ALTO WG W. Roome
Internet-Draft S. Randriamasy
Intended status: Standards Track Nokia Bell Labs
Expires: January 14, 2021 Y. Yang
Yale University
J. Zhang
Tongji University
K. Gao
Sichuan University
July 13, 2020
Unified properties for the ALTO protocol
draft-ietf-alto-unified-props-new-12
Abstract
This document extends the Application-Layer Traffic Optimization
(ALTO) Protocol [RFC7285] by generalizing the concept of "endpoint
properties" to generic types of entities, and by presenting those
properties as maps, similar to the network and cost maps in
[RFC7285].
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on January 14, 2021.
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Copyright Notice
Copyright (c) 2020 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
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 6
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 6
3. Basic Features of the Unified Property Extension . . . . . . 6
3.1. Entity . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.2. Entity Domain . . . . . . . . . . . . . . . . . . . . . . 7
3.2.1. Entity Domain Type . . . . . . . . . . . . . . . . . 8
3.2.2. Entity Domain Name . . . . . . . . . . . . . . . . . 8
3.3. Entity Property Type . . . . . . . . . . . . . . . . . . 8
3.4. New information resource and media type: ALTO Property
Map . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
4. Advanced Features of the Unified Property Extension . . . . . 10
4.1. Entity Identifier and Entity Domain Name . . . . . . . . 10
4.2. Resource-Specific Entity Domain Name . . . . . . . . . . 10
4.3. Resource-Specific Entity Property Value . . . . . . . . . 11
4.4. Entity Hierarchy and Property Inheritance . . . . . . . . 12
4.4.1. Entity Hierarchy . . . . . . . . . . . . . . . . . . 12
4.4.2. Property Inheritance . . . . . . . . . . . . . . . . 13
4.4.3. Property Value Unicity . . . . . . . . . . . . . . . 13
4.5. Supported Properties on Entity Domains in Property Map
Capabilities . . . . . . . . . . . . . . . . . . . . . . 14
4.6. Defining Information Resource . . . . . . . . . . . . . . 14
4.6.1. Defining Information Resource and Media Type . . . . 15
4.6.2. Examples of specific resources media-types . . . . . 16
4.7. Defining Information Resource for Resource-Specific
Property Values . . . . . . . . . . . . . . . . . . . . . 17
4.7.1. Examples of defining resources media-types for
properties . . . . . . . . . . . . . . . . . . . . . 17
5. Protocol Specification: Basic Data Type . . . . . . . . . . . 17
5.1. Entity Domain . . . . . . . . . . . . . . . . . . . . . . 17
5.1.1. Entity Domain Type . . . . . . . . . . . . . . . . . 18
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5.1.2. Entity Domain Name . . . . . . . . . . . . . . . . . 18
5.1.3. Entity Identifier . . . . . . . . . . . . . . . . . . 20
5.1.4. Hierarchy and Inheritance . . . . . . . . . . . . . . 20
5.2. Entity Property . . . . . . . . . . . . . . . . . . . . . 21
5.2.1. Entity Property Type . . . . . . . . . . . . . . . . 21
5.2.2. Entity Property Name . . . . . . . . . . . . . . . . 22
5.2.3. Format for Entity Property Value . . . . . . . . . . 22
6. Entity Domain Types Defined in this Document . . . . . . . . 22
6.1. Internet Address Domain Types . . . . . . . . . . . . . . 23
6.1.1. IPv4 Domain . . . . . . . . . . . . . . . . . . . . . 23
6.1.2. IPv6 Domain . . . . . . . . . . . . . . . . . . . . . 23
6.1.3. Hierarchy and Inheritance of Internet Address Domains 23
6.1.4. Defining Information Resource Media Type for domain
types IPv4 and IPv6 . . . . . . . . . . . . . . . . . 25
6.2. PID Domain . . . . . . . . . . . . . . . . . . . . . . . 25
6.2.1. Entity Domain Type . . . . . . . . . . . . . . . . . 25
6.2.2. Domain-Specific Entity Identifiers . . . . . . . . . 25
6.2.3. Hierarchy and Inheritance . . . . . . . . . . . . . . 25
6.2.4. Defining Information Resource Media Type for Domain
Type PID . . . . . . . . . . . . . . . . . . . . . . 25
6.2.5. Relationship To Internet Addresses Domains . . . . . 26
6.3. Internet Address Properties vs. PID Properties . . . . . 26
7. Property Map . . . . . . . . . . . . . . . . . . . . . . . . 26
7.1. Media Type . . . . . . . . . . . . . . . . . . . . . . . 27
7.2. HTTP Method . . . . . . . . . . . . . . . . . . . . . . . 27
7.3. Accept Input Parameters . . . . . . . . . . . . . . . . . 27
7.4. Capabilities . . . . . . . . . . . . . . . . . . . . . . 27
7.5. Uses . . . . . . . . . . . . . . . . . . . . . . . . . . 27
7.6. Response . . . . . . . . . . . . . . . . . . . . . . . . 27
8. Filtered Property Map . . . . . . . . . . . . . . . . . . . . 29
8.1. Media Type . . . . . . . . . . . . . . . . . . . . . . . 29
8.2. HTTP Method . . . . . . . . . . . . . . . . . . . . . . . 29
8.3. Accept Input Parameters . . . . . . . . . . . . . . . . . 29
8.4. Capabilities . . . . . . . . . . . . . . . . . . . . . . 30
8.5. Uses . . . . . . . . . . . . . . . . . . . . . . . . . . 30
8.6. Response . . . . . . . . . . . . . . . . . . . . . . . . 30
8.7. Entity property type defined in this document . . . . . . 32
9. Impact on Legacy ALTO Servers and ALTO Clients . . . . . . . 32
9.1. Impact on Endpoint Property Service . . . . . . . . . . . 32
9.2. Impact on Resource-Specific Properties . . . . . . . . . 32
9.3. Impact on Other Properties . . . . . . . . . . . . . . . 32
10. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 33
10.1. Network Map . . . . . . . . . . . . . . . . . . . . . . 33
10.2. Property Definitions . . . . . . . . . . . . . . . . . . 33
10.3. Properties for Abstract Network Elements . . . . . . . . 34
10.4. Information Resource Directory (IRD) . . . . . . . . . . 35
10.5. Full Property Map Example . . . . . . . . . . . . . . . 37
10.6. Filtered Property Map Example #1 . . . . . . . . . . . . 38
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10.7. Filtered Property Map Example #2 . . . . . . . . . . . . 39
10.8. Filtered Property Map Example #3 . . . . . . . . . . . . 41
10.9. Filtered Property Map Example #4 . . . . . . . . . . . . 42
10.10. Filtered Property Map for ANEs Example #5 . . . . . . . 43
11. Security Considerations . . . . . . . . . . . . . . . . . . . 44
12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 44
12.1. application/alto-* Media Types . . . . . . . . . . . . . 45
12.2. ALTO Entity Domain Type Registry . . . . . . . . . . . . 46
12.2.1. Consistency Procedure between ALTO Address Type
Registry and ALTO Entity Domain Type Registry . . . 46
12.2.2. ALTO Entity Domain Type Registration Process . . . . 48
12.3. ALTO Entity Property Type Registry . . . . . . . . . . . 49
13. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 50
14. References . . . . . . . . . . . . . . . . . . . . . . . . . 51
14.1. Normative References . . . . . . . . . . . . . . . . . . 51
14.2. Informative References . . . . . . . . . . . . . . . . . 52
Appendix A. Scope of Property Map . . . . . . . . . . . . . . . 52
A.1. Example Property Map . . . . . . . . . . . . . . . . . . 53
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 54
1. Introduction
The ALTO protocol [RFC7285] introduces the concept of "properties"
attached to "endpoint addresses", and defines the Endpoint Property
Service (EPS) to allow ALTO clients to retrieve those properties.
While useful, the EPS, as defined in [RFC7285], has at least three
limitations.
First, the EPS allows properties to be associated with only endpoints
which are identified by individual communication addresses like IPv4
and IPv6 addresses. It is reasonable to think that collections of
endpoints, as defined by CIDRs [RFC4632] or PIDs, may also have
properties. Furthermore, recent ALTO use cases show that properties
of network flows [RFC7011] and routing elements [RFC7921] are also
very useful. Since the EPS cannot be extended to those generic
entities, new services, with new request and response messages, would
have to be defined for them.
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 which is also not globally
unique. Additionally, a generic entity such as a PID may have an
identifier that is not globally unique. For example, a PID
identifier may be used in multiple network maps, where in each
network map, this PID identifier points to a different set of
addresses.
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Third, the EPS is only defined as a POST-mode service. Clients must
request the properties for an explicit set of endpoint addresses. By
contrast, [RFC7285] defines a GET-mode cost map resource which
returns all available costs, so a client can get a full set of costs
once, and then 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. However, in practice, it is highly unlikely that
properties will be defined for every endpoint address. It is much
more likely that properties may be defined for only a subset of
endpoint addresses, and the specification of properties uses an
aggregation representation to allow enumeration. This is
particularly true if blocks of endpoint addresses with a common
prefix (e.g., a CIDR) have the same value for a property. Entities
in other domains may very well allow aggregated representation and
hence be enumerable as well.
To address the three limitations, this document specifies a protocol
extension for defining and retrieving ALTO properties:
o 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 abstracted network element as defined in [REF path-vector], or
other physical or logical objects used by ALTO. Each entity is
included in a collection called an ALTO Entity Domain. Since each
ALTO Entity Domain includes only one type of entities, each Entity
Domain can be classified by the type of entities in it.
o 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.
o The third limitation is addressed by defining two new types of
ALTO information resources: Property Map, detailed in Section 7
and Filtered Property Map, detailed in Section 8. The former is a
GET-mode resource that 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 [RFC7285]. The latter is a POST-mode
resource that returns the values for a set of properties and
entities requested by the client, and is analogous to a filtered
network map or a filtered cost map.
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The protocol extension defined in this document is extensible. New
entity domain types can be defined without revising the specification
defined in this document. Similarly, new cost metrics and new
endpoint properties can be defined in other documents without
revising the protocol specification defined in [RFC7285].
This document subsumes the Endpoint Property Service defined in
[RFC7285], although that service may be retained for legacy clients
(see Section 9).
This document assumes the reader is familiar with the base ALTO
protocol defined in [RFC7285].
1.1. Terminology
TODO: TBC
o Client: When starting with a capital "C", this term refers to an
ALTO client.
o Server: When starting with a capital "S", this term refers to an
ALTO server.
o TBC
2. Requirements Language
TODO: REAL RFC xrefs 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. When the words
appear in lower case, they are to be interpreted with their natural
language meanings.
3. Basic Features of the Unified Property Extension
This section gives a high-level overview of the 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 on objects that extend ALTO
Endpoints and are called ALTO Entities, entities for short.
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 that is defined by its network address, but
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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, where as all endpoints are entities, not all
entities are endpoints.
Examples of entities are:
o an ALTO endpoint, defined in [RFC7285], that represents an
application or a host identified by a communication address (e.g.,
an IPv4 or IPv6 address) in a network,
o 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,
o an autonomous system (AS), that has an AS number (ASN) as its
identifier and maps to a set of ipv4 and ipv6 addresses,
o a country with a code as specified in [ISO3166-1], to which
applications such as CDN providers associate properties and
capabilities,
o a TCP/IP network flow, that is identified by a TCP/IP 5-Tuple
specifying its source and destination addresses and port numbers
and the utilized protocol,
o a routing element, that is specified in [RFC7921] and is
associated with routing capabilities information,
o an abstract network element, that represents an abstraction of a
network part such as a routable network node, one or more links, a
network domain or their aggregation.
3.2. Entity Domain
An entity domain defines a set of entities of the same semantic type.
An entity domain is characterized by its type and identified by its
name.
In this document, an entity must be owned by exactly one entity
domain name. An entity identifier must point 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 object 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.
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3.2.1. Entity Domain Type
The type of an entity domain type defines the semantics of a type of
entity. Entity domain types can be defined in different documents.
For example: the present document defines entity domain types "ipv4",
"ipv6" and "pid" in sections Section 6.1 and Section 6.2. The entity
domain type "ane", that defines Abstract Network Elements (ANEs), is
introduced in [I-D.ietf-alto-path-vector]. The entity domain type
that defines country codes is introduced in
[draft-ietf-alto-cdni-request-routing-alto]. An entity domain type
is expected to be registered at the IANA, as specified in section
Section 12.2.2 and similarly to an ALTO address type.
3.2.2. Entity Domain Name
The name of an entity domain is defined in the scope of an ALTO
server. An entity domain name can be identical to its relevant
entity domain type in the following case: when the entities of an
entity domain have an identifier that points to the same object
throughout all the information resources of the Server that provide
entity properties for this domain. For example, a domain of type
"ipv4" that contains entities identified by a public IPv4 address can
be named "ipv4" because its entities are uniquely identified by all
the resources of the Server.
In some cases, a domain type and domain name must be different.
Indeed, for some domain types, entities are defined relatively to a
given information resource. As a consequence, entities in such
domains may be defined in a resource handling this domain type but
not in other resources handling this same domain type. Moreover,
across different ALTO information resources handling a domain type,
an entity identifier may point to different objects. This is the
case for entities of domain type "pid". A PID is defined relatively
to a network map. For example: an entity "mypid10" of domain type
"pid" may be defined in a given network map resource and be undefined
in other network maps, or may even map to a different set of endpoint
addresses. In this case, naming an entity domain only by its type
"pid" does not guarantee that its entities are owned by exactly one
entity domain name. Section 4.2 and related of this document
describe how a domain is uniquely identified 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. Simularly to an entity domain, an entity property is
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characterized by its type and identified by its name. An entity
property type is expected to be registered at the IANA, as specified
in section Section 12.3.
For example:
o an entity in the "ipv4" domain may have a property whose value is
an Autonomous System (AS) number indicating the AS that owns this
IPv4 address and another property named "countrycode" indicating a
country code mapping to this address,
o an entity identified by its country code in the "countrycode"
domain, defined in [draft-ietf-alto-cdni-request-routing-alto] may
have a property indicating what delivery protocol is used by a
CDN,
o 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:
o the identifier "countrycode" may point to both the entity domain
type "countrycode" and the property type "countrycode".
o the identifier "pid" may point to both the entity domain type
"pid" and the property type "pid".
Likewise, a same identifier may point to both a domain name and a
property name.
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 on
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".
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A Property Map can be queried as a GET-mode resource, thus conveying
values of all properties on all entities indicated in its
capabilities. It can also be queried as a POST-mode resource, thus
conveying a selection of properties on a selection of entities.
4. Advanced Features of the Unified Property Extension
4.1. Entity Identifier and Entity Domain Name
In [RFC7285], an endpoint has an identifier which 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, 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:
o if an entity is an endpoint with example routable IPv4 address
"192.0.2.14", its identifier is associated with domain name "ipv4"
and is "ipv4:192.0.2.14",
o if an entity is a PID named "mypid10" in network map resource
"netmap2", its identifier is associated with domain name
"netmap2.pid" and is "netmap2.pid:mypid10".
4.2. Resource-Specific Entity Domain Name
Some entities are defined and identified in a unique and global way.
This is the case for instance for entities that are endpoints
identified by a routable 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 to any specific ALTO
information resources.
Some other entities and entity types are only defined relatively to a
given information resource. This is the case for entities of domain
type "pid", that 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
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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 resources-specific entity domain. This concept applies to domain
types where entities are defined relatively 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. Example 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" allows to
distinguish 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 relatively
to an information resource. That is, an entity may have a property
of a given type, whose values are associated to 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. So that 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 will likely
be 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 of [RFC7285]
entitled "Resource-Specific Endpoint Properties". When a property
value depends on a given information resource, the name of this
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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 on the property name
format are provided in Section 5.2.
4.4. Entity Hierarchy and Property Inheritance
For some domain types, entities can be grouped in 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 a 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 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.
This document introduces, for applicable domain types, "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 using a single identifier to identify a
set of individual entities. For example, a 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. 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".
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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 the ASN property 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 "ASN" property value of block
"ipv4:192.0.1.0/24" because the address "ipv4:192.0.1.1" is included
by 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 "sub" sets that are covered by this set
identifier. In this case, inheritance rules must specify how
entities in "sub" sets inherit property values from their "super"
set. For instance, if the "ASN" property is defined only for the
entity set identified by block "ipv4:192.0.1.0/24", the entity set
identified by "ipv4:192.0.1.0/30" and thus included in the former
set, may inherit the "ASN" property values from set
"ipv4:192.0.1.0/24".
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. Indeed, a property map may define a property on a hierarchy
of entity sets that inherit property values from one or more
including sets in the upper levels. On the other hand, a property
value, defined at a lower level of the hierarchy may be different
from the value defined at an upper level. In such a case, a set in
the lower level of the hierarchy may potentially end up with
different values. This may be the case for address blocs with
increasing prefix length, on which a property value gets 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 entity sets 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.
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4.5. Supported Properties on Entity Domains in Property Map
Capabilities
A property type is not necessarily applicable to any domain type, or
an ALTO Server may just not provide a property on all applicable
domains. For instance, a property type reflecting link bandwidth is
likely not defined on entities of a domain of type "country-code".
Therefore an ALTO server providing Property Maps specifies the
properties that can be queried on the different entity domains it
supports.
This document explains how the IRD capabilities of a Property Map
resource unambiguously expose what properties a Client can query on a
given entity domain.
o a field named "mappings" lists the names of the entity domains
supported by the Property Map,
o for each listed entity domain, a list of the names of the
applicable properties is provided.
An example is provided in Section 10.4. 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:
o it avoids a Client to query a property on entity domains on which
it is not defined,
o it allows a Client to query, for an entity E, values for a
property P that are defined in different information resources,
o it allows a Client to query a property P on entities that are
defined in different information resources.
Further specifications are provided in Section 7.4.
4.6. Defining Information Resource
A Client willing to query properties on entities belonging to a
domain needs to know how to retrieve these entities. To this end, he
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
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specific resource, query the resource and retrieve the entities. For
example:
o 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 cannot be
recognized outside "netmap1", for instance because these are local
non routable addresses,
o an entity domain named "netmap1.pid" includes the PIDs listed in
network map "netmap1".
o an entity domain named "ipv4" is resource-agnostic and covers all
the routable IPv4 addresses.
Besides, it is also necessary to inform a Client about which
associations of specific resources and entity domain types are
allowed, because it is not possible to prevent a Server from exposing
inappropriate associations. 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 them, that is, 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. The resource "costmap3" therefore 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, that lists all the PIDs
used in a cost map, 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 "pid" and this concept is
explained in Section 4.6.1.
4.6.1. Defining Information Resource and Media Type
For the reasons explained in the previous section, this document
indroduces the concept of defining information resource and 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. This concept applies to resource specific domains. This
is useful for entity domain types that are by essence domain-
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specific, such as "pid" and "ane" domain types. It is also useful
for resource-specific entity domains constructed from resource-
agnostic domain types, such as for example, network map specific
domains of local IPv4 addresses.
The defining information resource of an entity domain D has the
following specificities:
o it has an entry in the IRD,
o it defines the entities of D,
o it does not use another information resource that defines these
entities,
o it defines and exposes entity identifiers that are all persistent.
o its media type is unique and equal to the one that is specified
for the defining information resource of an entity domain type.
A fundamental attribute of a defining information resource is its
media type. There is a unique association of an entity domain type
with the media type of its defining information resources. If an
entity domain type allows defining information resources, their media
type is specified in the document that defines this entity domain
type and in the document that requests the registration of this
domain type at the IANA.
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 resources a resource specific entity
domain with a non compliant media type for the domain type, the
Client can avoid transaction errors by ignoring them.
4.6.2. Examples of specific resources media-types
Here are some examples of specific information resources types
associated to entity domain types and their media type.
o 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.
o 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.
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o For entity domain type "ane", defined in
[I-D.ietf-alto-path-vector]: a specific property map resource can
be associated to ANEs that have a persistent identifier and have
an entry in the IRD. ANEs that have a persistent identifier are
defined in a property map that is indicated in the IRD, therefore
the media type associated with entity domain type "ane" is
"application/alto-propmap+json".
4.7. Defining Information Resource 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 example for property type
"pid", whose values are by essence defined relatively to a specific
network map. The PID value for an IPv4 address differ in different
network maps or not be defined for some of them. Property values may
be specific to different types of information resources. For
example: the value for property "pid" is specific to a network map.
The value for property type "cdnifci-capab" is specific to the
information resource "cdnifci-map", defined in [draft-ietf-alto-cdni-
request-routing-alto], while network maps do not define property
"fci-capability" for ipv4 addresses and a cdnifci-map does not define
"pid" values for IPv4 addresses.
Thus, similarly to resource specific entity domains, the Client needs
to be aware of aware of appropriate associations of information
resource and property types.
4.7.1. Examples of defining resources media-types for properties
Here are some examples of specific information resources types
associated to entity property types and their media type.
o For property type "pid": the media type of the specific resource
is "application/alto-networkmap+json", because PIDs are defined in
network map resources.
o For property type "cdni-fci-capability": the media type of the
specific resource is "application/alto-cdnifci+json"
5. Protocol Specification: Basic Data Type
5.1. Entity Domain
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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), hyphen ("-",
U+002D), and low line ("_", U+005F). The ?.? separator MUST NOT be
used unless specifically indicated in a further extension document.
For example, the strings "ipv4", "ipv6", and "pid" are valid entity
domain types. "ipv4.anycast" and "pid.local" are invalid.
The type EntityDomainType is used in this document to denote a JSON
string meeting the preceding requirement.
An entity domain type defines the semantics of a type of entity,
indenpendently of any specifying resource. Each entity domain type
MUST be registered with the IANA. The format of the entity
identifiers (see Section 5.1.3) in that type of entity domains, as
well as any hierarchical or inheritance rules (see Section 5.1.4) for
those entities, MUST be specified at the same time.
5.1.2. Entity Domain 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 sub-sections.
Each entity domain is identified by a unique entity domain name which
is a string of the following format:
EntityDomainName ::= [ [ ResourceID ] '.' ] EntityDomainType
Where the presence and construction of 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 the resource ID format definition in Section 10.1 of
[RFC7285] specifies that: "the '.' separator is reserved for future
use and MUST NOT be used unless specifically indicated in this
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document, or an extension document". The present extension keeps the
format specification of [RFC7285], hence the '.' separator MUST NOT
be used in an information resources ID.
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 ID using
the ResourceID type defined in Section 10.2 of [RFC7285], followed by
the '.' separator (U+002E), followed by an 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. Hence, 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 on entities that are neither
resource-specific nor resource-agnostic but are instead defined
within the property map itself. This may be the case when an ALTO
Server provides information on a set of entities that is specific to
this property map would not be relevant for another one and that does
not depend on a specific resource.
For example: a specialised property map may define a domain of type
"ane", defined in [I-D.ietf-alto-path-vector], that contains a set of
ANEs with a persistent identifier that are relevant only for 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.
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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" SHOULD 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::1/48".
The format of the second part of an entity identifier depends on the
entity domain type, and MUST be specified when defining a new entity
domain type and registering it with the 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.
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.
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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 ("-", 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.
Each entity property type MUST be registered with the IANA. The
intended semantics of the entity property type MUST be specified at
the same time.
Identifiers prefixed with "priv:" are reserved for Private Use
[RFC5226] without a need to register with IANA. All other
identifiers for entity property types appearing in an HTTP request or
response with an "application/alto-*" media type MUST be registered
in the "ALTO Entity Property Type Registry", defined in Section 12.3.
For an entity property identifier with the "priv:" prefix, an
additional string (e.g., company identifier or random string) MUST
follow (i.e., "priv:" only is not a valid endpoint property
identifier) to reduce potential collisions.
To distinguish with the endpoint property type, the entity property
type has the following features.
o Some entity property types may be applicable to entities in only
particular types of entity domains, not all. For example, the
"pid" property is not applicable to entities in a "pid" typed
entity domain, but is applicable to entities in the "ipv4" or
"ipv6" domains.
o The intended semantics of the value of an entity property may also
depend on the entity domain type of this entity. For example,
suppose that the "geo-location" property is defined as the
coordinates of a point, encoded as (say) "latitude longitude
[altitude]." When applied to an entity that represents a specific
host computer, identified by an address in the "ipv4" or "ipv6"
entity domain, the property defines the host's location. However,
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when applied to an entity in a "pid" domain, the property would
indicate the location of the center 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 a 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.
When the associated information resource of the entity property is
the current information resource itself, the ResourceID in the
property name SHOULD be ignored. For example, the ".asn" property of
an "ipv4" entity indicates the AS number of the AS which this IPv4
address is owned by.
5.2.3. Format for Entity Property Value
[RFC7285] in Section 11.4.1.6, 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. The present document first, extends the property service to
Entities. Second it 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
This document requires the definition of each entity domain type MUST
include (1) the entity domain type name and (2) domain-specific
entity identifiers, and MAY include (3) hierarchy and inheritance
semantics optionally. This document defines three initial entity
domain types as follows.
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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. IPv4 Domain
6.1.1.1. Entity Domain Type
ipv4
6.1.1.2. Domain-Specific Entity Identifiers
Individual addresses are strings as specified by the IPv4Addresses
rule of Section 3.2.2 of [RFC3986]; Hierarchical addresses are
prefix-match strings as specified in Section 3.1 of [RFC4632]. To
define properties, an individual Internet address and the
corresponding full-length prefix are considered aliases for the same
entity. Thus "ipv4:192.0.2.0" and "ipv4:192.0.2.0/32" are
equivalent.
6.1.2. IPv6 Domain
6.1.2.1. Entity Domain Type
ipv6
6.1.2.2. Domain-Specific Entity Identifiers
Individual addresses are strings as specified by Section 4 of
[RFC5952]; Hierarchical addresses are prefix-match strings as
specified in Section 7 of [RFC5952]. 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 a hierarchical Internet address C
which prefix-matches I, then the address I inherits the value of P
defined for the hierarchical address C. If more than one such
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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 inheritances, and hence
no ambiguity.
Hierarchical addresses can also inherit properties: if a property P
is not defined for the hierarchical address C, but is defined for
another hierarchical address C' which covers all IP addresses in C,
and C' has a shorter prefix length than C, then C MAY inherits the
property from C'. If there are multiple such hierarchical addresses
like C', C MUST inherit from the hierarchical address 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
Figure 1: Defined Property Values.
Then the following entities have the indicated values:
ipv4:192.0.2.0: P=v4
ipv4:192.0.2.1: P=v3
ipv4:192.0.2.16: P=v1
ipv4:192.0.2.32: P=v1
ipv4:192.0.2.64: (not defined)
ipv4:192.0.2.0/32: P=v4
ipv4:192.0.2.0/31: P=v3
ipv4:192.0.2.0/29: P=v2
ipv4:192.0.2.0/27: P=v1
ipv4:192.0.2.0/25: (not defined)
Figure 2: Inherited Property Values.
An ALTO server MAY explicitly indicate a property as not having a
value for a particular entity. That is, a server MAY say that
property P of entity X is "defined to have no value", instead of
"undefined". To indicate "no value", a server MAY perform different
behaviours:
o If that entity would inherit a value for that property, then the
ALTO server MUST return a "null" value for that property. In this
case, the ALTO client MUST recognize a "null" value as "no value"
and "do not apply the inheritance rules for this property."
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o If the entity would not inherit a value, then the ALTO server MAY
return "null" or just omit the property. In this case, the ALTO
client cannot infer the value for this property of this entity
from the Inheritance rules. So the client MUST interpret that
this property has no value.
If the ALTO server does not define any properties for an entity, then
the server MAY omit that entity from the response.
6.1.4. Defining Information Resource Media Type for domain types IPv4
and IPv6
Entity domain types "ipv4" and "ipv6" both allow to define 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. PID Domain
The PID 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
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 to define 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:
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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 some or all properties
of a PID to the prefixes in that PID.
For example, suppose "PID1" consists of the prefix
"ipv4:192.0.2.0/24", and has the property "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 are completely separate,
the question may arise as to which entity domain is the best for a
property. In general, the Internet address domains are RECOMMENDED
for properties that are closely related to the Internet address, or
are associated with, and inherited through, hierarchical addresses.
The PID domain is RECOMMENDED for properties that arise from the
definition of the PID, rather than from the Internet address prefixes
in that PID.
For example, because Internet addresses are allocated to service
providers by blocks of prefixes, an "ISP" property would be best
associated with the Internet address domain. 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.
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 "pid"
domain, and the "ASN" property of entities in "ipv4" and "ipv6"
domains.
Section 10.5 gives an example of a property map request and its
response.
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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
None.
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
dependent resources of this property map. It is an array of the
resource ID(s) of the resource(s).
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:
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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:
o If the entity is in a resource-specific entity domain, the ALTO
server SHOULD only return self-defined properties and resource-
specific properties which depend on the same resource as the
entity does. The ALTO client SHOULD ignore the resource-specific
property in this entity if their mapping is not registered in the
ALTO Resource Entity Property Transfer Registry of the type of the
corresponding resource.
o If the entity is in a shared entity domain, the ALTO server SHOULD
return self-defined properties and all resource-specific
properties defined for all resource-specific entities which have
the same domain-specific entity identifier as this entity does.
For efficiency, the ALTO server SHOULD omit property values that are
inherited rather than explicitly defined; if a client needs inherited
values, the client SHOULD use the entity domain's inheritance rules
to deduce those values.
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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.
Section 10.6, Section 10.7, Section 10.8 and Section 10.9 give
examples of filtered property map requests and responses.
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:
object {
EntityID entities<1..*>;
EntityPropertyName properties<1..*>;
} ReqFilteredPropertyMap;
with fields:
entities: List of entity identifiers for which the specified
properties are to be returned. The ALTO server MUST interpret
entries appearing multiple times as if they appeared only once.
The domain of each entity MUST be included in the list of entity
domains in this resource's "capabilities" field (see Section 8.4).
properties: List of properties to be returned for each entity. Each
specified property MUST be included in the list of properties in
this resource's "capabilities" field (see Section 8.4). The ALTO
server MUST interpret entries appearing multiple times as if they
appeared only once.
Note that the "entities" and "properties" fields MUST have at
least one entry each.
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8.4. Capabilities
The capabilities are defined by an object of type
PropertyMapCapabilities, as defined in Section 7.4.
8.5. Uses
Same to the "uses" field of the Property Map resource (see
Section 7.5).
8.6. Response
The response MUST indicate an error, using ALTO protocol error
handling, as defined in Section 8.5 of [RFC7285], if the request is
invalid.
Specifically, a filtered property map request can be invalid as
follows:
o An entity identifier in "entities" in the request is invalid if:
* The domain of this entity is not defined in the "entity-
domains" capability of this resource in the IRD;
* The entity identifier is an invalid identifier in the entity
domain.
A valid entity identifier is never an error, even if this filtered
property map resource does not define any properties for it.
If an entity identifier in "entities" in the request is invalid,
the ALTO server MUST return an "E_INVALID_FIELD_VALUE" error
defined in Section 8.5.2 of [RFC7285], and the "value" field of
the error message SHOULD indicate this entity identifier.
o A property name in "properties" in the request is invalid if this
property name is not defined in the "properties" capability of
this resource in the IRD.
It is not an error that a filtered property map resource does not
define a requested property's value for a particular entity. In
this case, the ALTO server MUST omit that property from the
response for that endpoint.
If a property name in "properties" in the request is invalid, the
ALTO server MUST return an "E_INVALID_FIELD_VALUE" error defined
in Section 8.5.2 of [RFC7285]. The "value" field of the error
message SHOULD indicate the property name.
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The response to a valid request is the same as for the Property Map
(see Section 7.6), except that:
o If the requested entities include entities in the shared entity
domain, the "dependent-vtags" field in its "meta" field MUST
include version tags of all dependent resources appearing in the
"uses" field.
o If the requested entities only include entities in resource-
specific entity domains, the "dependent-vtags" field in its "meta"
field MUST include version tags of resources which requested
resource-specific entity domains and requested resource-specific
properties are dependent on.
o 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 cover properties for all identifiers in this
hierarchical identifier.
It is important that the filtered property map response MUST include
all inherited property values for the requested entities and all the
entities which are able to inherit property values from them. To
achieve this goal, the ALTO server MAY follow three rules:
o If a property for a requested entity is inherited from another
entity not included in the request, the response SHOULD include
this property for the requested entity. For example, A full
property map may skip a property P for an entity A (e.g.,
ipv4:192.0.2.0/31) if P can be derived using inheritance from
another entity B (e.g., ipv4:192.0.2.0/30). A filtered property
map request may include only A but not B. In such a case, the
property P SHOULD be included in the response for A.
o If there are entities covered by a requested entity but having
different values for the requested properties, the response SHOULD
include all those entities and the different property values for
them. For example, considering a request for property P of entity
A (e.g., ipv4:192.0.2.0/31), if P has value v1 for
A1=ipv4:192.0.2.0/32 and v2 for A2=ipv4:192.0.2.1/32, then, the
response SHOULD include A1 and A2.
o If an entity in the response is already covered by some other
entities in the same response, it SHOULD be removed from the
response for compactness. For example, in the previous example,
the entity A=ipv4:192.0.2.0/31 SHOULD be removed because A1 and A2
cover all the addresses in A.
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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"
The intended semantics are the same as in [RFC7285]
The defining information resource for property type MUST be a network
map.
The media type of a defining information resource is therefore:
application/alto-networkmap+json
This document requests a IANA registration for this property
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 the functionality of the Endpoint Property Service
(EPS) defined in Section 11.4 of [RFC7285], it is RECOMMENDED that
the EPS be deprecated in favor of Property Map and Filtered Property
Map. However, ALTO servers MAY provide an EPS for the benefit of
legacy clients.
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 ID of the resource they depend
upon, while global property names have no such prefix. The property
map and the filtered property map defined in this document defines
the similar categories for entity properties. The difference is that
there is no "global" entity properties but the "self-defined" entity
properties as the special case of the "resource-specific" entity
properties instead.
9.3. Impact on Other Properties
In general, there should be little or no impact on other previously
defined properties. The only consideration is that properties can
now be defined on hierarchical entity identifiers, rather than just
individual entity identifiers, which might change the semantics of a
property.
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10. Examples
10.1. Network Map
The examples in this section use a very simple default network map:
defaultpid: ipv4:0.0.0.0/0 ipv6:::0/0
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
Figure 3: Example Default Network Map
And another simple alternative network map:
defaultpid: ipv4:0.0.0.0/0 ipv6:::0/0
pid1: ipv4:192.0.2.0/27
pid2: ipv4:192.0.3.0/27
Figure 4: Example Alternative Network Map
10.2. Property Definitions
Beyond "pid", the examples in this section use four additional
properties for Internet address domains, "ISP", "ASN", "country" and
"state", with the following values:
ISP ASN country state
ipv4:192.0.2.0/23: BitsRus - us -
ipv4:192.0.2.0/28: - 12345 - NJ
ipv4:192.0.2.16/28: - 12345 - CT
ipv4:192.0.2.1: - - - PA
ipv4:192.0.3.0/28: - 12346 - TX
ipv4:192.0.3.16/28: - 12346 - MN
Figure 5: Example Property Values for Internet Address Domains
And the examples in this section use the property "region" for the
PID domain of the default network map with the following values:
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region
pid:defaultpid: -
pid:pid1: us-west
pid:pid2: us-east
pid:pid3: us-south
pid:pid4: us-north
Figure 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 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: 12345
pid:pid2: 12346
Figure 7: Example Property Values for Alternative Network Map's PID
Domain
10.3. Properties for Abstract Network Elements
Additionally, the examples in this section consider a facilitated
entity domain: "ane" (Abstract Network Element). Abstract network
elements allow ALTO clients to discover information beyond the end-
to-end routing costs. Examples of abstract network elements include:
Forwarding elements: Forwarding elements include optical wires,
physical layer links, IP tunnels, etc. Forwarding elements share
the common property "maxresbw".
Value-added services: Value-added services include HTTP caches, 5G
UPF nodes, mobile edge computing, etc. Value-added services share
the common property "persistent-entities", which contains
information that points to the entry point of the service.
Different value-added services may have specific properties, e.g.,
an abstract network element of a mobile edge may provide a list of
flavors to the client.
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maxresbw persistent-entities mec-flavors
ane:L001 100 Mbps
ane:L002 100 Mbps
ane:CACHE1 http-proxy:192.0.2.1
ane:MEC01 mec:192.0.2.1 {gpu:2G, ssd:128G}
ane:MEC02 mec:192.0.2.2 {gpu:1G, ssd:128G}
The "ane" entities are usually not used alone, but associated with
other ALTO resources, e.g., cost maps. It means that the ALTO server
may not define a property map resource to provide properties of "ane"
entities. The property map payload for "ane" entities may be
provided in the response of other ALTO resources in some way.
10.4. Information Resource Directory (IRD)
The following IRD defines the relevant resources of the ALTO server.
It provides two property maps, one for the "ISP" and "ASN"
properties, and another for the "country" and "state" properties.
The server could have provided a single property map for all four
properties, but did not, presumably because the organization that
runs the ALTO server believes any given client is not interested in
all four properties.
The server provides two filtered property maps. The first returns
all four properties, and the second just returns the "pid" property
for the default network map.
The filtered property maps for the "ISP", "ASN", "country" and
"state" properties do not depend on the default network map (it does
not have a "uses" capability), because the definitions of those
properties do not depend on the default network map. The Filtered
Property Map for the "pid" property does have a "uses" capability for
the default network map, because that defines the values of the "pid"
property.
Note that for legacy clients, the ALTO server provides an Endpoint
Property Service for the "pid" property for the default network map.
The server also provides a facilitated ALTO resource which accepts
the filtered cost map request but returns a multipart message
including a cost map and an associated property map for "ane"
entities.
"meta" : {
...
"default-alto-network-map" : "default-network-map"
},
"resources" : {
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"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"
},
.... property map resources ....
"ia-property-map" : {
"uri" : "http://alto.example.com/propmap/full/inet-ia",
"media-type" : "application/alto-propmap+json",
"uses": [ "default-network-map", "alt-network-map" ],
"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",
"uses": [ "default-network-map", "alt-network-map" ],
"capabilities" : {
"mappings": {
"ipv4": [ ".ISP", ".ASN", ".country", ".state" ],
"ipv6": [ ".ISP", ".ASN", ".country", ".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",
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"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 8: Example IRD
10.5. Full Property Map Example
The following example uses the properties and IRD defined above in
Section 10.4 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
"ipv4:192.0.2.0", because values of all those properties for this
entity are inherited from other entities.
Also note that the entities "ipv4:192.0.2.0/28" and
"ipv4:192.0.2.16/28" are merged into "ipv4:192.0.2.0/27", because
they have the same value of the "ASN" property. The same rule
applies to the entities "ipv4:192.0.3.0/28" and "ipv4:192.0.3.0/28".
Both of "ipv4:192.0.2.0/27" and "ipv4:192.0.3.0/27" omit the value
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for the "ISP" property, because it is inherited from
"ipv4:192.0.2.0/23".
GET /propmap/full/inet-ia HTTP/1.1
Host: alto.example.com
Accept: application/alto-propmap+json,application/alto-error+json
HTTP/1.1 200 OK
Content-Length: ###
Content-Type: application/alto-propmap+json
{
"meta": {
"dependent-vtags": [
{"resource-id": "default-network-map",
"tag": "3ee2cb7e8d63d9fab71b9b34cbf764436315542e"},
{"resource-id": "alt-network-map",
"tag": "c0ce023b8678a7b9ec00324673b98e54656d1f6d"}
]
},
"property-map": {
"ipv4:192.0.2.0/23": {".ISP": "BitsRus"},
"ipv4:192.0.2.0/27": {".ASN": "12345"},
"ipv4:192.0.3.0/27": {".ASN": "12346"}
}
}
10.6. Filtered Property Map Example #1
The following example uses the filtered property map resource to
request the "ISP", "ASN" and "state" properties for several IPv4
addresses.
Note that the value of "state" for "ipv4:192.0.2.0" is the only
explicitly defined property; the other values are all derived by the
inheritance rules for Internet address entities.
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POST /propmap/lookup/inet-iacs HTTP/1.1
Host: alto.example.com
Accept: application/alto-propmap+json,application/alto-error+json
Content-Length: ###
Content-Type: application/alto-propmapparams+json
{
"entities" : [ "ipv4:192.0.2.0",
"ipv4:192.0.2.1",
"ipv4:192.0.2.17" ],
"properties" : [ ".ISP", ".ASN", ".state" ]
}
HTTP/1.1 200 OK
Content-Length: ###
Content-Type: application/alto-propmap+json
{
"meta": {
"dependent-vtags": [
{"resource-id": "default-network-map",
"tag": "3ee2cb7e8d63d9fab71b9b34cbf764436315542e"},
{"resource-id": "alt-network-map",
"tag": "c0ce023b8678a7b9ec00324673b98e54656d1f6d"}
]
},
"property-map": {
"ipv4:192.0.2.0":
{".ISP": "BitsRus", ".ASN": "12345", ".state": "PA"},
"ipv4:192.0.2.1":
{".ISP": "BitsRus", ".ASN": "12345", ".state": "NJ"},
"ipv4:192.0.2.17":
{".ISP": "BitsRus", ".ASN": "12345", ".state": "CT"}
}
}
10.7. Filtered Property Map Example #2
The following example uses the filtered property map resource to
request the "ASN", "country" and "state" properties for several IPv4
prefixes.
Note that the property values for both entities "ipv4:192.0.2.0/26"
and "ipv4:192.0.3.0/26" are not explicitly defined. They are
inherited from the entity "ipv4:192.0.2.0/23".
Also note that some entities like "ipv4:192.0.2.0/28" and
"ipv4:192.0.2.16/28" in the response are not listed in the request
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explicitly. The response includes them because they are refinements
of the requested entities and have different values for the requested
properties.
The entity "ipv4:192.0.4.0/26" is not included in the response,
because there are neither entities which it is inherited from, nor
entities inherited from it.
POST /propmap/lookup/inet-iacs HTTP/1.1
Host: alto.example.com
Accept: application/alto-propmap+json,application/alto-error+json
Content-Length: ###
Content-Type: application/alto-propmapparams+json
{
"entities" : [ "ipv4:192.0.2.0/26",
"ipv4:192.0.3.0/26",
"ipv4:192.0.4.0/26" ],
"properties" : [ ".ASN", ".country", ".state" ]
}
HTTP/1.1 200 OK
Content-Length: ###
Content-Type: application/alto-propmap+json
{
"meta": {
"dependent-vtags": [
{"resource-id": "default-network-map",
"tag": "3ee2cb7e8d63d9fab71b9b34cbf764436315542e"},
{"resource-id": "alt-network-map",
"tag": "c0ce023b8678a7b9ec00324673b98e54656d1f6d"}
]
},
"property-map": {
"ipv4:192.0.2.0/26": {".country": "us"},
"ipv4:192.0.2.0/28": {".ASN": "12345",
".state": "NJ"},
"ipv4:192.0.2.16/28": {".ASN": "12345",
".state": "CT"},
"ipv4:192.0.2.0": {".state": "PA"},
"ipv4:192.0.3.0/26": {".country": "us"},
"ipv4:192.0.3.0/28": {".ASN": "12345",
".state": "TX"},
"ipv4:192.0.3.16/28": {".ASN": "12345",
".state": "MN"}
}
}
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10.8. 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: ###
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 ]
}
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HTTP/1.1 200 OK
Content-Length: ###
Content-Type: application/alto-propmap+json
{
"meta": {
"dependent-vtags": [
{"resource-id": "default-network-map",
"tag": "3ee2cb7e8d63d9fab71b9b34cbf764436315542e"},
{"resource-id": "alt-network-map",
"tag": "c0ce023b8678a7b9ec00324673b98e54656d1f6d"}
]
},
"property-map": {
"ipv4:192.0.2.128": {"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"}
}
}
10.9. Filtered Property Map Example #4
The following example uses the filtered property map resource to
request the "region" property for several PIDs defined in "default-
network-map". The value of the "region" property for each PID is not
defined by "default-network-map", but the reason why the PID is
defined by the network operator.
POST /propmap/lookup/region HTTP/1.1
Host: alto.example.com
Accept: application/alto-propmap+json,application/alto-error+json
Content-Length: ###
Content-Type: application/alto-propmapparams+json
{
"entities" : ["default-network-map.pid:pid1",
"default-network-map.pid:pid2"],
"properties" : [ ".region" ]
}
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HTTP/1.1 200 OK
Content-Length: ###
Content-Type: application/alto-propmap+json
{
"meta" : {
"dependent-vtags" : [
{"resource-id": "default-network-map",
"tag": "7915dc0290c2705481c491a2b4ffbec482b3cf62"}
]
},
"property-map": {
"default-network-map.pid:pid1": {
".region": "us-west"
},
"default-network-map.pid:pid2": {
".region": "us-east"
}
}
}
10.10. 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: ###
Content-Type: application/alto-propmapparams+json
{
"entities" : [".ane:dc21", ".ane:dc45.srv9", ".ane:dc6.srv-cluster8"]
"properties" : [ "storage-capacity", "cpu"]
}
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HTTP/1.1 200 OK
Content-Length: ###
Content-Type: application/alto-propmap+json
{
"meta" : {
},
"property-map": {
".ane:dc21":
{"storage-capacity" : 40000 Gbytes, "cpu" : 500 Cores},
".ane:dc45.srv9":
{"storage-capacity" : 100 Gbytes, "cpu" : 20 Cores},
".ane:dc6.srv-cluster8":
{"storage-capacity" : 6000 Gbytes, "cpu" : 100 Cores},
}
}
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.
A particular fundamental security consideration when an ALTO server
provides a Property Map is to define precisely the policies on who
can access what properties for which entities. Security mechanisms
such as authentication and confidentiality mechanisms then should be
applied to enforce the policy. For example, a policy can be that a
property P can be accessed only by its owner (e.g., the customer who
is allocated a given IP address). Then, the ALTO server will need to
deploy corresponding mechanisms to realize the policy. The policy
may allow non-owners to access a coarse-grained value of the property
P. In such a case, the ALTO server may provide a different URI to
provide the information.
12. IANA Considerations
This document defines additional application/alto-* media types, and
extends the ALTO endpoint property registry.
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12.1. application/alto-* Media Types
This document registers two additional ALTO media types, listed in
Table 1.
+--------------+--------------------------+------------------------+
| Type | Subtype | Specification |
+--------------+--------------------------+------------------------+
| application | alto-propmap+json | Section 7.1 |
| application | alto-propmapparams+json | Section 8.3 |
+--------------+--------------------------+------------------------+
Table 1: Additional ALTO Media Types.
Type name: application
Subtype name: This document registers multiple subtypes, as listed
in Table 1.
Required parameters: n/a
Optional parameters: n/a
Encoding considerations: Encoding considerations are identical to
those specified for the "application/json" media type. See
[RFC7159].
Security considerations: Security considerations related to the
generation and consumption of ALTO Protocol messages are discussed
in Section 15 of [RFC7285].
Interoperability considerations: This document specifies formats of
conforming messages and the interpretation thereof.
Published specification: This document is the specification for
these media types; see Table 1 for the section documenting each
media type.
Applications that use this media type: ALTO servers and ALTO clients
either stand alone or are embedded within other applications.
Additional information:
Magic number(s): n/a
File extension(s): This document uses the mime type to refer to
protocol messages and thus does not require a file extension.
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Macintosh file type code(s): n/a
Person & email address to contact for further information: See
Authors' Addresses section.
Intended usage: COMMON
Restrictions on usage: n/a
Author: See Authors' Addresses section.
Change controller: Internet Engineering Task Force
(mailto:iesg@ietf.org).
12.2. ALTO Entity Domain Type Registry
This document requests IANA to create and maintain the "ALTO Entity
Domain Type Registry", listed in Table 2.
+-------------+---------------------------+-------------------------+
| Identifier | Entity Identifier | Hierarchy & Inheritance |
| | Encoding | |
+-------------+---------------------------+-------------------------+
| ipv4 | See Section 6.1.1 | See Section 6.1.3 |
| ipv6 | See Section 6.1.2 | See Section 6.1.3 |
| pid | See Section 6.2 | None |
+-------------+---------------------------+-------------------------+
Table 2: ALTO Entity Domains.
This registry serves two purposes. First, it ensures uniqueness of
identifiers referring to ALTO entity domains. Second, it states the
requirements for allocated entity domains.
12.2.1. Consistency Procedure between ALTO Address Type Registry and
ALTO Entity Domain Type Registry
One potential issue of introducing the "ALTO Entity Domain Type
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 Type Registry" MAY match an address type defined
in "ALTO Address Type Registry". It is necessary to precisely define
and guarantee the consistency between "ALTO Address Type Registry"
and "ALTO Entity Domain Registry".
We define that the ALTO Entity Domain Type Registry is consistent
with ALTO Address Type Registry if two conditions are satisfied:
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o When an address type is already or able to be registered in the
ALTO Address Type Registry [RFC7285], the same identifier MUST be
used when a corresponding entity domain type is registered in the
ALTO Entity Domain Type Registry.
o If an ALTO entity domain type has the same identifier as an ALTO
address type, their addresses encoding MUST be compatible.
To achieve this consistency, the following items MUST be checked
before registering a new ALTO entity domain type in a future
document:
o Whether the ALTO Address Type Registry contains an address type
that can be used as an entity identifier for the candidate domain
identifier. This has been done for the identifiers "ipv4" and
"ipv6" in Table 2.
o Whether the candidate entity identifier of the type of the entity
domain is able to be an endpoint address, as defined in Sections
2.1 and 2.2 of [RFC7285].
When a new ALTO entity domain type is registered, the consistency
with the ALTO Address Type Registry MUST be ensured by the following
procedure:
o Test: Do corresponding entity identifiers match a known "network"
address type?
* If yes (e.g., cell, MAC or socket addresses):
+ Test: Is such an address type present in the ALTO Address
Type Registry?
- If yes: Set the new ALTO entity domain 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 Type Registry following Section 14.4 of
[RFC7285].
+ Use the new ALTO entity domain type identifier to register a
new ALTO entity domain type in the ALTO Entity Domain Type
Registry following Section 12.2.2 of this document.
* If no (e.g., pid name, ane name or country code): Proceed with
the ALTO Entity Domain Type registration as described in
Section 12.2.2.
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12.2.2. ALTO Entity Domain Type Registration Process
New ALTO entity domain types are assigned after IETF Review [RFC5226]
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 SHOULD indicate how an entity
in a registered type of domain is encoded as an EntityID, and, if
applicable, the rules defining the entity hierarchy and property
inheritance. Updates and deletions of ALTO entity domains follow the
same procedure.
Registered ALTO entity domain 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 the IANA to add a new value to the registry MUST include
the following information:
o Identifier: The name of the desired ALTO entity domain type.
o Entity Identifier Encoding: The procedure for encoding the
identifier of an entity of the registered type as an EntityID (see
Section 5.1.3). If corresponding entity identifiers of an entity
domain match a known "network" address type, the Entity Identifier
Encoding of this domain identifier MUST include both Address
Encoding and Prefix Encoding of the same identifier registered in
the ALTO Address Type Registry [RFC7285]. For the purpose of
defining properties, an individual entity identifier and the
corresponding full-length prefix MUST be considered aliases for
the same entity.
o Hierarchy: If the entities form a hierarchy, the procedure for
determining that hierarchy.
o Inheritance: If entities can inherit property values from other
entities, the procedure for determining that inheritance.
o Media type of defining information resource: some entity domain
types allow their entity domain type name to be combined with an
information resource name to define a resource-specific entity
domain. Such an information resource is called "defining
information resource". In this case, the authorized media type of
specific information resources MUST be specified in the document
defining the entity domain type. When this entity domain type
allows combinations with defining resources, this must be
indicated and the conditions fully specified in the document. The
defining information resource for an entity domain type is the one
that:
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* has an entry in the IRD,
* defines these entities,
* does not use another information resource that defines these
entities,
* defines and exposes entity identifiers that are all persistent.
* has a unique media type equal to the one specified in the
document defining the entity domain type.
This information is useful when Servers indicate resource specific
entity domains in the property map capabilities. Clients need to
know if the combination of information resource type and entity
domain type is allowed. See also, Section 4.6 and Section 5.1 for
more information.
o 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.
o Security Considerations: In some usage scenarios, entity
identifiers carried in ALTO Protocol messages may reveal
information about an ALTO client or an ALTO service provider.
Applications and ALTO service providers using addresses of the
registered type should be made aware of how (or if) the addressing
scheme relates to private information and network proximity.
This specification requests registration of the identifiers "ipv4",
"ipv6" and "pid", as shown in Table 2.
12.3. ALTO Entity Property Type Registry
This document requests IANA to create and maintain the "ALTO Entity
Property Type Registry", listed in Table 3.
This registry extends the "ALTO Endpoint Property Type Registry"
created by [RFC7285] in that a property is defined on one or more
entity domains, rather than just on the IPv4 and IPv6 Internet
address domains. entry in this registry is an ALTO entity property
type defined in Section 5.2.1. Thus, registered ALTO entity property
type identifier MUST conform to the syntactical requirements
specified in that section.
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+-------------+---------------------------------+
| Identifier | Intended Semantics |
+-------------+---------------------------------+
| pid | See Section 7.1.1 of [RFC7285] |
+-------------+---------------------------------+
Table 3: ALTO Entity Property Types.
Requests to the IANA to add a new value to the registry MUST include
the following information:
o Identifier: The unique id for the desired ALTO entity property
type. The format MUST be as defined in Section 5.2.1 of this
document. It includes the information of the applied ALTO entity
domain and the property name.
o Intended Semantics: ALTO entity properties carry with them
semantics to guide their usage by ALTO clients. Hence, a document
defining a new type SHOULD provide guidance to both ALTO service
providers and applications utilizing ALTO clients as to how values
of the registered ALTO entity property should be interpreted.
o Security Considerations: ALTO entity properties expose information
to ALTO clients. ALTO service providers should be made aware 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 such sensitive information is
required for ALTO-based operations. Regarding this discussion, the
request SHOULD follow the recommendations of Section 14.3. ALTO
Endpoint Property Type Registry in [RFC7285].
This document requests registration of the identifier "pid", listed
in Table 3. Semantics for this property are documented in
Section (TODO: add ref) and security considerations are documented in
Section TODO:ref.
13. Acknowledgments
The authors would like to thank discussions with Kai Gao, Qiao Xiang,
Shawn Lin, Xin Wang, Danny Perez, and Vijay Gurbani. The authors
thank Dawn Chen (Tongji University), and Shenshen Chen (Tongji/Yale
University) for their contributions to earlier drafts.
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14. References
14.1. Normative References
[ISO3166-1]
The International Organization for Standardization, "Codes
for the representation of names of countries and their
subdivisions -- Part 1: Country codes, ISO 3166-1:2013",
2013.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, DOI 10.17487/RFC3986, January 2005,
<https://www.rfc-editor.org/info/rfc3986>.
[RFC4632] Fuller, V. and T. Li, "Classless Inter-domain Routing
(CIDR): The Internet Address Assignment and Aggregation
Plan", BCP 122, RFC 4632, DOI 10.17487/RFC4632, August
2006, <https://www.rfc-editor.org/info/rfc4632>.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", RFC 5226,
DOI 10.17487/RFC5226, May 2008,
<https://www.rfc-editor.org/info/rfc5226>.
[RFC5952] Kawamura, S. and M. Kawashima, "A Recommendation for IPv6
Address Text Representation", RFC 5952,
DOI 10.17487/RFC5952, August 2010,
<https://www.rfc-editor.org/info/rfc5952>.
[RFC7011] Claise, B., Ed., Trammell, B., Ed., and P. Aitken,
"Specification of the IP Flow Information Export (IPFIX)
Protocol for the Exchange of Flow Information", STD 77,
RFC 7011, DOI 10.17487/RFC7011, September 2013,
<https://www.rfc-editor.org/info/rfc7011>.
[RFC7159] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
Interchange Format", RFC 7159, DOI 10.17487/RFC7159, March
2014, <https://www.rfc-editor.org/info/rfc7159>.
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[RFC7285] Alimi, R., Ed., Penno, R., Ed., Yang, Y., Ed., Kiesel, S.,
Previdi, S., Roome, W., Shalunov, S., and R. Woundy,
"Application-Layer Traffic Optimization (ALTO) Protocol",
RFC 7285, DOI 10.17487/RFC7285, September 2014,
<https://www.rfc-editor.org/info/rfc7285>.
[RFC7921] Atlas, A., Halpern, J., Hares, S., Ward, D., and T.
Nadeau, "An Architecture for the Interface to the Routing
System", RFC 7921, DOI 10.17487/RFC7921, June 2016,
<https://www.rfc-editor.org/info/rfc7921>.
[RFC8008] Seedorf, J., Peterson, J., Previdi, S., van Brandenburg,
R., and K. Ma, "Content Delivery Network Interconnection
(CDNI) Request Routing: Footprint and Capabilities
Semantics", RFC 8008, DOI 10.17487/RFC8008, December 2016,
<https://www.rfc-editor.org/info/rfc8008>.
14.2. Informative References
[draft-ietf-alto-cdni-request-routing-alto]
Roome, J., Yang, Y., Ma, K., Peterson, J., and J. Zhang,
"Content Delivery Network Interconnection (CDNI) Request
Routing: CDNI Footprint and Capabilities Advertisement
using ALTO (work in progress)", 2020.
[I-D.ietf-alto-path-vector]
Gao, K., Lee, Y., Randriamasy, S., Yang, Y., and J. Zhang,
"ALTO Extension: Path Vector", draft-ietf-alto-path-
vector-09 (work in progress), November 2019,
<http://www.ietf.org/internet-drafts/draft-ietf-alto-path-
vector-09.txt>.
Appendix A. Scope of Property Map
Using entity domains to organize entities, an ALTO property map
resource can be regarded as given sets of properties for given entity
domains. If we ignore the resource-agnostic entity domains, we can
regard an ALTO property map resource as a set of (ri, di) => (ro, po)
mappings, where (ri, di) means a resource-specific entity domain of
type di defined by the information resource ri, and (ro, po) means a
resource-specific entity property po defined by the information
resource ro.
For each (ri, di) => (ro, po) mapping, the scope of an ALTO property
map resource must be one of the cases in the following diagram:
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domain.resource domain.resource
(ri) = r (ri) = this
+-----------------|-----------------+
prop.resource | Export | Non-exist |
(ro) = r | | |
+-----------------|-----------------+
prop.resource | Extend | Define |
(ro) = this | | |
+-----------------|-----------------+
where "this" represents the resulting property map resource, and "r"
represents an existing ALTO information resource other the resulting
property map resource.
o ri = ro = r ("export" mode): the property map resource just
transforms the property mapping di => po defined by r into the
unified representation format and exports it. For example: r =
"netmap1", di = "ipv4", po = "pid". The property map resource
exports the "ipv4 => pid" mapping defined by "netmap1".
o ri = r, ro = this ("extend" mode): the property map extends
properties of entities in the entity domain (r, di) and defines a
new property po on them. For example: the property map resource
("this") defines a "geolocation" property on domain "netmap1.pid".
o ri = ro = this ("define" mode): the property map defines a new
intrinsic entity domain and defines property po for each entity in
this domain. For example: the property map resource ("this")
defines a new entity domain "asn" and defines a property
"ipprefixes" on this domain.
o ri = this, ro = r: in the scope of a property map resource, it
does not make sense that another existing ALTO information
resource defines a property for this property map resource.
A.1. Example Property Map
The following figure shows an example property map called Property
Map 1, which depends on two network maps and provides three sets of
mappings by
o exporting a mapping from ipv4 entities to PIDs defined by two
different network maps,
o extending geo-location properties to ipv4 entities defined by
Network Map 1,
o and defining a new mapping from ASNs to traffic load properties.
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(Define)
+----------+ +-------------+
->| Property |<---------------------------+--------| asn | load |
/ | Map 1 | | |-------------|
/ +----------+ | | 1234 | 95% |
| ^ | | 5678 | 70% |
| | \ +-------------+
| | (Export) \ (Extend)
| +---------+ +------------------------+ \ +--------------+
| | Network |----| ipv4 | pid | -----| geo-location |
| | Map 1 | |------------------------| +--------------+
| +---------+ | 192.168.0.0/24 | pid1 | - - -> | New York |
| | 192.168.1.0/24 | pid2 | - - -> | Shanghai |
| +------------------------+ +--------------+
| (Export)
\ +---------+ +------------------------+
---| Network |----| ipv4 | pid |
| Map 2 | |------------------------|
+---------+ | 192.168.0.0/24 | Paris |
| ... | ... |
+------------------------+
More detailed examples are shown in Section 10.
Authors' Addresses
Wendy Roome
Nokia Bell Labs (Retired)
124 Burlington Rd
Murray Hill, NJ 07974
USA
Phone: +1-908-464-6975
Email: wendy@wdroome.com
Sabine Randriamasy
Nokia Bell Labs
Route de Villejust
NOZAY 91460
FRANCE
Email: Sabine.Randriamasy@nokia-bell-labs.com
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Y. Richard Yang
Yale University
51 Prospect Street
New Haven, CT 06511
USA
Phone: +1-203-432-6400
Email: yry@cs.yale.edu
Jingxuan Jensen Zhang
Tongji University
4800 Caoan Road
Shanghai 201804
China
Email: jingxuan.n.zhang@gmail.com
Kai Gao
Sichuan University
Chengdu 610000
China
Email: kaigao@scu.edu.cn
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