      to convey via the CDNI request routing interface.  Such
      information would provide updates on information previously agreed
      in contracts between the participating CDNs.  In other words, the
      CDNI FCI is a means for a dCDN to provide changes/updates
      regarding a footprint and/or capabilities that it has prior agreed
      to serve in a contract with a uCDN.  Hence, server push and
      incremental encoding will be necessary techniques.

   o  Multiple types of footprints (ipv4cidr, ipv6cidr, asn and
      countrycode) are defined in [RFC8006].

   o  A "Set of IP-prefixes" can contain both full IP addresses (i.e., a
      /32 for IPv4 and a /128 for IPv6) and IP prefixes with an
      arbitrary prefix length.  There must also be support for multiple
      IP address versions, i.e., IPv4 and IPv6, in such a footprint.

   o  For all of these mandatory-to-implement footprint types,
      footprints can be viewed as constraints for delegating requests to
      a dCDN: A dCDN footprint advertisement tells the uCDN the
      limitations for delegating a request to the dCDN.  For IP prefixes
      or ASN(s), the footprint signals to the uCDN that it should
      consider the dCDN a candidate only if the IP address of the
      request routing source falls within the prefix set (or ASN,
      respectively).  The CDNI specifications do not define how a given
      uCDN determines what address ranges are in a particular ASN.
      Similarly, for country codes, a uCDN should only consider the dCDN



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      a candidate if it covers the country of the request routing
      source.  The CDNI specifications do not define how a given uCDN
      determines the country of the request routing source.  Multiple
      footprint constraints are additive, i.e., the advertisement of
      different types of footprint narrows the dCDN candidacy
      cumulatively.

   o  The following capabilities are defined as "base" capabilities;
      that is, they are required in all cases and therefore constitute
      mandatory capabilities to be supported by the CDNI FCI: (1)
      Delivery Protocol; (2) Acquisition Protocol; (3) Redirection Mode;
      (4) Capabilities related to CDNI Logging; (5) Capabilities related
      to CDNI Metadata.

2.2.  ALTO Background and Benefits

   Application-Layer Traffic Optimization (ALTO) [RFC7285] is an
   approach for guiding the resource provider selection process in
   distributed applications that can choose among several candidate
   resources providers to retrieve a given resource.  By conveying
   network layer (topology) information, an ALTO server can provide
   important information to "guide" the resource provider selection
   process in distributed applications.  Usually, it is assumed that an
   ALTO server conveys information that these applications cannot or
   have difficulty to measure themselves [RFC5693].

   Originally, ALTO was motivated by optimizing cross-ISP traffic
   generated by P2P applications [RFC5693].  Recently, however, ALTO is
   also being considered for improving the request routing in CDNs
   [I-D.jenkins-alto-cdn-use-cases].  The CDNI problem statement
   explicitly mentions ALTO as a candidate protocol for "actual
   algorithms for selection of CDN or Surrogate by Request-Routing
   systems" [RFC6707].

   The following reasons make ALTO a suitable candidate protocol for
   downstream CDN selection as part of CDNI request routing and in
   particular for an FCI protocol:

   o  ALTO is a protocol specifically designed to improve application
      layer traffic (and application layer connections among hosts on
      the Internet) by providing additional information to applications
      that these applications could not easily retrieve themselves.  For
      CDNI, this is exactly the case: a uCDN wants to improve
      application layer CDN request routing by using dedicated
      information (provided by a dCDN) that the uCDN could not easily
      obtain otherwise.  ALTO can help a uCDN to select a proper dCDN by
      first providing dCDNs' capabilities as well as footprints (see




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      Section 3) and then providing costs of surrogates in a dCDN by
      ALTO cost maps.

   o  The semantics of an ALTO network map is an exact match for the
      needed information to convey a footprint by a downstream CDN, in
      particular if such a footprint is being expressed by IP-prefix
      ranges.  Please see Section 4.

   o  Security: Identifications between uCDNs and dCDNs are extremely
      important.  ALTO maps can be signed and hence provide inherent
      integrity protection.  Please see Section 9.

   o  RESTful-Design: The ALTO protocol has undergone extensive
      revisions in order to provide a RESTful design regarding the
      client-server interaction specified by the protocol.  A CDNI FCI
      interface based on ALTO would inherit this RESTful design.  Please
      see Section 3.

   o  Error-handling: The ALTO protocol has undergone extensive
      revisions in order to provide sophisticated error-handling, in
      particular regarding unexpected cases.  A CDNI FCI interface based
      on ALTO would inherit this thought-through and mature error-
      handling.  Please see Section 5.

   o  Filtered map service: The ALTO map filtering service would allow a
      uCDN to query only for parts of an ALTO map.  For example,
      filtered unified property map service can enable a uCDN to query
      properties of a part of footprints in an effective way (see
      Section 6).

   o  Server-initiated Notifications and Incremental Updates: When the
      footprint or the capabilities of a downstream CDN change (i.e.,
      unexpectedly from the perspective of an upstream CDN), server-
      initiated notifications would enable a dCDN to directly inform an
      upstream CDN about such changes.  Consider the case where - due to
      failure - part of the footprint of the dCDN is not functioning,
      i.e., the CDN cannot serve content to such clients with reasonable
      QoS.  Without server-initiated notifications, the uCDN might still
      use a very recent network and cost map from dCDN, and therefore
      redirect requests to dCDN which it cannot serve.  Similarly, the
      possibility for incremental updates would enable efficient
      conveyance of the aforementioned (or similar) status changes by
      the dCDN to the uCDN.  The newest design of ALTO supports server
      pushed incremental updates [I-D.ietf-alto-incr-update-sse].

   o  Content Availability on Hosts: A dCDN might want to express CDN
      capabilities in terms of certain content types (e.g., codecs/
      formats, or content from certain content providers).  The new



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      endpoint property for ALTO would enable a dCDN to make such
      information available to an upstream CDN.  This would enable a
      uCDN to determine if a given dCDN actually has the capabilities
      for a given request with respect to the type of content requested.

   o  Resource Availability on Hosts or Links: The capabilities on links
      (e.g. maximum bandwidth) or caches (e.g. average load) might be
      useful information for an upstream CDN for optimized downstream
      CDN selection.  For instance, if a uCDN receives a streaming
      request for content with a certain bitrate, it needs to know if it
      is likely that a dCDN can fulfill such stringent application-level
      requirements (i.e., can be expected to have enough consistent
      bandwidth) before it redirects the request.  In general, if ALTO
      could convey such information via new endpoint properties, it
      would enable more sophisticated means for downstream CDN selection
      with ALTO.  ALTO Path Vector Extension [I-D.ietf-alto-path-vector]
      is designed to allow ALTO clients to query information such as
      capacity regions for a given set of flows.

3.  CDNI FCI Map

   The ALTO protocol is based on an ALTO Information Service Framework
   which consists of several services, where all ALTO services are
   "provided through a common transport protocol, messaging structure
   and encoding, and transaction model" [RFC7285].  The ALTO protocol
   specification [RFC7285] defines several such services, e.g. the ALTO
   map service.

   This document defines a new ALTO Map Service called "CDNI FCI Map
   Service" which conveys JSON objects of media type "application/alto-
   cdnifcimap+json".  These JSON objects are used to transport
   BaseAdvertisementObject objects defined in [RFC8008]; this document
   specifies how to transport such BaseAdvertisementObject objects via
   the ALTO protocol with the ALTO "CDNI FCI Map Service".  Given that
   the "CDNI FCI Map Service" is very similar in structure to the two
   already defined map services (network maps and cost maps), the
   specification of CDNI FCI Map below uses the same specification
   structure for Cost Map specification in Section 11.2.3 of [RFC7285]
   when specifying cost maps.

3.1.  Media Type

   The media type of the CDNI FCI Map is "application/alto-
   cdnifcimap+json".







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3.2.  HTTP Method

   A CDNI FCI map resource is requested using the HTTP GET method.

3.3.  Accept Input Parameters

   None.

3.4.  Capabilities

   None.

3.5.  Uses

   The resource ID of the resource based on which the CDNI FCI map will
   be defined.  For example, if a CDNI FCI map depends on a network map,
   the resource ID of the network map MUST be included in "uses" field.
   Please see Section 4 for details.  If the CDNI FCI map does not
   depend on any other resources, "uses" field MUST NOT appear.

3.6.  Response

   The "meta" field of a CDNI FCI map response MUST include the "vtag"
   field defined in Section 10.3 of [RFC7285].  This field provides the
   version of the retrieved CDNI FCI map.

   If a CDNI FCI map response depends on a resource such as a network
   map, it MUST include the "dependent-vtags" field, whose value is an
   array to indicate the version tags of the resources used, where each
   resource is specified in "uses" of the IRD.  The current defined
   dependent resource is only network map, and the usage of it is
   described in Section 4.

   The data component of an ALTO CDNI FCI map response is named "cdni-
   fci-map", which is a JSON object of type CDNIFCIMapData:

       object {
           CDNIFCIMapData cdni-fci-map;
       } InfoResourceCDNIFCIMap : ResponseEntityBase;

       object {
           BaseAdvertisementObject capabilities<1..*>;
       } CDNIFCIMapData;

   Specifically, a CDNIFCIMapData object is a JSON object that includes
   only one property named "capabilities", whose value is an array of
   BaseAdvertisementObject objects.




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   The syntax and semantics of BaseAdvertisementObject are well defined
   in Section 5.1 of [RFC8008].  A BaseAdvertisementObject object
   includes multiple properties, including capability-type, capability-
   value and footprints, where footprints are defined in Section 4.2.2.2
   of [RFC8006].

   To be self-contained, we give a non-normative specification of
   BaseAdvertisementObject below.  As mentioned above, the normative
   specification of BaseAdvertisementObject is in [RFC8008]

       object {
           JSONString capability-type;
           JSONValue capability-value;
           Footprint footprints<0..*>;
       } BaseAdvertisementObject;

       object {
           JSONString footprint-type;
           JSONString footprint-value<1..*>;
       } Footprint;

   For each BaseAdvertisementObject, the ALTO client MUST interpret
   footprints appearing multiple times as if they appeared only once.
   If footprints in a BaseAdvertisementObject is null or empty or not
   appearing, the ALTO client MUST understand that the capabilities in
   this BaseAdvertisementObject have the "global" coverage.

   Note: Further optimization of BaseAdvertisement objects to
   effectively provide the advertisement of capabilities with footprint
   restrictions is certainly possible.  For example, these two examples
   below both describe that the dCDN can provide capabilities
   ["http/1.1", "https/1.1"] for the same footprints.  However, the
   latter one is smaller in its size.

   EXAMPLE 1
       {
         "meta" : {...},
         "cdni-fci-map": {
           "capabilities": [
             {
               "capability-type": "FCI.DeliveryProtocol",
               "capability-value": {
                 "delivery-protocols": [
                   "http/1.1"
                 ]
               },
               "footprints": [
                 <Footprint objects>



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               ]
             },
             {
               "capability-type": "FCI.DeliveryProtocol",
               "capability-value": {
                 "delivery-protocols": [
                   "https/1.1"
                 ]
               },
               "footprints": [
                 <Footprint objects>
               ]
             }
           ]
         }
       }

   EXAMPLE 2
       {
         "meta" : {...},
         "cdni-fci-map": {
           "capabilities": [
             {
               "capability-type": "FCI.DeliveryProtocol",
               "capability-value": {
                 "delivery-protocols": [
                   "https/1.1",
                   "http/1.1"
                 ]
               },
               "footprints": [
                 <Footprint objects>
               ]
             }
           ]
         }
       }

   Since such optimizations are not necessary for the basic
   interconnection of CDNs, the specifics of such mechanisms are outside
   the scope of this document.

3.7.  Examples








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3.7.1.  IRD Example

   Below is the information resource directory (IRD) of a simple,
   example ALTO server.  The server provides both base ALTO information
   resources (e.g., network maps) and CDNI FCI information resources
   (e.g., CDNI FCI map), demonstrating a single, integrated environment.

   Specifically, the IRD announces two network maps, one CDNI FCI map
   without dependency, one CDNI FCI map depending on a network map, one
   filtered CDNI FCI map to be defined in Section 5, one unified
   property map including "cdni-fci-capabilities" as its entities'
   property, one filtered unified property map including "cdni-fci-
   capabilities" and "pid" as its entities' properties, and two update
   stream services (one for updating CDNI FCI maps, and the other for
   updating property maps).

    GET /directory HTTP/1.1
    Host: alto.example.com
    Accept: application/alto-directory+json,application/alto-error+json

    {
      "meta" : { ... },
      "resources": {
        "my-default-network-map": {
          "uri" : "http://alto.example.com/networkmap",
          "media-type" : "application/alto-networkmap+json"
        },
        "my-eu-netmap" : {
          "uri" : "http://alto.example.com/myeunetmap",
          "media-type" : "application/alto-networkmap+json"
        },
        "my-default-cdnifci-map": {
          "uri" : "http://alto.example.com/cdnifcimap",
          "media-type": "application/alto-cdnifcimap+json"
        },
        "my-filtered-cdnifci-map" : {
          "uri" : "http://alto.example.com/cdnifcimap/filtered",
          "media-type" : "application/alto-cdnifcimap+json",
          "accepts" : "application/alto-cdnifcimapfilter+json",
          "uses" : [ "my-default-cdnifci-map" ]
        },
        "my-cdnifci-map-with-network-map-footprints": {
          "uri" : "http://alto.example.com/networkcdnifcimap",
          "media-type" : "application/alto-cdnifcimap+json",
          "uses" : [ "my-eu-netmap" ]
        },
        "cdnifci-property-map" : {
          "uri" : "http://alto.example.com/propmap/full/cdnifci",



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          "media-type" : "application/alto-propmap+json",
          "capabilities" : {
            "domain-types" : [ "ipv4", "ipv6", "coutrycode", "asn" ],
            "prop-types" : [ "cdni-fci-capabilities" ]
          }
        },
        "filtered-cdnifci-property-map" : {
          "uri" : "http://alto.example.com/propmap/lookup/cdnifci-pid",
          "media-type" : "application/alto-propmap+json",
          "accepts" : "application/alto-propmapparams+json",
          "capabilities" : {
            "domain-types" : [ "ipv4", "ipv6", "coutrycode", "asn" ],
            "prop-types" : [ "cdni-fci-capabilities", "pid" ]
           }
        },
        "update-my-cdni-fci-maps" : {
          "uri": "http:///alto.example.com/updates/cdnifcimaps",
          "media-type" : "text/event-stream",
          "accepts" : "application/alto-updatestreamparams+json",
          "uses" : [
            "my-default-network-map",
            "my-eu-netmap",
            "my-default-cdnifci-map",
            "my-filtered-cdnifci-map"
            "my-cdnifci-map-with-network-map-footprints"
          ],
          "capabilities" : {
            "incremental-change-media-types" : {
              "my-default-network-map" : "application/json-patch+json",
              "my-eu-netmap" : "application/json-patch+json",
              "my-default-cdnifci-map" :
              "application/merge-patch+json,application/json-patch+json",
              "my-filtered-cdnifci-map" :
              "application/merge-patch+jso,application/json-patch+json",
              "my-cdnifci-map-with-network-map-footprints" :
              "application/merge-patch+json,application/json-patch+json"
            }
          }
        },
        "update-my-props": {
          "uri" : "http://alto.example.com/updates/properties",
          "media-type" : "text/event-stream",
          "uses" : [
            "cdnifci-property-map",
            "filtered-cdnifci-property-map"
          ],
          "capabilities" : {
            "incremental-change-media-types": {



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              "cdnifci-property-map" :
              "application/merge-patch+json,application/json-patch+json",
              "filtered-cdnifci-property-map":
              "application/merge-patch+json,application/json-patch+json"
            }
          }
        }
      }
    }

3.7.2.  Basic Example

   In this example, we demonstrate a simple CDNI FCI map; this map does
   not depend on other resources.  There are three
   BaseAdvertisementObjects in this map and these objects' capabilities
   are http/1.1 delivery protocol, [http/1.1, https/1.1] delivery
   protocol and https/1.1 acquisition protocol respectively.

     GET /cdnifcimap HTTP/1.1
     Host: alto.example.com
     Accept: application/alto-cdnifcimap+json
     Accept: application/alto-error+json

     HTTP/1.1 200 OK
     Content-Length: XXX
     Content-Type: application/alto-cdnifcimap+json
     {
       "meta" : {
         "vtag": {
           "resource-id": "my-default-cdnifci-map",
           "tag": "da65eca2eb7a10ce8b059740b0b2e3f8eb1d4785"
         }
       },
       "cdni-fci-map": {
         "capabilities": [
           {
             "capability-type": "FCI.DeliveryProtocol",
             "capability-value": {
               "delivery-protocols": [
                 "http/1.1"
               ]
             },
             "footprints": [
               <Footprint objects>
             ]
           },
           {
             "capability-type": "FCI.DeliveryProtocol",



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             "capability-value": {
               "delivery-protocols": [
                 "https/1.1",
                 "http/1.1"
               ]
             },
             "footprints": [
               <Footprint objects>
             ]
           },
           {
             "capability-type": "FCI.AcquisitionProtocol",
             "capability-value": {
               "acquisition-protocols": [
                 "https/1.1"
               ]
             },
             "footprints": [
               <Footprint objects>
             ]
           }
         ]
       }
     }

3.7.3.  Incremental Updates Example

   A benefit of using ALTO to provide CDNI FCI maps is that such maps
   can be updated using ALTO incremental updates.  Below is an example
   that also shows the benefit of having both JSON merge patch and JSON
   patch to encode updates.

   At first, an ALTO client requests the ALTO server updates for "my-
   default-cdnifci-map", and the ALTO server returns the "control-uri"
   followed by the full CDNI FCI map.  Then when there is a huge change
   in footprint objects in delivery-protocol http/1.1, the ALTO server
   uses JSON merge patch to encode the change and sends it to the ALTO
   client.  Later on, the ALTO server notifies the ALTO client that
   "ipv4:192.0.2.0/24" is added into the footprints in delivery-protocol
   http/1.1 by sending the change encoded by JSON patch to the ALTO
   client.

     POST /updates/cdnifcimaps HTTP/1.1
     Host: alto.example.com
     Accept: text/event-stream,application/alto-error+json
     Content-Type: application/alto-updatestreamparams+json
     Content-Length: ###




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     { "add": {
         "my-cdnifci-stream": {
             "resource-id": "my-default-cdnifci-map"
         }
     }

     HTTP/1.1 200 OK
     Connection: keep-alive
     Content-Type: text/event-stream

     event: application/alto-updatestreamcontrol+json
     data: {"control-uri":
     data: "http://alto.example.com/updates/streams/3141592653589"}

     event: application/alto-cdnifcimap+json,my-default-cdnifci-map
     data: { ... full CDNI FCI map ... }

     event: application/merge-patch+json,my-default-cdnifci-map
     data: {
     data:   "meta": {
     data:     "vtag": {
     data:       "tag": "dasdfa10ce8b059740bddsfasd8eb1d47853716"
     data:     }
     data:   },
     data:   {
     data:     "capability-type": "FCI.DeliveryProtocol",
     data:     "capability-value": {
     data:       "delivery-protocols": [
     data:         "http/1.1"
     data:       ]
     data:     },
     data:     "footprints": [
     data:       <Footprint objects that are different from
     data:        footprint objects in delivery-protocols http/1.1>
     data:     ]
     data:   }
     data: }

     event: application/json-patch+json,my-default-cdnifci-map
     data: [
     data:   {
     data:     "op": "replace",
     data:     "path": "/meta/vtag/tag",
     data:     "value": "a10ce8b059740b0b2e3f8eb1d4785acd42231bfe"
     data:   },
     data:   { "op": "add",
     data:     "path": "/cdni-fci-map/capabilities/0/footprints/-",
     data:     "value": "ipv4:192.0.2.0/24"



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     data:   }
     data: ]

4.  CDNI FCI Map using ALTO Network Map

4.1.  Network Map Footprint Type: altonetworkmap

   In addition to the already defined CDNI footprint types (e.g.,
   ipv4cidr, ipv6cidr, asn, countrycode), ALTO network maps can be a
   type of FCI footprint.

   Specifically, CDNI footprints using ALTO network maps should use a
   new CDNI Footprint Type called "altonetworkmap".

   "altonetworkmap" footprint type indicates that the corresponding
   footprint value is a list of PIDNames as defined in [RFC7285].  These
   PIDNames are references of PIDs in a network map resource.  Hence a
   CDNI FCI map with "altonetworkmap" footprints depends on a network
   map.  For such a CDNI FCI map, the "dependent-vtag" field with a
   reference to a network map it depends on MUST be included in it (see
   the example in Section 4.2.3).

4.2.  Examples

4.2.1.  IRD Example

   We use the same IRD example given in Section 3.7.1.

4.2.2.  ALTO Network Map for CDNI FCI Footprints Example

   Below is an example network map whose resource id is "my-eu-netmap",
   and this map is referenced by the CDNI FCI map example in
   Section 4.2.3.

    GET /networkmap HTTP/1.1
    Host: http://alto.example.com/myeunetmap
    Accept: application/alto-networkmap+json,application/alto-error+json














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    HTTP/1.1 200 OK
    Content-Length: XXX
    Content-Type: application/alto-networkmap+json

    {
      "meta" : {
        "vtag": [
          {"resource-id": "my-eu-netmap",
           "tag": "3ee2cb7e8d63d9fab71b9b34cbf764436315542e"
          }
        ]
      },
      "network-map" : {
        "south-france" : {
          "ipv4" : [ "192.0.2.0/24", "198.51.100.0/25" ]
        },
        "germany" : {
          "ipv4" : [ "192.0.3.0/24"]
        }
      }
    }

4.2.3.  ALTO Network Map Footprints in CDNI FCI Map

   In this example, we show a CDNI FCI map that depends on a network map
   described in Section 4.2.2.

    GET /networkcdnifcimap HTTP/1.1
    Host: alto.example.com
    Accept: application/alto-cdnifcimap+json,application/alto-error+json





















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    HTTP/1.1 200 OK
    Content-Length: 618
    Content-Type: application/alto-cdnifcimap+json

    {
      "meta" : {
        "dependent-vtags" : [
          {
            "resource-id": "my-eu-netmap",
            "tag": "3ee2cb7e8d63d9fab71b9b34cbf764436315542e"
          }
        ]
      },
      "cdni-fci-map": {
        "capabilities": [
          { "capability-type": "FCI.DeliveryProtocol",
            "capability-value": [
              "http/1.1"
            ]
          },
          { "capability-type": "FCI.DeliveryProtocol",
            "capability-value": [
              "https/1.1"
            ],
            "footprints": [
              { "footprint-type": "altonetworkmap",
                "footprint-value": [
                  "germany",
                  "south-france"
                ]
              }
            ]
          }
        ]
      }
    }

4.2.4.  Incremental Updates Example

   In this example, the ALTO client is interested in changes of "my-
   cdnifci-map-with-network-map-footprints".  Considering two changes,
   the first one is to change footprints of http/1.1 Delivery Protocol
   capability, and the second one is to remove "south-france" from the
   footprints of https/1.1 delivery protocol capability.

     POST /updates/cdnifcimaps HTTP/1.1
     Host: alto.example.com
     Accept: text/event-stream,application/alto-error+json



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     Content-Type: application/alto-updatestreamparams+json
     Content-Length: ###

     { "add": {
         "my-network-map-cdnifci-stream": {
             "resource-id": "my-cdnifci-map-with-network-map-footprints"
         }
     }

     HTTP/1.1 200 OK
     Connection: keep-alive
     Content-Type: text/event-stream

     event: application/alto-updatestreamcontrol+json
     data: {"control-uri":
     data: "http://alto.example.com/updates/streams/3141592653590"}

     event: application/alto-cdnifcimap+json,my-fci-stream
     data: { ... full CDNI FCI map ... }

     event: application/merge-patch+json,my-fci-stream
     data: {
     data:   "meta": {
     data:     "dependent-vtags" : [
     data:      {
     data:        "resource-id": "my-eu-netmap",
     data:        "tag": "3ee2cb7e8d63d9fab71b9b34cbf764436315542e"
     data:      }
     data:     ],
     data:     "vtag": {
     data:       "tag": "dasdfa10ce8b059740bddsfasd8eb1d47853716"
     data:     }
     data:   },
     data:   {
     data:     "capability-type": "FCI.DeliveryProtocol",
     data:     "capability-value": {
     data:       "delivery-protocols": [
     data:         "http/1.1"
     data:       ]
     data:     },
     data:     "footprints": [
     data:       <Footprint objects that are different from
     data:        footprint objects in delivery-protocols http/1.1>
     data:     ]
     data:   }
     data: }

     event: application/json-patch+json,my-fci-stream



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     data: [
     data:   {
     data:     "op": "replace",
     data:     "path": "/meta/vtag/tag",
     data:     "value": "a10ce8b059740b0b2e3f8eb1d4785acd42231bfe"
     data:   },
     data:   { "op": "remove",
     data:     "path": "/cdni-fci-map/capabilities/2/footprints/0/
     data:       footprint-value/1",
     data:   }
     data: ]

5.  Filtered CDNI FCI Map using Capabilities

   Section 3 and Section 4 describe CDNI FCI Map Service which can be
   used to enable a uCDN to get capabilities with footprints constrains
   from dCDNs.  However, always getting full CDNI FCI maps from dCDNs is
   very inefficient, hence we introduce a new service named "Filtered
   CDNI FCI Map Service" to allow a client to filter a CDNI FCI map
   using a client-given set of capabilities.  For each entry of the CDNI
   FCI map, only if the entry contains at least one of the client-given
   capabilities will it be returned to the client.  The relationship
   between a filtered CDNI FCI map and a CDNI FCI map is similar to the
   relationship between a filtered network/cost map and a network/cost
   map.

5.1.  Media Type

   Since a filtered CDNI FCI map is still a CDNI FCI map, it uses the
   media type defined for CDNI FCI maps in Section 3.1.

5.2.  HTTP Method

   A filtered CDNI FCI map is requested using the HTTP POST method.

5.3.  Accept Input Parameters

   The input parameters for a filtered CDNI FCI map are supplied in the
   entity body of the POST request.  This document specifies the input
   parameters with a data format indicated by the media type
   "application/alto-cdnifcifilter+json" which is a JSON object of type
   ReqFilteredCDNIFCIMap, where:









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      object {
          JSONString capability-type;
          JSONValue capability-value;
      } CDNIFCICapability;

      object {
          [CDNIFCICapability cdni-fci-capabilities<0..*>;]
      } ReqFilteredCDNIFCIMap;

   with fields:

   capability-type:  The same as Base Advertisement Object's capability-
      type defined in Section 5.1 of [RFC8008].

   capability-value:  The same as Base Advertisement Object's
      capability-value defined in Section 5.1 of [RFC8008].

   cdni-fci-capabilities:  A list of CDNI FCI capabilities defined in
      Section 5.1 of [RFC8008] for which footprints are to be returned.
      If a list is empty or not appearing, the ALTO server MUST
      interpret it as a request for the full CDNI FCI Map. The ALTO
      server MUST interpret entries appearing in a list multiple times
      as if they appeared only once.  If a "capability-type" or a
      "capability-value" is not defined, the ALTO server MUST ignore
      this capability.  If there is only one capability in the list and
      its "capability-type" or "capability-value" is not defined, the
      ALTO server MUST return nothing.

5.4.  Capabilities

   None.

5.5.  Uses

   The resource ID of the CDNI FCI map based on which the filtering is
   performed.

5.6.  Response

   The response MUST indicate an error, using ALTO protocol error
   handling specified in Section 8.5 of the ALTO protocol [RFC7285], if
   the request is invalid.

   Specifically, a filtered CDNI FCI map request can be invalid as
   follows:

   o  The value of "capability-type" is null;




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   o  The value of "capability-value" is null;

   o  The value of "capability-value" is inconsistent with "capability-
      type".

   When the request is invalid, the ALTO server MUST return an
   "E_INVALID_FIELD_VALUE" error defined in Section 8.5.2 of [RFC7285],
   and the "value" field of the error message SHOULD indicate this CDNI
   FCI capability.

   The ALTO server return a filtered CDNI FCI map for a valid request.
   The format of a filtered CDNI FCI map is the same as an unfiltered
   CDNI FCI map.  See Section 3.6 for the format.

   The returned CDNI FCI map MUST contain only BaseAdvertisementObject
   objects whose CDNI capability object is the superset of one of CDNI
   capability object in "cdni-fci-capabilities".  Specifically, that a
   CDNI capability object A is the superset of another CDNI capability
   object B means that these two CDNI capability objects have the same
   capability type and mandatory properties in capability value of A
   MUST include mandatory properties in capability value of B
   semantically.  See Section 5.7.2 for a concrete example.

   The version tag included in the "vtag" field of the response MUST
   correspond to the full CDNI FCI map resource from which the filtered
   CDNI FCI map is provided.  This ensures that a single, canonical
   version tag is used independently of any filtering that is requested
   by an ALTO client.

5.7.  Examples

5.7.1.  IRD Example

   We use the same IRD example by Section 3.7.1.

5.7.2.  Basic Example

   This example filters the full CDNI FCI map in Section 3.7.2 by
   selecting only http/1.1 delivery protocol capability.  Only the first
   two BaseAdvertisementObjects in the full map will be returned because
   the first object's capability is http/1.1 delivery protocol and the
   second object's capability is http/1.1 and https/1.1 delivery
   protocols which is the superset of http/1.1 delivery protocol.

     POST /cdnifcimap/filtered HTTP/1.1
     HOST: alto.example.com
     Content-Type: application/cdnifilter+json
     Accept: application/alto-cdnifcimap+json



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     {
       "cdni-fci-capabilities": [
         {
           "capability-type": "FCI.DeliveryProtocol",
           "capability-value": {
             "delivery-protocols": [
               "http/1.1"
             ]
           }
         }
       ]
     }

     HTTP/1.1 200 OK
     Content-Length: XXX
     Content-Type: application/alto-cdnifcimap+json
     {
       "meta" : {
         "vtag": {
           "resource-id": "my-default-cdnifci-map",
           "tag": "da65eca2eb7a10ce8b059740b0b2e3f8eb1d4785"
         }
       },
       "cdni-fci-map": {
         "capabilities": [
           {
             "capability-type": "FCI.DeliveryProtocol",
             "capability-value": {
               "delivery-protocols": [
                 "http/1.1"
               ]
             },
             "footprints": [
               <Footprint objects>
             ]
           },
           {
             "capability-type": "FCI.DeliveryProtocol",
             "capability-value": {
               "delivery-protocols": [
                 "https/1.1",
                 "http/1.1"
               ]
             },
             "footprints": [
               <Footprint objects>
             ]
           }



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         ]
       }
     }

5.7.3.  Incremental Updates Example

   In this example, the ALTO client only cares about the updates of one
   Delivery Protocol object whose value is "http/1.1".  So it adds its
   limitation of capabilities in "input" field of the POST request.

     POST /updates/cdnifcimaps HTTP/1.1
     Host: fcialtoupdate.example.com
     Accept: text/event-stream,application/alto-error+json
     Content-Type: application/alto-updatestreamparams+json
     Content-Length: ###

     { "add": {
         "my-fci-stream": {
             "resource-id": "my-filtered-cdnifci-map",
             "input": {
               "cdni-fci-capabilities": [
               {
                 "capability-type": "FCI.DeliveryProtocol",
                 "capability-value": {
                   "delivery-protocols": [
                     "http/1.1"
                   ]
                 }
               }
             ]
           }
         }
       }
     }

     HTTP/1.1 200 OK
     Connection: keep-alive
     Content-Type: text/event-stream

     event: application/alto-updatestreamcontrol+json
     data: {"control-uri":
     data: "http://alto.example.com/updates/streams/3141592653590"}

     event: application/alto-cdnifcimap+json,my-fci-stream
     data: { ... full filtered CDNI FCI map ... }

     event: application/merge-patch+json,my-fci-stream
     data: {



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     data:   "meta": {
     data:     "vtag": {
     data:       "tag": "dasdfa10ce8b059740bddsfasd8eb1d47853716"
     data:     }
     data:   },
     data:   {
     data:     "capability-type": "FCI.DeliveryProtocol",
     data:     "capability-value": {
     data:       "delivery-protocols": [
     data:         "http/1.1"
     data:       ]
     data:     },
     data:     "footprints": [
     data:       <Footprint objects that are different from
     data:        footprint objects in delivery-protocols http/1.1>
     data:     ]
     data:   }
     data: }

     event: application/json-patch+json,my-fci-stream
     data: [
     data:   {
     data:     "op": "replace",
     data:     "path": "/meta/vtag/tag",
     data:     "value": "a10ce8b059740b0b2e3f8eb1d4785acd42231bfe"
     data:   },
     data:   { "op": "add",
     data:     "path": "/cdni-fci-map/capabilities/0/footprints/-",
     data:     "value": "ipv4:192.0.2.0/24"
     data:   }
     data: ]

6.  Query Footprint Properties using ALTO Unified Property Service

   Above sections describe how a uCDN can get the whole capabilities and
   footprints from dCDNs and how a uCDN can get the footprints of given
   capabilities.  But there is another important case which is how a
   uCDN can get properties (i.e., capabilities) of given footprints.

   The most natrual way to solve this problem is to use ALTO unified
   property map defined in [I-D.ietf-alto-unified-props-new] since
   footprints can be easily presented as groups of entities and Filtered
   Property Maps are already well-defined.  In this section, we describe
   how ALTO clients look up properties for individual footprints.  We
   firstly describe how to represent footprint objects as unified
   property map entities, and then we provide examples of the full
   property map, the filtered property map and the incremental updates.




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6.1.  Representing Footprint Objects as Unified Property Map Entities

   A footprint object has two properties: footprint-type and footprint-
   value.  A footprint-value is an array of footprint values conforming
   to the specification associated with the registered footprint type
   ("ipv4cidr", "ipv6cidr", "asn", and "countrycode").  Since each
   unified property map entity has a unique address and each pair of
   footprint-type and a footprint value determines a group of unique
   addresses, a footprint object can be represented as a set of entities
   according to their different footprint-type and footprint values.
   However, [I-D.ietf-alto-unified-props-new] only defines IPv4 Domain
   and IPv6 Domain which represent footprint-type "ipv4cidr" and
   "ipv6cidr" respectively.  To represent footprint-type "asn" and
   "countrycode", this document registers two new domains in Section 8.

   Here gives an example of representing a footprint object as a set of
   unified property map entities.

   {"footprint-type": "ipv4cidr", "footprint-value": ["192.0.2.0/24",
   "198.51.100.0/24"]} --> "ipv4:192.168.2.0/24", "ipv4:198.51.100.0/24"

6.1.1.  ASN Domain

   This document specifies a new domain in addition to the ones in
   [I-D.ietf-alto-unified-props-new].  ASN is the abbreviation of
   Autonomous System Number.

6.1.1.1.  Domain Name

   asn

6.1.1.2.  Domain-Specific Entity Addresses

   The entity address of asn domain is encoded as a string consisting of
   the characters "as" (in lowercase) followed by the ASN [RFC6793].

6.1.1.3.  Hierarchy and Inheritance

   There is no hierarchy or inheritance for properties associated with
   ASN.

6.1.2.  COUNTRYCODE Domain

   This document specifies a new domain in addition to the ones in
   [I-D.ietf-alto-unified-props-new].






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6.1.2.1.  Domain Name

   countrycode

6.1.2.2.  Domain-Specific Entity Addresses

   The entity address of countrycode domain is encoded as an ISO 3166-1
   alpha-2 code [ISO3166-1] in lowercase.

6.1.2.3.  Hierarchy and Inheritance

   There is no hierarchy or inheritance for properties associated with
   country codes.

6.2.  Examples

6.2.1.  IRD Example

   We use the same IRD example given by Section 3.7.1.

6.2.2.  Property Map Example

   This example shows a full unified property map in which entities are
   footprints and entities' property is "cdni-fci-capabilities".



























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    GET /propmap/full/cdnifci HTTP/1.1
    HOST: alto.example.com
    Accept: application/alto-propmap+json,application/alto-error+json

    HTTP/1.1 200 OK
    Content-Length: ###
    Content-Type: application/alto-propmap+json

    {
      "property-map": {
        "meta": {
          "dependent-vtags": [
            {"resource-id": "my-default-cdnifci-map",
             "tag": "7915dc0290c2705481c491a2b4ffbec482b3cf62"}
          ]
        },
        "countrycode:us": {
          "cdni-fci-capabilities": [
            {"capability-type": "FCI.DeliveryProtocol",
             "capability-value": {"delivery-protocols": ["http/1.1"]}}]
        },
        "ipv4:192.0.2.0/24": {
          "cdni-fci-capabilities": [
            {"capability-type": "FCI.DeliveryProtocol",
             "capability-value": {"delivery-protocols": ["http/1.1"]}}]
        },
        "ipv4:198.51.100.0/24": {
          "cdni-fci-capabilities": [
            {"capability-type": "FCI.DeliveryProtocol",
             "capability-value": {"delivery-protocols": ["http/1.1"]}}]
        },
        "ipv6:2001:db8::/32": {
          "cdni-fci-capabilities": [
            {"capability-type": "FCI.DeliveryProtocol",
             "capability-value": {"delivery-protocols": ["http/1.1"]}}]
        },
        "asn:as64496": {
          "cdni-fci-capabilities": [
            {"capability-type": "FCI.DeliveryProtocol",
             "capability-value": {"delivery-protocols": ["http/1.1",
                                                         "https/1.1"]}}]
        }
      }
    }







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6.2.3.  Filtered Property Map Example

   In this example, we use filtered property map service to get "pid"
   and "cdni-fci-capabilities" properties for two footprints
   "ipv4:192.0.2.0/24" and "ipv6:2001:db8::/32".

      POST /propmap/lookup/cdnifci-pid HTTP/1.1
      HOST: alto.example.com
      Content-Type: application/alto-propmapparams+json
      Accept: application/alto-propmap+json,application/alto-error+json
      Content-Length:

      {
        "entities": [
          "ipv4:192.0.2.0/24",
          "ipv6:2001:db8::/32"
        ],
        "properties": [ "cdni-fci-capabilities", "pid" ]
      }

    HTTP/1.1 200 OK
    Content-Length: ###
    Content-Type: application/alto-propmap+json

    {
      "property-map": {
        "meta": {
          "dependent-vtags": [
             {"resource-id": "my-default-cdnifci-map",
               "tag": "7915dc0290c2705481c491a2b4ffbec482b3cf62"},
             {"resource-id": "my-default-networkmap",
               "tag": "7915dc0290c2705481c491a2b4ffbec482b3cf63"}
          ]
        },
        "ipv4:192.0.2.0/24": {
          "cdni-fci-capabilities": [
            {"capability-type": "FCI.DeliveryProtocol",
             "capability-value": {"delivery-protocols": ["http/1.1"]}}],
          "pid": "pid1"
        },
        "ipv6:2001:db8::/32": {
          "cdni-fci-capabilities": [
            {"capability-type": "FCI.DeliveryProtocol",
             "capability-value": {"delivery-protocols": ["http/1.1"]}}],
          "pid": "pid3"
        }
      }
    }



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6.2.4.  Incremental Updates Example

   In this example, here is a client want to request updates for the
   properties "cdni-fci-capabilities" and "pid" for two footprints
   "ipv4:192.0.2.0/24" and "ipv6:2001:db8::/32".

      POST /updates/properties HTTP/1.1
      Host: alto.example.com
      Accept: text/event-stream,application/alto-error+json
      Content-Type: application/alto-updatestreamparams+json
      Content-Length: ###

      { "add": {
        "property-map-including-capability-property": {
          "resource-id": "filtered-cdnifci-property-map",
            "input": {
              "properties": ["cdni-fci-capabilities", "pid"],
              "entities": [
                "ipv4:192.0.2.0/24",
                "ipv6:2001:db8::/32"
              ]
            }
          }
      }

      HTTP/1.1 200 OK
      Connection: keep-alive
      Content-Type: text/event-stream

      event: application/alto-updatestreamcontrol+json
      data: {"control-uri":
      data: "http://alto.example.com/updates/streams/1414213562373"}

      event: application/alto-cdnifcimap+json,my-fci-stream
      data: { ... full filtered unified property map ... }

      event: application/merge-patch+json,my-fci-stream
      data: {
      data:   "property-map":
      data:   {
      data:     "meta": {
      data:       "dependent-vtags": [
      data:         {"resource-id": "my-default-cdnifci-map",
      data:          "tag": "2beeac8ee23c3dd1e98a73fd30df80ece9fa5627"},
      data:         {"resource-id": "my-default-networkmap",
      data:          "tag": "7915dc0290c2705481c491a2b4ffbec482b3cf63"}
      data:       ]
      data:     },



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      data:     "ipv4:192.0.2.0/24":
      data:     {
      data:     "cdni-fci-capabilities": [
      data:       {"capability-type": "FCI.DeliveryProtocol",
      data:        "capability-value": {
      data:          "delivery-protocols": ["http/1.1"]}}]
      data:     }
      data:   }
      data: }

      event: application/json-patch+json,my-fci-stream
      data: {[
      data: {
      data:   { "op": "replace",
      data:       "path": "/meta/dependent-vtags/0/tag",
      data:       "value": "61b23185a50dc7b334577507e8f00ff8c3b409e4"
      data:   },
      data:   { "op": "replace",
      data:       "path": "/property-map/ipv4:192.0.2.0/124/",
      data:       "value": "pid5"
      data:   }
      data: }
      data: ]}

7.  Design Decisions and Discussions

7.1.  Table versus Map

   A major design decision is if the Map service is suitable to provide
   the CDNI FCI.  Current ALTO protocol uses Map service to provide
   network information, such as Network Maps, Cost Maps and Property
   Maps.  Their common idea is to use Map-like data structure to
   represent information.  It is different from the data structure of
   the CDNI FCI designed in [RFC8008], which suggests to use a set of
   BaseAdvertisementObjects to represent the CDNI FCI information, which
   actually is Table-like data structure.  Both Table and Map can be
   represented as a set of data entries.  But the difference of them is
   whether there is a primary key to index each data entry.

   The main advantage of Map-like data design is to simplify the filter-
   based query.  According to the discussion in [RFC8008] about benefits
   and concerns of advertisement-based design and query-based design,
   filter-based query can make the CDNI FCI scalable when the dCDN has
   thousands or tens of thousands of FCI objects.  To transfer Table-
   like data to Map-like data, introducing the primary key is necessary.
   This document already defines two different solution to introduce the
   primary key: (1) set unique identifiers for CDNI capability objects;
   (2) set unique identifiers for CDNI footprint objects.



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   But the major concern of the Map-like data design is the redundancy.
   In Map-like data design, whatever we choose CDNI capability objects
   or footprint objects as the key, each data entry can only represent
   the 1-N relation.  But there are lots of CDNI FCI objects have the
   N-N relation.

7.2.  Filter-based Query versus Test-based Query

   Another design decision is the query approach.  ALTO is a query-based
   protocol.  So using ALTO, uCDN should send a query request to the
   dCDN to pull the CDNI FCI proactively.  To make the query efficiently
   instead of pulling the whole FCI data base every time, query approach
   design is very important.

   This document only defines the filter-based query.  A uCDN can
   specify a set of FCI capability objects or footprint objects to only
   query the information including them.  But there are two limitations:
   (1) uCDN cannot filter both of them simultaneously; (2) cannot
   specify complex filters.

   One example is that uCDN wants to filter all CDNI FCI objects whose
   capabilities are in range C1 and footprints are in range F1, or
   capabilities are in range C2 and footprints are in range F2.

8.  IANA Considerations

8.1.  CDNI Metadata Footprint Type Registry

    +-----------------+-----------------------+-----------------------+
    | Footprint Type  | Description           | Specification         |
    +-----------------+-----------------------+-----------------------+
    | altonetworkmap  | A list of PID-names   | RFCthis               |
    +-----------------+-----------------------+-----------------------+

                   Table 1: CDNI Metadata Footprint Type

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

8.2.  ALTO Entity Domain Registry

   As proposed in Section 9.2 of [I-D.ietf-alto-unified-props-new],
   "ALTO Entity Domain Registry" is requested.  Besides, two new domains
   are to be registered, listed in Table 2.







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   +--------------+-------------------------+--------------------------+
   | Identifier   | Entity Address Encoding | Hierarchy & Inheritance  |
   +--------------+-------------------------+--------------------------+
   | asn          | See Section 6.1.1.2     | None                     |
   | countrycode  | See Section 6.1.2.2     | None                     |
   +--------------+-------------------------+--------------------------+

                        Table 2: ALTO Entity Domain

8.3.  ALTO CDNI FCI Property Type Registry

   The "ALTO CDNI FCI Property Type Registry" is required by the ALTO
   Entity Domain "asn", "countrycode", "pid", "ipv4" and "ipv6", listed
   in Table 3.

   +------------------------+------------------------------------------+
   | Identifier             | Intended Semantics                       |
   +------------------------+------------------------------------------+
   | cdni-fci-capabilities  | An array of CDNI FCI capability objects  |
   +------------------------+------------------------------------------+

                   Table 3: ALTO CDNI FCI Property Type

9.  Security Considerations

   Although CDNI FCI Map resource defined in this document is relatively
   different from other existed resources defined in the base protocol,
   the Security Considerations of the base protocol (Section 15 of
   RFC7285) still apply.

   For authenticity and Integrity of ALTO information, an attacker may
   disguise itself as an ALTO server in a dCDN, and it may provide false
   capabilities and footprints to an ALTO client in a uCDN by the CDNI
   FCI map.  Such false information may lead a uCDN to select a wrong
   dCDN to serve user requests or even block uCDNs utilizing some dCDNs
   in good condition.

   For potential undesirable guidance from authenticated ALTO
   information, dCDNs can provide a uCDN with limited capabilities and
   smaller footprint coverage so that dCDNs can avoid transferring
   traffic for a uCDN which they should have to transfer.

   For confidentiality of ALTO information, an attacker may infer the
   whole and exact capabilities and footprints of a dCDN by means of
   pretending it is one of different uCDNs of a dCDN respectively,
   getting different CDNI FCI maps from a dCDN and combining these maps
   together.




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   For privacy for ALTO users, querying footprint properties using ALTO
   unified property may expose network location identifiers (IP
   addresses or fine-grained PIDs) to the ALTO server in a dCDN.  In
   such case, a dCDN may potentially monitor and analyze user behaviors
   and communication patterns of uCDNs' customers.

   For availability of ALTO services, an attacker may get the potential
   huge full CDNI FCI maps from an ALTO server in a dCDN continuously to
   run out of bandwidth resources of that ALTO server or may query
   filtered CDNI FCI services with complex capabilities to run out of
   computation resources of an ALTO server.

   Protection Strategies described in RFC 7285 can solve problems
   mentioned above well.  However, the isolation of full/filtered CDNI
   FCI maps should also be considered.

   If a dCDN signs agreements with multiple uCDNs, it must isolate full/
   filtered CDNI FCI maps for different uCDNs in that uCDNs will not
   redirect requests which should not have to served by this dCDN to
   this dCDN and it may not disclose extra information to uCDNs.

   To avoid this risk, a dCDN may consider generating URIs of different
   full/filtered CDNI FCI maps by hashing its company ID, a uCDN's
   company ID as well as their agreements.  And it needs to avoid
   expoing all full/filtered CDNI FCI maps resources in one of its IRDs.

10.  Acknowledgments

   The authors would like to thank Daryl Malas, Matt Caulfield for their
   timely reviews and invaluable comments.

   Jan Seedorf is partially supported by the GreenICN project (GreenICN:
   Architecture and Applications of Green Information Centric
   Networking), a research project supported jointly by the European
   Commission under its 7th Framework Program (contract no. 608518) and
   the National Institute of Information and Communications Technology
   (NICT) in Japan (contract no. 167).  The views and conclusions
   contained herein are those of the authors and should not be
   interpreted as necessarily representing the official policies or
   endorsements, either expressed or implied, of the GreenICN project,
   the European Commission, or NICT.

11.  References








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11.1.  Normative References

   [ISO3166-1]
              The International Organization for Standardization, "Codes
              for the representation of names of countries and their
              subdivisions -- Part 1: Country codes", ISO 3166-1:2013,
              2013.

   [RFC5693]  Seedorf, J. and E. Burger, "Application-Layer Traffic
              Optimization (ALTO) Problem Statement", RFC 5693,
              DOI 10.17487/RFC5693, October 2009,
              <https://www.rfc-editor.org/info/rfc5693>.

   [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>.

   [RFC6793]  Vohra, Q. and E. Chen, "BGP Support for Four-Octet
              Autonomous System (AS) Number Space", RFC 6793,
              DOI 10.17487/RFC6793, December 2012,
              <https://www.rfc-editor.org/info/rfc6793>.

   [RFC7285]  Alimi, R., Ed., Penno, R., Ed., Yang, Y., Ed., Kiesel, S.,
              Previdi, S., Roome, W., Shalunov, S., and R. Woundy,
              "Application-Layer Traffic Optimization (ALTO) Protocol",
              RFC 7285, DOI 10.17487/RFC7285, September 2014,
              <https://www.rfc-editor.org/info/rfc7285>.

   [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>.

   [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>.







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11.2.  Informative References

   [I-D.ietf-alto-incr-update-sse]
              Roome, W. and Y. Yang, "ALTO Incremental Updates Using
              Server-Sent Events (SSE)", draft-ietf-alto-incr-update-
              sse-07 (work in progress), July 2017.

   [I-D.ietf-alto-path-vector]
              Bernstein, G., Chen, S., Gao, K., Lee, Y., Roome, W.,
              Scharf, M., Yang, Y., and J. Zhang, "ALTO Extension: Path
              Vector Cost Type", draft-ietf-alto-path-vector-04 (work in
              progress), July 2018.

   [I-D.ietf-alto-unified-props-new]
              Roome, W. and Y. Yang, "Extensible Property Maps for the
              ALTO Protocol", draft-ietf-alto-unified-props-new-00 (work
              in progress), July 2017.

   [I-D.jenkins-alto-cdn-use-cases]
              Niven-Jenkins, B., Watson, G., Bitar, N., Medved, J., and
              S. Previdi, "Use Cases for ALTO within CDNs", draft-
              jenkins-alto-cdn-use-cases-03 (work in progress), June
              2012.

Authors' Addresses

   Jan Seedorf
   HFT Stuttgart - Univ. of Applied Sciences
   Schellingstrasse 24
   Stuttgart  70174
   Germany

   Phone: +49-0711-8926-2801
   Email: jan.seedorf@hft-stuttgart.de


   Y.R. Yang
   Tongji/Yale University
   51 Prospect Street
   New Haven, CT  06511
   United States of America

   Email: yry@cs.yale.edu
   URI:   http://www.cs.yale.edu/~yry/







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   Kevin J. Ma
   Ericsson
   43 Nagog Park
   Acton, MA  01720
   United States of America

   Phone: +1-978-844-5100
   Email: kevin.j.ma@ericsson.com


   Jon Peterson
   NeuStar
   1800 Sutter St Suite 570
   Concord, CA  94520
   United States of America

   Email: jon.peterson@neustar.biz


   Xiao Shawn Lin
   Tongji University
   4800 Cao'an Hwy
   Shanghai  201804
   China

   Email: x.shawn.lin@gmail.com

























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