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diff --git a/doc/rfc/rfc9240.txt b/doc/rfc/rfc9240.txt new file mode 100644 index 0000000..27b647d --- /dev/null +++ b/doc/rfc/rfc9240.txt @@ -0,0 +1,2933 @@ + + + + +Internet Engineering Task Force (IETF) W. Roome +Request for Comments: 9240 S. Randriamasy +Category: Standards Track Nokia Bell Labs +ISSN: 2070-1721 Y. Yang + Yale University + J. Zhang + Tongji University + K. Gao + Sichuan University + July 2022 + + + An Extension for Application-Layer Traffic Optimization (ALTO): Entity + Property Maps + +Abstract + + This document specifies an extension to the base Application-Layer + Traffic Optimization (ALTO) Protocol that generalizes the concept of + "endpoint properties", which have been tied to IP addresses so far, + to entities defined by a wide set of objects. Further, these + properties are presented as maps, similar to the network and cost + maps in the base ALTO Protocol. While supporting the endpoints and + related Endpoint Property Service defined in RFC 7285, the ALTO + Protocol is extended in two major directions. First, from endpoints + restricted to IP addresses to entities covering a wider and + extensible set of objects; second, from properties for specific + endpoints to entire entity property maps. These extensions introduce + additional features that allow entities and property values to be + specific to a given information resource. This is made possible by a + generic and flexible design of entity and property types. + +Status of This Memo + + This is an Internet Standards Track document. + + This document is a product of the Internet Engineering Task Force + (IETF). It represents the consensus of the IETF community. It has + received public review and has been approved for publication by the + Internet Engineering Steering Group (IESG). Further information on + Internet Standards is available in Section 2 of RFC 7841. + + Information about the current status of this document, any errata, + and how to provide feedback on it may be obtained at + https://www.rfc-editor.org/info/rfc9240. + +Copyright Notice + + Copyright (c) 2022 IETF Trust and the persons identified as the + document authors. All rights reserved. + + This document is subject to BCP 78 and the IETF Trust's Legal + Provisions Relating to IETF Documents + (https://trustee.ietf.org/license-info) in effect on the date of + publication of this document. Please review these documents + carefully, as they describe your rights and restrictions with respect + to this document. Code Components extracted from this document must + include Revised BSD License text as described in Section 4.e of the + Trust Legal Provisions and are provided without warranty as described + in the Revised BSD License. + +Table of Contents + + 1. Introduction + 1.1. Terminology and Notation + 2. Requirements Language + 3. Basic Features of the Entity Property Map Extension + 3.1. Entity + 3.2. Entity Domain + 3.2.1. Entity Domain Type + 3.2.2. Entity Domain Name + 3.3. Entity Property Type + 3.4. New Information Resource and Media Type: ALTO Property Map + 4. Advanced Features of the Entity Property Map Extension + 4.1. Entity Identifier and Entity Domain Name + 4.2. Resource-Specific Entity Domain Name + 4.3. Resource-Specific Entity Property Value + 4.4. Entity Hierarchy and Property Inheritance + 4.4.1. Entity Hierarchy + 4.4.2. Property Inheritance + 4.4.3. Property Value Unicity + 4.5. Supported Properties for Entity Domains in Property Map + Capabilities + 4.6. Defining Information Resource for Resource-Specific Entity + Domains + 4.6.1. Defining Information Resource and Its Media Type + 4.6.2. Examples of Defining Information Resources and Their + Media Types + 4.7. Defining Information Resources for Resource-Specific + Property Values + 5. Protocol Specification: Basic Data Types + 5.1. Entity Domain + 5.1.1. Entity Domain Type + 5.1.2. Entity Domain Name + 5.1.3. Entity Identifier + 5.1.4. Hierarchy and Inheritance + 5.2. Entity Property + 5.2.1. Entity Property Type + 5.2.2. Entity Property Name + 5.2.3. Format for Entity Property Value + 6. Entity Domain Types Defined in This Document + 6.1. Internet Address Domain Types + 6.1.1. Entity Domain Type: IPv4 + 6.1.2. Entity Domain Type: IPv6 + 6.1.3. Hierarchy and Inheritance of Internet Address Domains + 6.1.4. Defining Information Resource Media Type for Domain + Types IPv4 and IPv6 + 6.2. Entity Domain Type: PID + 6.2.1. Entity Domain Type Identifier + 6.2.2. Domain-Specific Entity Identifiers + 6.2.3. Hierarchy and Inheritance + 6.2.4. Defining Information Resource Media Type for Domain + Type PID + 6.2.5. Relationship To Internet Addresses Domains + 6.3. Internet Address Properties vs. PID Properties + 7. Property Map + 7.1. Media Type + 7.2. HTTP Method + 7.3. Accept Input Parameters + 7.4. Capabilities + 7.5. Uses + 7.6. Response + 8. Filtered Property Map + 8.1. Media Type + 8.2. HTTP Method + 8.3. Accept Input Parameters + 8.4. Capabilities + 8.5. Uses + 8.6. Filtered Property Map Response + 8.7. Entity Property Type Defined in This Document + 8.7.1. Entity Property Type: pid + 9. Impact on Legacy ALTO Servers and ALTO Clients + 9.1. Impact on Endpoint Property Service + 9.2. Impact on Resource-Specific Properties + 9.3. Impact on Other Properties + 10. Examples + 10.1. Network Map + 10.2. Property Definitions + 10.3. Information Resource Directory (IRD) + 10.4. Full Property Map Example + 10.5. Filtered Property Map Example #1 + 10.6. Filtered Property Map Example #2 + 10.7. Filtered Property Map Example #3 + 10.8. Filtered Property Map Example #4 + 10.9. Filtered Property Map for ANEs Example #5 + 11. Security Considerations + 12. IANA Considerations + 12.1. application/alto-propmap+json Media Type + 12.2. alto-propmapparams+json Media Type + 12.3. ALTO Entity Domain Types Registry + 12.3.1. Consistency Procedure between ALTO Address Types + Registry and ALTO Entity Domain Types Registry + 12.3.2. ALTO Entity Domain Type Registration Process + 12.4. ALTO Entity Property Types Registry + 13. References + 13.1. Normative References + 13.2. Informative References + Appendix A. Features Introduced with the Entity Property Maps + Extension + Acknowledgments + Authors' Addresses + +1. Introduction + + The ALTO Protocol [RFC7285] introduces the concept of "properties" + attached to "endpoint addresses". It also 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 three limitations, which are elaborated here. + + First, the EPS allows properties to be associated only with endpoints + that are identified by individual communication addresses like IPv4 + and IPv6 addresses. It is reasonable to think that collections of + endpoints identified by Provider-Defined Identifiers (PIDs) may also + have properties. Furthermore, recent ALTO use cases show that + properties of entities such as Abstract Network Elements as defined + in [PATH-VECTOR] are also useful. However, the current EPS is + restricted to individual endpoints and cannot be applied to those + entities. + + Second, the EPS only allows endpoints identified by global + communication addresses. However, an endpoint address may be a local + IP address or an anycast IP address that may not be globally unique. + Additionally, an entity such as a PID may have an identifier that is + not globally unique. That is, the same PID may be used in multiple + network maps, while in each network map, this PID points to a + different set of addresses. + + Third, in Section 11.4 of [RFC7285], the EPS is only defined as a + POST-mode service. ALTO clients must request the properties for an + explicit set of endpoint addresses. By contrast, Section 11.2.3 of + [RFC7285] defines a GET-mode cost map resource that returns all + available costs, so an ALTO Client can retrieve a full set of costs + once and then process cost lookups without querying the ALTO server. + [RFC7285] does not define a similar 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. In particular, the number of endpoint addresses involved + by an ALTO server can be quite large. To avoid enumerating a large + number of endpoint addresses inefficiently, the ALTO server might + define properties for a sufficiently large subset of endpoints and + then use an aggregation representation to reference endpoints in + order to allow efficient enumeration. This is particularly true if + blocks of endpoint addresses with a common prefix have the same value + for a property. Entities in other domains may very well allow + aggregated representation and hence be enumerable as well. + + To address these three limitations, this document specifies an ALTO + Protocol extension for defining and retrieving ALTO properties: + + * The first limitation is addressed by introducing a generic concept + called ALTO entity, which generalizes an endpoint and may + represent a PID, a network element, a cell in a cellular network, + an Abstract Network Element [PATH-VECTOR], or other physical or + logical objects involved in a network topology. Each entity is + included in a collection called an ALTO entity domain. Since each + ALTO entity domain includes only one type of entity, each entity + domain can be classified by the type of enclosed entities. + + * The second limitation is addressed by using resource-specific + entity domains. A resource-specific entity domain contains + entities that are defined and identified with respect to a given + ALTO information resource, which provides scoping. For example, + an entity domain containing PIDs is identified with respect to the + network map in which these PIDs are defined. Likewise, an entity + domain containing local IP addresses may be defined with respect + to a local network map. + + * The third limitation is addressed by defining two new types of + ALTO information resources: property map (Section 7) and filtered + property map (Section 8). The former is a resource that is + requested using the HTTP GET method, returns the property values + for all entities in one or more entity domains, and is analogous + to a network map or a cost map in Section 11.2 of [RFC7285]. The + latter is a resource that is requested using the HTTP POST method, + returns the values for sets of properties and entities requested + by the client, and is analogous to a filtered network map or a + filtered cost map. + + The entity property maps extension described in this document + introduces a number of features that are summarized in Appendix A, + where Table 11 lists the features and references the sections in this + document that give their high-level and their normative descriptions. + + The protocol extension defined in this document can be augmented. + New entity domain types can be defined without revising the present + specification. Similarly, new cost metrics and new endpoint + properties can be defined in other documents without revising the + protocol specification defined in [RFC7285]. + +1.1. Terminology and Notation + + This document uses the following terms and abbreviations that will be + further defined in the document. While this document introduces the + feature "entity property map", it will use both the term "property + map" and "entity property map" to refer to this feature. + + Transaction: A request/response exchange between an ALTO client and + an ALTO server. + + Client: When used with a capital "C", this term refers to an ALTO + client. Note that expressions "ALTO client", "ALTO Client", and + "Client" are equivalent. + + Server: When used with a capital "S", this term refers to an ALTO + server. Note that expressions "ALTO server", "ALTO Server", and + "Server" are equivalent. + + EPS: An abbreviation for Endpoint Property Service. + + This document uses the notation defined in Section 8.2 of [RFC7285]. + +2. Requirements Language + + The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", + "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and + "OPTIONAL" in this document are to be interpreted as described in + BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all + capitals, as shown here. + +3. Basic Features of the Entity Property Map Extension + + This section gives a high-level overview of the basic features + involved in ALTO entity property maps. It assumes the reader is + familiar with the ALTO Protocol [RFC7285]. The purpose of this + extension is to convey properties for objects that extend ALTO + endpoints and are called ALTO Entities, or entities for short. + + The features introduced in this section can be used standalone. + However, in some cases, these features may depend on particular + information resources and need to be defined with respect to them. + To this end, Section 4 introduces additional features that extend the + ones presented in this section. + +3.1. Entity + + The concept of an ALTO entity generalizes the concept of an ALTO + endpoint defined in Section 2.1 of [RFC7285]. An entity is an object + that can be an endpoint defined by its network address, but it can + also be an object that has a defined mapping to a set of one or more + network addresses or an object that is not even related to any + network address. Thus, whereas all endpoints are entities, not all + entities are endpoints. + + Examples of entities are: + + * an ALTO endpoint that represents an application or a host + identified by a communication address (e.g., an IPv4 or IPv6 + address) in a network, + + * a PID, defined in [RFC7285], that has a provider-defined, human- + readable identifier specified by an ALTO network map, which maps a + PID to a set of IPv4 and IPv6 addresses, + + * an Autonomous System (AS) that has an AS number (ASN) as its + identifier and maps to a set of IPv4 and IPv6 addresses, which is + defined in [RFC9241], + + * a country with a code specified in [ISO3166-1] to which + applications such as content delivery network (CDN) providers + associate properties and capabilities, which is defined in + [RFC9241], + + * a TCP or UDP network flow that is identified by a 5-tuple + specifying its source and destination addresses and port numbers, + and the IP protocol (TCP or UDP), + + * a routing element, as specified in [RFC7921], that is associated + with routing capabilities information, or + + * an Abstract Network Element, as specified in [PATH-VECTOR], that + represents an abstraction of a network part such as a router, one + or more links, a network domain, or their aggregation. + + Some of the example entities listed above have already been + documented as ALTO entities. The other examples are provided for + illustration as potential entities. + +3.2. Entity Domain + + An entity domain defines a set of entities of the same semantic type. + An entity domain is characterized by a type and identified by a name. + + In this document, an entity is owned by exactly one entity domain + name. An entity identifier points to exactly one entity. If two + entities in two different entity domains refer to the same physical + or logical object, they are treated as different entities. For + example, if an end host has both an IPv4 and an IPv6 address, these + two addresses will be treated as two entities, defined respectively + in the "ipv4" and "ipv6" entity domains. + +3.2.1. Entity Domain Type + + The entity domain type defines the semantics of the type of entity + found in an entity domain. Entity domain types can be defined in + different documents. For example: the present document defines + entity domain types "ipv4" and "ipv6" in Section 6.1 and "pid" in + Section 6.2. The entity domain type "ane", which defines Abstract + Network Elements (ANEs), is introduced in [PATH-VECTOR]. The + "countrycode" entity domain type that defines country codes is + introduced in [RFC9241]. An entity domain type MUST be registered + with IANA, as specified in Section 12.3.2. + +3.2.2. Entity Domain Name + + In this document, the identifier of an entity domain is mostly called + "entity domain name". The identifier of an entity domain is scoped + to an ALTO server. An entity domain identifier can sometimes be + identical to the identifier of its relevant entity domain type. This + is the case when the entities of a domain have an identifier that + points to the same object throughout all the information resources of + the Server that are providing entity properties for this domain. For + example, a domain of type "ipv4" containing entities that are + identified by a public IPv4 address can be named "ipv4" because its + entities are uniquely identified by all the Server resources. + + In some cases, the name of an entity domain cannot be simply its + entity domain type. Indeed, for some domain types, entities are + defined relative to a given information resource. This is the case + for entities of domain type "pid". A PID is defined relative to a + network map. For example, an entity "mypid10" of domain type "pid" + may be defined in a given network map and be undefined in other + network maps. The entity "mypid10" may even be defined in two + different network maps, and it may map in each of these network maps + to a different set of endpoint addresses. In this case, naming an + entity domain only by its type "pid" does not guarantee that its set + of entities is owned by exactly one entity domain. + + Sections 4.2 and 5.1.2 describe how a domain is uniquely identified + across the ALTO server by a name that associates the domain type and + the related information resource. + +3.3. Entity Property Type + + An entity property defines a property of an entity. This is similar + to the endpoint property defined in Section 7.1 of [RFC7285]. An + entity property can convey either network-aware or network-agnostic + information. Similar to an entity domain, an entity property is + characterized by a type and identified by a name. An entity property + type MUST be registered with IANA, as specified in Section 12.4. + + Below are listed some examples with real and fictitious entity domain + and property names: + + * an entity in the "ipv4" domain type may have a property whose + value is an Autonomous System (AS) number indicating the AS to + which this IPv4 address belongs and another property named + "countrycode" indicating a country code mapping to this address, + + * an entity identified by its country code in the entity domain type + "countrycode", defined in [RFC9241], may have a property + indicating what delivery protocol is used by a CDN, or + + * an entity in the "netmap1.pid" domain may have a property that + indicates the central geographical location of the endpoints it + includes. + + It should be noted that some identifiers may be used for both an + entity domain type and a property type. For example: + + * the identifier "countrycode" may point to both the entity domain + type "countrycode" and the fictitious property type "countrycode". + + * the identifier "pid" may point to both the entity domain type + "pid" and the property type "pid". + + Likewise, the same identifier may point to both a domain name and a + property name. For example: the identifier "netmap10.pid" may point + to either the domain defined by the PIDs of network map "netmap10" or + to a property that returns, for an entity defined by its IPv4 + address, the PID of "netmap10" that contains this entity. Such cases + are further explained in Section 4. + +3.4. New Information Resource and Media Type: ALTO Property Map + + This document introduces a new ALTO information resource named + property map. An ALTO property map provides a set of properties for + one or more sets of entities. A property may apply to different + entity domain types and names. For example, an ALTO property map may + define the "ASN" property for both "ipv4" and "ipv6" entity domains. + + The present extension also introduces a new media type. + + This document uses the same definition of an information resource as + Section 9.1 of [RFC7285]. ALTO uses media types to uniquely indicate + the data format used to encode the content to be transmitted between + an ALTO server and an ALTO client in the HTTP entity body. In the + present case, an ALTO property map resource is defined by the media + type "application/alto-propmap+json". + + A property map can be queried as a GET-mode resource, thus conveying + all properties for all entities indicated in its capabilities. It + can also be queried as a POST-mode resource, thus conveying a + selection of properties for a selection of entities. + +4. Advanced Features of the Entity Property Map Extension + + This section gives a high-level overview of the advanced features + involved in ALTO entity property maps. Most of these features extend + the features defined in Section 3. + +4.1. Entity Identifier and Entity Domain Name + + In [RFC7285], an endpoint has an identifier that is explicitly + associated with the "ipv4" or "ipv6" address domain. Examples are + "ipv4:192.0.2.14" and "ipv6:2001:db8::12". + + In this document, example IPv4 and IPv6 addresses and prefixes are + taken from the address ranges reserved for documentation by [RFC5737] + and [RFC3849]. + + In this document, an entity must be owned by exactly one entity + domain name, and an entity identifier must point to exactly one + entity. To ensure this, an entity identifier is explicitly attached + to the name of its entity domain, and an entity domain type + characterizes the semantics and identifier format of its entities. + + The encoding format of an entity identifier is further specified in + Section 5.1.3 of this document. + + For instance: + + * if an entity is an endpoint with IPv4 address "192.0.2.14", its + identifier is associated with entity domain name "ipv4" and is + "ipv4:192.0.2.14"; + + * if an entity is a PID named "mypid10" in network map resource + "netmap2", its identifier is associated with entity domain name + "netmap2.pid" and is "netmap2.pid:mypid10". + +4.2. Resource-Specific Entity Domain Name + + Some entities are defined and identified uniquely and globally in the + context of an ALTO server. This is the case, for instance, when + entities are endpoints that are identified by a reachable IPv4 or + IPv6 address. The entity domain for such entities can be globally + defined and named "ipv4" or "ipv6". Those entity domains are called + resource-agnostic entity domains in this document, as they are not + associated with any specific ALTO information resources. + + Some other entities and entity types are only defined relative to a + given information resource. This is the case for entities of domain + type "pid", which can only be understood with respect to the network + map where they are defined. For example, a PID named "mypid10" may + be defined to represent a set S1 of IP addresses in a network map + resource named "netmap1". Another network map "netmap2" may use the + same name "mypid10" and define it to represent another set S2 of IP + addresses. The identifier "pid:mypid10" may thus point to different + objects because the information on the originating information + resource is lost. + + To solve this ambiguity, the present extension introduces the concept + of resource-specific entity domain. This concept applies to domain + types where entities are defined relative to a given information + resource. It can also apply to entity domains that are defined + locally, such as local networks of objects identified with a local + IPv4 address. + + In such cases, an entity domain type is explicitly associated with an + identifier of the information resource where these entities are + defined. Such an information resource is referred to as the + "specific information resource". Using a resource-aware entity + domain name, an ALTO property map can unambiguously identify distinct + entity domains of the same type, on which entity properties may be + queried. Examples of resource-specific entity domain names may look + like "netmap1.pid" or "netmap2.pid". Thus, a name association such + as "netmap1.pid:mypid10" and "netmap2.pid:mypid10" distinguishes the + two abovementioned PIDs that are both named "mypid10" but in two + different resources, "netmap1" and "netmap2". + + An information resource is defined in the scope of an ALTO Server and + so is an entity domain name. The format of a resource-specific + entity domain name is further specified in Section 5.1.2. + +4.3. Resource-Specific Entity Property Value + + Like entity domains, some types of properties are defined relative to + an information resource. That is, an entity may have a property of a + given type whose values are associated with different information + resources. + + For example, suppose entity "192.0.2.34" defined in the "ipv4" domain + has a property of type "pid" whose value is the PID to which address + "192.0.2.34" is attached in a network map. The mapping of network + addresses to PIDs is specific to a network map and probably different + from one network map resource to another one. Thus, if a property + "pid" is defined for entity "192.0.2.34" in two different network + maps "netmap1" and "netmap2", the value for this property can be a + different value in "netmap1" and "netmap2". + + To support information-resource-dependent property values, this + document uses the same approach as in Section 10.8.1 + ("Resource-Specific Endpoint Properties") of [RFC7285]. When a + property value depends on a given information resource, the name of + this property MUST be explicitly associated with the information + resource that defines it. + + For example, the property "pid" queried on entity "ipv4:192.0.2.34" + and defined in both "netmap1" and "netmap2" can be named + "netmap1.pid" and "netmap2.pid". This allows a Client to get a + property of the same type but defined in different information + resources with a single query. Specifications for the property name + format are provided in Section 5.2. + +4.4. Entity Hierarchy and Property Inheritance + + For some domain types, there is an underlying structure that allows + entities to be efficiently grouped into a set and be defined by the + identifier of this set. This is the case for domain types "ipv4" and + "ipv6", where individual Internet addresses can be grouped in blocks. + When the same property value applies to a whole set, a Server can + define a property for the identifier of this set instead of + enumerating all the entities and their properties. This allows a + substantial reduction of transmission payload both for the Server and + the Client. For example, all the entities included in the set + defined by the address block "ipv6:2001:db8::1/64" share the same + properties and values defined for this block. + + Additionally, entity sets sometimes are related by inclusion, + hierarchy, or other relations. This allows defining inheritance + rules for entity properties that propagate properties among related + entity sets. The Server and the Client can use these inheritance + rules for further payload savings. Entity hierarchy and property + inheritance rules are specified in the documents that define the + applicable domain types. The present document defines these rules + for the "ipv4" and "ipv6" domain types. + + For applicable domain types, this document introduces entity property + inheritance rules with the following concepts: entity hierarchy, + property inheritance, and property value unicity. A detailed + specification of entity hierarchy and property inheritance rules is + provided in Section 5.1.4. + +4.4.1. Entity Hierarchy + + An entity domain may allow the use of a single identifier to identify + a set of related individual entities. For example, a Classless + Inter-Domain Routing (CIDR) block can be used to identify a set of + IPv4 or IPv6 entities. A CIDR block is called a hierarchical entity + identifier, as it can reflect inclusion relations among entity sets. + That is, in an entity hierarchy, "supersets" are defined at upper + levels and include "subsets" defined at lower levels. For example, + the CIDR "ipv4:192.0.1.0/24" includes all the individual IPv4 + entities identified by the CIDR "ipv4:192.0.1.0/26". This document + will sometimes use the term "hierarchical address" to refer to a + hierarchical entity identifier. + +4.4.2. Property Inheritance + + A property may be defined for a hierarchical entity identifier, while + it may be undefined for individual entities covered by this + identifier. In this case, these individual entities inherit the + property value defined for the identifier that covers them. For + example, suppose a property map defines a property P for which it + assigns value V1 only for the hierarchical entity identifier + "ipv4:192.0.1.0/24" but not for individual entities in this block. + Suppose also that inheritance rules are specified for CIDR blocks in + the "ipv4" domain type. When receiving this property map, a Client + can infer that entity "ipv4:192.0.1.1" inherits the property value V1 + of block "ipv4:192.0.1.0/24" because the address "ipv4:192.0.1.1" is + included in the CIDR block "ipv4:192.0.1.0/24". + + Property value inheritance rules also apply among entity sets. A + property map may define values for an entity set belonging to a + hierarchy but not for "subsets" that are covered by this set + identifier. In this case, inheritance rules must specify how + entities in "subsets" inherit property values from their "superset". + For instance, suppose a property P is defined only for the entity set + defined by address block "ipv4:192.0.1.0/24". We know that entity + set "ipv4:192.0.1.0/30" is included in "ipv4:192.0.1.0/24". + Therefore, the entities of "ipv4:192.0.1.0/30" may inherit the value + of property P from set "ipv4:192.0.1.0/24" if an inheritance rule + from "ipv4" CIDR blocks to included "ipv4" CIDR blocks is specified. + +4.4.3. Property Value Unicity + + The inheritance rules must ensure that an entity belonging to a + hierarchical set of entities inherits no more than one property + value, for the sake of consistency. Indeed, a property map may + define a property for a hierarchy of entity sets that inherits + property values from one or more supersets (located at upper levels). + On the other hand, a property value defined for a subset (located at + a lower level) may be different from the value defined for a + superset. In such a case, subsets may potentially end up with + different property values. This may be the case for address blocks + with increasing prefix length, on which a property value becomes + increasingly accurate and thus may differ. For example, a fictitious + property such as "geo-location" or "average transfer volume" may be + defined at a progressively finer grain for lower-level subsets of + entities defined with progressively longer CIDR prefixes. It seems + more interesting to have property values of progressively higher + accuracy. A unicity rule applied to the entity domain type must + specify an arbitration rule among the different property values for + an entity. An example illustrating the need for such rules is + provided in Section 6.1.3. + +4.5. Supported Properties for Entity Domains in Property Map + Capabilities + + A property type is not necessarily applicable to any domain type, or + an ALTO Server may choose not to provide a property for all + applicable domains. For instance, a property type reflecting link + bandwidth is likely not defined for entities of a domain of type + "countrycode". Therefore, an ALTO server providing property maps + needs to specify the properties that can be queried on the different + entity domains it supports. + + This document explains how the Information Resource Directory (IRD) + capabilities of a property map resource unambiguously expose which + properties a Client can query on a given entity domain: + + * a field named "mappings" lists the names of the entity domains + supported by the property map, and + + * for each listed entity domain, a list of the names of the + applicable properties is provided. + + An example is provided in Section 10.3. The "mappings" field + associates entity domains and properties that can be resource- + agnostic or resource-specific. This allows a Client to formulate + compact and unambiguous entity property queries, possibly relating to + one or more information resources. In particular: + + * it prevents a Client from querying a property for entity domains + for which it is not defined; + + * it allows a Client to query, for an entity E, values for a + property P that are defined in several information resources; and + + * it allows a Client to query a property P on entities that are + defined in several information resources. + + Further details are provided in Section 7.4. + +4.6. Defining Information Resource for Resource-Specific Entity Domains + + A Client willing to query entity properties belonging to a domain + needs to know how to retrieve these entities. To this end, the + Client can look up the "mappings" field exposed in IRD capabilities + of a property map; see Section 4.5. This field, in its keys, exposes + all the entity domains supported by the property map. The syntax of + the entity domain identifier specified in Section 5.1.2 allows the + client to infer whether the entity domain is resource-specific or + not. The Client can extract, if applicable, the identifier of the + specific resource, query the resource, and retrieve the entities. + For example: + + * an entity domain named "netmap1.ipv4" includes the IPv4 addresses + that appear in the "ipv4" field of the endpoint address group of + each PID in the network map "netmap1" and that have no meaning + outside "netmap1" because, for instance, these are local addresses + not reachable outside some private network; + + * an entity domain named "netmap1.pid" includes the PIDs listed in + network map "netmap1"; and + + * an entity domain named "ipv4" is resource-agnostic and covers all + the reachable IPv4 addresses. + + Besides, it is not possible to prevent a Server from mistakenly + exposing inappropriate associations of information resources and + entity domain types. To prevent failures due to invalid queries, it + is necessary to inform the Client which associations are allowed. An + informed Client will just ignore inappropriate associations exposed + by a Server and avoid error-prone transactions with the Server. + + For example, the association "costmap3.pid" is not allowed for the + following reason: although a cost map exposes PID identifiers, it + does not define the set of addresses included in this PID. Neither + does a cost map list all the PIDs on which properties can be queried + because a cost map only exposes PID pairs on which a queried cost + type is defined. Therefore, the resource "costmap3" does not enable + a Client to extract information on the existing PID entities or on + the addresses they contain. + + Instead, the cost map uses a network map where all the PIDs used in a + cost map are defined together with the addresses contained by the + PIDs. This network map is qualified in this document as the defining + information resource for the entity domain of type "pid", and this + concept is explained in Section 4.6.1. + +4.6.1. Defining Information Resource and Its Media Type + + For the reasons explained in Section 4.6, this document introduces + the concept of "Defining Information Resource and its Media Type". + + A defining information resource for an entity domain D is the + information resource where entities of D are defined. That is, all + the information on the entities of D can be retrieved in this + resource. A defining information resource is defined for resource- + specific entity domains. It does not exist for entity domains that + are not resource-specific such as "ipv4" or "ipv6". Neither does it + exist for entity domains that are covering entity identifiers already + defined in other standardization documents, as is the case for + country code identifiers standardized in [ISO3166-1] or AS numbers + allocated by IANA. This is useful for entity domain types that are + by essence domain-specific, such as the domain type "pid". It is + also useful for resource-specific entity domains constructed from + resource-agnostic domain types, such as network-map-specific domains + of local IPv4 addresses. + + The defining information resource of a resource-specific entity + domain D, when it exists, is unique and has the following + characteristics: + + * it has an entry in the IRD; + + * it defines the entities of D; + + * it does not use another information resource that defines these + entities; + + * it defines and exposes entity identifiers that are all persistent; + and + + * its media type is equal to the one that is specified for the + defining information resource of an entity domain type. + + A fundamental characteristic of a defining information resource is + its media type. There is a unique association between an entity + domain type and the media type of its defining information resource. + When an entity domain type allows associations with defining + information resources, the media type of the potential defining + information resource MUST be specified: + + * in the document that defines this entity domain type, and + + * in the "ALTO Entity Domain Types" IANA registry. + + When the Client wants to use a resource-specific entity domain, it + needs to be cognizant of the media type of its defining information + resource. If the Server exposes a resource-specific entity domain + with a noncompliant media type for the defining resource, the Client + MUST ignore the entities from that entity domain to avoid errors. + +4.6.2. Examples of Defining Information Resources and Their Media Types + + Here are examples of defining information resource types and their + media types associated with different entity domain types: + + * For entity domain type "pid", the media type of the specific + resource is "application/alto-networkmap+json" because PIDs are + defined in network map resources. + + * For entity domain types "ipv4" and "ipv6", the media type of the + specific resource is "application/alto-networkmap+json" because + IPv4 and IPv6 addresses covered by the Server are defined in + network map resources. + + * For entities of domain type "ane"; [PATH-VECTOR] defines entities + named "ANE", where ANE stands for Abstract Network Element, and + the entity domain type "ane". An ANE may have a persistent + identifier, say, "entity-4", that is provided by the Server as a + value of the "persistent-entity-id" property of this ANE. Further + properties may then be queried on an ANE by using its persistent + entity identifier. These properties are available from a + persistent property map that defines properties for a specific + "ane" domain. Together with the persistent identifier, the Server + also provides the property map resource identifier where the "ane" + domain containing "entity-4" is defined. The definition of the + "ane" entity domain containing "entity-4" is thus specific to the + property map. Therefore, for entities of domain type "ane" that + have a persistent identifier, the media type of the defining + information resource is "application/alto-propmap+json". + + * Last, the entity domain types "asn" and "countrycode" defined in + [RFC9241] do not have a defining information resource. Indeed, + the entity identifiers in these two entity domain types are + already standardized in documents that the Client can use. + +4.7. Defining Information Resources for Resource-Specific Property + Values + + As explained in Section 4.3, a property type may take values that are + resource-specific. This is the case for property type "pid", whose + values are by essence defined relative to a specific network map. + That is, the PID value returned for an IPv4 address is specific to + the network map defining this PID and may differ from one network map + to another one. + + Another example is provided in [RFC9241], which defines property type + "cdni-capabilities". The value of this property is specific to a + Content Delivery Network Interconnection (CDNI) Advertisement + resource, which provides a list of CDNI capabilities. The property + is provided for entity domain types "ipv4", "ipv6", "asn", and + "countrycode". However, a CDNI Advertisement resource does not + define PID values for IPv4 addresses, while a network map does not + define CDNI capabilities for IPv4 addresses. + + Similar to resource-specific entity domains, the Client needs to be + cognizant of appropriate associations of information resource and + property types. Therefore, when specifying and registering a + property type whose values are resource-specific, the media type of + its defining information resource needs to be specified. For + example: + + * The media type of the defining information resource for property + type "pid" is "application/alto-networkmap+json". + + * The media type of the defining information resource for property + type "cdni-capabilities" defined in [RFC9241] is "application/ + alto-cdni+json". + +5. Protocol Specification: Basic Data Types + +5.1. Entity Domain + +5.1.1. Entity Domain Type + + An entity domain has a type, which is uniquely identified by a string + that MUST be no more 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), the hyphen-minus + ('-', U+002D), the colon (':', U+003A), or the low line ('_', + U+005F). + + The usage of colon (':', U+003A) MUST obey the rules below: + + * The colon (':', U+003A) character MUST NOT appear more than once; + + * The colon character MUST NOT be used unless within the string + "priv:"; + + * The string "priv:" MUST NOT be used unless it starts the string + that identifies an entity domain type; and + + * For an entity domain type identifier with the "priv:" prefix, an + additional string (e.g., company identifier or random string) MUST + follow "priv:" to reduce potential collisions. + + For example, the strings "ipv4", "ipv6", "pid", and "priv:example- + test-edt", are valid entity domain types. "ipv4.anycast", + "pid.local", and "priv:" are invalid. + + Although "_", "-", "__--" are valid entity domain types, it is + desirable to add characters, such as alphanumeric ones, for better + intelligibility. + + The type EntityDomainType is used in this document to denote a JSON + string meeting the preceding requirements. + + An entity domain type defines the semantics of a type of entity, + independently of any specifying resource. All entity domain types + that are not prefixed with "priv:" MUST be registered with IANA in + the "ALTO Entity Domain Types" registry, defined in Section 12.3, + following the procedure specified in Section 12.3.2 of this document. + The format of the entity identifiers (see Section 5.1.3) in that + entity domain type, as well as any hierarchical or inheritance rules + (see Section 5.1.4) for those entities, MUST be specified in the IANA + registration. + + Entity domain type identifiers prefixed with "priv:" are reserved for + Private Use (see [RFC8126]) without a need to register with IANA. + The definition of a private-use entity domain type MUST apply the + same way in all property maps of an IRD where it is present. + +5.1.2. Entity Domain Name + + As discussed in Section 3.2, an entity domain is characterized by a + type and identified by a name. + + This document distinguishes three categories of entity domains: + resource-specific entity domains, resource-agnostic entity domains, + and self-defined entity domains. Their entity domain names are + constructed as specified in the following subsections. + + Each entity domain is identified by a unique entity domain name. + Borrowing the symbol "::=" from the Backus-Naur Form notation + [RFC5511], the format of an entity domain name is defined as follows: + + EntityDomainName ::= [ [ ResourceID ] '.' ] EntityDomainType + + The presence and construction of the component + + "[ [ ResourceID ] '.' ]" + + depends on the category of entity domain. + + Note that the '.' separator is not allowed in EntityDomainType, and + hence there is no ambiguity on whether an entity domain name refers + to a resource-agnostic entity domain or a resource-specific entity + domain. + + Note also that Section 10.1 of [RFC7285] specifies the format of the + PID name, which is the format of the resource identifier including + the following specification: + + | The '.' separator is reserved for future use and MUST NOT be used + | unless specifically indicated in this document, or an extension + | document. + + The present extension keeps the format specification of [RFC7285], + hence the '.' separator MUST NOT be used in an information resource + identifier. + +5.1.2.1. Resource-Specific Entity Domain + + A resource-specific entity domain is identified by an entity domain + name constructed as follows. It MUST start with a resource + identifier using the ResourceID type defined in Section 10.2 of + [RFC7285], followed by the '.' separator (U+002E), followed by a + string of the type EntityDomainType specified in Section 5.1.1. + + For example, if an ALTO server provides two network maps "netmap-1" + and "netmap-2", these network maps can define two resource-specific + domains of type "pid", respectively identified by "netmap-1.pid" and + "netmap-2.pid". + +5.1.2.2. Resource-Agnostic Entity Domain + + A resource-agnostic entity domain contains entities that are + identified independently of any information resource. The identifier + of a resource-agnostic entity domain is simply the identifier of its + entity domain type. For example, "ipv4" and "ipv6" identify the two + resource-agnostic Internet address entity domains defined in + Section 6.1. + +5.1.2.3. Self-Defined Entity Domain + + A property map can define properties for entities that are specific + to a unique information resource, which is the property map itself. + This may be the case when an ALTO Server provides properties for a + set of entities that are defined only in this property map, are not + relevant to another one, and do not depend on another specific + resource. + + For example: a specialized property map may define a domain of type + "ane", defined in [PATH-VECTOR], that contains a set of ANEs + representing data centers that each have a persistent identifier and + are relevant only to this property map. + + In this case, the entity domain is qualified as "self-defined". The + identifier of a self-defined entity domain can be of the format: + + EntityDomainName ::= '.' EntityDomainType + + where '.' indicates that the entity domain only exists within the + property map resource using it. + + A self-defined entity domain can be viewed as a particular case of + resource-specific entity domain, where the specific resource is the + current resource that uses this entity domain. In that case, for the + sake of simplification, the component ResourceID MUST be omitted in + its entity domain name. + +5.1.3. Entity Identifier + + Entities in an entity domain are identified by entity identifiers + (EntityID) of the following format: + + EntityID ::= EntityDomainName ':' DomainTypeSpecificEntityID + + Examples from the Internet address entity domains include individual + IP addresses such as "net1.ipv4:192.0.2.14" and + "net1.ipv6:2001:db8::12", as well as address blocks such as + "net1.ipv4:192.0.2.0/26" and "net1.ipv6:2001:db8::/48". + + The format of the second part of an entity identifier, + DomainTypeSpecificEntityID, depends on the entity domain type and + MUST be specified when defining a new entity domain type and + registering it with IANA. Identifiers MAY be hierarchical, and + properties MAY be inherited based on that hierarchy. 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 two entity identifiers with different, valid textual + representations may refer to the same entity, for a given entity + domain. For example, the strings "net1.ipv6:2001:db8::1" and + "net1.ipv6:2001:db8:0:0:0:0:0:1" refer to the same entity in the + "ipv6" entity domain. Such equivalences should be established by the + object represented by DomainTypeSpecificEntityID. For example, + [RFC5952] establishes equivalence for IPv6 addresses, while [RFC4632] + does so for IPv4 addresses. + +5.1.4. Hierarchy and Inheritance + + To simplify the representation, some types of entity domains allow + the ALTO Client and Server to use a hierarchical entity identifier + format to represent a block of individual entities. For instance, in + an IPv4 domain "net1.ipv4", a CIDR "net1.ipv4:192.0.2.0/26" covers 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. + +5.2. Entity Property + + Each entity property has a type to indicate the encoding and the + semantics of the value of this entity property, and has a name to + identify it. + +5.2.1. Entity Property Type + + The type EntityPropertyType is used in this document to indicate a + string denoting an entity property 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 hyphen-minus ('-', U+002D), the colon (':', + U+003A), or the low line ('_', U+005F). Note that the '.' separator + is not allowed because it is reserved to separate an entity property + type and an information resource identifier when an entity property + is resource-specific. + + While Section 5.1.1 allows the use of the character ":" with + restrictions on entity domain identifiers, it can be used without + restrictions on entity property type identifiers. This relates to + [RFC7285], where a Server can define properties for endpoints "ipv4" + and "ipv6". In the present extension, there is a mapping of ALTO + entity domain types "ipv4" and "ipv6" to ALTO address types "ipv4" + and "ipv6". Properties defined for "ipv4" and "ipv6" endpoints + should be reusable on "ipv4" and "ipv6" entities. Forbidding the + usage of ":" in a non-private entity property type identifier would + not allow the use of properties previously defined for "ipv4" and + "ipv6" endpoints because their identifiers would be invalid. + + Although ":" or "_::-" are valid entity domain types, it is desirable + to add characters, such as alphanumeric ones, for better + intelligibility. + + Identifiers prefixed with "priv:" are reserved for Private Use + [RFC8126] without a need to register with IANA. All other + identifiers for entity property types MUST be registered in the "ALTO + Entity Property Types" registry, which is defined in Section 12.4. + The intended semantics of the entity property type MUST be specified + in the IANA registration. + + For an entity property identifier with the "priv:" prefix, an + additional string (e.g., company identifier or random string) MUST + follow the prefix to reduce potential collisions, that is, the string + "priv:" alone is not a valid entity property identifier. The + definition of a private-use entity property type must apply the same + way in all property maps of an IRD where it is present. + + To distinguish from the endpoint property type, the entity property + type has the following characteristics: + + * Some entity property types are applicable only to entities in + particular entity domain types. For example, the property type + "pid" is applicable to entities in the entity domain types "ipv4" + or "ipv6", while it is not applicable to entities in an entity + domain of type "pid". + + * The intended semantics of the value of an entity property may also + depend on the entity domain type. For example, suppose that a + property named "geo-location" is defined as the coordinates of a + point and is encoded as: "latitude longitude [altitude]." When + applied to an entity that represents a specific host computer and + identified by an address in an entity domain of type "ipv4" or + "ipv6", the "geo-location" property would define the host's + location. However, when applied to an entity in a domain of type + "pid", the property would indicate a location representative of + all hosts in this "pid" entity. + +5.2.2. Entity Property Name + + Each entity property is identified by an entity property name, which + is a string of the following format: + + EntityPropertyName ::= [ [ ResourceID ] '.' ] EntityPropertyType + + Similar to the endpoint property type defined in Section 10.8 of + [RFC7285], each entity property may be defined by either the property + map itself (self-defined) or some other specific information resource + (resource-specific). + + The entity property name of a resource-specific entity property + starts with a string of the type ResourceID defined in [RFC7285], + followed by the '.' separator (U+002E) and an EntityDomainType typed + string. For example, the "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. + + The specific information resource of an entity property may be the + current information resource itself, that is, the property map + defining the property. In that case, the ResourceID in the property + name SHOULD be omitted. For example, the property name ".ASN" + applied to an entity identified by its IPv4 address indicates the AS + number of the AS that "owns" the entity, where the returned AS number + is defined by the property map itself. + +5.2.3. Format for Entity Property Value + + Section 11.4.1.6 of [RFC7285] specifies that an implementation of the + Endpoint Property Service specified in [RFC7285] SHOULD assume that + the property value is a JSONString and fail to parse if it is not. + This document extends the format of a property value by allowing it + to be a JSONValue instead of just a JSONString. + +6. Entity Domain Types Defined in This Document + + The definition of each entity domain type MUST include the entity + domain type name and the domain-specific entity identifiers. The + definition of an entity domain type MAY include hierarchy and + inheritance semantics. This document defines three initial entity + domain types as follows. + +6.1. Internet Address Domain Types + + The document defines two entity domain types (IPv4 and IPv6) for + Internet addresses. Both types are resource-agnostic entity domain + types and hence define corresponding resource-agnostic entity domains + as well. Since the two domains use the same hierarchy and + inheritance semantics, we define the semantics together, instead of + repeating for each. + +6.1.1. Entity Domain Type: IPv4 + +6.1.1.1. Entity Domain Type Identifier + + The identifier for this entity domain type is "ipv4". + +6.1.1.2. Domain-Specific Entity Identifiers + + Individual addresses are strings as specified by the IPv4address rule + in Section 3.2.2 of [RFC3986]; hierarchical addresses are strings as + specified by the prefix notation in Section 3.1 of [RFC4632]. An + individual Internet address and the corresponding full-length prefix + are considered aliases for the same entity on which to define + properties. Thus, "ipv4:192.0.2.0" and "ipv4:192.0.2.0/32" are + equivalent. + +6.1.2. Entity Domain Type: IPv6 + +6.1.2.1. Entity Domain Type Identifier + + The identifier for this Entity Domain Type is "ipv6". + +6.1.2.2. Domain-Specific Entity Identifiers + + Individual addresses are strings as specified by Section 4 of + [RFC5952]; hierarchical addresses are strings as specified by IPv6 + address prefixes notation in Section 2.3 of [RFC4291]. To define + 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. + +6.1.3. Hierarchy and Inheritance of 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 a hierarchical Internet address C + that represents a set of addresses containing I, then the address I + inherits the value of P defined for the hierarchical address C. If + more than one such hierarchical addresses define a value for P, I + inherits the value of P in the hierarchical address with the longest + prefix. Note that this longest prefix rule ensures no multiple value + inheritances, and hence no ambiguity. + + Hierarchical addresses can also inherit properties. For instance, if + a property P: + + * is not defined for the hierarchical address C, + + * but is defined for a set of hierarchical addresses where: + + - each address C' in the set contains all IP addresses in C, and + + - C' has a shorter prefix length than C, + + then C MUST inherit the property P from the C' having the longest + prefix length. + + 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 | + +--------------------+------+ + + Table 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) | + +--------------------+---------------+ + + Table 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 + behaviors: + + * If entity X would inherit a value for property P, and if the ALTO + server decides to say that "X has no value for P", then the ALTO + server MUST return a "null" value for that property on X. In this + case, the ALTO client MUST recognize the JSON "null" value as "no + value" and interpret it as "do not apply the inheritance rules for + this property on X". + + * 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. Thus, 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. + +6.1.4. Defining Information Resource Media Type for Domain Types IPv4 + and IPv6 + + Entity domain types "ipv4" and "ipv6" both allow the definition of + resource-specific entity domains. When resource-specific domains are + defined with entities of domain type "ipv4" or "ipv6", the defining + information resource for an entity domain of type "ipv4" or "ipv6" + MUST be a network map. The media type of a defining information + resource is therefore: + + application/alto-networkmap+json + +6.2. Entity Domain Type: PID + + The PID entity domain associates property values with the PIDs in a + network map. Accordingly, this entity domain always depends on a + network map. + +6.2.1. Entity Domain Type Identifier + + The identifier for this Entity Domain Type is "pid". + +6.2.2. Domain-Specific Entity Identifiers + + The entity identifiers are the PID names of the associated network + map. + +6.2.3. Hierarchy and Inheritance + + There is no hierarchy or inheritance for properties associated with + PIDs. + +6.2.4. Defining Information Resource Media Type for Domain Type PID + + The entity domain type "pid" allows the definition of resource- + specific entity domains. When resource-specific domains are defined + with entities of domain type "pid", the defining information resource + for entity domain type "pid" MUST be a network map. The media type + of a defining information resource is therefore: + + application/alto-networkmap+json + +6.2.5. Relationship To Internet Addresses Domains + + The PID domain and the Internet address domains are completely + independent; the properties associated with a PID have no relation to + the properties associated with the prefixes or endpoint addresses in + that PID. An ALTO server MAY choose to assign all the properties of + a PID to the prefixes in that PID or only some of these properties. + + For example, suppose "PID1" consists of the prefix + "ipv4:192.0.2.0/24" and has the property 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 the property P, and if they do, + it is not necessarily v1. + +6.3. Internet Address Properties vs. PID Properties + + Because the Internet address and PID domains relate to completely + distinct domain types, the question may arise as to which entity + domain type is the best for a property. In general, the Internet + address domain types are RECOMMENDED for properties that are closely + related to the Internet address or are associated with, and inherited + through, hierarchical addresses. + + The PID domain type 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" property would be best + associated with Internet address domain types. On the other hand, a + property that explains why a PID was formed, or how it relates to a + provider's network, would best be associated with the PID domain + type. + +7. 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 a + domain of type "pid", and the "ASN" property of entities in domains + of types "ipv4" and "ipv6". Section 10.4 gives an example of a + property map request and its response. + + Downloading the whole property map is a way for the Client to obtain + the entity identifiers that can be used as input for a filtered + property map request. However, a whole property map may be too + voluminous for a Client that only wants the list of applicable entity + identifiers. How to obtain the list of entities of a filtered + property map in a simplified response is specified in Section 8. + +7.1. Media Type + + The media type of a property map is "application/alto-propmap+json". + +7.2. HTTP Method + + The property map is requested using the HTTP GET method. + +7.3. Accept Input Parameters + + A property map has no Accept Input parameters. + +7.4. Capabilities + + The capabilities are defined by an object of type + PropertyMapCapabilities: + + object { + EntityPropertyMapping mappings; + } PropertyMapCapabilities; + + object-map { + EntityDomainName -> EntityPropertyName<1..*>; + } EntityPropertyMapping + + with fields: + + mappings: A JSON object whose keys are names of entity domains and + values are the supported entity properties of the corresponding + entity domains. + +7.5. Uses + + The "uses" field of a property map resource in an IRD entry specifies + the resources in this same IRD on which this property map directly + depends. It is an array of resource identifier(s). This array + identifies the defining information resources associated with the + resource-specific entity domains and properties that are indicated in + this resource. + +7.6. 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 -> EntityProps; + } PropertyMapData; + + object { + 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 property values of other data types are signaled. + + For each entity in the property map: + + * If the entity is in a resource-specific entity domain, the ALTO + server MUST only return self-defined properties and resource- + specific properties that depend on the same resource as the entity + does. The ALTO client MUST ignore any resource-specific property + for this entity if the mapping between this resource-specific + property and this entity is not indicated, in the IRD, in the + "mappings" capability of the property map resource. + + * If the entity identifier is resource-agnostic, the ALTO server + SHOULD return the self-defined properties and all the resource- + specific properties defined in the property-defining information + resources that are indicated, in the IRD, in the "mappings" + capability of the property map resource, unless property values + can be omitted upon some inheritance rules. + + The ALTO server MAY omit property values that are inherited rather + than explicitly defined in order to achieve more compact encoding. + As a consequence, the ALTO Client MUST NOT assume inherited property + values will all be present. If the Client needs inherited values, it + MUST use the entity domain's inheritance rules to deduce those + values. + +8. Filtered Property Map + + A filtered property map returns the values of a set of properties for + a set of entities selected by the client. + + Sections 10.5, 10.6, 10.7, and 10.8 give examples of filtered + property map requests and responses. + + While the IRD lists all the names of the supported properties, it + only lists the names of the supported entity domains and not the + entity identifiers. Sometimes a client only wants to know what + entity identifiers it can provide as input to a filtered property map + request but does not want to download the full property map, or it + may want to check whether some given entity identifiers are eligible + for a query. To support these cases, the filtered property map + supports a lightweight response with empty property values. + +8.1. Media Type + + The media type of a property map resource is "application/alto- + propmap+json". + +8.2. HTTP Method + + The filtered property map is requested using the HTTP POST method. + +8.3. 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. ReqFilteredPropertyMap is designed to + support the following cases of client requests: + + * The client wants the value of a selected set of properties for a + selected set of entities; + + * The client wants all property values on all the entities; + + * The client wants all entities for which a property is defined but + is not interested in their property values; or + + * The client wants to cross-check whether some entity identifiers + are present in the filtered property map but is not interested in + their property values. + + The third case is equivalent to querying the whole unfiltered + property map, which can also be achieved with a GET request. Some + Clients, however, may prefer to systematically make filtered property + map queries, where filtering parameters may sometimes be empty. + + The JSON object ReqFilteredPropertyMap is specified as follows: + + object { + EntityID entities<0..*>; + [EntityPropertyName properties<0..*>;] + } ReqFilteredPropertyMap; + + with fields: + + entities: A list of entity identifiers for which the specified + properties are to be returned. If the list is empty, the ALTO + Server MUST interpret the list as if it contained a list of all + entities currently defined in the filtered property map. The + domain of each entity MUST be included in the list of entity + domains in this resource's "capabilities" field (see Section 8.4). + The ALTO server MUST interpret entries appearing multiple times as + if they appeared only once. + + properties: A list of properties to be returned for each entity. If + the list is empty, the ALTO Sever MUST interpret the list as if it + contained a list of all properties currently defined in the + filtered property map. Each specified property MUST be included + in the list of properties in this resource's "capabilities" field + (see Section 8.4). The ALTO server MUST interpret entries + appearing multiple times as if they appeared only once. This + field is optional. If it is absent, the Server returns a property + value equal to the literal string "{}" for all the entity + identifiers of the "entities" field for which at least one + property is defined. + + Note that the field "properties" is optional. In addition, when the + "entities" field is an empty list, it corresponds to a query for all + applicable entity identifiers of the filtered property map, with no + current interest on any particular property. When the "entities" + field is not empty, it allows the Client to check whether the listed + entity identifiers can be used as input to a filtered property map + query. + +8.4. Capabilities + + The capabilities are defined by an object of type + PropertyMapCapabilities, as defined in Section 7.4. + +8.5. Uses + + This is the same as the "uses" field of the property map resource + (see Section 7.5). + +8.6. Filtered Property Map 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 in the + following cases: + + * The input field "entities" is absent from the Client request. In + this case, the Server MUST return an "E_MISSING_FIELD" error as + defined in Section 8.5.2 of [RFC7285]. + + * An entity identifier in the "entities" field of the request is + invalid. This occurs when: + + - The domain of this entity is not defined in the "mappings" + capability of this resource in the IRD, or + + - The entity identifier is not valid for the entity domain. + + A valid entity identifier never generates an error, even if the + filtered property map resource does not define any properties for + it. + + If an entity identifier in the "entities" field of 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 the provided invalid entity + identifier. + + * A property name in the "properties" field of the request is + invalid. This occurs when this property name is not defined in + the "properties" capability of this resource in the IRD. + + When a filtered property map resource does not define a value for + a property requested for a particular entity, it is not an error. + In this case, the ALTO server MUST omit that property from the + response for that endpoint. + + If a property name in the "properties" field 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. + + Some identifiers can be interpreted as both an entity name and a + property name, as is the case for "pid" if it were erroneously used + alone. In such a case, the Server SHOULD follow Section 8.5.2 of + [RFC7285], which says: + + | For an E_INVALID_FIELD_VALUE error, the server may include an + | optional field named "field" in the "meta" field of the response, + | to indicate the field that contains the wrong value. + + The response to a valid request is the same as for the property map + (see Section 7.6) except that: + + * If the requested entities include entities with a resource- + agnostic identifier, the "dependent-vtags" field in its "meta" + field MUST include version tags of all dependent resources + appearing in the "uses" field. + + * If the requested entities only include entities in resource- + specific entity domains, the "dependent-vtags" field in its "meta" + field MUST include the version tags of the resources on which the + requested resource-specific entity domains and the requested + resource-specific properties are dependent. + + * The response only includes the entities and properties requested + by the client. If an entity in the request is identified by a + hierarchical identifier (e.g., a "ipv4" or "ipv6" prefix), the + response MUST return all properties that are present for any + address covered by the prefix, even though some of those + properties may not be present for all addresses covered by the + prefix. + + * When the input member "properties" is absent from the client + request, the Server returns a property map containing all the + requested entity identifiers for which one or more properties are + defined. For all the entities of the returned map, the returned + property value is equal to "{}". + + The filtered property map response MUST include all the inherited + property values for the requested entities and all the entities that + are able to inherit property values from the requested entities. To + achieve this goal, the ALTO server MAY follow two rules: + + * If a property for a requested entity is inherited from another + entity not included in the request, the response MUST 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 MUST be included in the response for A. + + * If there are entities covered by a requested entity but they have + different values for the requested properties, the response MUST + include all those entities and the different property values for + them. For example, consider 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. + + For the sake of response compactness, the ALTO server SHOULD obey the + following rule: + + * If an entity identifier in the response is already covered by + other entities identifiers in the same response, it SHOULD be + removed from the response. 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. + +8.7. Entity Property Type Defined in This Document + + This document defines the entity property type "pid". This property + type extends the ALTO endpoint property type "pid" defined in + Section 7.1.1 of [RFC7285] as follows: the property has the same + semantics and applies to IPv4 and IPv6 addresses; the difference is + that the IPv4 and IPv6 addresses have evolved from the status of + endpoints to the status of entities. + + The defining information resource for property type MUST be a network + map. + +8.7.1. Entity Property Type: pid + + Identifier: pid + + Semantics: the intended semantics are the same as in [RFC7285] for + the ALTO endpoint property type "pid". + + Media type of defining information resource: application/alto- + networkmap+json + + Security considerations: for entity property type "pid" are the same + as documented in [RFC7285] for the ALTO endpoint property type + "pid". + +9. Impact on Legacy ALTO Servers and ALTO Clients + +9.1. Impact on Endpoint Property Service + + Since the property map and the filtered property map defined in this + document provide a functionality that covers the EPS defined in + Section 11.4 of [RFC7285], ALTO servers may prefer to provide + property map and filtered property map in place of EPS. However, for + the legacy endpoint properties, it is recommended that ALTO servers + also provide EPS so that legacy clients can still be supported. + +9.2. 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 identifier of the resource they + depend on, while global property names have no such prefix. The + property map and the filtered property map specified in this document + define similar categories of entity properties. The difference is + that entity property maps do not define "global" entity properties. + Instead, they define self-defined entity properties as a special case + of "resource-specific" entity properties, where the specific resource + is the property map itself. This means that self-defined properties + are defined within the scope of the property map. + +9.3. Impact on Other Properties + + In the present extension, properties can be defined for sets of + entity addresses, rather than just individual endpoint addresses as + initially defined in [RFC7285]. This might change the semantics of a + property. These sets can be, for example, hierarchical IP address + blocks. For instance, a property such as the fictitious "geo- + location" defined for a set of IP addresses would have a value + corresponding to a location representative of all the addresses in + this set. + +10. Examples + + In this document, the HTTP message bodies of all the examples use + Unix-style line-ending character (%x0A) as the line separator. + +10.1. Network Map + + The examples in this section use a very simple default network map: + + +-------------+--------------------------+ + | defaultpid: | ipv4:0.0.0.0/0 ipv6:::/0 | + +-------------+--------------------------+ + | pid1: | ipv4:192.0.2.0/25 | + +-------------+--------------------------+ + | pid2: | ipv4:192.0.2.0/27 | + +-------------+--------------------------+ + | pid3: | ipv4:192.0.3.0/28 | + +-------------+--------------------------+ + | pid4: | ipv4:192.0.3.16/28 | + +-------------+--------------------------+ + + Table 3: Example Default Network Map + + And another simple alternative network map: + + +-------------+--------------------------+ + | defaultpid: | ipv4:0.0.0.0/0 ipv6:::/0 | + +-------------+--------------------------+ + | pid1: | ipv4:192.0.2.0/27 | + +-------------+--------------------------+ + | pid2: | ipv4:192.0.3.0/27 | + +-------------+--------------------------+ + + Table 4: Example Alternative Network Map + +10.2. Property Definitions + + Beyond "pid", the examples in this section use four additional, + fictitious property types for entities of domain type "ipv4": + "countrycode", "ASN", "ISP", and "state". These properties are + assumed to be resource-agnostic so their name is identical to their + type. The entities have the following values: + + +=====================+=========+=======+=============+=======+ + | | ISP | ASN | countrycode | state | + +=====================+=========+=======+=============+=======+ + | ipv4:192.0.2.0/23: | BitsRus | - | us | - | + +---------------------+---------+-------+-------------+-------+ + | ipv4:192.0.2.0/28: | - | 65543 | - | NJ | + +---------------------+---------+-------+-------------+-------+ + | ipv4:192.0.2.16/28: | - | 65543 | - | CT | + +---------------------+---------+-------+-------------+-------+ + | ipv4:192.0.2.1: | - | - | - | PA | + +---------------------+---------+-------+-------------+-------+ + | ipv4:192.0.3.0/28: | - | 65544 | - | TX | + +---------------------+---------+-------+-------------+-------+ + | ipv4:192.0.3.16/28: | - | 65544 | - | MN | + +---------------------+---------+-------+-------------+-------+ + + Table 5: Example Property Values for Internet Address Domains + + 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: | us-west | + +-----------------+----------+ + | pid:pid2: | us-east | + +-----------------+----------+ + | pid:pid3: | us-south | + +-----------------+----------+ + | pid:pid4: | us-north | + +-----------------+----------+ + + Table 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 "ipv4:192.0.2.1" is "BitsRus" because of + "ipv4:192.0.2.0/24". But the "region" property for "pid:defaultpid" + has no value because there is no entity from which it can inherit. + + 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: | 65543 | + +-----------------+-------+ + | pid:pid2: | 65544 | + +-----------------+-------+ + + Table 7: Example + Property Values for + Alternative Network + Map's PID Domain + +10.3. Information Resource Directory (IRD) + + The following IRD defines ALTO Server information resources that are + relevant to the Entity Property Service. It provides a property map + for the "ISP" and "ASN" properties. The server could have provided a + single property map for all four properties, but it does not, + presumably because the organization that runs the ALTO server + believes that a client is not necessarily interested in getting all + four properties. + + The server provides several filtered property maps. The first + returns all four properties, and the second returns only the "pid" + property for the default network map and the "alt-network-map". + + The filtered property maps for the "ISP", "ASN", "countrycode", 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 providing the "pid" property does have a "uses" + capability for the default network map because the default network + map defines the values of the "pid" property. + + Note that for legacy clients, the ALTO server provides an Endpoint + Property Service for the "pid" property defined for the endpoints of + the default network map and the "alt-network-map". + + The server provides another filtered Property map resource, named + "ane-dc-property-map", that returns fictitious properties named + "storage-capacity", "ram", and "cpu" for ANEs that have a persistent + identifier. The entity domain to which the ANEs belong is self- + defined and valid only within the property map. + + The other property maps in the returned IRD are shown here for + purposes of illustration. + + GET /directory HTTP/1.1 + Host: alto.example.com + Accept: application/alto-directory+json,application/alto-error+json + + HTTP/1.1 200 OK + Content-Length: 2713 + Content-Type: application/alto-directory+json + + { + "meta" : { + "default-alto-network-map" : "default-network-map" + }, + "resources" : { + "default-network-map" : { + "uri" : "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" + }, + "ia-property-map" : { + "uri" : "http://alto.example.com/propmap/full/inet-ia", + "media-type" : "application/alto-propmap+json", + "capabilities" : { + "mappings": { + "ipv4": [ ".ISP", ".ASN" ], + "ipv6": [ ".ISP", ".ASN" ] + } + } + }, + "iacs-property-map" : { + "uri" : "http://alto.example.com/propmap/lookup/inet-iacs", + "media-type" : "application/alto-propmap+json", + "accepts": "application/alto-propmapparams+json", + "capabilities" : { + "mappings": { + "ipv4": [ ".ISP", ".ASN", ".countrycode", ".state" ], + "ipv6": [ ".ISP", ".ASN", ".countrycode", ".state" ] + } + } + }, + "region-property-map": { + "uri": "http://alto.example.com/propmap/lookup/region", + "media-type": "application/alto-propmap+json", + "accepts": "application/alto-propmapparams+json", + "uses" : [ "default-network-map", "alt-network-map" ], + "capabilities": { + "mappings": { + "default-network-map.pid": [ ".region" ], + "alt-network-map.pid": [ ".ASN" ] + } + } + }, + "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", "alt-network-map" ], + "capabilities" : { + "mappings": { + "ipv4": [ "default-network-map.pid", + "alt-network-map.pid" ], + "ipv6": [ "default-network-map.pid", + "alt-network-map.pid" ] + } + } + }, + "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", + "alt-network-map.pid" ] + } + }, + "ane-dc-property-map": { + "uri" : "http://alto.example.com/propmap/lookup/ane-dc", + "media-type" : "application/alto-propmap+json", + "accepts": "application/alto-propmapparams+json", + "capabilities": { + "mappings": { + ".ane" : [ "storage-capacity", "ram", "cpu" ] + } + } + } + } + } + + Figure 1: Example IRD + +10.4. Full Property Map Example + + The following example uses the properties and IRD defined in + Section 10.3 to retrieve a property map for entities with the "ISP" + and "ASN" properties. + + Note that, to be compact, the response does not include the entity + "ipv4:192.0.2.1" 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 "ipv4:192.0.3.16/28". Both + "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: 418 + 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": "BitsRus"}, + "ipv4:192.0.2.0/27": {".ASN": "65543"}, + "ipv4:192.0.3.0/27": {".ASN": "65544"} + } + } + +10.5. 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 "ipv4:192.0.2.1" is the only + explicitly defined property; the other values are all derived from + 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: 158 + 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" ] + } + + HTTP/1.1 200 OK + Content-Length: 540 + 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": "BitsRus", ".ASN": "65543", ".state": "NJ"}, + "ipv4:192.0.2.1": + {".ISP": "BitsRus", ".ASN": "65543", ".state": "PA"}, + "ipv4:192.0.2.17": + {".ISP": "BitsRus", ".ASN": "65543", ".state": "CT"} + } + } + +10.6. Filtered Property Map Example #2 + + The following example uses the filtered property map resource to + request the "ASN", "countrycode", 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 explicitly listed in the + request. 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 from which it is inherited, 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: 174 + 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", ".countrycode", ".state" ] + } + + HTTP/1.1 200 OK + Content-Length: 774 + 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": {".countrycode": "us"}, + "ipv4:192.0.2.0/28": {".ASN": "65543", + ".state": "NJ"}, + "ipv4:192.0.2.16/28": {".ASN": "65543", + ".state": "CT"}, + "ipv4:192.0.2.1": {".state": "PA"}, + "ipv4:192.0.3.0/26": {".countrycode": "us"}, + "ipv4:192.0.3.0/28": {".ASN": "65544", + ".state": "TX"}, + "ipv4:192.0.3.16/28": {".ASN": "65544", + ".state": "MN"} + } + } + +10.7. Filtered Property Map Example #3 + + The following example uses the filtered property map resource to + request the "default-network-map.pid" property and the "alt-network- + map.pid" property for a set of IPv4 addresses and prefixes. + + Note that the entity "ipv4:192.0.3.0/27" is decomposed into two + entities: "ipv4:192.0.3.0/28" and "ipv4:192.0.3.16/28", as they have + different "default-network-map.pid" property values. + + POST /propmap/lookup/pid HTTP/1.1 + Host: alto.example.com + Accept: application/alto-propmap+json,application/alto-error+json + Content-Length: 222 + Content-Type: application/alto-propmapparams+json + + { + "entities" : [ + "ipv4:192.0.2.128", + "ipv4:192.0.2.0/27", + "ipv4:192.0.3.0/27" ], + "properties" : [ "default-network-map.pid", + "alt-network-map.pid" ] + } + + HTTP/1.1 200 OK + Content-Length: 774 + 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": { + "ipv4:192.0.2.128": {"default-network-map.pid": "defaultpid", + "alt-network-map.pid": "defaultpid"}, + "ipv4:192.0.2.0/27": {"default-network-map.pid": "pid2", + "alt-network-map.pid": "pid1"}, + "ipv4:192.0.3.0/28": {"default-network-map.pid": "pid3", + "alt-network-map.pid": "pid2"}, + "ipv4:192.0.3.16/28": {"default-network-map.pid": "pid4", + "alt-network-map.pid": "pid2"} + } + } + +10.8. Filtered Property Map Example #4 + + Here is an example of using the filtered property map to query the + regions for several PIDs in "default-network-map". The "region" + property is specified as a self-defined property, i.e., the values of + this property are defined by this property map resource. + + POST /propmap/lookup/region HTTP/1.1 + Host: alto.example.com + Accept: application/alto-propmap+json,application/alto-error+json + Content-Length: 132 + Content-Type: application/alto-propmapparams+json + + { + "entities" : ["default-network-map.pid:pid1", + "default-network-map.pid:pid2"], + "properties" : [ ".region" ] + } + + HTTP/1.1 200 OK + Content-Length: 326 + Content-Type: application/alto-propmap+json + + { + "meta" : { + "dependent-vtags" : [ + {"resource-id": "default-network-map", + "tag": "7915dc0290c2705481c491a2b4ffbec482b3cf62"} + ] + }, + "property-map": { + "default-network-map.pid:pid1": { + ".region": "us-west" + }, + "default-network-map.pid:pid2": { + ".region": "us-east" + } + } + } + +10.9. Filtered Property Map for ANEs Example #5 + + The following example uses the filtered property map resource "ane- + dc-property-map" to request properties "storage-capacity" and "cpu" + on several ANEs defined in this property map. + + POST /propmap/lookup/ane-dc HTTP/1.1 + Host: alto.example.com + Accept: application/alto-propmap+json,application/alto-error+json + Content-Length: 155 + Content-Type: application/alto-propmapparams+json + + { + "entities" : [".ane:dc21", + ".ane:dc45-srv9", + ".ane:dc6-srvcluster8"], + "properties" : [ "storage-capacity", "cpu"] + } + + HTTP/1.1 200 OK + Content-Length: 295 + Content-Type: application/alto-propmap+json + + { + "meta" : { + }, + "property-map": { + ".ane:dc21": + {"storage-capacity" : 40000, "cpu" : 500}, + ".ane:dc45-srv9": + {"storage-capacity" : 100, "cpu" : 20}, + ".ane:dc6-srvcluster8": + {"storage-capacity" : 6000, "cpu" : 100} + } + } + +11. 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. + + ALTO clients using this extension should in addition be aware that + the entity properties they require may convey more details than the + endpoint properties conveyed by using [RFC7285]. Client requests may + reveal details of their activity or plans thereof such that a + malicious Server, which is in a position to do so, may monetize or + use for attacks or undesired surveillance. Likewise, ALTO Servers + expose entities and properties related to specific parts of the + infrastructure that reveal details of capabilities, locations, or + resource availability. These details may be maliciously used for + competition purposes, or to cause resource shortage or undesired + publication. + + To address these concerns, the property maps provided by this + extension require additional attention to two security considerations + discussed in: Section 15.2 ("Potential Undesirable Guidance from + Authenticated ALTO Information") of [RFC7285] and Section 15.3 + ("Confidentiality of ALTO Information") of [RFC7285]. Threats to the + availability of the ALTO service caused by highly demanding queries + should be addressed as specified in Section 15.5 of [RFC7285]. + + * Potential undesirable guidance from authenticated ALTO + information: this can be caused by Property values that change + over time and thus lead to performance degradation or system + rejection of application requests. + + To avoid these consequences, a more robust ALTO client should + adopt and extend protection strategies specified in Section 15.2 + of [RFC7285]. For example, to be notified immediately when a + particular ALTO value that the Client depends on changes, it is + RECOMMENDED that both the ALTO Client and ALTO Server using this + extension implement "Application-Layer Traffic Optimization (ALTO) + Incremental Updates Using Server-Sent Events (SSE)" [RFC8895]. + + * Confidentiality of ALTO information: as discussed in Section 15 of + [RFC7285], properties may have sensitive customer-specific + information. If this is the case, an ALTO Server may limit access + to those properties by providing several different property maps. + For a nonsensitive properties, the ALTO Server would provide a URI + that accepts requests from any client. Sensitive properties, on + the other hand, would only be available via a secure URI that + would require client authentication. Another way is to expose + highly abstracted, coarse-grained property values to all Clients + while restricting access to URIs that expose more fine-grained + values to authorized Clients. Restricted access URIs may be + gathered in delegate IRDs as specified in Section 9.2.4 of + [RFC7285]. + + Also, while technically this document does not introduce any + security risks not inherent in the Endpoint Property Service + defined by [RFC7285], the GET-mode property map resource defined + in this document does make it easier for a client to download + large numbers of property values. Accordingly, an ALTO Server + should limit GET-mode property maps to properties that do not + contain sensitive data. + + Section 12 of this document specifies that the ALTO service + provider MUST be aware of the potential sensitivity of exposed + entity domains and properties. Section 12.3.2 (ALTO Entity Domain + Type Registration Process) of this document specifies that when + the registration of an entity domain type is requested of IANA, + the request MUST include security considerations that show + awareness of how the exposed entity addresses may be related to + private information about an ALTO client or an infrastructure + service provider. Likewise, Section 12.4 (ALTO Entity Property + Types Registry) of this document specifies that when the + registration of a property type is requested of IANA, the request + MUST include security considerations that explain why this + property type is required for ALTO-based operations. + + The risk of ALTO information being leaked to malicious Clients or + third parties is addressed similarly to Section 7 of [RFC8896]. + ALTO clients and servers SHOULD support TLS 1.3 [RFC8446]. + +12. IANA Considerations + + This document defines additional application/alto-* media types, + which are listed in Table 8. It defines the "ALTO Entity Domain + Types" registry that extends the "ALTO Address Types" registry + defined in [RFC7285]. It also defines the "ALTO Entity Property + Types" registry that extends the "ALTO Endpoint Property Types" + registry defined in [RFC7285]. + + +=============+=========================+===============+ + | Type | Subtype | Specification | + +=============+=========================+===============+ + | application | alto-propmap+json | Section 7.1 | + +-------------+-------------------------+---------------+ + | application | alto-propmapparams+json | Section 8.3 | + +-------------+-------------------------+---------------+ + + Table 8: Additional ALTO Media Types + +12.1. application/alto-propmap+json Media Type + + Type name: + application + + Subtype name: + alto-propmap+json + + Required parameters: + n/a + + Optional parameters: + n/a + + Encoding considerations: + Encoding considerations are identical to those specified for the + "application/json" media type. See [RFC8259]. + + Security considerations: + Security considerations related to the generation and consumption + of ALTO Protocol messages are discussed in Section 15 of [RFC7285] + and Section 11 of this document. + + Interoperability considerations: + n/a + + Published specification: + This document is the specification for this media type. See + Section 7.1. + + Applications that use this media type: + ALTO servers and ALTO clients [RFC7285], either standalone or + embedded within other applications, when the queried resource is a + property map, whether filtered or not. + + Fragment identifier considerations: + n/a + + Additional information: + Magic number(s): n/a + + File extension(s): n/a + + 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 (iesg@ietf.org). + +12.2. alto-propmapparams+json Media Type + + Type name: + application + + Subtype name: + alto-propmapparams+json + + Required parameters: + n/a + + Optional parameters: + n/a + + Encoding considerations: + Encoding considerations are identical to those specified for the + "application/json" media type. See [RFC8259]. + + Security considerations: + Security considerations related to the generation and consumption + of ALTO Protocol messages are discussed in Section 15 of [RFC7285] + and Section 11 of this document. + + Interoperability considerations: + n/a + + Published specification: + This document is the specification for this media type. See + Section 8.3. + + Applications that use this media type: + ALTO servers and ALTO clients [RFC7285], either standalone or + embedded within other applications, when the queried resource is a + filtered property map. This media type indicates the data format + used by the ALTO client to supply the property map filtering + parameters. + + Fragment identifier considerations: + n/a + + Additional information: + Magic number(s): n/a + + File extension(s): n/a + + 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 (iesg@ietf.org). + +12.3. ALTO Entity Domain Types Registry + + IANA has created and will maintain the "ALTO Entity Domain Types" + registry listed in Table 9. The first row lists information items + that must be provided with each registered entity domain type. + Section 12.3.2 specifies how to document these items and in addition + provides guidance on the security considerations item that must be + documented. + + +==========+===========+=============+======================+=======+ + |Identifier|Entity |Hierarchy and|Media Type of Defining|Mapping| + | |Identifier |Inheritance |Resource |to ALTO| + | |Encoding | | |Address| + | | | | |Type | + +==========+===========+=============+======================+=======+ + |ipv4 |See Section|See |application/alto- |true | + | |6.1.1 |Section 6.1.3|networkmap+json | | + +----------+-----------+-------------+----------------------+-------+ + |ipv6 |See Section|See |application/alto- |true | + | |6.1.2 |Section 6.1.3|networkmap+json | | + +----------+-----------+-------------+----------------------+-------+ + |pid |See |None |application/alto- |false | + | |Section 6.2| |networkmap+json | | + +----------+-----------+-------------+----------------------+-------+ + + Table 9: ALTO Entity Domain Types + + This registry serves two purposes. First, it ensures uniqueness of + identifiers referring to ALTO entity domain types. Second, it states + the requirements for allocated entity domain types. + + As specified in Section 5.1.1, identifiers prefixed with "priv:" are + reserved for Private Use without a need to register with IANA + +12.3.1. Consistency Procedure between ALTO Address Types Registry and + ALTO Entity Domain Types Registry + + One potential issue of introducing the "ALTO Entity Domain Types" + registry is its relationship with the "ALTO Address Types" registry + already defined in Section 14.4 of [RFC7285]. In particular, the + entity identifier of a type of an entity domain registered in the + "ALTO Entity Domain Types" registry MAY match an address type defined + in "ALTO Address Types" registry. It is necessary to precisely + define and guarantee the consistency between "ALTO Address Types" + registry and "ALTO Entity Domain Types" registry. + + We define that the "ALTO Entity Domain Types" registry is consistent + with "ALTO Address Types" registry if two conditions are satisfied: + + * When an address type is already registered or is able to be + registered in the "ALTO Address Types" registry [RFC7285], the + same identifier MUST be used when a corresponding entity domain + type is registered in the "ALTO Entity Domain Types" registry. + + * If an ALTO entity domain type has the same identifier as an ALTO + address type, their address encodings MUST be compatible. + + To achieve this consistency, the following items MUST be checked + before registering a new ALTO entity domain type in a future + document: + + * Whether the "ALTO Address Types" registry contains an address type + that can be used as an identifier for the candidate entity domain + type identifier. This has been done for the identifiers "ipv4" + and "ipv6" of Table 9. + + * Whether the candidate entity domain type identifier can + potentially be an endpoint address type, as defined in Sections + 2.1 and 2.2 of [RFC7285]. + + When a new ALTO entity domain type is registered, the consistency + with the "ALTO Address Types" registry MUST be ensured by the + following procedure: + + * Test: Do corresponding entity domain type identifiers match a + known "network" address type? + + - If yes (e.g., cell, MAC, or socket addresses): + + o Test: Is such an address type present in the "ALTO Address + Types" registry? + + + If yes: Set the new ALTO entity domain type identifier to + be the found ALTO address type identifier. + + + If no: Define a new ALTO entity domain type identifier + and use it to register a new address type in the "ALTO + Address Types" registry following Section 14.4 of + [RFC7285]. + + o Use the new ALTO entity domain type identifier to register a + new ALTO entity domain type in the "ALTO Entity Domain + Types" registry following Section 12.3.2 of this document. + + - If no (e.g., PID name, ANE name, or "countrycode"): Proceed + with the ALTO Entity Domain Type registration as described in + Section 12.3.2. + +12.3.2. ALTO Entity Domain Type Registration Process + + New ALTO entity domain types are assigned after IETF Review [RFC8126] + to ensure that proper documentation regarding the new ALTO entity + domain types and their security considerations has been provided. + RFCs defining new entity domain types MUST indicate how an entity in + a registered type of domain is encoded as an EntityID and, if + applicable, provide the rules for defining the entity hierarchy and + property inheritance. Updates and deletions of ALTO entity domains + types follow the same procedure. + + Registered ALTO entity domain type identifiers MUST conform to the + syntactical requirements specified in Section 5.1.2. Identifiers are + to be recorded and displayed as strings. + + Requests to IANA to add a new value to the "ALTO Entity Domain Types" + registry MUST include the following information: + + Identifier: The name of the desired ALTO entity domain type. + + Entity Identifier Encoding: The procedure for encoding the + identifier of an entity of the registered domain type as an + EntityID (see Section 5.1.3). If corresponding entity identifiers + of an entity domain type 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 Types" registry [RFC7285]. To + define properties, an individual entity identifier and the + corresponding full-length prefix MUST be considered aliases for + the same entity. + + Hierarchy: If the entities form a hierarchy, the procedure for + determining that hierarchy. + + Inheritance: If entities can inherit property values from other + entities, the procedure for determining that inheritance. + + Media type of defining information resource: Some entity domain + types allow an entity domain name to be combined with an + information resource name to define a resource-specific entity + domain. Such an information resource is called a "defining + information resource" and is defined in Section 4.6. For each + entity domain type, the potential defining information resources + have one common media type. This unique common media type is + specific to the entity domain type and MUST be specified. + + Mapping to ALTO Address Type: A boolean value to indicate if the + entity domain type can be mapped to the ALTO address type with the + same identifier. + + 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 + cognizant of how (or if) the addressing scheme relates to private + information and network proximity. + + IANA has registered the identifiers "ipv4", "ipv6", and "pid", as + shown in Table 9. + +12.4. ALTO Entity Property Types Registry + + IANA has created and will maintain the "ALTO Entity Property Types" + registry, which is listed in Table 10. + + This registry extends the "ALTO Endpoint Property Types" registry, + defined in [RFC7285], in that a property type is defined for one or + more entity domains, rather than just for IPv4 and IPv6 Internet + address domains. An entry in this registry is an ALTO entity + property type defined in Section 5.2.1. Thus, a registered ALTO + entity property type identifier MUST conform to the syntactical + requirements specified in that section. + + As specified in Section 5.2.1, identifiers prefixed with "priv:" are + reserved for Private Use without a need to register with IANA. + + The first row of Table 10 lists information items that must be + provided with each registered entity property type. + + +============+====================+=================================+ + | Identifier | Intended Semantics | Media Type of | + | | | Defining Resource | + +============+====================+=================================+ + | pid | See Section 7.1.1 | application/alto- | + | | of [RFC7285] | networkmap+json | + +------------+--------------------+---------------------------------+ + + Table 10: ALTO Entity Property Types + + New ALTO entity property types are assigned after IETF Review + [RFC8126] to ensure that proper documentation regarding the new ALTO + entity property types and their security considerations has been + provided. RFCs defining new entity property types SHOULD indicate + how a property of a registered type is encoded as a property name. + Updates and deletions of ALTO entity property types follow the same + procedure. + + Requests to IANA to add a new value to the registry MUST include the + following information: + + Identifier: The identifier for the desired ALTO entity property + type. The format MUST be as defined in Section 5.2.1 of this + document. + + 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. + + Media type of defining information resource: when the property type + allows values to be defined relative to a given information + resource, the latter is referred to as the "defining information + resource"; see the description in Section 4.7. For each property + type, the potential defining information resources have one common + media type. This unique common media type is specific to the + property type and MUST be specified. + + Security Considerations: ALTO entity properties expose information + to ALTO clients. ALTO service providers should be cognizant of + the security ramifications related to the exposure of an entity + property. + + In security considerations, the request should also discuss the + sensitivity of the information and why it is required for ALTO-based + operations. Regarding this discussion, the request SHOULD follow the + recommendations of the "ALTO Endpoint Property Types" registry in + Section 14.3 of [RFC7285]. + + IANA has registered the identifier "pid", which is listed in + Table 10. Semantics for this property are documented in + Section 7.1.1 of [RFC7285]. No security issues related to the + exposure of a "pid" identifier are considered, as it is exposed with + the Network Map Service defined and mandated in [RFC7285]. + +13. References + +13.1. Normative References + + [ISO3166-1] + International Organization for Standardization, "Codes for + the representation of names of countries and their + subdivisions -- Part 1: Country codes", ISO 3166-1:2020, + August 2020. + + [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>. + + [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing + Architecture", RFC 4291, DOI 10.17487/RFC4291, February + 2006, <https://www.rfc-editor.org/info/rfc4291>. + + [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>. + + [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>. + + [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>. + + [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for + Writing an IANA Considerations Section in RFCs", BCP 26, + RFC 8126, DOI 10.17487/RFC8126, June 2017, + <https://www.rfc-editor.org/info/rfc8126>. + + [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC + 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, + May 2017, <https://www.rfc-editor.org/info/rfc8174>. + + [RFC8259] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data + Interchange Format", STD 90, RFC 8259, + DOI 10.17487/RFC8259, December 2017, + <https://www.rfc-editor.org/info/rfc8259>. + + [RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol + Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, + <https://www.rfc-editor.org/info/rfc8446>. + + [RFC8895] Roome, W. and Y. Yang, "Application-Layer Traffic + Optimization (ALTO) Incremental Updates Using Server-Sent + Events (SSE)", RFC 8895, DOI 10.17487/RFC8895, November + 2020, <https://www.rfc-editor.org/info/rfc8895>. + +13.2. Informative References + + [PATH-VECTOR] + Gao, K., Lee, Y., Randriamasy, S., Yang, Y. R., and J. J. + Zhang, "An ALTO Extension: Path Vector", Work in Progress, + Internet-Draft, draft-ietf-alto-path-vector-25, 20 March + 2022, <https://datatracker.ietf.org/doc/html/draft-ietf- + alto-path-vector-25>. + + [RFC3849] Huston, G., Lord, A., and P. Smith, "IPv6 Address Prefix + Reserved for Documentation", RFC 3849, + DOI 10.17487/RFC3849, July 2004, + <https://www.rfc-editor.org/info/rfc3849>. + + [RFC5511] Farrel, A., "Routing Backus-Naur Form (RBNF): A Syntax + Used to Form Encoding Rules in Various Routing Protocol + Specifications", RFC 5511, DOI 10.17487/RFC5511, April + 2009, <https://www.rfc-editor.org/info/rfc5511>. + + [RFC5737] Arkko, J., Cotton, M., and L. Vegoda, "IPv4 Address Blocks + Reserved for Documentation", RFC 5737, + DOI 10.17487/RFC5737, January 2010, + <https://www.rfc-editor.org/info/rfc5737>. + + [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>. + + [RFC8896] Randriamasy, S., Yang, R., Wu, Q., Deng, L., and N. + Schwan, "Application-Layer Traffic Optimization (ALTO) + Cost Calendar", RFC 8896, DOI 10.17487/RFC8896, November + 2020, <https://www.rfc-editor.org/info/rfc8896>. + + [RFC9241] Seedorf, J., Yang, Y., Ma, K., Peterson, J., and J. Zhang, + "Content Delivery Network Interconnection (CDNI) Footprint + and Capabilities Advertisement Using Application-Layer + Traffic Optimization (ALTO)", RFC 9241, + DOI 10.17487/RFC9241, July 2022, + <https://www.rfc-editor.org/info/rfc9241>. + +Appendix A. Features Introduced with the Entity Property Maps Extension + + The entity property maps extension described in this document + introduces a number of features that are summarized in table below. + The first column provides the name of the feature. The second column + provides the section number of this document that gives a high-level + description of the feature. The third column provides the section + number of this document that gives a normative description relating + to the feature, when applicable. + + +=======================+=============+======================+ + | Feature | High-Level | Related Normative | + | | Description | Description | + +=======================+=============+======================+ + | Entity | Section 3.1 | Section 5.1.3 | + +-----------------------+-------------+----------------------+ + | Entity domain | Section 3.2 | | + +-----------------------+-------------+----------------------+ + | Entity domain type | Section | Section 5.1.1 | + | | 3.2.1 | | + +-----------------------+-------------+----------------------+ + | Entity domain name | Section | Section 5.1.2 | + | | 3.2.2 | | + +-----------------------+-------------+----------------------+ + | Entity property type | Section 3.3 | Sections 5.2, 5.2.1, | + | | | 5.2.2, and 5.2.3 | + +-----------------------+-------------+----------------------+ + | Entity property map | Section 3.4 | Sections 7 and 8 | + +-----------------------+-------------+----------------------+ + | Resource-specific | Section 4.2 | Sections 5.1.2 and | + | entity domain name | | 5.1.2.1 | + +-----------------------+-------------+----------------------+ + | Resource-specific | Section 4.3 | Section 5.2.3 | + | entity property value | | | + +-----------------------+-------------+----------------------+ + | Entity Hierarchy and | Section 4.4 | Section 5.1.4 | + | property inheritance | | | + +-----------------------+-------------+----------------------+ + | Defining information | Sections | Sections 12.3.2 and | + | resource | 4.6 and 4.7 | 12.4 | + +-----------------------+-------------+----------------------+ + + Table 11: Features Introduced with ALTO Entity Property Maps + +Acknowledgments + + The authors would like to thank Dawn Chen and Shenshen Chen for their + contributions to earlier drafts. Thank you also to Qiao Xiang, Shawn + Lin, and Xin Wang for fruitful discussions. Last, big thanks to + Danny Perez and Luis Contreras for their substantial working group + review feedback and suggestions for improving this document, to Vijay + Gurbani, ALTO WG Chair, and Martin Duke, Transport Area Director, for + their thorough review, discussions, guidance, and shepherding, which + further helped to enrich this document. + +Authors' Addresses + + Wendy Roome + Nokia Bell Labs (Retired) + 124 Burlington Rd + Murray Hill, NJ 07974 + United States of America + Phone: +1-908-464-6975 + Email: wendy@wdroome.com + + + Sabine Randriamasy + Nokia Bell Labs + Route de Villejust + 91460 NOZAY + France + Email: Sabine.Randriamasy@nokia-bell-labs.com + + + Y. Richard Yang + Yale University + 51 Prospect Street + New Haven, CT 06511 + United States of America + Phone: +1-203-432-6400 + Email: yry@cs.yale.edu + + + Jingxuan Jensen Zhang + Tongji University + 4800 Cao'An Hwy + Shanghai + 201804 + China + Email: jingxuan.n.zhang@gmail.com + + + Kai Gao + Sichuan University + No.24 South Section 1, Yihuan Road + Chengdu + 610000 + China + Email: kaigao@scu.edu.cn |