ALTO & CDNI WGs J. Seedorf
Internet-Draft HFT Stuttgart - Univ. of Applied Sciences
Intended status: Standards Track Y. Yang
Expires: 21 May 2021 Yale
K. Ma
Ericsson
J. Peterson
Neustar
J. Zhang
Tongji
17 November 2020
Content Delivery Network Interconnection (CDNI) Request Routing: CDNI
Footprint and Capabilities Advertisement using ALTO
draft-ietf-alto-cdni-request-routing-alto-14
Abstract
The Content Delivery Networks Interconnection (CDNI) framework
[RFC6707] defines a set of protocols to interconnect CDNs, to achieve
multiple goals such as extending the reach of a given CDN to areas
that are not covered by that particular CDN. One component that is
needed to achieve the goal of CDNI described in [RFC7336] is the CDNI
Request Routing Footprint & Capabilities Advertisement interface
(FCI). [RFC8008] defines precisely the semantics of FCI and provides
guidelines on the FCI protocol, but the exact protocol is explicitly
outside the scope of that document. This document defines an FCI
protocol using the Application-Layer Traffic Optimization (ALTO)
protocol, following the guidelines defined in [RFC8008].
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119][RFC8174] when, and only when, they appear in all
capitals, as shown here.
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/.
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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 21 May 2021.
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 publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Background . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1. Semantics of FCI Advertisement . . . . . . . . . . . . . 5
2.2. ALTO Background and Benefits . . . . . . . . . . . . . . 6
3. CDNI Advertisement Service . . . . . . . . . . . . . . . . . 8
3.1. Media Type . . . . . . . . . . . . . . . . . . . . . . . 9
3.2. HTTP Method . . . . . . . . . . . . . . . . . . . . . . . 9
3.3. Accept Input Parameters . . . . . . . . . . . . . . . . . 9
3.4. Capabilities . . . . . . . . . . . . . . . . . . . . . . 9
3.5. Uses . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.6. Response . . . . . . . . . . . . . . . . . . . . . . . . 9
3.7. Examples . . . . . . . . . . . . . . . . . . . . . . . . 12
3.7.1. IRD Example . . . . . . . . . . . . . . . . . . . . . 12
3.7.2. Basic Example . . . . . . . . . . . . . . . . . . . . 15
3.7.3. Incremental Updates Example . . . . . . . . . . . . . 16
4. CDNI Advertisement Service using ALTO Network Map . . . . . . 18
4.1. Network Map Footprint Type: altopid . . . . . . . . . . . 18
4.2. Examples . . . . . . . . . . . . . . . . . . . . . . . . 19
4.2.1. IRD Example . . . . . . . . . . . . . . . . . . . . . 19
4.2.2. ALTO Network Map for CDNI Advertisement Example . . . 19
4.2.3. ALTO PID Footprints in CDNI Advertisement . . . . . . 20
4.2.4. Incremental Updates Example . . . . . . . . . . . . . 21
5. Filtered CDNI Advertisement using CDNI Capabilities . . . . . 22
5.1. Media Type . . . . . . . . . . . . . . . . . . . . . . . 22
5.2. HTTP Method . . . . . . . . . . . . . . . . . . . . . . . 22
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5.3. Accept Input Parameters . . . . . . . . . . . . . . . . . 23
5.4. Capabilities . . . . . . . . . . . . . . . . . . . . . . 23
5.5. Uses . . . . . . . . . . . . . . . . . . . . . . . . . . 23
5.6. Response . . . . . . . . . . . . . . . . . . . . . . . . 24
5.7. Examples . . . . . . . . . . . . . . . . . . . . . . . . 24
5.7.1. IRD Example . . . . . . . . . . . . . . . . . . . . . 24
5.7.2. Basic Example . . . . . . . . . . . . . . . . . . . . 25
5.7.3. Incremental Updates Example . . . . . . . . . . . . . 26
6. Query Footprint Properties using ALTO Property Map Service . 27
6.1. Representing Footprint Objects as Property Map
Entities . . . . . . . . . . . . . . . . . . . . . . . . 27
6.1.1. ASN Domain . . . . . . . . . . . . . . . . . . . . . 28
6.1.2. COUNTRYCODE Domain . . . . . . . . . . . . . . . . . 29
6.2. Representing CDNI Capabilities as Property Map Entity
Properties . . . . . . . . . . . . . . . . . . . . . . . 29
6.2.1. Defining Information Resource Media Type for Property
Type cdni-capabilities . . . . . . . . . . . . . . . 29
6.2.2. Intended Semantics of Property Type
cdni-capabilities . . . . . . . . . . . . . . . . . . 30
6.3. Examples . . . . . . . . . . . . . . . . . . . . . . . . 30
6.3.1. IRD Example . . . . . . . . . . . . . . . . . . . . . 30
6.3.2. Property Map Example . . . . . . . . . . . . . . . . 30
6.3.3. Filtered Property Map Example . . . . . . . . . . . . 31
6.3.4. Incremental Updates Example . . . . . . . . . . . . . 33
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 34
7.1. application/alto-* Media Types . . . . . . . . . . . . . 34
7.2. CDNI Metadata Footprint Type Registry . . . . . . . . . . 35
7.3. ALTO Entity Domain Type Registry . . . . . . . . . . . . 36
7.4. ALTO Entity Property Type Registry . . . . . . . . . . . 36
8. Security Considerations . . . . . . . . . . . . . . . . . . . 37
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 38
10. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 39
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 39
11.1. Normative References . . . . . . . . . . . . . . . . . . 39
11.2. Informative References . . . . . . . . . . . . . . . . . 40
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 41
1. Introduction
The ability to interconnect multiple content delivery networks (CDNs)
has many benefits, including increased coverage, capability, and
reliability. The Content Delivery Networks Interconnection (CDNI)
framework [RFC6707] defines four interfaces to achieve the
interconnection of CDNs: (1) the CDNI Request Routing Interface; (2)
the CDNI Metadata Interface; (3) the CDNI Logging Interface; and (4)
the CDNI Control Interface.
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Among the four interfaces, the CDNI Request Routing Interface
provides key functions, as specified in [RFC6707]: "The CDNI Request
Routing interface enables a Request Routing function in an Upstream
CDN to query a Request Routing function in a Downstream CDN to
determine if the Downstream CDN is able (and willing) to accept the
delegated Content Request. It also allows the Downstream CDN to
control what should be returned to the User Agent in the redirection
message by the upstream Request Routing function." At a high level,
the scope of the CDNI Request Routing Interface, therefore, contains
two main tasks: (1) determining if the dCDN (downstream CDN) is
willing to accept a delegated content request, and (2) redirecting
the content request coming from a uCDN (upstream CDN) to the proper
entry point or entity in the dCDN.
Correspondingly, the request routing interface is broadly divided
into two functionalities: (1) the CDNI Footprint & Capabilities
Advertisement interface (FCI) defined in [RFC8008], and (2) the CDNI
Request Routing Redirection interface (RI) defined in [RFC7975].
Since this document focuses on the first functionality (CDNI FCI),
below is more details about it.
Specifically, CDNI FCI allows both an advertisement from a dCDN to a
uCDN (push) and a query from a uCDN to a dCDN (pull) so that the uCDN
knows whether it can redirect a particular user request to that dCDN.
A key component in defining CDNI FCI is defining objects describing
the footprints and capabilities of a dCDN. Such objects are already
defined in [RFC8008]. A protocol to transport and update such
objects between a uCDN and a dCDN, however, is not defined. Hence,
the scope of this document is to define such a protocol by
introducing a new Application-Layer Traffic Optimization (ALTO)
[RFC7285] service called "CDNI Advertisement Service".
There are multiple benefits in using ALTO as a transport protocol, as
discussed in Section 2.2.
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The rest of this document is organized as follows. Section 2
provides non-normative background on both CDNI FCI and ALTO.
Section 3 introduces the most basic service, called "CDNI
Advertisement Service", to realize CDNI FCI using ALTO. Section 4
demonstrates a key benefit of using ALTO: the ability to integrate
CDNI FCI with ALTO network maps. Such integration provides new
granularity to describe footprints. Section 5 introduces "Filtered
CDNI Advertisement Service" to allow a uCDN to get footprints with
given capabilities instead of getting the full resource, which can be
large. Section 6 further shows another benefit of using ALTO: the
ability to query footprint properties using ALTO unified properties.
In this way, a uCDN can effectively fetch capabilities of footprints
in which it is interested. IANA and security considerations are
discussed in Section 7 and Section 8 respectively.
2. Background
The design of CDNI FCI transport using ALTO depends on the
understanding of both FCI semantics and ALTO. Hence, this document
starts with a non-normative review for both. The review uses the
terminologies for CDNI as defined in [RFC6707], [RFC8006] and
[RFC8008]; those for ALTO as defined in [RFC7285] and
[I-D.ietf-alto-unified-props-new].
2.1. Semantics of FCI Advertisement
[RFC8008] (CDNI "Footprint and Capabilities Semantics") defines the
semantics of CDNI FCI, provides guidance on what Footprint and
Capabilities mean in a CDNI context, and specifies the requirements
on the CDNI FCI transport protocol. The definitions in [RFC8008]
depend on [RFC8006]. Below is a non-normative review of key related
points of [RFC8008] and [RFC8006]. For detailed information and
normative specification, the reader is referred to these two RFCs.
* Multiple types of mandatory-to-implement footprints (ipv4cidr,
ipv6cidr, asn, and countrycode) are defined in [RFC8006]. A "Set
of IP-prefixes" can contain both full IP addresses (i.e., a /32
for IPv4 or a /128 for IPv6) and IP prefixes with an arbitrary
prefix length. There must also be support for multiple IP address
versions, i.e., IPv4 and IPv6, in such a footprint.
* Multiple initial types of capabilities are defined in [RFC8008]
including (1) Delivery Protocol, (2) Acquisition Protocol, (3)
Redirection Mode, (4) Capabilities related to CDNI Logging, and
(5) Capabilities related to CDNI Metadata. They are required in
all cases and therefore considered as mandatory-to-implement
capabilities for all CDNI FCI implementations.
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* Footprint and capabilities are defined together and cannot be
interpreted independently from each other. Specifically,
[RFC8008] integrates footprint and capabilities with an approach
of "capabilities with footprint restrictions", by expressing
capabilities on a per footprint basis.
* Specifically, for all mandatory-to-implement footprint types,
footprints can be viewed as constraints for delegating requests to
a dCDN: A dCDN footprint advertisement tells the uCDN the
limitations for delegating a request to the dCDN. For IP prefixes
or ASN(s), the footprint signals to the uCDN that it should
consider the dCDN a candidate only if the IP address of the
request routing source falls within the prefix set (or ASN,
respectively). The CDNI specifications do not define how a given
uCDN determines what address ranges are in a particular ASN.
Similarly, for country codes, a uCDN should only consider the dCDN
a candidate if it covers the country of the request routing
source. The CDNI specifications do not define how a given uCDN
determines the country of the request routing source. Multiple
footprint constraints are additive, i.e., the advertisement of
different types of footprint narrows the dCDN candidacy
cumulatively.
* Given that a large part of Footprint and Capabilities
Advertisement may actually happen in contractual agreements, the
semantics of CDNI Footprint and Capabilities advertisement refers
to answering the following question: what exactly still needs to
be advertised by the CDNI FCI? For instance, updates about
temporal failures of part of a footprint can be useful information
to convey via the CDNI FCI. Such information would provide
updates on information previously agreed in contracts between the
participating CDNs. In other words, the CDNI FCI is a means for a
dCDN (downstream CDN) to provide changes/updates regarding a
footprint and/or capabilities that it has prior agreed to serve in
a contract with a uCDN (upstream CDN). Hence, server push and
incremental encoding will be necessary techniques.
2.2. ALTO Background and Benefits
Application-Layer Traffic Optimization (ALTO) [RFC7285] defines an
approach for conveying network layer (topology) information to
"guide" the resource provider selection process in distributed
applications that can choose among several candidate resources
providers to retrieve a given resource. Usually, it is assumed that
an ALTO server conveys information that these applications cannot
measure or have difficulty measuring themselves [RFC5693].
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Originally, ALTO was motivated by optimizing cross-ISP traffic
generated by P2P applications [RFC5693]. However, ALTO can also be
used for improving the request routing in CDNs. In particular, the
CDNI problem statement [RFC6707] explicitly mentions ALTO as a
candidate protocol for "actual algorithms for selection of CDN or
Surrogate by Request-Routing systems".
The following reasons make ALTO a suitable candidate protocol for
dCDN (downstream CDN) selection as part of CDNI request routing and,
in particular, for an FCI protocol:
* Application Layer-oriented: ALTO is a protocol specifically
designed to improve application layer traffic (and application
layer connections among hosts on the Internet) by providing
additional information to applications that these applications
could not easily retrieve themselves. This matches the need of
CDNI: a uCDN wants to improve application layer CDN request
routing by using information (provided by a dCDN) that the uCDN
could not easily obtain otherwise. Hence, ALTO can help a uCDN to
select a proper dCDN by first providing dCDNs' capabilities as
well as footprints (see Section 3) and then providing costs of
surrogates in a dCDN by ALTO cost maps.
* Security: The identification between uCDNs and dCDNs is an
important requirement. ALTO maps can be signed and hence provide
inherent integrity protection. Please see Section 8.
* RESTful Design: The ALTO protocol has undergone extensive
revisions in order to provide a RESTful design regarding the
client-server interaction specified by the protocol. A CDNI FCI
interface based on ALTO would inherit this RESTful design. Please
see Section 3.
* Error-handling: The ALTO protocol provides extensive error-
handling in the whole request and response process (see
Section 8.5 of [RFC7285]). A CDNI FCI interface based on ALTO
would inherit this this extensive error-handling framework.
Please see Section 5.
* Map Service: The semantics of an ALTO network map is an exact
match for the needed information to convey a footprint by a dCDN,
in particular, if such a footprint is being expressed by IP-prefix
ranges. Please see Section 4.
* Filtered Map Service: The ALTO map filtering service would allow a
uCDN to query only for parts of an ALTO map. For example, the
ALTO filtered property map service can enable a uCDN to query
properties of a part of footprints efficiently (see Section 6).
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* Server-initiated Notifications and Incremental Updates: When the
footprint or the capabilities of a dCDN change (i.e., unexpectedly
from the perspective of a uCDN), server-initiated notifications
would enable a dCDN to inform a uCDN about such changes directly.
Consider the case where - due to failure - part of the footprint
of the dCDN is not functioning, i.e., the CDN cannot serve content
to such clients with reasonable QoS. Without server-initiated
notifications, the uCDN might still use a recent network and cost
map from the dCDN, and therefore redirect requests to the dCDN
which it cannot serve. Similarly, the possibility for incremental
updates would enable efficient conveyance of the aforementioned
(or similar) status changes by the dCDN to the uCDN. The newest
design of ALTO supports server pushed incremental updates
[RFC8895].
* Content Availability on Hosts: A dCDN might want to express CDN
capabilities in terms of certain content types (e.g., codecs/
formats, or content from certain content providers). The new
endpoint property for ALTO would enable a dCDN to make such
information available to a uCDN. This would enable a uCDN to
determine whether a dCDN actually has the capabilities for a given
type of content requested.
* Resource Availability on Hosts or Links: The capabilities on links
(e.g., maximum bandwidth) or caches (e.g., average load) might be
useful information for a uCDN for optimized dCDN selection. For
instance, if a uCDN receives a streaming request for content with
a certain bitrate, it needs to know if it is likely that a dCDN
can fulfill such stringent application-level requirements (i.e.,
can be expected to have enough consistent bandwidth) before it
redirects the request. In general, if ALTO could convey such
information via new endpoint properties, it would enable more
sophisticated means for dCDN selection with ALTO. ALTO Path
Vector Extension [I-D.ietf-alto-path-vector] is designed to allow
ALTO clients to query information such as capacity regions for a
given set of flows.
3. CDNI Advertisement Service
The ALTO protocol is based on the ALTO Information Service Framework
which consists of multiple services, where all ALTO services are
"provided through a common transport protocol, messaging structure
and encoding, and transaction model" [RFC7285]. The ALTO protocol
specification [RFC7285] defines multiple initial services, e.g., the
ALTO network map service and cost map service.
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This document defines a new ALTO service called "CDNI Advertisement
Service" which conveys JSON objects of media type "application/alto-
cdni+json". These JSON objects are used to transport
BaseAdvertisementObject objects defined in [RFC8008]; this document
specifies how to transport such BaseAdvertisementObject objects via
the ALTO protocol with the ALTO "CDNI Advertisement Service".
Similar to other ALTO services, this document defines the ALTO
information resource for the "CDNI Advertisement Service" as follows.
3.1. Media Type
The media type of the CDNI Advertisement resource is "application/
alto-cdni+json".
3.2. HTTP Method
A CDNI Advertisement resource is requested using the HTTP GET method.
3.3. Accept Input Parameters
None.
3.4. Capabilities
None.
3.5. Uses
The "uses" field SHOULD NOT appear unless the CDNI Advertisement
resource depends on other ALTO information resources. If the CDNI
Advertisement resource has dependent resources, the resource IDs of
its dependent resources MUST be included into the "uses" field. This
document only defines one potential dependent resource for the CDNI
Advertisement resource. See Section 4 for details of when and how to
use it. Future documents may extend the CDNI Advertisement resource
and allow other dependent resources.
3.6. Response
The "meta" field of a CDNI Advertisement response MUST include the
"vtag" field defined in Section 10.3 of [RFC7285]. This field
provides the version of the retrieved CDNI FCI resource.
If a CDNI Advertisement response depends on other ALTO information
resources, it MUST include the "dependent-vtags" field, whose value
is an array to indicate the version tags of the resources used, where
each resource is specified in "uses" of its IRD entry.
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The data component of an ALTO CDNI Advertisement response is named
"cdni-advertisement", which is a JSON object of type
CDNIAdvertisementData:
object {
CDNIAdvertisementData cdni-advertisement;
} InfoResourceCDNIAdvertisement : ResponseEntityBase;
object {
BaseAdvertisementObject capabilities-with-footprints<0..*>;
} CDNIAdvertisementData;
Specifically, a CDNIAdvertisementData object is a JSON object that
includes only one property named "capabilities-with-footprints",
whose value is an array of BaseAdvertisementObject objects.
The syntax and semantics of BaseAdvertisementObject are well defined
in Section 5.1 of [RFC8008]. A BaseAdvertisementObject object
includes multiple properties, including capability-type, capability-
value, and footprints, where footprints are defined in
Section 4.2.2.2 of [RFC8006].
To be self-contained, below is a non-normative specification of
BaseAdvertisementObject. As mentioned above, the normative
specification of BaseAdvertisementObject is in [RFC8008].
object {
JSONString capability-type;
JSONValue capability-value;
Footprint footprints<0..*>;
} BaseAdvertisementObject;
object {
JSONString footprint-type;
JSONString footprint-value<1..*>;
} Footprint;
For each BaseAdvertisementObject, the ALTO client MUST interpret
footprints appearing multiple times as if they appeared only once.
If footprints in a BaseAdvertisementObject is null or empty or not
appearing, the ALTO client MUST understand that the capabilities in
this BaseAdvertisementObject have the "global" coverage.
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Note: Further optimization of BaseAdvertisement objects to
effectively provide the advertisement of capabilities with footprint
restrictions is certainly possible. For example, these two examples
below both describe that the dCDN can provide capabilities
["http/1.1", "https/1.1"] for the same footprints. However, the
latter one is smaller in its size.
EXAMPLE 1
{
"meta" : {...},
"cdni-advertisement": {
"capabilities-with-footprints": [
{
"capability-type": "FCI.DeliveryProtocol",
"capability-value": {
"delivery-protocols": [
"http/1.1"
]
},
"footprints": [
<Footprint objects>
]
},
{
"capability-type": "FCI.DeliveryProtocol",
"capability-value": {
"delivery-protocols": [
"https/1.1"
]
},
"footprints": [
<Footprint objects>
]
}
]
}
}
EXAMPLE 2
{
"meta" : {...},
"cdni-advertisement": {
"capabilities-with-footprints": [
{
"capability-type": "FCI.DeliveryProtocol",
"capability-value": {
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"delivery-protocols": [
"https/1.1",
"http/1.1"
]
},
"footprints": [
<Footprint objects>
]
}
]
}
}
Since such optimizations are not required for the basic
interconnection of CDNs, the specifics of such mechanisms are outside
the scope of this document.
This document only requires the ALTO server to provide the initial
FCI-specific CDNI Payload Types defined in [RFC8008] as the
mandatory-to-implement CDNI capabilities. There may be other
documents extending BaseAdvertisementObject and additional CDNI
capabilities. They are outside the scope of this document. To
support them, future documents can extend the specification defined
in this document.
3.7. Examples
3.7.1. IRD Example
Below is the information resource directory (IRD) of a simple,
example ALTO server. The server provides both base ALTO information
resources (e.g., network maps) and CDNI FCI related information
resources (e.g., CDNI Advertisement resources), demonstrating a
single, integrated environment.
Specifically, the IRD announces two network maps, one CDNI
Advertisement resource without dependency, one CDNI Advertisement
resource depending on a network map, one filtered CDNI Advertisement
resource to be defined in Section 5, one property map including
"cdni-capabilities" as its entity property, one filtered property map
including "cdni-capabilities" and "pid" as its entity properties, and
two update stream services (one for updating CDNI Advertisement
resources, and the other for updating property maps).
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GET /directory HTTP/1.1
Host: alto.example.com
Accept: application/alto-directory+json,application/alto-error+json
HTTP/1.1 200 OK
Content-Length: 3571
Content-Type: application/alto-directory+json
{
"meta" : {
"default-alto-network-map": "my-default-network-map"
},
"resources": {
"my-default-network-map": {
"uri" : "https://alto.example.com/networkmap",
"media-type" : "application/alto-networkmap+json"
},
"my-eu-netmap" : {
"uri" : "https://alto.example.com/myeunetmap",
"media-type" : "application/alto-networkmap+json"
},
"my-default-cdnifci": {
"uri" : "https://alto.example.com/cdnifci",
"media-type": "application/alto-cdni+json"
},
"my-cdnifci-with-pid-footprints": {
"uri" : "https://alto.example.com/networkcdnifci",
"media-type" : "application/alto-cdni+json",
"uses" : [ "my-eu-netmap" ]
},
"my-filtered-cdnifci" : {
"uri" : "https://alto.example.com/cdnifci/filtered",
"media-type" : "application/alto-cdni+json",
"accepts" : "application/alto-cdnifilter+json"
},
"cdnifci-property-map" : {
"uri" : "https://alto.example.com/propmap/full/cdnifci",
"media-type" : "application/alto-propmap+json",
"uses": [ "my-default-cdni" ],
"capabilities" : {
"mappings": {
"ipv4": [ "my-default-cdni.cdni-capabilities" ],
"ipv6": [ "my-default-cdni.cdni-capabilities" ],
"countrycode": [
"my-default-cdni.cdni-capabilities" ],
"asn": [ "my-default-cdni.cdni-capabilities" ]
}
}
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},
"filtered-cdnifci-property-map" : {
"uri" : "https://alto.example.com/propmap/lookup/cdnifci-pid",
"media-type" : "application/alto-propmap+json",
"accepts" : "application/alto-propmapparams+json",
"uses": [ "my-default-cdni", "my-default-network-map" ],
"capabilities" : {
"mappings": {
"ipv4": [ "my-default-cdni.cdni-capabilities",
"my-default-network-map.pid" ],
"ipv6": [ "my-default-cdni.cdni-capabilities",
"my-default-network-map.pid" ],
"countrycode": [
"my-default-cdni.cdni-capabilities" ],
"asn": [ "my-default-cdni.cdni-capabilities" ]
}
}
},
"update-my-cdni-fci" : {
"uri": "https:///alto.example.com/updates/cdnifci",
"media-type" : "text/event-stream",
"accepts" : "application/alto-updatestreamparams+json",
"uses" : [
"my-default-network-map",
"my-eu-netmap",
"my-default-cdnifci",
"my-filtered-cdnifci",
"my-cdnifci-with-pid-footprints"
],
"capabilities" : {
"incremental-change-media-types" : {
"my-default-network-map" : "application/json-patch+json",
"my-eu-netmap" : "application/json-patch+json",
"my-default-cdnifci" :
"application/merge-patch+json,application/json-patch+json",
"my-filtered-cdnifci" :
"application/merge-patch+json,application/json-patch+json",
"my-cdnifci-with-pid-footprints" :
"application/merge-patch+json,application/json-patch+json"
}
}
},
"update-my-props": {
"uri" : "https://alto.example.com/updates/properties",
"media-type" : "text/event-stream",
"uses" : [
"cdnifci-property-map",
"filtered-cdnifci-property-map"
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],
"capabilities" : {
"incremental-change-media-types": {
"cdnifci-property-map" :
"application/merge-patch+json,application/json-patch+json",
"filtered-cdnifci-property-map":
"application/merge-patch+json,application/json-patch+json"
}
}
}
}
}
3.7.2. Basic Example
This basic example demonstrates a simple CDNI Advertisement resource,
which does not depend on other resources. There are three
BaseAdvertisementObjects in this resource and these objects'
capabilities are http/1.1 delivery protocol, [http/1.1, https/1.1]
delivery protocol, and https/1.1 acquisition protocol, respectively.
GET /cdnifci HTTP/1.1
Host: alto.example.com
Accept: application/alto-cdni+json,
application/alto-error+json
HTTP/1.1 200 OK
Content-Length: 1235
Content-Type: application/alto-cdni+json
{
"meta" : {
"vtag": {
"resource-id": "my-default-cdnifci",
"tag": "da65eca2eb7a10ce8b059740b0b2e3f8eb1d4785"
}
},
"cdni-advertisement": {
"capabilities-with-footprints": [
{
"capability-type": "FCI.DeliveryProtocol",
"capability-value": {
"delivery-protocols": [
"http/1.1"
]
},
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"footprints": [
{
"footprint-type": "ipv4cidr",
"footprint-value": [ "192.0.2.0/24" ]
}
]
},
{
"capability-type": "FCI.DeliveryProtocol",
"capability-value": {
"delivery-protocols": [
"https/1.1",
"http/1.1"
]
},
"footprints": [
{
"footprint-type": "ipv4cidr",
"footprint-value": [ "198.51.100.0/24" ]
}
]
},
{
"capability-type": "FCI.AcquisitionProtocol",
"capability-value": {
"acquisition-protocols": [
"https/1.1"
]
},
"footprints": [
{
"footprint-type": "ipv4cidr",
"footprint-value": [ "203.0.113.0/24" ]
}
]
}
]
}
}
3.7.3. Incremental Updates Example
A benefit of using ALTO to provide CDNI Advertisement resources is
that such resources can be updated using ALTO incremental updates.
Below is an example that also shows the benefit of having both JSON
merge patch and JSON patch to encode updates.
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At first, an ALTO client requests updates for "my-default-cdnifci",
and the ALTO server returns the "control-uri" followed by the full
CDNI Advertisement response. Then when there is a change in the
delivery-protocols in that http/1.1 is removed (from [http/1.1,
https/1.1] to only https/1.1) due to maintenance of the https/1.1
clusters, the ALTO server regenerates the new CDNI Advertisement
resource and pushes the full replacement to the ALTO client. Later
on, the ALTO server notifies the ALTO client that "192.0.2.0/24" is
added into the "ipv4" footprint object for delivery-protocol
https/1.1 by sending the change encoded by JSON patch to the ALTO
client.
POST /updates/cdnifci HTTP/1.1
Host: alto.example.com
Accept: text/event-stream,application/alto-error+json
Content-Type: application/alto-updatestreamparams+json
Content-Length: 92
{ "add": {
"my-cdnifci-stream": {
"resource-id": "my-default-cdnifci"
}
}
}
HTTP/1.1 200 OK
Connection: keep-alive
Content-Type: text/event-stream
event: application/alto-updatestreamcontrol+json
data: {"control-uri":
data: "https://alto.example.com/updates/streams/3141592653589"}
event: application/alto-cdni+json,my-cdnifci-stream
data: { ... full CDNI Advertisement resource ... }
event: application/alto-cdni+json,my-cdnifci-stream
data: {
data: "meta": {
data: "vtag": {
data: "tag": "dasdfa10ce8b059740bddsfasd8eb1d47853716"
data: }
data: },
data: "cdni-advertisement": {
data: "capabilities": [
data: {
data: "capability-type": "FCI.DeliveryProtocol",
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data: "capability-value": {
data: "delivery-protocols": [
data: "https/1.1"
data: ]
data: },
data: "footprints": [
data: { "footprint-type": "ipv4cidr",
data: "footprint-value": [ "203.0.113.0/24" ]
data: }
data: ]
data: },
data: { ... other CDNI advertisement object ... }
data: ]
data: }
data: }
event: application/json-patch+json,my-cdnifci-stream
data: [
data: { "op": "replace",
data: "path": "/meta/vtag/tag",
data: "value": "a10ce8b059740b0b2e3f8eb1d4785acd42231bfe"
data: },
data: { "op": "add",
data: "path": "/cdni-advertisement/capabilities-with-footprints
/0/footprints/0/footprint-value/-",
data: "value": "192.0.2.0/24"
data: }
data: ]
4. CDNI Advertisement Service using ALTO Network Map
4.1. Network Map Footprint Type: altopid
The ALTO protocol defines a concept called PID to represent a group
of IPv4 or IPv6 addresses which can be applied the same management
policy. The PID is an alternative to the pre-defined CDNI footprint
types (i.e., ipv4cidr, ipv6cidr, asn, and countrycode).
To leverage this concept, this document defines a new CDNI Footprint
Type called "altopid". A CDNI Advertisement resource can depend on
an ALTO network map resource and use "altopid" footprints to compress
its CDNI Footprint Payload.
Specifically, the "altopid" footprint type indicates that the
corresponding footprint value is a list of PIDNames as defined in
[RFC7285]. These PIDNames are references of PIDs in a network map
resource. Hence a CDNI Advertisement resource using "altopid"
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footprints depends on a network map. For such a CDNI Advertisement
resource, the resource id of its dependent network map MUST be
included in the "uses" field of its IRD entry, and the "dependent-
vtag" field with a reference to this network map MUST be included in
its response (see the example in Section 4.2.3).
4.2. Examples
4.2.1. IRD Example
The examples below use the same IRD given in Section 3.7.1.
4.2.2. ALTO Network Map for CDNI Advertisement Example
Below is an example network map whose resource id is "my-eu-netmap",
and this map is referenced by the CDNI Advertisement example in
Section 4.2.3.
GET /myeunetmap HTTP/1.1
Host: alto.example.com
Accept: application/alto-networkmap+json,application/alto-error+json
HTTP/1.1 200 OK
Content-Length: 309
Content-Type: application/alto-networkmap+json
{
"meta": {
"vtag": [
{ "resource-id": "my-eu-netmap",
"tag": "3ee2cb7e8d63d9fab71b9b34cbf764436315542e"
}
]
},
"network-map": {
"south-france" : {
"ipv4": [ "192.0.2.0/24", "198.51.100.0/25" ]
},
"germany": {
"ipv4": [ "203.0.113.0/24" ]
}
}
}
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4.2.3. ALTO PID Footprints in CDNI Advertisement
This example shows a CDNI Advertisement resource that depends on a
network map described in Section 4.2.2.
GET /networkcdnifci HTTP/1.1
Host: alto.example.com
Accept: application/alto-cdni+json,application/alto-error+json
HTTP/1.1 200 OK
Content-Length: 738
Content-Type: application/alto-cdni+json
{
"meta" : {
"dependent-vtags" : [
{
"resource-id": "my-eu-netmap",
"tag": "3ee2cb7e8d63d9fab71b9b34cbf764436315542e"
}
]
},
"cdni-advertisement": {
"capabilities-with-footprints": [
{ "capability-type": "FCI.DeliveryProtocol",
"capability-value": [ "https/1.1" ],
"footprints": [
{ "footprint-type": "altopid",
"footprint-value": [ "south-france" ]
}
]
},
{ "capability-type": "FCI.AcquisitionProtocol",
"capability-value": [ "https/1.1" ],
"footprints": [
{ "footprint-type": "altopid",
"footprint-value": [ "germany", "south-france" ]
}
]
}
]
}
}
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4.2.4. Incremental Updates Example
In this example, the ALTO client is interested in changes of "my-
cdnifci-with-pid-footprints" and its dependent network map "my-eu-
netmap". Considering two changes, the first one is to change
footprints of the https/1.1 delivery protocol capability, and the
second one is to remove "south-france" from the footprints of the
https/1.1 acquisition protocol capability.
POST /updates/cdnifci HTTP/1.1
Host: alto.example.com
Accept: text/event-stream,application/alto-error+json
Content-Type: application/alto-updatestreamparams+json
Content-Length: 183
{ "add": {
"my-eu-netmap-stream": {
"resource-id": "my-eu-netmap"
},
"my-netmap-cdnifci-stream": {
"resource-id": "my-cdnifci-with-pid-footprints"
}
}
}
HTTP/1.1 200 OK
Connection: keep-alive
Content-Type: text/event-stream
event: application/alto-updatestreamcontrol+json
data: {"control-uri":
data: "https://alto.example.com/updates/streams/3141592653590"}
event: application/alto-networkmap+json,my-eu-netmap-stream
data: { ... full Network Map of my-eu-netmap ... }
event: application/alto-cdnifci+json,my-netmap-cdnifci-stream
data: { ... full CDNI Advertisement resource ... }
event: application/json-patch+json,my-netmap-cdnifci-stream
data: [
data: { "op": "replace",
data: "path": "/meta/vtag/tag",
data: "value": "dasdfa10ce8b059740bddsfasd8eb1d47853716"
data: },
data: { "op": "add",
data: "path":
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data: "/cdni-advertisement/capabilities-with-footprints
/0/footprints/0/footprint-value/-",
data: "value": "germany"
data: }
data: ]
event: application/json-patch+json,my-netmap-cdnifci-stream
data: [
data: { "op": "replace",
data: "path": "/meta/vtag/tag",
data: "value": "a10ce8b059740b0b2e3f8eb1d4785acd42231bfe"
data: },
data: { "op": "remove",
data: "path":
data: "/cdni-advertisement/capabilities-with-footprints
/1/footprints/0/footprint-value/1"
data: }
data: ]
5. Filtered CDNI Advertisement using CDNI Capabilities
Section 3 and Section 4 describe CDNI Advertisement Service which can
be used to enable a uCDN to get capabilities with footprint
restrictions from dCDNs. However, since always getting full CDNI
Advertisement resources from dCDNs is inefficient, this document
introduces a new service named "Filtered CDNI Advertisement Service",
to allow a client to filter a CDNI Advertisement resource using a
client-given set of CDNI capabilities. For each entry of the CDNI
Advertisement response, an entry will only be returned to the client
if it contains at least one of the client given CDNI capabilities.
The relationship between a filtered CDNI Advertisement resource and a
CDNI Advertisement resource is similar to the relationship between a
filtered network/cost map and a network/cost map.
5.1. Media Type
A filtered CDNI Advertisement resource uses the same media type
defined for the CDNI Advertisement resource in Section 3.1.
5.2. HTTP Method
A filtered CDNI Advertisement resource is requested using the HTTP
POST method.
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5.3. Accept Input Parameters
The input parameters for a filtered CDNI Advertisement resource 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-cdnifilter+json" which is a JSON object
of type ReqFilteredCDNIAdvertisement, where:
object {
JSONString capability-type;
JSONValue capability-value;
} CDNICapability;
object {
[CDNIFCICapability cdni-capabilities<0..*>;]
} ReqFilteredCDNIAdvertisement;
with fields:
capability-type: The same as Base Advertisement Object's capability-
type defined in Section 5.1 of [RFC8008].
capability-value: The same as Base Advertisement Object's
capability-value defined in Section 5.1 of [RFC8008].
cdni-fci-capabilities: A list of CDNI capabilities defined in
Section 5.1 of [RFC8008] for which footprints are to be returned.
If a list is empty or not appearing, the ALTO server MUST
interpret it as a request for the full CDNI Advertisement
resource. The ALTO server MUST interpret entries appearing in a
list multiple times as if they appeared only once. If the ALTO
server does not define any footprints for a CDNI capability, it
MUST omit this capability from the response.
5.4. Capabilities
None.
5.5. Uses
Same to the "uses" field of the CDNI Advertisement resource (see
Section 3.5).
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5.6. Response
The response MUST indicate an error, using ALTO protocol error
handling specified in Section 8.5 of the ALTO protocol [RFC7285], if
the request is invalid.
Specifically, a filtered CDNI Advertisement request is invalid if:
* the value of "capability-type" is null;
* the value of "capability-value" is null;
* the value of "capability-value" is inconsistent with "capability-
type".
When a request is invalid, the ALTO server MUST return an
"E_INVALID_FIELD_VALUE" error defined in Section 8.5.2 of [RFC7285],
and the "value" field of the error message SHOULD indicate this CDNI
capability.
The ALTO server returns a filtered CDNI Advertisement resource for a
valid request. The format of a filtered CDNI Advertisement resource
is the same as a full CDNI Advertisement resource (See Section 3.6.)
The returned CDNI Advertisement resource MUST contain only
BaseAdvertisementObject objects whose CDNI capability object is the
superset of one of CDNI capability object in "cdni-fci-capabilities".
Specifically, that a CDNI capability object A is the superset of
another CDNI capability object B means that these two CDNI capability
objects have the same capability type and mandatory properties in
capability value of A MUST include mandatory properties in capability
value of B semantically. See Section 5.7.2 for a concrete example.
The version tag included in the "vtag" field of the response MUST
correspond to the full CDNI Advertisement resource from which the
filtered CDNI Advertisement resource is provided. This ensures that
a single, canonical version tag is used independently of any
filtering that is requested by an ALTO client.
5.7. Examples
5.7.1. IRD Example
The examples below use the same IRD example as in Section 3.7.1.
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5.7.2. Basic Example
This example filters the full CDNI Advertisement resource in
Section 3.7.2 by selecting only the http/1.1 delivery protocol
capability. Only the second BaseAdvertisementObjects in the full
resource will be returned because the second object's capability is
http/1.1 and https/1.1 delivery protocols which is the superset of
https/1.1 delivery protocol.
POST /cdnifci/filtered HTTP/1.1
HOST: alto.example.com
Accept: application/alto-cdni+json
Content-Type: application/cdnifilter+json
Content-Length: 176
{
"cdni-capabilities": [
{
"capability-type": "FCI.DeliveryProtocol",
"capability-value": {
"delivery-protocols": [ "https/1.1" ]
}
}
]
}
HTTP/1.1 200 OK
Content-Length: 571
Content-Type: application/alto-cdni+json
{
"meta" : {
"vtag": {
"resource-id": "my-filtered-cdnifci",
"tag": "da65eca2eb7a10ce8b059740b0b2e3f8eb1d4785"
}
},
"cdni-advertisement": {
"capabilities-with-footprints": [
{
"capability-type": "FCI.DeliveryProtocol",
"capability-value": {
"delivery-protocols": [
"https/1.1",
"http/1.1"
]
},
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"footprints": [
{
"footprint-type": "ipv4cidr",
"footprint-value": [ "198.51.100.0/24" ]
}
]
}
]
}
}
5.7.3. Incremental Updates Example
In this example, the ALTO client only cares about the updates of one
advertisement object for delivery protocol capability whose value
includes "https/1.1". So it adds its limitation of capabilities in
"input" field of the POST request.
POST /updates/cdnifci HTTP/1.1
Host: fcialtoupdate.example.com
Accept: text/event-stream,application/alto-error+json
Content-Type: application/alto-updatestreamparams+json
Content-Length: 346
{
"add": {
"my-filtered-fci-stream": {
"resource-id": "my-filtered-cdnifci",
"input": {
"cdni-capabilities": [
{
"capability-type": "FCI.DeliveryProtocol",
"capability-value": {
"delivery-protocols": [ "https/1.1" ]
}
}
]
}
}
}
}
HTTP/1.1 200 OK
Connection: keep-alive
Content-Type: text/event-stream
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event: application/alto-updatestreamcontrol+json
data: {"control-uri":
data: "https://alto.example.com/updates/streams/3141592653590"}
event: application/alto-cdni+json,my-filtered-fci-stream
data: { ... filtered CDNI Advertisement resource ... }
event: application/json-patch+json,my-filtered-fci-stream
data: [
data: {
data: "op": "replace",
data: "path": "/meta/vtag/tag",
data: "value": "a10ce8b059740b0b2e3f8eb1d4785acd42231bfe"
data: },
data: { "op": "add",
data: "/cdni-advertisement/capabilities-with-footprints
/0/footprints/0/footprint-value/-",
data: "value": "192.0.2.0/24"
data: }
data: ]
6. Query Footprint Properties using ALTO Property Map Service
Besides the requirement of retrieving footprints of given
capabilities, another common requirement for uCDN is to query CDNI
capabilities of given footprints.
Considering each footprint as an entity with properties including
CDNI capabilities, a natural way to satisfy this requirement is to
use the ALTO property map as defined in
[I-D.ietf-alto-unified-props-new]. This section describes how ALTO
clients look up properties for individual footprints. First, it
describes how to represent footprint objects as entities in the ALTO
property map. Then it describes how to represent footprint
capabilities as entity properties in the ALTO property map. Finally,
it provides examples of the full property map and the filtered
property map supporting CDNI capabilities, and their incremental
updates.
6.1. Representing Footprint Objects as Property Map Entities
A footprint object has two properties: footprint-type and footprint-
value. A footprint-value is an array of footprint values conforming
to the specification associated with the registered footprint type
("ipv4cidr", "ipv6cidr", "asn", "countrycode", and "altopid").
Considering each ALTO entity defined in
[I-D.ietf-alto-unified-props-new] also has two properties: entity
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domain type and domain-specific identifier, a straightforward
approach to represent a footprint as an ALTO entity is to represent
its footprint-type as an entity domain type, and its footprint value
as a domain-specific identifier.
Each existing footprint type can be represented as an entity domain
type as follows:
* According to [I-D.ietf-alto-unified-props-new], "ipv4" and "ipv6"
are two predefined entity domain types, which can be used to
represent "ipv4cidr" and "ipv6cidr" footprints respectively.
* "pid" is also a predefined entity domain type, which can be used
to represent "altopid" footprints. Note that "pid" is a resource-
specific entity domain. To represent an "altopid" footprint, the
specifying information resource of the corresponding "pid" entity
domain MUST be the dependent network map used by the CDNI
Advertisement resource providing this "altopid" footprint.
* However, no existing entity domain type can represent "asn" and
"countrycode" footprints. To represent footprint-type "asn" and
"countrycode", this document registers two new domains in
Section 7 in addition to the ones in
[I-D.ietf-alto-unified-props-new].
Here is an example of representing a footprint object of "ipv4cidr"
type as a set of "ipv4" entities in the ALTO property map. The
representation of the footprint object of "ipv6cidr" type is similar.
{ "footprint-type": "ipv4cidr",
"footprint-value": ["192.0.2.0/24", "198.51.100.0/24"]
} --> "ipv4:192.0.2.0/24", "ipv4:198.51.100.0/24"
6.1.1. ASN Domain
The ASN domain associates property values with Autonomous Systems in
the Internet.
6.1.1.1. Entity Domain Type
asn
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6.1.1.2. Domain-Specific Entity Identifiers
The entity identifier of an entity in an asn domain is encoded as a
string consisting of the characters "as" (in lowercase) followed by
the Autonomous System Number [RFC6793].
6.1.1.3. Hierarchy and Inheritance
There is no hierarchy or inheritance for properties associated with
ASN.
6.1.2. COUNTRYCODE Domain
The COUNTRYCODE domain associates property values with countries.
6.1.2.1. Entity Domain Type
countrycode
6.1.2.2. Domain-Specific Entity Identifiers
The entity identifier of an entity in a countrycode domain is encoded
as an ISO 3166-1 alpha-2 code [ISO3166-1] in lowercase.
6.1.2.3. Hierarchy and Inheritance
There is no hierarchy or inheritance for properties associated with
country codes.
6.2. Representing CDNI Capabilities as Property Map Entity Properties
This document defines a new entity property type called "cdni-
capabilities". An ALTO server can provide a property map resource
mapping the "cdni-capablities" entity property type for a CDNI
Advertisement resource that it provides to an "ipv4", "ipv6", "asn"
or "countrycode" entity domain.
6.2.1. Defining Information Resource Media Type for Property Type cdni-
capabilities
The entity property type "cdni-capabilities" allows to define
resource-specific entity properties. When resource-specific entity
properties are defined with entity property type "cdni-capabilities",
the defining information resource for a "cdni-capabilities" property
MUST be a CDNI Advertisement resource provided by the ALTO server.
The media type of the defining information resource for a "cdni-
capabilities" property is therefore:
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application/alto-cdni+json
6.2.2. Intended Semantics of Property Type cdni-capabilities
A "cdni-capabilities" property for an entity is to indicate all the
CDNI capabilities that a corresponding CDNI Advertisement resource
provides for the footprint represented by this entity. Thus, the
value of a "cdni-capabilities" property MUST be a JSON array. Each
element in a "cdni-capabilities" property MUST be an JSON object as
format of CDNICapability (see Section 5.3). The value of a "cdni-
capabilities" property for an "ipv4", "ipv6", "asn", "countrycode" or
"altopid" entity MUST include all the CDNICapability objects that are
provided by the defining CDNI Advertisement resource and the
represented footprint object of this entity are in their footprint
restrictions.
6.3. Examples
6.3.1. IRD Example
The examples use the same IRD example given by Section 3.7.1.
6.3.2. Property Map Example
This example shows a full property map in which entities are
footprints and entities' property is "cdni-capabilities".
GET /propmap/full/cdnifci HTTP/1.1
HOST: alto.example.com
Accept: application/alto-propmap+json,application/alto-error+json
HTTP/1.1 200 OK
Content-Length: 1522
Content-Type: application/alto-propmap+json
{
"property-map": {
"meta": {
"dependent-vtags": [
{ "resource-id": "my-default-cdnifci",
"tag": "7915dc0290c2705481c491a2b4ffbec482b3cf62"}
]
},
"countrycode:us": {
"my-default-cdnifci.cdni-capabilities": [
{ "capability-type": "FCI.DeliveryProtocol",
"capability-value": {
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"delivery-protocols": ["http/1.1"]}}]
},
"ipv4:192.0.2.0/24": {
"my-default-cdnifci.cdni-capabilities": [
{ "capability-type": "FCI.DeliveryProtocol",
"capability-value": {
"delivery-protocols": ["http/1.1"]}}]
},
"ipv4:198.51.100.0/24": {
"my-default-cdnifci.cdni-capabilities": [
{ "capability-type": "FCI.DeliveryProtocol",
"capability-value": {
"delivery-protocols": ["https/1.1", "http/1.1"]}}]
},
"ipv4:203.0.113.0/24": {
"my-default-cdnifci.cdni-capabilities": [
{ "capability-type": "FCI.AcquisitionProtocol",
"capability-value": {
"acquisition-protocols": ["http/1.1"]}}]
},
"ipv6:2001:db8::/32": {
"my-default-cdnifci.cdni-capabilities": [
{ "capability-type": "FCI.DeliveryProtocol",
"capability-value": {
"delivery-protocols": ["http/1.1"]}}]
},
"asn:as64496": {
"my-default-cdnifci.cdni-capabilities": [
{ "capability-type": "FCI.DeliveryProtocol",
"capability-value": {
"delivery-protocols": ["https/1.1", "http/1.1"]}}]
}
}
}
6.3.3. Filtered Property Map Example
This example uses the filtered property map service to get "pid" and
"cdni-capabilities" properties for two footprints "ipv4:192.0.2.0/24"
and "ipv6:2001:db8::/32".
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POST /propmap/lookup/cdnifci-pid HTTP/1.1
HOST: alto.example.com
Content-Type: application/alto-propmapparams+json
Accept: application/alto-propmap+json,application/alto-error+json
Content-Length: 181
{
"entities": [
"ipv4:192.0.2.0/24",
"ipv6:2001:db8::/32"
],
"properties": [ "my-default-cdnifci.cdni-capabilities",
"my-default-networkmap.pid" ]
}
HTTP/1.1 200 OK
Content-Length: 796
Content-Type: application/alto-propmap+json
{
"property-map": {
"meta": {
"dependent-vtags": [
{"resource-id": "my-default-cdnifci",
"tag": "7915dc0290c2705481c491a2b4ffbec482b3cf62"},
{"resource-id": "my-default-networkmap",
"tag": "7915dc0290c2705481c491a2b4ffbec482b3cf63"}
]
},
"ipv4:192.0.2.0/24": {
"my-default-cdnifci.cdni-capabilities": [
{"capability-type": "FCI.DeliveryProtocol",
"capability-value": {"delivery-protocols": ["http/1.1"]}}],
"my-default-networkmap.pid": "pid1"
},
"ipv6:2001:db8::/32": {
"my-default-cdnifci.cdni-capabilities": [
{"capability-type": "FCI.DeliveryProtocol",
"capability-value": {"delivery-protocols": ["http/1.1"]}}],
"my-default-networkmap.pid": "pid3"
}
}
}
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6.3.4. Incremental Updates Example
In this example, the client is interested in updates for the
properties "cdni-capabilities" and "pid" of two footprints
"ipv4:192.0.2.0/24" and "countrycode:fr".
POST /updates/properties HTTP/1.1
Host: alto.example.com
Accept: text/event-stream,application/alto-error+json
Content-Type: application/alto-updatestreamparams+json
Content-Length: 337
{ "add": {
"fci-propmap-stream": {
"resource-id": "filtered-cdnifci-property-map",
"input": {
"properties": [ "my-default-cdnifci.cdni-capabilities",
"my-default-networkmap.pid" ],
"entities": [ "ipv4:192.0.2.0/24",
"ipv6:2001:db8::/32" ]
}
}
}
}
HTTP/1.1 200 OK
Connection: keep-alive
Content-Type: text/event-stream
event: application/alto-updatestreamcontrol+json
data: {"control-uri":
data: "https://alto.example.com/updates/streams/1414213562373"}
event: application/alto-cdni+json,fci-propmap-stream
data: { ... filtered property map ... }
event: application/merge-patch+json,fci-propmap-stream
data: {
data: "property-map": {
data: "meta": {
data: "dependent-vtags": [
data: { "resource-id": "my-default-cdnifci",
data: "tag": "2beeac8ee23c3dd1e98a73fd30df80ece9fa5627"},
data: { "resource-id": "my-default-networkmap",
data: "tag": "7915dc0290c2705481c491a2b4ffbec482b3cf63"}
data: ]
data: },
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data: "ipv4:192.0.2.0/24": {
data: "my-default-cdnifci.cdni-capabilities": [
data: { "capability-type": "FCI.DeliveryProtocol",
data: "capability-value": {
data: "delivery-protocols": ["http/1.1", "https/1.1"]}}]
data: }
data: }
data: }
event: application/json-patch+json,fci-propmap-stream
data: [
data: { "op": "replace",
data: "path": "/meta/dependent-vtags/0/tag",
data: "value": "61b23185a50dc7b334577507e8f00ff8c3b409e4"
data: },
data: { "op": "replace",
data: "path":
data: "/property-map/countrycode:fr/my-default-networkmap.pid",
data: "value": "pid5"
data: }
data: ]
7. IANA Considerations
7.1. application/alto-* Media Types
This document registers two additional ALTO media types, listed in
Table 1.
+=============+======================+===============+
| Type | Subtype | Specification |
+=============+======================+===============+
| application | alto-cdni+json | Section 3 |
+-------------+----------------------+---------------+
| application | alto-cdnifilter+json | Section 5 |
+-------------+----------------------+---------------+
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
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Encoding considerations: Encoding considerations are identical to
those specified for the "application/json" media type. See
[RFC7159].
Security considerations: Security considerations related to the
generation and consumption of ALTO Protocol messages are discussed
in Section 15 of [RFC7285].
Interoperability considerations: This document specifies formats of
conforming messages and the interpretation thereof.
Published specification: This document is the specification for
these media types; see Table 1 for the section documenting each
media type.
Applications that use this media type: ALTO servers and ALTO clients
either stand alone or are embedded within other applications.
Additional information: Magic number(s): n/a
File extension(s): This document uses the
mime type to refer to protocol messages and thus does not
require a file extension.
Macintosh file type code(s): n/a
Person & email address to contact for further information: See
Authors' Addresses section.
Intended usage: COMMON
Restrictions on usage: n/a
Author: See Authors' Addresses section.
Change controller: Internet Engineering Task Force
(mailto:iesg@ietf.org).
7.2. CDNI Metadata Footprint Type Registry
As proposed in Section 7.2 of [RFC8006], "CDNI Metadata Footprint
Types" registry is requested. A new footprint type is to be
registered, listed in Table 2.
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+================+=====================+======================+
| Footprint Type | Description | Specification |
+================+=====================+======================+
| altopid | A list of PID names | Section 4 of RFCthis |
+----------------+---------------------+----------------------+
Table 2: CDNI Metadata Footprint Type
[RFC Editor: Please replace RFCthis with the published RFC number for
this document.]
7.3. ALTO Entity Domain Type Registry
As proposed in Section 11.2 of [I-D.ietf-alto-unified-props-new],
"ALTO Entity Domain Type Registry" is requested. Two new entity
domain types are to be registered, listed in Table 3.
+=============+================+=============+===================+
| Identifier | Entity Address | Hierarchy & | Media Type of |
| | Encoding | Inheritance | Defining Resource |
+=============+================+=============+===================+
| asn | See Section | None | None |
| | 6.1.1.2 of | | |
| | RFCthis | | |
+-------------+----------------+-------------+-------------------+
| countrycode | See Section | None | None |
| | 6.1.2.2 of | | |
| | RFCthis | | |
+-------------+----------------+-------------+-------------------+
Table 3: Additional ALTO Entity Domain Types
[RFC Editor: Please replace RFCthis with the published RFC number for
this document.]
7.4. ALTO Entity Property Type Registry
As proposed in Section 11.3 of [I-D.ietf-alto-unified-props-new],
"ALTO Entity Property Type Registry" is required. A new entity
property type is to be registered, listed in Table 4.
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+===================+====================+===================+
| Identifier | Intended Semantics | Media Type of |
| | | Defining Resource |
+===================+====================+===================+
| cdni-capabilities | Section 6.2 of | application/alto- |
| | RFCthis | cdni+json |
+-------------------+--------------------+-------------------+
Table 4: Additional ALTO Entity Property Type
[RFC Editor: Please replace RFCthis with the published RFC number for
this document.]
8. Security Considerations
As an extension of the base ALTO protocol ([RFC7285]), this document
fits into the architecture of the base protocol. And hence Security
Considerations of the base protocol (Section 15 of [RFC7285]) fully
apply when this extension is provided by an ALTO server.
In the context of CDNI Advertisement, additional security
considerations should be included as follows:
* For authenticity and integrity of ALTO information, an attacker
may disguise itself as an ALTO server for a dCDN, and provide
false capabilities and footprints to a uCDN using the CDNI
Advertisement service. Such false information may lead a uCDN to
(1) select an incorrect dCDN to serve user requests, or (2) skip
uCDNs in good conditions.
* For potential undesirable guidance from authenticated ALTO
information, a dCDN can provide a uCDN with limited capabilities
and smaller footprint coverage so that the dCDN can avoid
transferring traffic for a uCDN which they should have to
transfer.
* For confidentiality and privacy of ALTO information, footprint
properties integrated with ALTO unified property may expose
network location identifiers (e.g., IP addresses or fine-grained
PIDs).
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* For availability of ALTO services, an attacker may conduct service
degradation attacks using services defined in this document to
disable ALTO services of a network. It may request potentially
large, full CDNI Advertisement resources from an ALTO server in a
dCDN continuously, to consume the bandwidth resources of that ALTO
server. It may also query filtered property map services with
many smaller individual footprints, to consume the computation
resources of the ALTO server.
Although protection strategies as described in Section 15 of
[RFC7285] should be applied to address aforementioned security
considerations, one additional information leakage risk introduced by
this document could not be addressed by these strategies. In
particular, if a dCDN signs agreements with multiple uCDNs without
any isolation, this dCDN may disclose extra information of one uCDN
to another one. In that case, one uCDN may redirect requests which
should not have to be served by this dCDN to it.
To reduce the risk, a dCDN should isolate full/filtered CDNI
Advertisement resources for different uCDNs. It could consider
generating URIs of different full/filtered CDNI Advertisement
resources by hashing its company ID, a uCDN's company ID as well as
their agreements. A dCDN should avoid exposing all full/filtered
CDNI Advertisement resources in one of its IRDs.
9. Acknowledgments
The authors thank Matt Caulfield, Danny Alex Lachos Perez, Daryl
Malas and Sanjay Mishra for their timely reviews and invaluable
comments.
Jan Seedorf has been partially supported by the GreenICN project
(GreenICN: Architecture and Applications of Green Information Centric
Networking), a research project supported jointly by the European
Commission under its 7th Framework Program (contract no. 608518) and
the National Institute of Information and Communications Technology
(NICT) in Japan (contract no. 167). The views and conclusions
contained herein are those of the authors and should not be
interpreted as necessarily representing the official policies or
endorsements, either expressed or implied, of the GreenICN project,
the European Commission, or NICT.
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This document has also been supported by the Coordination Support
Action entitled 'Supporting European Experts Presence in
lnternational Standardisation Activities in ICT' ("StandlCT.eu")
funded by the European Commission under the Horizon 2020 Programme
with Grant Agreement no. 780439. The views and conclusions contained
herein are those of the authors and should not be interpreted as
necessarily representing the official policies or endorsements,
either expressed or implied, of the European Commission.
10. Contributors
Mr. Xiao Shawn Lin is an author of an early version of this document,
with many contributions.
11. References
11.1. Normative References
[ISO3166-1]
The International Organization for Standardization, "Codes
for the representation of names of countries and their
subdivisions -- Part 1: Country codes", ISO 3166-1:2013,
2013.
[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>.
[RFC6793] Vohra, Q. and E. Chen, "BGP Support for Four-Octet
Autonomous System (AS) Number Space", RFC 6793,
DOI 10.17487/RFC6793, December 2012,
<https://www.rfc-editor.org/info/rfc6793>.
[RFC7159] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
Interchange Format", RFC 7159, DOI 10.17487/RFC7159, March
2014, <https://www.rfc-editor.org/info/rfc7159>.
[RFC7285] Alimi, R., Ed., Penno, R., Ed., Yang, Y., Ed., Kiesel, S.,
Previdi, S., Roome, W., Shalunov, S., and R. Woundy,
"Application-Layer Traffic Optimization (ALTO) Protocol",
RFC 7285, DOI 10.17487/RFC7285, September 2014,
<https://www.rfc-editor.org/info/rfc7285>.
[RFC8006] Niven-Jenkins, B., Murray, R., Caulfield, M., and K. Ma,
"Content Delivery Network Interconnection (CDNI)
Metadata", RFC 8006, DOI 10.17487/RFC8006, December 2016,
<https://www.rfc-editor.org/info/rfc8006>.
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[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>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
11.2. Informative References
[I-D.ietf-alto-path-vector]
Gao, K., Lee, Y., Randriamasy, S., Yang, Y., and J. Zhang,
"ALTO Extension: Path Vector", Work in Progress, Internet-
Draft, draft-ietf-alto-path-vector-12, 2 November 2020,
<http://www.ietf.org/internet-drafts/draft-ietf-alto-path-
vector-12.txt>.
[I-D.ietf-alto-unified-props-new]
Roome, W., Randriamasy, S., Yang, Y., Zhang, J., and K.
Gao, "Unified properties for the ALTO protocol", Work in
Progress, Internet-Draft, draft-ietf-alto-unified-props-
new-13, 2 November 2020, <http://www.ietf.org/internet-
drafts/draft-ietf-alto-unified-props-new-13.txt>.
[RFC5693] Seedorf, J. and E. Burger, "Application-Layer Traffic
Optimization (ALTO) Problem Statement", RFC 5693,
DOI 10.17487/RFC5693, October 2009,
<https://www.rfc-editor.org/info/rfc5693>.
[RFC6707] Niven-Jenkins, B., Le Faucheur, F., and N. Bitar, "Content
Distribution Network Interconnection (CDNI) Problem
Statement", RFC 6707, DOI 10.17487/RFC6707, September
2012, <https://www.rfc-editor.org/info/rfc6707>.
[RFC7336] Peterson, L., Davie, B., and R. van Brandenburg, Ed.,
"Framework for Content Distribution Network
Interconnection (CDNI)", RFC 7336, DOI 10.17487/RFC7336,
August 2014, <https://www.rfc-editor.org/info/rfc7336>.
[RFC7975] Niven-Jenkins, B., Ed. and R. van Brandenburg, Ed.,
"Request Routing Redirection Interface for Content
Delivery Network (CDN) Interconnection", RFC 7975,
DOI 10.17487/RFC7975, October 2016,
<https://www.rfc-editor.org/info/rfc7975>.
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[RFC8895] Roome, W. and Y. Yang, "Application-Layer Traffic
Optimization (ALTO) Incremental Updates Using Server-Sent
Events (SSE)", RFC 8895, DOI 10.17487/RFC8895, November
2020, <https://www.rfc-editor.org/info/rfc8895>.
Authors' Addresses
Jan Seedorf
HFT Stuttgart - Univ. of Applied Sciences
Schellingstrasse 24
Stuttgart 70174
Germany
Phone: +49-0711-8926-2801
Email: jan.seedorf@hft-stuttgart.de
Y.R. Yang
Yale University
51 Prospect Street
New Haven, CT 06511
United States of America
Email: yry@cs.yale.edu
URI: http://www.cs.yale.edu/~yry/
Kevin J. Ma
Ericsson
43 Nagog Park
Acton, MA 01720
United States of America
Phone: +1-978-844-5100
Email: kevin.j.ma.ietf@gmail.com
Jon Peterson
NeuStar
1800 Sutter St Suite 570
Concord, CA 94520
United States of America
Email: jon.peterson@neustar.biz
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Jingxuan Jensen Zhang
Tongji University
4800 Cao'an Hwy
Shanghai 201804
China
Email: jingxuan.zhang@tongji.edu.cn
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