ALTO WG                                                         W. Roome
Internet-Draft                                            S. Randriamasy
Intended status: Standards Track                         Nokia Bell Labs
Expires: September 12, 2019 January 9, 2020                                         Y. Yang
                                                         Yale University
                                                                J. Zhang
                                                       Tongji University
                                                          March 11,
                                                            July 8, 2019

                Unified Properties for the ALTO Protocol
                  draft-ietf-alto-unified-props-new-07
                  draft-ietf-alto-unified-props-new-08

Abstract

   This document extends the Application-Layer Traffic Optimization
   (ALTO) Protocol [RFC7285] by generalizing the concept of "endpoint
   properties" to domains of other entities, and by presenting those
   properties as maps, similar to the network and cost maps in ALTO.
   [RFC7285].

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 RFC 2119 [RFC2119].

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. January 9, 2020.

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
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   publication of this document.  Please review these documents
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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3   4
   2.  Definitions and  Overview: Basic Concepts  . . . . . . . . . . . . . . . . . .   4   5
     2.1.  Entity  . . . . . . . . . . . . . . . . . . . . . . . . .   4   5
     2.2.  Entity Domain . Property . . . . . . . . . . . . . . . . . . . . .   5   6
     2.3.  Domain Name .  Property Map  . . . . . . . . . . . . . . . . . . . . . .   5   6
     2.4.  Entity Identifier . .  Information Resource  . . . . . . . . . . . . . . . . . .   6
     2.5.  Property Type and Property Name .  Entity Domain . . . . . . . . . . . .   6
     2.6.  Hierarchy and Inheritance . . . . . . . . . .   7
       2.5.1.  Resource-Specific Entity Domain . . . . . .   7
     2.7.  Relationship with Other ALTO Resources . . . . .   7
       2.5.2.  Relationship between Entity and Entity Domain . . . .   7
   3.
       2.5.3.  Aggregated Entity Domains Domain  . . . . . . . . . . . . . .   7
       2.5.4.  Resource-Specific Entity Property . . . . . . . . . .   8
     3.1.  Internet Address Domains
     2.6.  Scope of Property Map . . . . . . . . . . . . . . . .   9
       3.1.1.  IPv4 Domain . .   8
     2.7.  Entity Hierarchy and Property Inheritance . . . . . . . .   9
   3.  Protocol Specification: Basic Data Type . . . . . . . . . . .   9
       3.1.2.  IPv6  10
     3.1.  Entity Domain . . . . . . . . . . . . . . . . . . . . .   9
       3.1.3.  Hierarchy and Inheritance of ipv4/ipv6 Domains  . . .   9
     3.2.  PID  10
       3.1.1.  Entity Domain Type  . . . . . . . . . . . . . . . . .  10
       3.1.2.  Entity Domain Name  . . . . . .  11
       3.2.1.  Domain Name . . . . . . . . . . . .  10
       3.1.3.  Entity Identifier . . . . . . . . .  11
       3.2.2.  Domain-Specific Entity Identifiers . . . . . . . . .  11
       3.2.3.
       3.1.4.  Hierarchy and Inheritance . . . . . . . . . . . . . .  11
       3.2.4.  Relationship To Internet Addresses Domains  12
     3.2.  Entity Property . . . . .  11
     3.3.  Internet Address Properties vs. PID Properties . . . . .  11
   4.  Property Map . . . . . . . . . . .  12
       3.2.1.  Entity Property Type  . . . . . . . . . . . . .  12
     4.1.  Media Type . . .  12
       3.2.2.  Entity Property Name  . . . . . . . . . . . . . . . .  13
     3.3.  Information Resource Export . . . .  12
     4.2.  HTTP Method . . . . . . . . . . .  13
       3.3.1.  Resource-Specific Entity Domain Export  . . . . . . .  13
       3.3.2.  Entity Property Mapping Export  . . . . .  12
     4.3.  Accept Input Parameters . . . . . .  14
   4.  Entity Domain Types . . . . . . . . . . .  12
     4.4.  Capabilities . . . . . . . . . .  14
     4.1.  Internet Address Domain Types . . . . . . . . . . . .  12
     4.5.  Uses . .  14
       4.1.1.  IPv4 Domain . . . . . . . . . . . . . . . . . . . . .  14
       4.1.2.  IPv6 Domain . . .  13
     4.6.  Response . . . . . . . . . . . . . . . . . .  15
       4.1.3.  Hierarchy and Inheritance of Internet Address Domains  15
     4.2.  PID Domain  . . . . . .  13
   5.  Filtered Property Map . . . . . . . . . . . . . . . . .  16
       4.2.1.  Entity Domain Type  . . .  14
     5.1.  Media Type . . . . . . . . . . . . . .  16
       4.2.2.  Domain-Specific Entity Identifiers  . . . . . . . . .  14
     5.2.  HTTP Method  16
       4.2.3.  Hierarchy and Inheritance . . . . . . . . . . . . . .  17
       4.2.4.  Relationship To Internet Addresses Domains  . . . . .  17
     4.3.  Internet Address Properties vs. PID Properties  . . . .  14
     5.3.  Accept Input Parameters . . .  17
   5.  Entity Domains and Property Mappings in Information Resources  17
     5.1.  Network Map Resource  . . . . . . . . . . . . . .  14
     5.4.  Capabilities . . . .  17
       5.1.1.  Resource-Specific Entity Domain . . . . . . . . . . .  18
       5.1.2.  Entity Property Mapping . . . . . . .  15
     5.5.  Uses . . . . . . . .  18
     5.2.  Endpoint Property Resource  . . . . . . . . . . . . . . .  18
       5.2.1.  Resource-Specific Entity Domain . . .  15
     5.6.  Response . . . . . . . .  18
       5.2.2.  Entity Property Mapping . . . . . . . . . . . . . . .  19
     5.3.  Property Map Resource .  15
   6.  Impact on Legacy ALTO Servers and ALTO Clients . . . . . . .  17
     6.1.  Impact on Endpoint Property Service . . . . . . . . . .  19
   6.  Property Map  .  17
     6.2.  Impact on Resource-Specific Properties . . . . . . . . .  17
     6.3.  Impact on the pid Property . . . . . . . . . . . . . .  19
     6.1.  Media Type  .  17
     6.4.  Impact on Other Properties . . . . . . . . . . . . . . .  18
   7.  Examples . . . . . . .  19
     6.2.  HTTP Method . . . . . . . . . . . . . . . . . . .  18
     7.1.  Network Map . . . .  19
     6.3.  Accept Input Parameters . . . . . . . . . . . . . . . . .  19
     6.4.  Capabilities  . .  18
     7.2.  Property Definitions . . . . . . . . . . . . . . . . . .  18
     7.3.  Information Resource Directory (IRD) . .  19
     6.5.  Uses  . . . . . . . .  19
     7.4.  Property Map Example . . . . . . . . . . . . . . . . . .  21
     7.5.  Filtered Property Map Example #1  20
     6.6.  Response  . . . . . . . . . . . .  22
     7.6.  Filtered Property Map Example #2 . . . . . . . . . . . .  23
     7.7.  20
   7.  Filtered Property Map Example #3 . . . . . . . . . . . .  24
     7.8.  Filtered Property Map Example #4 . . . . . . . .  21
     7.1.  Media Type  . . . .  25
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .  26
   9.  IANA Considerations  21
     7.2.  HTTP Method . . . . . . . . . . . . . . . . . . . . .  27
     9.1.  application/alto-* Media Types . .  21
     7.3.  Accept Input Parameters . . . . . . . . . . .  27
     9.2.  ALTO Entity Domain Registry . . . . . .  21
     7.4.  Capabilities  . . . . . . . . .  28
       9.2.1.  Consistency Procedure between ALTO Address Type
               Registry and ALTO Entity Domain Registry . . . . . .  29
       9.2.2.  ALTO Entity Domain Registration Process . . . . . . .  30
     9.3.  ALTO Entity Property Type Registry  22
     7.5.  Uses  . . . . . . . . . . .  31
     9.4.  Acknowledgments . . . . . . . . . . . . . . .  22
     7.6.  Response  . . . . . .  32
   10. Normative References . . . . . . . . . . . . . . . . . .  22
   8.  Impact on Legacy ALTO Servers and ALTO Clients  . .  32
   Authors' Addresses . . . . .  24
     8.1.  Impact on Endpoint Property Service . . . . . . . . . . .  24
     8.2.  Impact on Resource-Specific Properties  . . . . . . .  33

1.  Introduction

   The . .  24
     8.3.  Impact on the pid Property  . . . . . . . . . . . . . . .  25
     8.4.  Impact on Other Properties  . . . . . . . . . . . . . . .  25
   9.  Examples  . . . . . . . . . . . . . . . . . . . . . . . . . .  25
     9.1.  Network Map . . . . . . . . . . . . . . . . . . . . . . .  25
     9.2.  Property Definitions  . . . . . . . . . . . . . . . . . .  26
     9.3.  Information Resource Directory (IRD)  . . . . . . . . . .  27
     9.4.  Property Map Example  . . . . . . . . . . . . . . . . . .  29
     9.5.  Filtered Property Map Example #1  . . . . . . . . . . . .  30
     9.6.  Filtered Property Map Example #2  . . . . . . . . . . . .  31
     9.7.  Filtered Property Map Example #3  . . . . . . . . . . . .  32
     9.8.  Filtered Property Map Example #4  . . . . . . . . . . . .  33
   10. Security Considerations . . . . . . . . . . . . . . . . . . .  34
   11. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  35
     11.1.  application/alto-* Media Types . . . . . . . . . . . . .  35
     11.2.  ALTO Entity Domain Type Registry . . . . . . . . . . . .  36
       11.2.1.  Consistency Procedure between ALTO Address Type
                Registry and ALTO Entity Domain Registry . . . . . .  37
       11.2.2.  ALTO Entity Domain Registration Process  . . . . . .  38

     11.3.  ALTO Entity Property Type Registry . . . . . . . . . . .  39
     11.4.  ALTO Resource-Specific Entity Domain Registries  . . . .  40
       11.4.1.  Network Map  . . . . . . . . . . . . . . . . . . . .  40
       11.4.2.  Endpoint Property  . . . . . . . . . . . . . . . . .  40
     11.5.  ALTO Resource Entity Property Mapping Registries . . . .  40
       11.5.1.  Network Map  . . . . . . . . . . . . . . . . . . . .  40
   12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  41
   13. Normative References  . . . . . . . . . . . . . . . . . . . .  41
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  42

1.  Introduction

   The ALTO protocol [RFC7285] introduces the concept of "properties"
   attached to "endpoint addresses", and defines the Endpoint Property
   Service (EPS) to allow ALTO clients to retrieve those properties.
   While useful, the EPS, as defined in [RFC7285], has at least two
   limitations.

   First, it allows properties to be associated with only a particular
   domain of entities, namely individual IP addresses.  It is reasonable
   to think that collections of endpoints, as defined by CIDRs [RFC4632]
   or PIDs, may also have properties.  Since the EPS cannot be extended
   to new entity domains, new services, with new request and response
   messages, would have to be defined for new entity domains.

   Second, the EPS is only defined as a POST-mode service.  Clients must
   request the properties for an explicit set of endpoint addresses.  By
   contrast, [RFC7285] defines a GET-mode cost map resource which
   returns all available costs, so a client can get a full set of costs
   once, and then processes costs lookups without querying the ALTO
   server.  [RFC7285] does not define an equivalent service for endpoint
   properties.  At first a map of endpoint properties might seem
   impractical, because it could require enumerating the property value
   for every possible endpoint.  But in practice, it is highly unlikely
   that properties will be defined for every endpoint address.  It is
   much more likely that properties may be defined for only a subset of
   endpoint addresses, and the specification of properties uses an
   aggregation representation to allow enumeration.  This is
   particularly true if blocks of endpoint addresses with a common
   prefix (e.g., a CIDR) have the same value for a property.  Entities
   in other domains may very well allow aggregated representation and
   hence be enumerable as well.

   This document specifies a new approach for defining and retrieving
   ALTO properties to address the two limitations.  Specifically, this
   document addresses the first limitation by introducing a generic
   concept called ALTO Entity Domains, where an entity is a
   generalization of an endpoint to also represent, a PID, a network
   element, or a cell in a cellular network, etc.  As a consequence,
   ALTO Entity Domains defined in this document are a super-set of ALTO
   Address Types defined in [RFC7285].  Their exact relationship is
   specified in Section 11.2.1.

   Entity domains and property names are extensible.  New entity domains
   can be defined without revising the messages defined in this
   document, in the same way that new cost metrics and new endpoint
   properties can be defined without revising the messages defined in
   [RFC7285].

   Additional, this document addresses the second limitation by defining
   two new types of resources, namely Property Map (see Section 6) and
   Filtered Property Map (see Section 7).  The former is a GET-mode
   resource which returns the property values for all entities in a
   domain, and is analogous to a network map or a cost map in [RFC7285].
   The latter is a POST-mode resource which returns the values for a set
   of properties and entities requested by the client, and is analogous
   to a filtered network map or a filtered cost map.

   This document subsumes the Endpoint Property Service defined in
   [RFC7285], although that service may be retained for legacy clients
   (see Section 8).

2.  Overview: Basic Concepts

   Before we define the specification of unified properties, there are
   several basic concepts which we need to introduce.

2.1.  Entity

   The entity concept generalizes the concept of the endpoint defined in
   Section 2.1 of [RFC7285].  An entity is an object that can be an
   endpoint and is identified by its network address, but can also be an
   object that has a defined mapping to a set of one or more network
   addresses or is even not related to any network address.

   Examples of eligible entities are:

   o  a PID, defined in [RFC7285], that has a provider defined human
      readable abstract identifier defined by a ALTO network map, which
      maps a PID to a set of ipv4 and ipv6 addresses;

   o  an autonomous system (AS), that has an AS number (ASN) as its
      identifier and maps to a set of ipv4 and ipv6 addresses;

   o  a region representing a country, that is identified by its country
      code defined by ISO 3166 and maps to a set of cellular addresses;

   o  a TCP/IP network flow, that has a server defined identifier
      consisting of the defining TCP/IP 5-Tuple, , which is an example
      that all endpoints are entities while not all entities are
      endpoints;

   o  a routing element, that is specified in [RFC7921] and includes
      routing capability information;

   o  an abstract network element, that has a server defined identifier
      and represents a network node, link or their aggregation.

2.2.  Entity Property

   An entity property defines a property of an entity.  It is similar to
   the endpoint property defined by Section 7.1 of [RFC7285], but can be
   general besides network-aware.

   For example,

   o  an "ipv4" entity may have a property whose value is an Autonomous
      System (AS) number indicating the AS which this IPv4 address is
      owned by;

   o  a "pid" entity may have a property which indicates the central
      geographical location of endpoints included by it.

2.3.  Property Map

   An ALTO property map provides a set of properties for a set of
   entities.  These entities may be in different types.  For example, an
   ALTO property map may define the ASN property for both "ipv4" and
   "ipv6" entities.

2.4.  Information Resource

   This document uses the same definition of the information resource as
   defined by [RFC7285].  Each information resource usually has a JSON
   format representation following a specific schema defined by its
   media type.

   For example, an ALTO network map resource is represented by a JSON
   objectof type InfoResourceNetworkMap defined by the media type
   "application/alto-networkmap+json".

2.5.  Entity Domain

   An entity domain defines a set of entities in the same type.  This
   type is also called the type of this entity domain.

   Using entity domains, an ALTO property map can indicate which
   entities the ALTO client can query to get their properties.

2.5.1.  Resource-Specific Entity Domain

   To define an entity domain, one naive solution is to enumerate all
   entities in this entity domain.  But it is inefficient when the size
   of the entity domain is large.

   To avoid enumerating all entities, this document introduces an
   approach called "Resource-Specific Entity Domain" to define entity
   domains:

   Each information resource may define several types of entity domains.
   And for each type of entity domain, an information resource can
   define at most one entity domain.  For example, an ALTO netowrk map
   resource can define an IPv4 domain, an IPv6 domain and a pid domain.
   In this document, these entity domains are called resource-specific
   entity domains.  An ALTO protocol [RFC7285] introduces the concept of "properties"
   attached property map only need to "endpoint addresses", and defines indicate which
   types of entity domain defined by which information resources can be
   queried, the Endpoint Property
   Service (EPS) ALTO client will know which entities are effective to allow be
   queried.

2.5.2.  Relationship between Entity and Entity Domain

   In this document, an entity is owned by exact one entity domain.  It
   requires that when an ALTO clients client or server references an entity, it
   must indicate its entity domain explicitly.  Even two entities in two
   different entity domains may reflect to retrieve those properties.
   While useful, the EPS, same physical or logical
   object, we treat them as defined in [RFC7285], different entities.

   Because of this rule, although the resource-specific entity domain
   approach has at least two
   limitations.

   First, no ambiguity, it only allows properties may introduce redundancy.

2.5.3.  Aggregated Entity Domain

   Two entities in two different resource-specific entity domains may
   reflect to be associated with a particular the same physical or logical object.  For example, the
   IPv4 entity "192.0.2.34" in the IPv4 domain of entities, namely individual IP addresses.  It is reasonable
   to think that collections the network map
   "netmap1" and the IPv4 entity "192.0.2.34" in the IPv4 domain of endpoints, as defined the
   network map "netmap2" should indicate the same Internet endpoint
   addressed by CIDRs [RFC4632]
   or PIDs, may also have properties.  Since the EPS cannot be extended
   to new IPv4 address "192.0.2.34".

   Each entity domains, new services, with new request and response
   messages, would in each resource-specific entity domain may only have to be defined for new
   part of properties of its associated physical or logical object.  For
   example, the IPv4 entity domains.

   Second, in the EPS is IPv4 domain of the network map
   "netmap1" only has the PID property defined as a POST-mode service.  Clients must
   request by "netmap1"; same to the properties for an explicit set
   IPv4 entity in the IPv4 domain of endpoint addresses.  By
   contrast, [RFC7285] defines a GET-mode cost the network map resource which
   returns all available costs, so a "netmap2".  If the
   ALTO client can wants to get a full set the complete properties, using the resource-
   specific entity domain, the ALTO client has to query the IPv4 entity
   "192.0.2.34" twice.

   To simplify the query process of costs
   once, and then processes costs lookups without querying the ALTO
   server.  [RFC7285] does not define client, this document
   introduces the concept "Aggregated Entity Domain".  An aggregated
   entity domain defines an equivalent service for endpoint
   properties.  At first a map aggregated set of endpoint properties might seem
   impractical, because it could require enumerating entities coming from
   multiple resource-specific entity domains in the property value
   for every possible endpoint.  But same type.  An
   entity in practice, it is highly unlikely
   that the aggregated entity domain includes all properties will be
   defined for every endpoint address.  It is
   much more likely that the associated entity in each associated resource-
   specific entity domains.  For example, the IPv4 entity "192.0.2.34"
   in the aggregated entity domain between the IPv4 domain of "netmap1"
   and the IPv4 domain of "netmap2" has PID properties will only be defined for a subset of
   endpoint addresses, by both
   "netmap1" and that subset would be small enough "netmap2".

2.5.4.  Resource-Specific Entity Property

   According to be
   enumerated.  This is particularly true if blocks the example of endpoint
   addresses with a common prefix (e.g., a CIDR) the aggregated entity domain, an entity
   may have multiple properties in the same value type but associated to
   different information resources.  To distinguish them, this document
   uses the same approach proposed by Section 10.8.1 of [RFC7285], which
   is called "Resource-Specific Entity Property".

2.6.  Scope of Property Map

   Using entity domains to organize entities, an ALTO property map
   resource actually provides a set of properties for some entity
   domains.  If we ignore the syntax sugar of the aggregated entity
   domain, we can consider an ALTO property map resource just provides a property.  Furthermore, entities in other domains may very well be
   enumerable.

   This document proposes
   set of (ri, di) => (ro, po) mappings, where (ri, di) means a new approach to retrieve ALTO properties.
   Specifically, it defines two new types
   resource-specific entity domain of resources, namely Property
   Map (see Section 4) type di defined by the information
   resource ri, and Filtered Property Map (see Section 5).  The
   former is (ro, po) means a GET-mode resource-specific entity property
   po defined by the information resource which returns ro.

   For each (ri, di) => (ro, po) mapping, the scope of an ALTO property values for
   all entities
   map resource must be one of cases in a domain, and is analogous the following diagram:

                       domain.resource   domain.resource
                       (ri) = r          (ri) = this
                     +-----------------|-----------------+
       prop.resource | Export          | Non-exist       |
       (ro) = r      |                 |                 |
                     +-----------------|-----------------+
       prop.resource | Extend          | Define          |
       (ro) = this   |                 |                 |
                     +-----------------|-----------------+

   where "this" points to a network the resulting property map or a cost resource, "r"
   presents an existing ALTO information resource other the resulting
   property map in [RFC7285]. resource.

   o  ri = ro = r ("export" mode): the property map resource just
      transforms the property mapping di => po defined by r into the
      unified representation format and exports it.  For example: r =
      "netmap1", di = "ipv4", po = "pid".  The latter is a POST-mode property map resource which returns
      exports the values for a set of "ipv4 => pid" mapping defined by "netmap1".

   o  ri = r, ro = this ("extend" mode): the property map extends
      properties and of entities requested by in the
   client, entity domain (r, di) and is analogous to defines a filtered network
      new property po on them.  For example: the property map or resource
      ("this") defines a filtered cost
   map.

   Additionally, "geolocation" property on domain "netmap1.pid".

   o  ri = ro = this document introduces ALTO Entity Domains, where an
   entity is a generalization of an endpoint to also represent, a PID, a
   network element, or a cell in a cellular network, etc.  As ("define" mode): the property map defines a
   consequence, ALTO Entity Domains defined new
      intrinsic entity domain and defines property po for each entities
      in this document are domain.  For example: the property map resource ("this")
      defines a
   super-set of ALTO Address Types defined in [RFC7285].  Their exact
   relationship is specified in Section 9.2.1.

   Entity domains new entity domain "asn" and defines a property names are extensible.  New entity domains
   can be defined without revising the messages defined in
      "ipprefixes" on this
   document, domain.

   o  ri = this, ro = r: in the same way scope of a property map resource, it
      does not make sense that new cost metrics another existing ALTO information
      resource defines a property for this property map resource.

2.7.  Entity Hierarchy and new endpoint
   properties can be defined without revising Property Inheritance

   Enumerating all individual effective entities are inefficient.  Some
   types of entities have the messages defined hierarchy format, e.g., cidr, which stand
   for sets of individual entities.  Many entities in
   [RFC7285].

   This proposal subsumes the Endpoint Property Service defined in
   [RFC7285], although that service may be retained for legacy clients
   (see Section 6).

2.  Definitions and Concepts

2.1.  Entity

   The same
   hierarchical format entity generalizes sets may have the concept of same proprety values.
   To reduce the endpoint defined in
   Section 2.1 size of [RFC7285].  An entity is the property map representation, this document
   introduces an object that approach called "Property Inheritance".  Individual
   entities can be an
   endpoint and is identified by inherit the property from its network address, but can also be an
   object that hierarchical format entity
   set.

3.  Protocol Specification: Basic Data Type

3.1.  Entity Domain

3.1.1.  Entity Domain Type

   An entity domain has a type, which is defined mapping to by a set of one or string that MUST
   be no more network
   addresses or than 64 characters, and MUST NOT contain characters other
   than US-ASCII alphanumeric characters (U+0030-U+0039, U+0041-U+005A,
   and U+0061-U+007A), hyphen ("-", U+002D), and low line ("_", U+005F).
   For example, the strings "ipv4", "ipv6", and "pid" are valid entity
   domain types.

   The type EntityDomainType is even not related to any network address.

   Examples of eligible entities are:

   o  a PID, defined used in [RFC7285], that has a provider defined human
      readable abstract identifier and maps this document to denote a set of ipv4 and ipv6
      addresses,

   o  an ASN number, that has a specified identifier and direct mapping JSON
   string confirming to network addresses,

   o the preceding requirement.

   An entity domain type defines the semantics of a country code, that specified in ISO 3166 format and that can type of entity
   domains.  Each entity domain type MUST be
      retrieved from an IP registered with the IANA.
   The format of cellular address.  As a consequence, all
      endpoints are entities while not all entities are endpoints,

   o  a TCP/IP network flow, that has a server defined identifier and
      represents the entity identifiers (see Section 3.1.3) in a TCP/IP 5-Tuple,

   o  a routing element, that type
   of entity domains, as well as any hierarchical or inheritance rules
   (see Section 3.1.4) for those entities, MUST be specified in [RFC7921] and includes
      routing capability information,

   o at the same
   time.

3.1.2.  Entity Domain Name

   Each entity domain is identified by an abstract network element, that has entity domain name, a server defined identifier string
   of the following format:

   EntityDomainName ::= [ [ ResourceID ] '.' ] EntityDomainType

   This document distinguish three types of entity domains: resource-
   specific entity domains, self-defined entity domain and represents a network node, link or their aggregation.

2.2.  Entity Domain aggregated
   entity domains.  Their entity domain names are derived as follows.

   Each ALTO information resource MAY define a resource-specific entity MUST
   domain (which could be empty) in one and only one a given entity domain.  An domain type.  A
   resource-specific entity domain is identified by an entity domain is
   name derived as follows.  It MUST start with a class of entities.  Examples of entity domains are resource ID using the
   Internet address domains (see Section 3.1 and
   ResourceID type defined in [RFC7285], followed by the PID domain (see
   Section 3.2).  The future documents "." separator
   (U+002E), followed by an EntityDomainType typed string.  For example,
   if an ALTO server provides two network maps "netmap-1" and "netmap-
   2", they can define new entity two different "pid" domains to
   satisfy the additional requirements such as cellular network
   information identified by
   "netmap-1.pid" and routing capability exposure.  But they are not "netmap-2.pid" respectively.  To be simplified, in
   the scope of a specific information resource, the resource-specific
   entity domain defined by itself can be identified by the "."
   EntityDomainTyep without the ResourceID.

   When the associated information resource of a resource-specific
   entity domain is the current information resource itself, this document.

2.3.  Domain Name

   Each
   resource-specific entity domain has is a unique name.  A self-defined entity domain, and
   its ResourceID SHOULD be ignored from its entity domain name MUST name.

   Given a set of ALTO information resources, there MAY be no more
   than 32 characters, and MUST NOT contain characters other than US-
   ASCII alphanumeric characters (U+0030-U+0039, U+0041-U+005A, and
   U+0061-U+007A), hyphen ("-", U+002D), and low line ("_", U+005F). an aggregated
   entity domain in a given entity domain type amongst them.  An
   aggregated entity domain is simply identified by its entity domain
   type.  For example, the names given two network maps "net-map-1" and "net-map-
   2", "ipv4" and "ipv6" identify entities in the two aggregated Internet address entity
   domains (see Section 3.1).

   The type DomainName 4.1) between them.

   Note that the "." separator is used in this document to denote a JSON string
   with a domain name not allowed in this format.

   Domain names MUST be registered with the IANA, EntityDomainType and the format of the
   entity addresses (see Section 2.4) in that
   hence there is no ambiguity on whether an entity domain, as well as
   any hierarchical domain name refers
   to a global entity domain or inheritance rules (see Section 2.6) for those
   entities, MUST be specified at the same time.

2.4. a resource-specific entity domain.

3.1.3.  Entity Identifier

   Each entity has

   Entities in an identifier entity domain are identified by entity identifiers
   (EntityID) of the following format:

       EntityId

   EntityID ::= DomainName : DomainSpecificEntityId

   An entity identifier uniquely identifies a particular entity within
   an ALTO property map resource (see Section 4). EntityDomainName ':' DomainTypeSpecificEntityID

   Examples from the IP Internet address entity domains include individual
   IP addresses such as
   "ipv4:192.0.2.14" "net1.ipv4:192.0.2.14" and "ipv6:2001:db8::12",
   "net1.ipv6:2001:db8::12", as well as address blocks such as "ipv4:192.0.2.0/26"
   "net1.ipv4:192.0.2.0/26" and "ipv6:2001:db8::1/48".

   The type EntityId is used in this document to denote a JSON string
   with an entity identifier in this format. "net1.ipv6:2001:db8::1/48".

   The format of the second part of an entity identifier depends on the
   entity domain, domain type, and MUST be specified when registering a new
   entity
   domain. domain type.  Identifiers MAY be hierarchical, and properties
   MAY be inherited based on that hierarchy.  Again, the rules defining
   any hierarchy or inheritance MUST be defined when the entity domain
   type is registered.

   The type EntityID is used in this document to denote a JSON string
   representing an entity identifier in this format.

   Note that an two entity address MAY have identifiers with different textual
   representations,
   representations may refer to the same entity, for a given entity
   domain.  For example, the strings
   "ipv6:2001:db8::1" "net1.ipv6:2001:db8::1" and "ipv6:2001:db8:0:0:0:0:0:1"
   "net1.ipv6:2001:db8:0:0:0:0:0:1" refer to the same
   entity.

2.5.  Property Type and Property Name

   Every entity in the
   "ipv6" entity domain.

3.1.4.  Hierarchy and Inheritance

   To make the representation efficient, some domain types of entity domains
   MAY have one or more properties.  Every
   property is identified by allow the ALTO client/server to use a Property Type and is specific hierarchical format entity
   identifier to represent a
   domain.  Every block of individual entities. e.g., In an
   IPv4 domain "net1.ipv4", a cidr "net1.ipv4:192.0.2.0/26" represents
   64 individual IPv4 entities.  In this case, the corresponding
   property inheritance rule MUST be defined for the entity domain type.
   The hierarchy and inheritance rule MUST have no ambiguity.

3.2.  Entity Property

   Each entity property has a unique type to indicate the encoding and the
   semantics of the value of this entity property, and has a name to be
   identified.  One entity MAY have multiple properties in the same
   type.

3.2.1.  Entity Property Type.

   This Type

   The type EntityPropertyType is used in this document defines to indicate a
   string denoting an entity property types in type.  The string MUST be no more
   than 32 characters, and it MUST NOT contain characters other than US-
   ASCII alphanumeric characters (U+0030-U+0039, U+0041-U+005A, and
   U+0061-U+007A), the domain-specific
   semantics.  Multiple hyphen ("-", U+002D), the colon (":", U+003A), or
   the low line ('_', U+005F).

   Each entity property types type MUST be registered with similar the IANA.  The
   intended semantics MAY share of the same Property Name in different entity domains.  But each property type MUST be registered for a single specific specified at
   the same time.

   To distinguish with the endpoint property type, the entity domain
   for property
   type has the following reasons: features.

   o  Some properties entity property types may only be applicable for to entities in only
      particular types of entity domains, not all.  For example, the
      "pid" property is not applicable for to entities in the a "pid" domain. typed
      entity domain, but is applicable to entities in the "ipv4" or
      "ipv6" domains.

   o  The interpretation intended semantics of the value of a entity property may also
      depend on the
      entity domain.  For different entity domains, not only the
      intended semantics but also the dependent resource types may be
      totally different. entity domain type of this entity.  For example,
      suppose that the "geo-location" property is defined as the
      coordinates of a point, encoded as (say) "latitude longitude
      [altitude]."  When applied to an entity that represents a specific
      host computer, identified by an address in the ipv4 or ipv6 domain, the property defines the host's
      location and has no required dependency.  However, when applied to
      an entity in the "pid" domain, the property would indicate the
      location of the center of all hosts in this "pid" entity and
      depend on the Network Map defining this "pid" entity.

   Therefore, each property type has a unique identifier encoded with
   the following format:

   PropertyType ::= DomainName : PropertyName

   o  The "DomainName" indicates which entity domain the property type
      applies to.

   o  The "PropertyName" SHOULD relate to the semantics of this property
      type.  It does not have to be globally unique.  In other words,
      different property types could have the same property name applied
      to different entity domains, if they have the similar semantics.
      For example, the property types "ipv4:pid" and "ipv6:pid" have "ipv4" or "ipv6"
      entity domain, the
      same property name "pid" defines the host's location.  However,
      when applied to both "ipv4" and "ipv6"
      domains.

   Property types MUST be registered with the IANA, and an entity in a "pid" domain, the intended
   semantics, as well as property would
      indicate the media types location of dependent resources and the
   interpretation, MUST be specified at the same time.

2.6.  Hierarchy and Inheritance

   Entities in a given domain MAY form a hierarchy based on entity
   identifiers, and introducing hierarchy allows the introduction center of
   inheritance. all hosts in this "pid"
      entity.

3.2.2.  Entity Property Name

   Each entity domain MUST define its own hierarchy and
   inheritance rules when registered.  The hierarchy and inheritance
   rule makes it possible for property is identified by an entity to inherit property name, which
   is a string of the following format:

   EntityPropertyName ::= [ ResourceID ] '.' EntityPropertyType

   Similar to the endpoint property value from
   another entity type defined in the same domain.

2.7.  Relationship with Other ALTO Resources

   [RFC7285] recognizes that some properties for some Section 10.8 of
   [RFC7285], each entity domains MAY property may be defined by either the property
   map itself (self-defined) or some other specific to an ALTO resource, such as information resource
   (resource-specific).

   The entity property name of a network map.  Accordingly
   Section 10.8.1 resource-specific entity property
   starts with a string of [RFC7285] defines the concept of "resource-specific
   endpoint properties", and indicates that dependency type ResourceID defined in [RFC7285],
   followed by prefixing the
   property name with "." separator (U+002E) and a EntityDomainType typed
   string.  For example, the ID "pid" properties of an "ipv4" entity
   defined by two different maps "net-map-1" and "net-map-2" are
   identified by "net-map-1.pid" and "net-map-2.pid" respectively.

   When the associated information resource on which it depends.  That
   document defines one resource-specific property, namely of the "pid"
   property, whose value entity property is
   the name of current information resource itself, the PID containing that endpoint ResourceID in the associated network map.

   Because a
   property may name SHOULD be associated to more than one information
   resources within ignored.  For example, the ".asn" property of
   an "ipv4" entity domain, indicates the AS number of the AS which this document takes IPv4
   address is owned by.

3.3.  Information Resource Export

   Each information resource MAY export a different
   approach as follows:

   o  Firstly, instead set of defining the dependency by prefixing the entity domains and
   entity property name with mappings.

3.3.1.  Resource-Specific Entity Domain Export

   Each type of information resource MAY export several types of entity
   domains.  For example, a specific dependent network map resource identifier, this
      document introduces defines a Property Type that appends "pid" domain,
   a property name
      to an entity "ipv4" domain name, and registers the dependency types for
      this Property Type.  This gives a hint on the types "ipv6" domain (which may be empty).

   When a new ALTO information resource type is registered, if this type
   of dependent
      resources.  For example, information resource can export an existing type of entity domain,
   the fictitious property "pid:region"
      applying corresponding document MUST define how to entities in the PID export such type of
   entity domain depends on the network map
      in which the input PID entities have been defined; but the
      fictitious property "ipv4:region" does not depend on any from such type of information resource.

   o  Secondly, it sets a rule saying that in

   When a property map, all
      provided property types MUST have the same dependency types.  For
      example, "pid:region" and "ipv4:region" cannot be provided by new entity domain type is defined, if an
      individual property map.

   o  Finally, it identifies, existing type of
   information resource can export an entity domain in this entity
   domain type, the IRD and Server responses, the
      sequence corresponding document MUST define how to export
   such type of entity domain from such type of information resources associated to all provided
      properties in a particular property map.  If a property depends on
      some different resource.

3.3.2.  Entity Property Mapping Export

   For each entity domain which could be exported by an information resources
   resource, this information resource MAY also export some mapping from other properties, the
      ALTO server should define a different property map
   this entity domain to provide it. some entity property.  For example, the property "ipv4:pid" provided by a particular
      property map MUST depend on one and only one network map.  If
   map resource can map an
      ALTO server wants "ipv4" entity to provide "ipv4:pid" for PIDs defined in both
      network maps "net1" and "net2", it MUST define two individual
      property maps.

   To specify the aforementionned dependencies, its "pid" property.

   When a new ALTO information resource type is registered, if this document uses the
   "uses" and "dependent-vtags" fields defined respectively type
   of information resource can export an entity domain in Sections
   9.1.5 an existing
   entity domain type, and 11.1 of [RFC7285].

   o  the "uses" field is included map entities in this entity domain to an
   existing type of entity property, the IRD entry corresponding document MUST
   define how to export such type of an entity property.

   When a resources-
      dependent information new ALTO entity domain type or a new entity property type is
   defined, if an existing type of resource can export an entity domain
   in this entity domain type, and specifies the dependent IRD
      resource.

   o  the "dependent-vtags" member is used map entities in a Server response message this entity domain to specify
   this type of entity property, the dependent resource.

3. corresponding document MUST define
   how to export such type of an entity property.

4.  Entity Domains Domain Types

   This document defines three entity domains. domain types.  The definition of
   each entity domain type below includes the following: (1) entity
   domain type name, (2) entity domain-specific entity identifiers, and
   (3) hierarchy and inheritance semantics.

3.1.  Since a global entity
   domain type defines a single global entity domain, we say entity
   domain instead of entity domain type.

4.1.  Internet Address Domains Domain Types

   The document defines two entity domains domain types (IPv4 and IPv6) for
   Internet addresses.  Both types are global entity domains include individual addresses domain types and
   blocks of addresses.
   hence define a corresponding global entity domain as well.  Since the
   two domains use the same hierarchy and inheritance semantics, we
   define the semantics together, instead of repeating for each.

3.1.1.

4.1.1.  IPv4 Domain

3.1.1.1.

4.1.1.1.  Entity Domain Name Type

   ipv4

3.1.1.2.

4.1.1.2.  Domain-Specific Entity Identifiers

   Individual addresses are strings as specified by the IPv4Addresses
   rule of Section 3.2.2 of [RFC3986]; blocks of addresses are prefix-
   match strings as specified in Section 3.1 of [RFC4632].  For the
   purpose of defining properties, an individual Internet address and
   the corresponding full-length prefix are considered aliases for the
   same entity.  Thus "ipv4:192.0.2.0" and "ipv4:192.0.2.0/32" are
   equivalent.

3.1.2.

4.1.2.  IPv6 Domain

3.1.2.1.

4.1.2.1.  Entity Domain Name Type

   ipv6

3.1.2.2.

4.1.2.2.  Domain-Specific Entity Identifiers

   Individual addresses are strings as specified by Section 4 of
   [RFC5952]; blocks of addresses are prefix-match strings as specified
   in Section 7 of [RFC5952].  For the purpose of defining properties,
   an individual Internet address and the corresponding 128-bit prefix
   are considered aliases for the same entity.  That is,
   "ipv6:2001:db8::1" and "ipv6:2001:db8::1/128" are equivalent, and
   have the same set of properties.

3.1.3.

4.1.3.  Hierarchy and Inheritance of ipv4/ipv6 Internet Address Domains

   Both Internet address domains allow property values to be inherited.
   Specifically, if a property P is not defined for a specific Internet
   address I, but P is defined for some block C which prefix-matches I,
   then the address I inherits the value of P defined for block C.  If
   more than one such block defines a value for P, I inherits the value
   of P in the block with the longest prefix.  It is important to notice
   that this longest prefix rule will ensure no multiple inheritance,
   and hence no ambiguity.

   Address blocks can also inherit properties: if a property P is not
   defined for a block C, but is defined for some block C' which covers
   all IP addresses in C, and C' has a shorter mask than C, then block C
   inherits the property from C'.  If there are several such blocks C',
   C inherits from the block block with the longest prefix.

   As an example, suppose that a server defines a property P for the
   following entities:

                             ipv4:192.0.2.0/26: P=v1
                             ipv4:192.0.2.0/28: P=v2
                             ipv4:192.0.2.0/30: P=v3
                             ipv4:192.0.2.0:    P=v4

                    Figure 1: Defined Property Values.

   Then the following entities have the indicated values:

                         ipv4:192.0.2.0:    P=v4
                         ipv4:192.0.2.1:    P=v3
                         ipv4:192.0.2.16:   P=v1
                         ipv4:192.0.2.32:   P=v1
                         ipv4:192.0.2.64:   (not defined)
                         ipv4:192.0.2.0/32: P=v4
                         ipv4:192.0.2.0/31: P=v3
                         ipv4:192.0.2.0/29: P=v2
                         ipv4:192.0.2.0/27: P=v1
                         ipv4:192.0.2.0/25: (not defined)

                   Figure 2: Inherited Property Values.

   An ALTO server MAY explicitly indicate a property as not having a
   value for a particular entity.  That is, a server MAY say that
   property P of entity X is "defined to have no value", instead of
   "undefined".  To indicate "no value", a server MAY perform different
   behaviours:

   o  If that entity would inherit a value for that property, then the
      ALTO server MUST return a "null" value for that property.  In this
      case, the ALTO client MUST recognize a "null" value as "no value"
      and "do not apply the inheritance rules for this property."

   o  If the entity would not inherit a value, then the ALTO server MAY
      return "null" or just omit the property.  In this case, the ALTO
      client cannot infer the value for this property of this entity
      from the Inheritance rules.  So the client MUST interpret that
      this property has no value.

   If the ALTO server does not define any properties for an entity, then
   the server MAY omit that entity from the response.

4.2.  PID Domain

   The PID domain associates property values with the longest prefix.

   As an example, suppose that PIDs in a server defines network
   map.  Accordingly, this entity domain always depends on a property P network
   map.

4.2.1.  Entity Domain Type

   pid

4.2.2.  Domain-Specific Entity Identifiers

   The entity identifiers are the PID names of the associated network
   map.

4.2.3.  Hierarchy and Inheritance

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

4.2.4.  Relationship To Internet Addresses Domains

   The PID domain and the
   following entities:

                             ipv4:192.0.2.0/26: P=v1
                             ipv4:192.0.2.0/28: P=v2
                             ipv4:192.0.2.0/30: P=v3
                             ipv4:192.0.2.0:    P=v4

                    Figure 1: Defined Property Values.

   Then Internet address domains are completely
   independent; the following entities properties associated with a PID have no relation to
   the indicated values:

                         ipv4:192.0.2.0:    P=v4
                         ipv4:192.0.2.1:    P=v3
                         ipv4:192.0.2.16:   P=v1
                         ipv4:192.0.2.32:   P=v1
                         ipv4:192.0.2.64:   (not defined)
                         ipv4:192.0.2.0/32: P=v4
                         ipv4:192.0.2.0/31: P=v3
                         ipv4:192.0.2.0/29: P=v2
                         ipv4:192.0.2.0/27: P=v1
                         ipv4:192.0.2.0/25: (not defined)

                   Figure 2: Inherited Property Values. properties associated with the prefixes or endpoint addresses in
   that PID.  An ALTO server MAY explicitly indicate choose to assign some or all properties
   of a PID to the prefixes in that PID.

   For example, suppose "PID1" consists of the prefix
   "ipv4:192.0.2.0/24", and has the property as not having "P" with value "v1".  The
   Internet address entities "ipv4:192.0.2.0" and "ipv4:192.0.2.0/24",
   in the IPv4 domain MAY have a value for a particular entity.  That is, a server MAY say that the property P of entity X "P", and if they
   do, it is "defined not necessarily "v1".

4.3.  Internet Address Properties vs. PID Properties

   Because the Internet address and PID domains are completely separate,
   the question may arise as to have no value", instead of
   "undefined".  To indicate "no value", a server MAY perform different
   behaviours:

   o  If that which entity would inherit domain is the best for a value
   property.  In general, the Internet address domains are RECOMMENDED
   for properties that property, then are closely related to the
      ALTO server MUST return a "null" value Internet address, or
   are associated with, and inherited through, blocks of addresses.

   The PID domain is RECOMMENDED for properties that property.  In this
      case, arise from the ALTO client MUST recognize a "null" value as "no value"
      and "do not apply
   definition of the inheritance rules for this property."

   o  If PID, rather than from the entity Internet address prefixes
   in that PID.

   For example, because Internet addresses are allocated to service
   providers by blocks of prefixes, an "ISP" property would not inherit be best
   associated with the Internet address domain.  On the other hand, a value, then
   property that explains why a PID was formed, or how it relates a
   provider's network, would best be associated with the PID domain.

5.  Entity Domains and Property Mappings in Information Resources

5.1.  Network Map Resource

   The ALTO server MAY
      return "null" or just omit network map resource defined by the property.  In this case, media type "application/
   alto-networkmap+json" exports the following types of entity domains
   and entity property mappings.

5.1.1.  Resource-Specific Entity Domain

   An ALTO
      client cannot infer network map resource defines a "pid" domain, an "ipv4" domain
   and an "ipv6" domain by follows:

   o  The defined "pid" domain includes all PIDs in keys of the value for this property
      "network-map" object.

   o  The defined "ipv4" domain includes all IPv4 addresses appearing in
      the "ipv4" field of this entity
      from the Inheritance rules.  So endpoint address group of each PID.

   o  The defined "ipv6" domain includes all IPv6 addresses appearing in
      the client MUST interpret that
      this property has no value.

   If "ipv6" field of the endpoint address group of each PID.

5.1.2.  Entity Property Mapping

   For each of the preceding entity domains, an ALTO server does not define any network map
   resource provides the properties for mapping as follows:

   ipv4 -> pid:  An "networkmap" typed resource can map an entity, then
   the server MAY omit that "ipv4" entity from the response.

3.2.  PID Domain

   The PID domain associates
      to a "pid" property values with the PIDs in whose value is a network
   map.  Accordingly, PID defined by this entity domain always depends on a network
   map.

3.2.1.  Domain Name

   pid

3.2.2.  Domain-Specific Entity Identifiers

   The entity identifiers are
      "networkmap" resource and including the PID names IPv4 address of the associated network
   map.

3.2.3.  Hierarchy and Inheritance

   There this
      entity.

   ipv6 -> pid:  An "networkmap" typed resource can map an "ipv6" entity
      to a "pid" property whose value is no hierarchy or inheritance for properties associated with
   PIDs.

3.2.4.  Relationship To Internet Addresses Domains

   The a PID domain defined by this
      "networkmap" resource and including the Internet IPv6 address domains are completely
   independent; the properties associated with a PID have no relation to of this
      entity.

5.2.  Endpoint Property Resource

   The ALTO endpoint property resource defined by the properties associated with media type
   "application/alto-endpointprop+json" exports the prefixes or endpoint addresses in
   that PID. following types of
   entity domains and entity property mappings.

5.2.1.  Resource-Specific Entity Domain

   An ALTO server MAY choose to assign some or endpoint property resource defined an "ipv4" domain and an
   "ipv6" domain by follows:

   o  The defined "ipv4" domain includes all properties IPv4 addresses appearing in
      keys of a PID to the prefixes "endpoint-properties" object.

   o  The defined "ipv6" domain includes all IPv6 addresses appearing in that PID.
      keys of the "endpoint-properties" object.

5.2.2.  Entity Property Mapping

   For example, suppose "PID1" consists each of the prefix
   "ipv4:192.0.2.0/24", and has preceding entity domains, an ALTO endpoint property
   resource exports the properties mapping from it to each supported
   global endpoint property.  The property "P" with value "v1".  The
   Internet address entities "ipv4:192.0.2.0" and "ipv4:192.0.2.0/24",
   in is the IPv4 domain MAY have a corresponding
   global endpoint property value for in the property "P", and if they
   do, it is not necessarily "v1".

3.3.  Internet Address Properties vs. PID Properties

   Because "endpiont-properties" object.

5.3.  Property Map Resource

   To avoid the Internet address nested reference and PID domains are completely separate, its potential complexity, this
   document does not specify the question may arise as to which export rule of resource-specific entity
   domain is the best for a
   property.  In general, the Internet address domains are RECOMMENDED
   for properties that are closely related to the Internet address, or
   are associated with, and inherited through, blocks of addresses.

   The PID domain is RECOMMENDED for properties that arise from the
   definition of the PID, rather than from the Internet address prefixes
   in that PID.

   For example, because Internet addresses are allocated to service
   providers by blocks of prefixes, an "ISP" entity property would be best
   associated with the Internet address domain.  On mapping for the other hand, a ALTO property that explains why a PID was formed, or how it relates a
   provider's network, would best be associated with map resource
   defined by the PID domain.

4. media type "application/alto-propmap+json" (see
   Section 6.1).

6.  Property Map

   A property map returns the properties defined for all entities in one
   or more domains, e.g., the "location" property of entities in "pid"
   domain, and the "ASN" property of entities in "ipv4" and "ipv6"
   domains.

   Section 7.4 9.4 gives an example of a property map request and its
   response.

4.1.

6.1.  Media Type

   The media type of a property map is "application/alto-propmap+json".

4.2.

6.2.  HTTP Method

   The property map is requested using the HTTP GET method.

4.3.

6.3.  Accept Input Parameters

   None.

4.4.

6.4.  Capabilities

   The capabilities are defined by an object of type
   PropertyMapCapabilities:

       object {
         DomainName entity-domains<1..*>;
         PropertyName properties<1..*>;
         EntityPropertyMapping mappings;
       } PropertyMapCapabilities;

   where "entity-domains" is an array specifying the entity domains, and
   "properties" is an array specifying the property

       object-map {
         EntityDomainName -> EntityPropertyName<1..*>;
       } EntityPropertyMapping

   with fields:

   mappings:  A JSON object whose keys are names returned for
   entities in those domains.  The semantics is that this property map
   provides all property types generated by the cross product of
   "entity-domains" entity domains and "properties".  If a property in "properties" is
   NOT supported by a domain in "entity-domains", the server can declare
   different property maps to conform to the semantics.

   For example,
      values are the capability {"entity-domains": ["ipv4", "ipv6"],
   "properties": ["pid"]} means supported entity properties of the property map provides both property
   types "ipv4:pid" and "ipv6:pid".

4.5. corresponding
      entity domains.

6.5.  Uses

   The "uses" field of a property map resource in an IRD entry specifies
   dependencies as discussed in Section 2.7.
   dependent resources of this property map.  It is an array of the
   resource ID(s) of the resource(s) that properties of entities in
   domains specified in "entity-domains" depend on.

   In a single property map, every property value of every entity
   depends on the same array of resources.  Thus, if properties
   depending on different resources arrays would be provided, they MUST
   be split into different property maps.

   Note that according to [RFC7285], a legacy ALTO server with two
   network maps, with resource IDs "net1" and "net2", could offer a
   single Endpoint Property Service for the two properties "net1.pid"
   and "net2.pid".  An ALTO server which supports the property map
   resource defined in this document, would, instead, offer two
   different property maps for the "pid" property, one depending on
   "net1", and the other on "net2".

4.6. resource(s).

6.6.  Response

   If the entity domains in this property map depend on other resources,
   the "dependent-vtags" field in the "meta" field of the response MUST
   be an array that includes the version tags of those resources, and
   the order MUST be consistent with the "uses" field of this property
   map resource.  The data component of a property map response is named
   "property-map", which is a JSON object of type PropertyMapData,
   where:

       object {
         PropertyMapData property-map;
       } InfoResourceProperties : ResponseEntityBase;

       object-map {
         EntityId
         EntityID -> EntityProps;
       } PropertyMapData;

       object {
         PropertyName
         EntityPropertyName -> JSONValue;
       } EntityProps;

   The ResponseEntityBase type is defined in Section 8.4 of [RFC7285].

   Specifically, a PropertyMapData object has one member for each entity
   in the property map.  The entity's properties are encoded in the
   corresponding EntityProps object.  EntityProps encodes one name/value
   pair for each property, where the property names are encoded as
   strings of type PropertyName.  A protocol implementation SHOULD
   assume that the property value is either a JSONString or a JSON
   "null" value, and fail to parse if it is not, unless the
   implementation is using an extension to this document that indicates
   when and how
   implementation is using an extension to this document that indicates
   when and how property values of other data types are signaled.

   For each entity in the property map:

   o  If the entity is in a resource-specific entity domain, the ALTO
      server SHOULD only return self-defined properties and resource-
      specific properties which depend on the same resource as the
      entity does.  The ALTO client SHOULD ignore the resource-specific
      property values of other data types are signaled.

   For each in this entity if their mapping is not registered in the
      ALTO Resource Entity Property Map, Transfer Registry of the type of the
      corresponding resource.

   o  If the entity is in a shared entity domain, the ALTO server returns the
   value SHOULD
      return self-defined properties and all resource-specific
      properties defined for each of all resource-specific entities which have
      the properties specified in same domain-specific entity identifier as this resource's
   "capabilities" list. entity does.

   For efficiency, the ALTO server SHOULD omit property values that are
   inherited rather than explicitly defined; if a client needs inherited
   values, the client SHOULD use the entity domain's inheritance rules
   to deduce those values.

5.

7.  Filtered Property Map

   A filtered property map returns the values of a set of properties for
   a set of entities selected by the client.

   Section 7.5, 9.5, Section 7.6, 9.6, Section 7.7 9.7 and Section 7.8 9.8 give examples
   of filtered property map requests and responses.

5.1.

7.1.  Media Type

   The media type of a property map resource is "application/alto-
   propmap+json".

5.2.

7.2.  HTTP Method

   The filtered property map is requested using the HTTP POST method.

5.3.

7.3.  Accept Input Parameters

   The input parameters for a filtered property map request 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-propmapparams+json", which is a JSON object of type
   ReqFilteredPropertyMap:

     object {
       EntityId
       EntityID             entities<1..*>;
       PropertyName
       EntityPropertyName   properties<1..*>;
     } ReqFilteredPropertyMap;

   with fields:

   entities:  List of entity identifiers for which the specified
      properties are to be returned.  The ALTO server MUST interpret
      entries appearing multiple times as if they appeared only once.
      The domain of each entity MUST be included in the list of entity
      domains in this resource's "capabilities" field (see Section 5.4). 7.4).

   properties:  List of properties to be returned for each entity.  Each
      specified property MUST be included in the list of properties in
      this resource's "capabilities" field (see Section 5.4). 7.4).  The ALTO
      server MUST interpret entries appearing multiple times as if they
      appeared only once.

      Note that the "entities" and "properties" fields MUST have at
      least one entry each.

5.4.

7.4.  Capabilities

   The capabilities are defined by an object of type
   PropertyMapCapabilities, as defined in Section 4.4.

5.5. 6.4.

7.5.  Uses

   The "uses" field of a filtered property map is an array with the
   resource ID(s) of resource(s) that each domain in "entity-domains"
   depends on, in order

   Same to provide the properties specified in the
   "properties" capability.  The same "uses" rule as defined by field of the
   property map Property Map resource applies (see
   Section 4.5).

5.6. 6.5).

7.6.  Response

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

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

   o  An entity identifiers identifier in "entities" in the request is invalid if:

      *  The domain of this entity is not defined in the "entity-domain-
         types" "entity-
         domains" capability of this resource in the IRD;

      *  The entity identifier is an invalid identifier in the entity
         domain.

      A valid entity identifier is never an error, even if this filtered
      property map resource does not define any properties for it.

      If an entity identifier in "entities" in 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 entity identifier.

   o  A property name in "properties" in the request is invalid if this
      property name is not defined in the "property-types" "properties" capability of
      this resource in the IRD.

      It is not an error that a filtered property map resource does not
      define a requested property's value for a particular entity.  In
      this case, the ALTO server MUST omit that property from the
      response for that endpoint.

      If a property name in "properties" in the request is invalid, the
      ALTO server MUST return an "E_INVALID_FIELD_VALUE" error defined
      in Section 8.5.2 of [RFC7285].  The "value" field of the error
      message SHOULD indicate the property name.

   The response to a valid request is the same as for the Property Map
   (see Section 4.6), 6.6), except that:

   o  The  If the requested entities include entities in the shared entity
      domain, the "dependent-vtags" field in its "meta" field MUST
      include version tags of all dependent resources appearing in the
      "uses" field.

   o  If the requested entities only includes include entities in resource-
      specific entity domains, the "dependent-vtags" field in its "meta"
      field MUST include version tags of resources on which the requested properties of the
      resource-specific entity domains depend, and the order MUST be consistent with the
      "uses" field of this filtered property map resource. requested resource-specific
      properties are dependent on.

   o  It  The response only includes the entities and properties requested
      by the client.  If an entity in the request is an identified by a
      hierarchical identifier block (e.g., an "ipv4" or "ipv6" entity), address block),
      the response MUST cover properties for all identifiers in this block.
      hierarchical identifier.

   It is important that the filtered property map response MUST include
   all inherited property values for the requested entities and all the
   entities which are able to inherit property values from them.  To
   achieve this goal, the ALTO server MAY follow three rules:

   o  If a property for a requested entity is inherited from another
      entity not included in the request, the response SHOULD include
      this property for the requested entity.  For example, A full
      property map may skip a property P for an entity A (e.g.,
      ipv4:192.0.2.0/31) if P can be derived using inheritance from
      another entity B (e.g., ipv4:192.0.2.0/30).  A filtered property
      map request may include only A but not B.  In such a case, the
      property P SHOULD be included in the response for A.

   o  If there are entities covered by a requested entity but having
      different values for the requested properties, the response SHOULD
      include all those entities and the different property values for
      them.  For example, considering a request for property P of entity
      A (e.g., ipv4:192.0.2.0/31), if P has value v1 for
      A1=ipv4:192.0.2.0/32 and v2 for A2=ipv4:192.0.2.1/32, then, the
      response SHOULD include A1 and A2.

   o  If an entity in the response is already covered by some other
      entities in the same response, it SHOULD be removed from the
      response for compactness.  For example, in the previous example,
      the entity A=ipv4:192.0.2.0/31 SHOULD be removed because A1 and A2
      cover all the addresses in A.

   An ALTO client should be aware that the entities in the response MAY
   be different from the entities in its request.

6.

8.  Impact on Legacy ALTO Servers and ALTO Clients

6.1.

8.1.  Impact on Endpoint Property Service

   Since the property map and the filtered property map defined in this
   document provide the functionality of the Endpoint Property Service
   (EPS) defined in Section 11.4 of [RFC7285], it is RECOMMENDED that
   the EPS be deprecated in favor of Property Map and Filtered Property
   Map.  However, ALTO servers MAY provide an EPS for the benefit of
   legacy clients.

6.2.

8.2.  Impact on Resource-Specific Properties

   Section 10.8 of [RFC7285] defines two categories of endpoint
   properties: "resource-specific" and "global".  Resource-specific
   property names are prefixed with the ID of the resource they depend
   upon, while global property names have no such prefix.  The property
   map and the filtered property map defined in this document do not
   distinguish between those two types of properties.  Instead, if there
   is a dependency, it is indicated by the "uses" capability of a
   property map, and is shared by all properties and entity domains in
   that map.  Accordingly, it is RECOMMENDED that resource-specific
   endpoint properties be deprecated, and no new resource-specific
   endpoint properties be defined.

6.3.

8.3.  Impact on the pid Property

   Section 7.1.1 of [RFC7285] defines the resource-specific endpoint
   property name "pid", whose value is the name of the PID containing
   that endpoint.  For compatibility with legacy clients, an ALTO server
   which provides the "pid" property via the EPS MUST use that
   definition, and that syntax.

   However, when used with property maps, this document amends the
   definition of the "pid" property as follows.

   First, the name of the property is simply "pid"; the name is not
   prefixed with the resource ID of a network map.  The "uses"
   capability of the property map indicates the associated network map.
   This implies that a property map can only return the "pid" property
   for one network map; if an ALTO server provides several network maps,
   it MUST provide a Property Map for each of the network maps.

   Second, a client MAY request the "pid" property for a block of
   Internet addresses.  An ALTO server determines the value of "pid" for
   an address block C as the rules defined in Section 5.6. 7.6.

   Note that although an ALTO server MAY provide a GET-mode property map
   which returns the entire map for the "pid" property, there is no need
   to do so, because that map is simply the inverse of the network map.

6.4.

8.4.  Impact on Other Properties

   In general, there should be little or no impact on other previously
   defined properties.  The only consideration is that properties can
   now be defined on blocks of identifiers, rather than just individual
   identifiers, which might change the semantics of a property.

7.

9.  Examples

7.1.

9.1.  Network Map

   The examples in this section use a very simple default network map:

            defaultpid:  ipv4:0.0.0.0/0  ipv6:::0/0
            pid1:        ipv4:192.0.2.0/25
            pid2:        ipv4:192.0.2.0/28  ipv4:192.0.2.16/28
            pid3:
            pid3:        ipv4:192.0.3.0/28
            pid4:        ipv4:192.0.3.16/28

                   Figure 3: Example Default Network Map

   And another simple alternative network map:

            defaultpid:  ipv4:0.0.0.0/0  ipv6:::0/0
            pid1:        ipv4:192.0.2.0/28  ipv4:192.0.2.16/28
            pid2:        ipv4:192.0.3.0/28
            pid4:  ipv4:192.0.3.16/28

                 Figure 3: 4: Example Alternative Network Map

7.2.

9.2.  Property Definitions

   Beyond "pid", the examples in this section use four additional
   properties for Internet address domains, "ISP", "ASN", "country" and
   "state", with the following values:

                                   ISP    ASN   country   state
           ipv4:192.0.2.0/23:    BitsRus   -      us       -
           ipv4:192.0.2.0/28:       -    12345    -        NJ
           ipv4:192.0.2.16/28:      -    12345    -        CT
           ipv4:192.0.2.0:          -      -      -        PA
           ipv4:192.0.3.0/28:       -    12346    -        TX
           ipv4:192.0.3.16/28:      -    12346    -        MN

      Figure 4: 5: Example Property Values for Internet Address Domains

   And the examples in this section use the property "region" for the
   PID domain of the default network map with the following values:

                                          region
                       pid:defaultpid:     -
                       pid:pid1:           west           us-west
                       pid:pid2:           east           us-east
                       pid:pid3:           south           us-south
                       pid:pid4:           north           us-north

      Figure 5: 6: Example Property Values for Default Network Map's PID
                                  Domain

   Note that "-" means the value of the property for the entity is
   "undefined".  So the entity would inherit a value for this property
   by the inheritance rule if possible.  For example, the value of the
   "ISP" property for "ipv4:192.0.2.0" is "BitsRus" because of
   "ipv4:192.0.2.0/24".  But the "region" property for "pid:defaultpid"
   has no value because no entity from which it can inherit.

7.3.

   Similar to the PID domain of the default network map, the examples in
   this section use the property "ASN" for the PID domain of the
   alternative network map with the following values:

                                             ASN
                          pid:defaultpid:     -
                          pid:pid1:         12345
                          pid:pid2:         12346

    Figure 7: Example Property Values for Alternative Network Map's PID
                                  Domain

9.3.  Information Resource Directory (IRD)

   The following IRD defines the relevant resources of the ALTO server.
   It provides two property maps, one for the "ISP" and "ASN"
   properties, and another for the "country" and "state" properties.
   The server could have provided a single property map for all four
   properties, but did not, presumably because the organization that
   runs the ALTO server believes any given client is not interested in
   all four properties.

   The server provides two filtered property maps.  The first returns
   all four properties, and the second just returns the "pid" property
   for the default network map.

   The filtered property maps for the "ISP", "ASN", "country" and
   "state" properties do not depend on the default network map (it does
   not have a "uses" capability), because the definitions of those
   properties do not depend on the default network map.  The Filtered
   Property Map for the "pid" property does have a "uses" capability for
   the default network map, because that defines the values of the "pid"
   property.

   Note that for legacy clients, the ALTO server provides an Endpoint
   Property Service for the "pid" property for the default network map.

        "meta" : {
          ...
          "default-alto-network-map" : "default-network-map"
        },
        "resources" : {
          "default-network-map" : {
            "uri" : "http://alto.example.com/networkmap", "http://alto.example.com/networkmap/default",
            "media-type" : "application/alto-networkmap+json"
          },
          "alt-network-map" : {
            "uri" : "http://alto.example.com/networkmap/alt",
            "media-type" : "application/alto-networkmap+json"
          },
          .... property map resources ....
         "country-state-property-map"
          "ia-property-map" : {
            "uri" : "http://alto.example.com/propmap/full/inet-cs", "http://alto.example.com/propmap/full/inet-ia",
            "media-type" : "application/alto-propmap+json",
            "uses": [ "default-network-map", "alt-network-map" ],
            "capabilities" : {
              "entity-domains":
              "mappings": {
                "ipv4": [ "ipv4", "ipv6" ".ISP", ".ASN" ],
              "properties" :
                "ipv6": [  "country", "state" ".ISP", ".ASN" ]
              }
            }
          },
         "isp-asn-property-map"
          "iacs-property-map" : {
            "uri" : "http://alto.example.com/propmap/full/inet-ia", "http://alto.example.com/propmap/full/inet-iacs",
            "media-type" : "application/alto-propmap+json",
            "accepts": "application/alto-propmapparams+json",
            "uses": [ "default-network-map", "alt-network-map" ],
            "capabilities" : {
              "entity-domains":
              "mappings": {
                "ipv4": [ "ipv4", "ipv6" ".ISP", ".ASN", ".country", ".state" ],
              "properties" :
                "ipv6": [ "ISP", "ASN" ".ISP", ".ASN", ".country", ".state" ]
              }
            }
          },
         "iacs-property-map" :
          "region-property-map": {
            "uri" : "http://alto.example.com/propmap/lookup/inet-iacs",
            "media-type" :
            "uri": "http://alto.exmaple.com/propmap/region",
            "media-type": "application/alto-propmap+json",
            "accepts" :
            "accepts": "application/alto-propmapparams+json",
            "capabilities"
            "uses" : [ "default-network-map", "alt-network-map" ],
            "capabilities": {
              "mappings": {
              "entity-domains":
                "default-network-map.pid": [ "ipv4", "ipv6" ".region" ],
              "properties" :
                "alt-network-map.pid": [ "ISP", "ASN", "country", "state" ] ".ASN" ],
              }
            }
          },
         "pid-property-map"
          "ip-pid-property-map" : {
            "uri" : "http://alto.example.com/propmap/lookup/pid",
            "media-type" : "application/alto-propmap+json",
            "accepts" : "application/alto-propmapparams+json",
            "uses" : [ "default-network-map" ]
            "capabilities" : {
              "entity-domains" : [ "ipv4", "ipv6" "default-network-map", "alt-network-map" ],
              "properties"
            "capabilities" : [ "pid" ]
            }
         },
         "region-property-map": {
           "uri": "http://alto.exmaple.com/propmap/region",
           "media-type": "application/alto-propmap+json",
           "accepts": "application/alto-propmapparams+json",
           "uses" : [ "default-network-map" ],
           "capabilities":
              "mappings": {
             "domain-types":
                "ipv4": [ "pid" "default-network-map.pid",
                          "alt-network-map.pid" ],
             "properties":
                "ipv6": [ "region" "default-network-map.pid",
                          "alt-network-map.pid" ]
              }
            }
          },
         "legacy-pid-property"
          "legacy-endpoint-property" : {
             "uri" : "http://alto.example.com/legacy/eps-pid",
             "media-type" : "application/alto-endpointprop+json",
             "accepts" : "application/alto-endpointpropparams+json",
             "capabilities" : {
               "properties" : [ "default-network-map.pid" "default-network-map.pid",
                                "alt-network-map.pid" ]
             }
          }
        }

                           Figure 6: 8: Example IRD

7.4.

9.4.  Property Map Example

   The following example uses the properties and IRD defined above to
   retrieve a Property Map for entities with the "ISP" and "ASN"
   properties.

   Note that, to be compact, the response does not includes the entity
   "ipv4:192.0.2.0", because values of all those properties for this
   entity are inherited from other entities.

   Also note that the entities "ipv4:192.0.2.0/28" and
   "ipv4:192.0.2.16/28" are merged into "ipv4:192.0.2.0/27", because
   they have the same value of the "ASN" property.  The same rule
   applies to the entities "ipv4:192.0.3.0/28" and "ipv4:192.0.3.0/28".
   Both of "ipv4:192.0.2.0/27" and "ipv4:192.0.3.0/27" omit the value
   for the "ISP" property, because it is inherited from
   "ipv4:192.0.2.0/23".

   GET /propmap/full/inet-ia 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

   {
     "meta": {
       "dependent-vtags": [
         {"resource-id": "default-network-map",
          "tag": "3ee2cb7e8d63d9fab71b9b34cbf764436315542e"},
         {"resource-id": "alt-network-map",
          "tag": "c0ce023b8678a7b9ec00324673b98e54656d1f6d"}
       ]
     },
     "property-map": {
       "ipv4:192.0.2.0/23":   {"ISP":   {".ISP": "BitsRus"},
       "ipv4:192.0.2.0/27":   {"ASN":   {".ASN": "12345"},
       "ipv4:192.0.3.0/27":   {"ASN":   {".ASN": "12346"}
     }
   }

7.5.

9.5.  Filtered Property Map Example #1

   The following example uses the filtered property map resource to
   request the "ISP", "ASN" and "state" properties for several IPv4
   addresses.

   Note that the value of "state" for "ipv4:192.0.2.0" is the only
   explicitly defined property; the other values are all derived by the
   inheritance rules for Internet address entities.

   POST /propmap/lookup/inet-iacs HTTP/1.1
   Host: alto.example.com
   Accept: application/alto-propmap+json,application/alto-error+json
   Content-Length: ###
   Content-Type: application/alto-propmapparams+json

   {
     "entities" : [ "ipv4:192.0.2.0",
                    "ipv4:192.0.2.1",
                    "ipv4:192.0.2.17" ],
     "properties" : [ "ISP", "ASN", "state" ".ISP", ".ASN", ".state" ]
   }
   HTTP/1.1 200 OK
   Content-Length: ###
   Content-Type: application/alto-propmap+json

   {
     "meta": {
       "dependent-vtags": [
         {"resource-id": "default-network-map",
          "tag": "3ee2cb7e8d63d9fab71b9b34cbf764436315542e"},
         {"resource-id": "alt-network-map",
          "tag": "c0ce023b8678a7b9ec00324673b98e54656d1f6d"}
       ]
     },
     "property-map": {
       "ipv4:192.0.2.0":
              {"ISP":
              {".ISP": "BitsRus", "ASN": ".ASN": "12345", "state": ".state": "PA"},
       "ipv4:192.0.2.1":
              {"ISP":
              {".ISP": "BitsRus", "ASN": ".ASN": "12345", "state": ".state": "NJ"},
       "ipv4:192.0.2.17":
              {"ISP":
              {".ISP": "BitsRus", "ASN": ".ASN": "12345", "state": ".state": "CT"}
     }
   }

7.6.

9.6.  Filtered Property Map Example #2

   The following example uses the filtered property map resource to
   request the "ASN", "country" and "state" properties for several IPv4
   prefixes.

   Note that the property values for both entities "ipv4:192.0.2.0/26"
   and "ipv4:192.0.3.0/26" are not explicitly defined.  They are
   inherited from the entity "ipv4:192.0.2.0/23".

   Also note that some entities like "ipv4:192.0.2.0/28" and
   "ipv4:192.0.2.16/28" in the response are not listed in the request
   explicitly.  The response includes them because they are refinements
   of the requested entities and have different values for the requested
   properties.

   The entity "ipv4:192.0.4.0/26" is not included in the response,
   because there are neither entities which it is inherited from, nor
   entities inherited from it.

   POST /propmap/lookup/inet-iacs HTTP/1.1
   Host: alto.example.com
   Accept: application/alto-propmap+json,application/alto-error+json
   Content-Length: ###
   Content-Type: application/alto-propmapparams+json

   {
     "entities" : [ "ipv4:192.0.2.0/26",
                    "ipv4:192.0.3.0/26",
                    "ipv4:192.0.4.0/26" ],
     "properties" : [ "ASN", "country", "state" ".ASN", ".country", ".state" ]
   }

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

   {
     "meta": {
       "dependent-vtags": [
         {"resource-id": "default-network-map",
          "tag": "3ee2cb7e8d63d9fab71b9b34cbf764436315542e"},
         {"resource-id": "alt-network-map",
          "tag": "c0ce023b8678a7b9ec00324673b98e54656d1f6d"}
       ]
     },
     "property-map": {
       "ipv4:192.0.2.0/26":  {"country":  {".country": "us"},
       "ipv4:192.0.2.0/28":  {"ASN":  {".ASN": "12345",
                              "state":
                              ".state": "NJ"},
       "ipv4:192.0.2.16/28": {"ASN": {".ASN": "12345",
                              "state":
                              ".state": "CT"},
       "ipv4:192.0.2.0":     {"state":     {".state": "PA"},
       "ipv4:192.0.3.0/26":  {"country":  {".country": "us"},
       "ipv4:192.0.3.0/28":  {"ASN":  {".ASN": "12345",
                              "state":
                              ".state": "TX"},
       "ipv4:192.0.3.16/28": {"ASN": {".ASN": "12345",
                              "state":
                              ".state": "MN"}
    }
   }

7.7.

9.7.  Filtered Property Map Example #3

   The following example uses the filtered property map resource to
   request the "pid" property for several IPv4 addresses and prefixes.

   Note that the entity "ipv4:192.0.3.0/27" is redundant in the
   response.  Although it can inherit a value of "defaultpid" for the
   "pid" property from the entity "ipv4:0.0.0.0/0", none of addresses in
   it is in "defaultpid".  Because blocks "ipv4:192.0.3.0/28" and
   "ipv4:192.0.3.16/28" have already cover all addresses in that block.
   So an ALTO server who wants a compact response can omit this entity.

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

   {
     "entities" : [
                   "ipv4:192.0.2.128",
                   "ipv4:192.0.3.0/27" ],
     "properties" : [ "pid" "default-network-map.pid" ]
   }

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

   {
     "meta" :
     "meta": {
       "dependent-vtags" :
       "dependent-vtags": [
         {"resource-id": "default-network-map",
          "tag": "7915dc0290c2705481c491a2b4ffbec482b3cf62"} "3ee2cb7e8d63d9fab71b9b34cbf764436315542e"},
         {"resource-id": "alt-network-map",
          "tag": "c0ce023b8678a7b9ec00324673b98e54656d1f6d"}
       ]
     },
     "property-map": {
       "ipv4:192.0.2.128":   {"pid":   {"default-network-map.pid": "defaultpid"},
       "ipv4:192.0.2.0/27":  {"pid":  {"default-network-map.pid": "defaultpid"},
       "ipv4:192.0.3.0/28":  {"pid":  {"default-network-map.pid": "pid3"},
       "ipv4:192.0.3.16/28": {"pid": {"default-network-map.pid": "pid4"}
     }
   }

7.8.

9.8.  Filtered Property Map Example #4

   The following example uses the filtered property map resource to
   request the "region" property for several PIDs defined in "default-
   network-map".  The value of the "region" property for each PID is not
   defined by "default-network-map", but the reason why the PID is
   defined by the network operator.

   POST /propmap/lookup/region HTTP/1.1
   Host: alto.example.com
   Accept: application/alto-propmap+json,application/alto-error+json
   Content-Length: ###
   Content-Type: application/alto-propmapparams+json

   {
     "entities" : ["pid:pid1",
                   "pid:pid2"], ["default-network-map.pid:pid1",
                   "default-network-map.pid:pid2"],
     "properties" : [ "region" ".region" ]
   }

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

   {
     "meta" : {
       "dependent-vtags" : [
          {"resource-id": "default-network-map",
           "tag": "7915dc0290c2705481c491a2b4ffbec482b3cf62"}
       ]
     },
     "property-map": {
       "pid:pid1":
       "default-network-map.pid:pid1": {
         "region": "west"
         ".region": "us-west"
       },
       "pid:pid2":
       "default-network-map.pid:pid2": {
         "region": "east"
         ".region": "us-east"
       }
     }
   }

8.

10.  Security Considerations

   Both Property Map and Filtered Property Map defined in this document
   fit into the architecture of the ALTO base protocol, and hence the
   Security Considerations (Section 15 of [RFC7285]) of the base
   protocol fully apply: authenticity and integrity of ALTO information
   (i.e., authenticity and integrity of Property Maps), potential
   undesirable guidance from authenticated ALTO information (e.g.,
   potentially imprecise or even wrong value of a property such as geo-
   location), confidentiality of ALTO information (e.g., exposure of a
   potentially sensitive entity property such as geo-location), privacy
   for ALTO users, and availability of ALTO services should all be
   considered.

   A particular fundamental security consideration when an ALTO server
   provides a Property Map is to define precisely the policies on who
   can access what properties for which entities.  Security mechanisms
   such as authentication and confidentiality mechanisms then should be
   applied to enforce the policy.  For example, a policy can be that a
   property P can be accessed only by its owner (e.g., the customer who
   is allocated a given IP address).  Then, the ALTO server will need to
   deploy corresponding mechanisms to realize the policy.  The policy
   may allow non-owners to access a coarse-grained value of the property
   P.  In such a case, the ALTO server may provide a different URI to
   provide the information.

9.

11.  IANA Considerations

   This document defines additional application/alto-* media types, and
   extends the ALTO endpoint property registry.

9.1.

11.1.  application/alto-* Media Types

   This document registers two additional ALTO media types, listed in
   Table 1.

    +--------------+--------------------------+-----------------------+

   +--------------+--------------------------+------------------------+
   | Type         | Subtype                  | Specification          |
    +--------------+--------------------------+-----------------------+
   +--------------+--------------------------+------------------------+
   | application  | alto-propmap+json        | Section 4.1 6.1            |
   | application  | alto-propmapparams+json  | Section 5.3 7.3            |
    +--------------+--------------------------+-----------------------+
   +--------------+--------------------------+------------------------+

                   Table 1: Additional ALTO Media Types.

   Type name:  application

   Subtype name:  This document registers multiple subtypes, as listed
      in Table 1.

   Required parameters:  n/a

   Optional parameters:  n/a

   Encoding considerations:  Encoding considerations are identical to
      those specified for the "application/json" media type.  See
      [RFC7159].

   Security considerations:  Security considerations related to the
      generation and consumption of ALTO Protocol messages are discussed
      in Section 15 of [RFC7285].

   Interoperability considerations:  This document specifies formats of
      conforming messages and the interpretation thereof.

   Published specification:  This document is the specification for
      these media types; see Table 1 for the section documenting each
      media type.

   Applications that use this media type:  ALTO servers and ALTO clients
      either stand alone or are embedded within other applications.

   Additional information:

      Magic number(s):  n/a

      File extension(s):  This document uses the mime type to refer to
         protocol messages and thus does not require a file extension.

      Macintosh file type code(s):  n/a

   Person & email address to contact for further information:  See
      Authors' Addresses section.

   Intended usage:  COMMON

   Restrictions on usage:  n/a

   Author:  See Authors' Addresses section.

   Change controller:  Internet Engineering Task Force
      (mailto:iesg@ietf.org).

9.2.

11.2.  ALTO Entity Domain Type Registry

   This document requests IANA to create and maintain the "ALTO Entity
   Domain Type Registry", listed in Table 2.

   +------------+----------------+------------------+------------------+

   +-------------+---------------------------+-------------------------+
   | Identifier  | Entity Identifier         | Hierarchy &      | Mapping to ALTO  |
   |            | Identifier     | Inheritance | Address Type     |
   |            | Encoding       |                  |                  |
   +------------+----------------+------------------+------------------+
   | ipv4       | See            | See              | Yes              |
   |            | Section 3.1.1
   | Section 3.1.3    |                  |
   | ipv6       | See             | See Encoding                  | Yes                         |
   +-------------+---------------------------+-------------------------+
   | ipv4        | See Section 3.1.2 4.1.1         | See Section 3.1.3 4.1.3       |
   |
   | pid ipv6        | See Section 4.1.2         | None             | No See Section 4.1.3       |
   | pid         | See Section 3.2    | 4.2           | None                    |
   +------------+----------------+------------------+------------------+
   +-------------+---------------------------+-------------------------+

                       Table 2: ALTO Entity Domains.

   This registry serves two purposes.  First, it ensures uniqueness of
   identifiers referring to ALTO entity domains.  Second, it states the
   requirements for allocated entity domains.

9.2.1.

11.2.1.  Consistency Procedure between ALTO Address Type Registry and
         ALTO Entity Domain Registry

   One potential issue of introducing the "ALTO Entity Domain Registry"
   is its relationship with the "ALTO Address Types Registry" already
   defined in Section 14.4 of [RFC7285].  In particular, the entity
   identifier of an entity domain registered in the "ALTO Entity Domain
   Registry" MAY match an address type defined in "ALTO Address Type
   Registry".  It is necessary to precisely define and guarantee the
   consistency between "ALTO Address Type Registry" and "ALTO Entity
   Domain Registry".

   We define that the ALTO Entity Domain Registry is consistent with
   ALTO Address Type Registry if two conditions are satisfied:

   o  When an address type is already or able to be registered in the
      ALTO Address Type Registry [RFC7285], the same identifier MUST be
      used when a corresponding entity domain is registered in the ALTO
      Entity Domain Registry.

   o  If an ALTO entity domain has the same identifier as an ALTO
      address type, their addresses encoding MUST be compatible.

   To achieve this consistency, the following items MUST be checked
   before registering a new ALTO entity domain in a future document:

   o  Whether the ALTO Address Type Registry contains an address type
      that can be used as an entity identifier for the candidate domain
      identifier.  This has been done for the identifiers "ipv4" and
      "ipv6" in Table 2.

   o  Whether the candidate entity identifier of the entity domain is
      able to be an endpoint address, as defined in Sections 2.1 and 2.2
      of [RFC7285].

   When a new ALTO entity domain is registered, the consistency with the
   ALTO Address Type Registry MUST be ensured by the following
   procedure:

   o  Test: Do corresponding entity identifiers match a known "network"
      address type?

      *  If yes (e.g., cell, MAC or socket addresses):

         +  Test: Is such an address type present in the ALTO Address
            Type Registry?

            -  If yes: Set the new ALTO entity domain identifier to be
               the found ALTO address type identifier.

            -  If no: Define a new ALTO entity domain identifier and use
               it to register a new address type in the ALTO Address
               Type Registry following Section 14.4 of [RFC7285].

         +  Use the new ALTO entity domain identifier to register a new
            ALTO entity domain in the ALTO Entity Domain Registry
            following Section 9.2.2 11.2.2 of this document.

      *  If no (e.g., pid name, ane name or country code): Proceed with
         the ALTO Entity Domain registration as described in
         Section 9.2.2.

9.2.2. 11.2.2.

11.2.2.  ALTO Entity Domain Registration Process

   New ALTO entity domains are assigned after IETF Review [RFC5226] to
   ensure that proper documentation regarding the new ALTO entity
   domains and their security considerations has been provided.  RFCs
   defining new entity domains SHOULD indicate how an entity in a
   registered domain is encoded as an EntityId, and, if applicable, the
   rules defining the entity hierarchy and property inheritance.
   Updates and deletions of ALTO entity domains follow the same
   procedure.

   Registered ALTO entity domain identifiers MUST conform to the
   syntactical requirements specified in Section 2.3. 3.1.2.  Identifiers are
   to be recorded and displayed as strings.

   Requests to the IANA to add a new value to the registry MUST include
   the following information:

   o  Identifier: The name of the desired ALTO entity domain.

   o  Entity Identifier Encoding: The procedure for encoding the
      identifier of an entity of the registered type as an EntityId (see
      Section 2.4). 3.1.3).  If corresponding entity identifiers of an entity
      domain match a known "network" address type, the Entity Identifier
      Encoding of this domain identifier MUST include both Address
      Encoding and Prefix Encoding of the same identifier registered in
      the ALTO Address Type Registry [RFC7285].  For the purpose of
      defining properties, an individual entity identifier and the
      corresponding full-length prefix MUST be considered aliases for
      the same entity.

   o  Hierarchy: If the entities form a hierarchy, the procedure for
      determining that hierarchy.

   o  Inheritance: If entities can inherit property values from other
      entities, the procedure for determining that inheritance.

   o  Mapping to ALTO Address Type: A boolean value to indicate if the
      entity domain can be mapped to the ALTO address type with the same
      identifier.

   o  Security Considerations: In some usage scenarios, entity
      identifiers carried in ALTO Protocol messages may reveal
      information about an ALTO client or an ALTO service provider.
      Applications and ALTO service providers using addresses of the
      registered type should be made aware of how (or if) the addressing
      scheme relates to private information and network proximity.

   This specification requests registration of the identifiers "ipv4",
   "ipv6" and "pid", as shown in Table 2.

9.3.

11.3.  ALTO Entity Property Type Registry

   This document requests IANA to create and maintain the "ALTO Entity
   Property Type Registry", listed in Table 3.

   To distinguish with the "ALTO Endpoint Property Type Registry", each
   entry in this registry is an ALTO entity property type defined in
   Section 2.5. 3.2.1.  Thus, registered ALTO entity property type identifier
   MUST conform to the syntactical requirements specified in that
   section.

   The initial registered ALTO entity property types are listed in
   Table 3.

   +------------+------------------+-----------------------------------+

             +-------------+---------------------------------+
             | Identifier  | Intended         | Dependencies and Interpretation   |
   |            | Semantics              |
             +-------------+---------------------------------+
             |
   +------------+------------------+-----------------------------------+
   | ipv4:pid   | PID for the IPv4 | application/alto-networkmap+json, |
   |            | entity           | where the PID names are defined   |
   | ipv6:pid   | PID for the IPv6 | application/alto-networkmap+json, |
   |            | entity pid         | where the PID names are defined See Section 7.1.1 of [RFC7285]  |
   +------------+------------------+-----------------------------------+
             +-------------+---------------------------------+

                   Table 3: ALTO Entity Property Types.

   Requests to the IANA to add a new value to the registry MUST include
   the following information:

   o  Identifier: The unique id for the desired ALTO entity property
      type.  The format MUST be as defined in Section 2.5 3.2.1 of this
      document.  It includes the information of the applied ALTO entity
      domain and the property name.

   o  Intended Semantics: ALTO entity properties carry with them
      semantics to guide their usage by ALTO clients.  Hence, a document
      defining a new type SHOULD provide guidance to both ALTO service
      providers and applications utilizing ALTO clients as to how values
      of the registered ALTO entity property should be interpreted.

   o  Dependencies and Interpretation: Dependent ALTO resources MAY be
      required by ALTO clients to interpret ALTO entity properties.
      Hence, a document defining a new type SHOULD provide a sequence of
      media types in which the dependent ALTO resources are and the
      guidance how ALTO clients use them to interpret the property.

   This specification document requests registration of the identifiers
   "ipv4:pid" and "ipv6:pid", identifier "pid", as shown
   in Table 3.

9.4.

11.4.  ALTO Resource-Specific Entity Domain Registries

11.4.1.  Network Map

   Media-type: application/alto-networkmap+json

               +---------------------+---------------------+
               | Entity Domain Type  | Intended Semantics  |
               +---------------------+---------------------+
               | ipv4                | See Section 5.1.1   |
               | ipv6                | See Section 5.1.1   |
               | pid                 | See Section 5.1.1   |
               +---------------------+---------------------+

        Table 4: ALTO Network Map Resource-Specific Entity Domain.

11.4.2.  Endpoint Property

   Media-type: application/alto-endpointprop+json

               +---------------------+---------------------+
               | Entity Domain Type  | Intended Semantics  |
               +---------------------+---------------------+
               | ipv4                | See Section 5.2.1   |
               | ipv6                | See Section 5.2.1   |
               +---------------------+---------------------+

     Table 5: ALTO Endpoint Property Resource-Specific Entity Domain.

11.5.  ALTO Resource Entity Property Mapping Registries

11.5.1.  Network Map

   Media-type: application/alto-networkmap+json
   +----------------+-----------------+-------------+------------------+
   | Mapping        | Entity Domain   | Property    | Intended         |
   | Descriptor     | Type            | Type        | Semantics        |
   +----------------+-----------------+-------------+------------------+
   | ipv4 -> pid    | ipv4            | pid         | See              |
   |                |                 |             | Section 5.1.2    |
   | ipv6 -> pid    | ipv6            | pid         | See              |
   |                |                 |             | Section 5.1.2    |
   +----------------+-----------------+-------------+------------------+

            Table 6: ALTO Network Map Entity Property Mapping.

12.  Acknowledgments

   The authors would like to thank discussions with Kai Gao, Qiao Xiang,
   Shawn Lin, Xin Wang, Danny Perez, and Vijay Gurbani.  The authors
   thank Dawn Chen (Tongji University), and Shenshen Chen (Tongji/Yale
   University) for their contributions to earlier drafts.

10.

13.  Normative References

   [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>.

   [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
              Resource Identifier (URI): Generic Syntax", STD 66,
              RFC 3986, DOI 10.17487/RFC3986, January 2005,
              <https://www.rfc-editor.org/info/rfc3986>.

   [RFC4632]  Fuller, V. and T. Li, "Classless Inter-domain Routing
              (CIDR): The Internet Address Assignment and Aggregation
              Plan", BCP 122, RFC 4632, DOI 10.17487/RFC4632, August
              2006, <https://www.rfc-editor.org/info/rfc4632>.

   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", RFC 5226,
              DOI 10.17487/RFC5226, May 2008,
              <https://www.rfc-editor.org/info/rfc5226>.

   [RFC5952]  Kawamura, S. and M. Kawashima, "A Recommendation for IPv6
              Address Text Representation", RFC 5952,
              DOI 10.17487/RFC5952, August 2010,
              <https://www.rfc-editor.org/info/rfc5952>.

   [RFC7159]  Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
              Interchange Format", RFC 7159, DOI 10.17487/RFC7159, March
              2014, <https://www.rfc-editor.org/info/rfc7159>.

   [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>.

   [RFC7921]  Atlas, A., Halpern, J., Hares, S., Ward, D., and T.
              Nadeau, "An Architecture for the Interface to the Routing
              System", RFC 7921, DOI 10.17487/RFC7921, June 2016,
              <https://www.rfc-editor.org/info/rfc7921>.

Authors' Addresses

   Wendy Roome
   Nokia Bell Labs (Retired)
   124 Burlington Rd
   Murray Hill, NJ  07974
   USA

   Phone: +1-908-464-6975
   Email: wendy@wdroome.com

   Sabine Randriamasy
   Nokia Bell Labs
   Route de Villejust
   NOZAY  91460
   FRANCE

   Email: Sabine.Randriamasy@nokia-bell-labs.com

   Y. Richard Yang
   Yale University
   51 Prospect Street
   New Haven, CT  06511
   USA

   Phone: +1-203-432-6400
   Email: yry@cs.yale.edu
   Jingxuan Jensen Zhang
   Tongji University
   4800 Caoan Road
   Shanghai  201804
   China

   Email: jingxuan.n.zhang@gmail.com