| CDNI | J. Seedorf |
| Internet-Draft | HFT Stuttgart - Univ. of Applied Sciences |
| Intended status: Standards Track | Y. Yang |
| Expires: July 25, 2020 | Tongji/Yale |
| K. Ma | |
| Ericsson | |
| J. Peterson | |
| Neustar | |
| X. Lin | |
| J. Zhang | |
| Tongji | |
| January 22, 2020 |
Content Delivery Network Interconnection (CDNI) Request Routing: CDNI Footprint and Capabilities Advertisement using ALTO
draft-ietf-alto-cdni-request-routing-alto-09
The Content Delivery Networks Interconnection (CDNI) framework [RFC6707] defines a set of protocols to interconnect CDNs, to achieve multiple goals such as extending the reach of a given CDN to areas that are not covered by that particular CDN. One component that is needed to achieve the goal of CDNI described in [RFC7336] is the CDNI Request Routing Footprint & Capabilities Advertisement interface (FCI). [RFC8008] defines precisely the semantics of FCI and provides guidelines on the FCI protocol, but the exact protocol is explicitly outside the scope of that document. In this document, we follow the guidelines to define an FCI protocol using the Application-Layer Traffic Optimization (ALTO) protocol.
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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 July 25, 2020.
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 extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.
The ability to interconnect multiple content delivery networks (CDNs) has many benefits, including increased coverage, capability, and reliability. The Content Delivery Networks Interconnection (CDNI) framework [RFC6707] defines four interfaces to achieve interconnection of CDNs: (1) the CDNI Request Routing Interface; (2) the CDNI Metadata Interface; (3) the CDNI Logging Interface; and (4) the CDNI Control Interface.
Among the four interfaces, the CDNI Request Routing Interface provides key functions, as specified in [RFC6707]: "The CDNI Request Routing interface enables a Request Routing function in an Upstream CDN to query a Request Routing function in a Downstream CDN to determine if the Downstream CDN is able (and willing) to accept the delegated Content Request. It also allows the Downstream CDN to control what should be returned to the User Agent in the redirection message by the upstream Request Routing function." 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) CDNI Footprint & Capabilities Advertisement interface (FCI), and (2) CDNI Request Routing Redirection interface (RI). Since this document focuses on the first functionality, CDNI FCI, we will describe it in a more detailed way. CDNI FCI is an advertisement from a dCDN to a uCDN (push) or a query from a uCDN to a dCDN (pull) so that the uCDN knows whether it can redirect a particular user request to that dCDN.
A key component in defining CDNI FCI is defining objects describing the footprints and capabilities of a dCDN. Such objects are already 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 FCI Service".
There are multiple benefits in using ALTO as a transport protocol, as we discuss in Section 2.2.
The rest of this document is organized as follows. Section 2 provides non-normative background on both CDNI FCI and ALTO. Section 3 introduces the most basic service, called "CDNI FCI 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 a new granularity to describe footprints. Section 5 introduces "Filtered CDNI FCI Service" to allow a uCDN to get footprints with given capabilities instead of getting the full resource which can be huge. 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 some footprints in which it is interested. IANA and security considerations are discussed in Section 7 and Section 8 respectively.
Throughout this document, we use the terminologies for CDNI defined in [RFC6707], [RFC8006], [RFC8008] and we use the terminologies for ALTO defined in [RFC7285], [I-D.ietf-alto-unified-props-new].
The design of CDNI FCI transport using ALTO depends on the understanding of both FCI semantics and ALTO. Hence, we start with a review of both.
The CDNI document on "Footprint and Capabilities Semantics" [RFC8008] defines the semantics of CDNI FCI, and provides guidance on what Footprint and Capabilities mean in a CDNI context and how a protocol solution should in principle look. The definitions in [RFC8008] depend on [RFC8006]. Here we briefly summarize key related points of [RFC8008] and [RFC8006]. For a detailed discussion, the reader is referred to the RFCs.
Application-Layer Traffic Optimization (ALTO) [RFC7285] is an approach for guiding the resource provider selection process in distributed applications that can choose among several candidate resources providers to retrieve a given resource. By conveying network layer (topology) information, an ALTO server can provide important information to "guide" the resource provider selection process in distributed applications. Usually, it is assumed that an ALTO server conveys information that these applications cannot measure or have difficulty measuring themselves [RFC5693].
Originally, ALTO was motivated by optimizing cross-ISP traffic generated by P2P applications [RFC5693]. Recently, however, ALTO is also being considered for improving the request routing in CDNs [I-D.jenkins-alto-cdn-use-cases]. The CDNI problem statement explicitly mentions ALTO as a candidate protocol for "actual algorithms for selection of CDN or Surrogate by Request-Routing systems" [RFC6707].
The following reasons make ALTO a suitable candidate protocol for dCDN (downstream CDN) selection as part of CDNI request routing and in particular for an FCI protocol:
The ALTO protocol is based on an ALTO Information Service Framework which consists of several services, where all ALTO services are "provided through a common transport protocol, messaging structure and encoding, and transaction model" [RFC7285]. The ALTO protocol specification [RFC7285] defines several such services, e.g., the ALTO map service.
This document defines a new ALTO Service called "CDNI FCI Service" which conveys JSON objects of media type "application/alto-cdnifci+json". These JSON objects are used to transport BaseAdvertisementObject objects defined in [RFC8008]; this document specifies how to transport such BaseAdvertisementObject objects via the ALTO protocol with the ALTO "CDNI FCI Service". Similar to other ALTO services, this document defines the ALTO information resource for the "CDNI FCI Service" as follows.
The media type of the CDNI FCI resource is "application/alto-cdnifci+json".
A CDNI FCI resource is requested using the HTTP GET method.
None.
None.
The "uses" field SHOULD NOT appear unless the CDNI FCI resource depends on some ALTO information resources. If the CDNI FCI resource has some 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 FCI resource. See Section 4 for details of when and how to use it. Future documents may extend the CDNI FCI resource and allow other dependent resources.
The "meta" field of a CDNI FCI 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 FCI response depends on an ALTO information resource, 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.
The data component of an ALTO CDNI FCI response is named "cdni-fci", which is a JSON object of type CDNIFCIData:
object {
CDNIFCIData cdni-fci;
} InfoResourceCDNIFCI : ResponseEntityBase;
object {
BaseAdvertisementObject capabilities<1..*>;
} CDNIFCIData;
Specifically, a CDNIFCIData object is a JSON object that includes only one property named "capabilities", 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, we give a non-normative specification of BaseAdvertisementObject below. As mentioned above, the normative specification of BaseAdvertisementObject is in [RFC8008]
object {
JSONString capability-type;
JSONValue capability-value;
Footprint footprints<0..*>;
} BaseAdvertisementObject;
object {
JSONString footprint-type;
JSONString footprint-value<1..*>;
} Footprint;
For each BaseAdvertisementObject, the ALTO client MUST interpret footprints appearing multiple times as if they appeared only once. If footprints in a BaseAdvertisementObject is null or empty or not appearing, the ALTO client MUST understand that the capabilities in this BaseAdvertisementObject have the "global" coverage.
EXAMPLE 1
{
"meta" : {...},
"cdni-fci": {
"capabilities": [
{
"capability-type": "FCI.DeliveryProtocol",
"capability-value": {
"delivery-protocols": [
"http/1.1"
]
},
"footprints": [
<Footprint objects>
]
},
{
"capability-type": "FCI.DeliveryProtocol",
"capability-value": {
"delivery-protocols": [
"https/1.1"
]
},
"footprints": [
<Footprint objects>
]
}
]
}
}
EXAMPLE 2
{
"meta" : {...},
"cdni-fci": {
"capabilities": [
{
"capability-type": "FCI.DeliveryProtocol",
"capability-value": {
"delivery-protocols": [
"https/1.1",
"http/1.1"
]
},
"footprints": [
<Footprint objects>
]
}
]
}
}
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.
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 FCI resource), demonstrating a single, integrated environment.
Specifically, the IRD announces two network maps, one CDNI FCI resource without dependency, one CDNI FCI resource depending on a network map, one filtered CDNI FCI resource to be defined in Section 5, one property map including "cdni-fci-capabilities" as its entity property, one filtered property map including "cdni-fci-capabilities" and "pid" as its entity properties, and two update stream services (one for updating CDNI FCI resources, and the other for updating property maps).
GET /directory HTTP/1.1 Host: alto.example.com Accept: application/alto-directory+json,application/alto-error+json
{
"meta" : { ... },
"resources": {
"my-default-network-map": {
"uri" : "http://alto.example.com/networkmap",
"media-type" : "application/alto-networkmap+json"
},
"my-eu-netmap" : {
"uri" : "http://alto.example.com/myeunetmap",
"media-type" : "application/alto-networkmap+json"
},
"my-default-cdnifci": {
"uri" : "http://alto.example.com/cdnifci",
"media-type": "application/alto-cdnifci+json"
},
"my-cdnifci-with-pid-footprints": {
"uri" : "http://alto.example.com/networkcdnifci",
"media-type" : "application/alto-cdnifci+json",
"uses" : [ "my-eu-netmap" ]
},
"my-filtered-cdnifci" : {
"uri" : "http://alto.example.com/cdnifci/filtered",
"media-type" : "application/alto-cdnifci+json",
"accepts" : "application/alto-cdnifcifilter+json",
"uses" : [ "my-default-cdnifci" ]
},
"cdnifci-property-map" : {
"uri" : "http://alto.example.com/propmap/full/cdnifci",
"media-type" : "application/alto-propmap+json",
"uses": [ "my-default-cdni" ],
"capabilities" : {
"mappings": {
"ipv4": [ "my-default-cdni.cdni-fci-capabilities" ],
"ipv6": [ "my-default-cdni.cdni-fci-capabilities" ],
"countrycode": [
"my-default-cdni.cdni-fci-capabilities" ],
"asn": [ "my-default-cdni.cdni-fci-capabilities" ],
}
}
},
"filtered-cdnifci-property-map" : {
"uri" : "http://alto.example.com/propmap/lookup/cdnifci-pid",
"media-type" : "application/alto-propmap+json",
"accepts" : "application/alto-propmapparams+json",
"uses": [ "my-default-cdni", "my-default-network-map" ],
"capabilities" : {
"mappings": {
"ipv4": [ "my-default-cdni.cdni-fci-capabilities",
"my-default-network-map.pid" ],
"ipv6": [ "my-default-cdni.cdni-fci-capabilities",
"my-default-network-map.pid" ],
"countrycode": [
"my-default-cdni.cdni-fci-capabilities" ],
"asn": [ "my-default-cdni.cdni-fci-capabilities" ],
}
}
},
"update-my-cdni-fci" : {
"uri": "http:///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" : "http://alto.example.com/updates/properties",
"media-type" : "text/event-stream",
"uses" : [
"cdnifci-property-map",
"filtered-cdnifci-property-map"
],
"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"
}
}
}
}
}
In this example, we demonstrate a simple CDNI FCI resource; this resource 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-cdnifci+json,
application/alto-error+json
HTTP/1.1 200 OK
Content-Length: XXX
Content-Type: application/alto-cdnifci+json
{
"meta" : {
"vtag": {
"resource-id": "my-default-cdnifci",
"tag": "da65eca2eb7a10ce8b059740b0b2e3f8eb1d4785"
}
},
"cdni-fci": {
"capabilities": [
{
"capability-type": "FCI.DeliveryProtocol",
"capability-value": {
"delivery-protocols": [
"http/1.1"
]
},
"footprints": [
<Footprint objects>
]
},
{
"capability-type": "FCI.DeliveryProtocol",
"capability-value": {
"delivery-protocols": [
"https/1.1",
"http/1.1"
]
},
"footprints": [
<Footprint objects>
]
},
{
"capability-type": "FCI.AcquisitionProtocol",
"capability-value": {
"acquisition-protocols": [
"https/1.1"
]
},
"footprints": [
<Footprint objects>
]
}
]
}
}
A benefit of using ALTO to provide CDNI FCI 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.
At first, an ALTO client requests updates for "my-default-cdnifci", and the ALTO server returns the "control-uri" followed by the full CDNI FCI response. Then when there is a change in the delivery-protocols in that `http/1.1` is removed (from http/1.1 and https/1.1 to only https/1.1) due to maintenance of the https/1.1 clusters, the ALTO server uses JSON merge patch to encode the change and pushes the change 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: ###
{ "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: "http://alto.example.com/updates/streams/3141592653589"}
event: application/alto-cdnifci+json,my-default-cdnifci
data: { ... full CDNI FCI map ... }
event: application/merge-patch+json,my-default-cdnifci
data: {
data: "meta": {
data: "vtag": {
data: "tag": "dasdfa10ce8b059740bddsfasd8eb1d47853716"
data: }
data: },
data: "cdni-fci": {
data: "capabilities": [
data: {
data: "capability-type": "FCI.DeliveryProtocol",
data: "capability-value": {
data: "delivery-protocols": [
data: "https/1.1"
data: ]
data: },
data: "footprints": [
data: <Footprint objects in only https/1.1>
data: ]
data: }
data: ]
data: }
data: }
event: application/json-patch+json,my-default-cdnifci
data: [
data: { "op": "replace",
data: "path": "/meta/vtag/tag",
data: "value": "a10ce8b059740b0b2e3f8eb1d4785acd42231bfe"
data: },
data: { "op": "add",
data: "path":
data: "/cdni-fci/capabilities/1/footprints/0/footprint-value/-",
data: "value": "192.0.2.0/24"
data: }
data: ]
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).
Specifically, a CDNI FCI resource can depend on an ALTO network map resource and use a new CDNI Footprint Type called "altopid" to compress its CDNI Footprint Payload.
"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 FCI with "altopid" footprints depends on a network map. For such a CDNI FCI map, 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).
We use the same IRD example given in Section 3.7.1.
Below is an example network map whose resource id is "my-eu-netmap", and this map is referenced by the CDNI FCI example in Section 4.2.3.
GET /networkmap HTTP/1.1 Host: http://alto.example.com/myeunetmap Accept: application/alto-networkmap+json,application/alto-error+json
HTTP/1.1 200 OK
Content-Length: XXX
Content-Type: application/alto-networkmap+json
{
"meta" : {
"vtag": [
{"resource-id": "my-eu-netmap",
"tag": "3ee2cb7e8d63d9fab71b9b34cbf764436315542e"
}
]
},
"network-map" : {
"south-france" : {
"ipv4" : [ "192.0.2.0/24", "198.51.100.0/25" ]
},
"germany" : {
"ipv4" : [ "192.0.3.0/24"]
}
}
}
In this example, we show a CDNI FCI 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-cdnifci+json,application/alto-error+json
HTTP/1.1 200 OK
Content-Length: 618
Content-Type: application/alto-cdnifci+json
{
"meta" : {
"dependent-vtags" : [
{
"resource-id": "my-eu-netmap",
"tag": "3ee2cb7e8d63d9fab71b9b34cbf764436315542e"
}
]
},
"cdni-fci": {
"capabilities": [
{ "capability-type": "FCI.DeliveryProtocol",
"capability-value": [
"http/1.1"
]
},
{ "capability-type": "FCI.DeliveryProtocol",
"capability-value": [
"https/1.1"
],
"footprints": [
{ "footprint-type": "altopid",
"footprint-value": [
"germany",
"south-france"
]
}
]
}
]
}
}
In this example, the ALTO client is interested in changes of "my-cdnifci-with-pid-footprints". Considering two changes, the first one is to change footprints of http/1.1 Delivery Protocol capability, and the second one is to remove "south-france" from the footprints of https/1.1 delivery protocol capability.
POST /updates/cdnifci HTTP/1.1
Host: alto.example.com
Accept: text/event-stream,application/alto-error+json
Content-Type: application/alto-updatestreamparams+json
Content-Length: ###
{ "add": {
"my-network-map-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: "http://alto.example.com/updates/streams/3141592653590"}
event: application/alto-cdnifci+json,my-fci-stream
data: { ... full CDNI FCI resource ... }
event: application/merge-patch+json,my-fci-stream
data: {
data: "meta": {
data: "dependent-vtags" : [
data: {
data: "resource-id": "my-eu-netmap",
data: "tag": "3ee2cb7e8d63d9fab71b9b34cbf764436315542e"
data: }
data: ],
data: "vtag": {
data: "tag": "dasdfa10ce8b059740bddsfasd8eb1d47853716"
data: }
data: },
data: {
data: "capability-type": "FCI.DeliveryProtocol",
data: "capability-value": {
data: "delivery-protocols": [
data: "http/1.1"
data: ]
data: },
data: "footprints": [
data: <All footprint objects in http/1.1>
data: ]
data: }
data: }
event: application/json-patch+json,my-fci-stream
data: [
data: {
data: "op": "replace",
data: "path": "/meta/vtag/tag",
data: "value": "a10ce8b059740b0b2e3f8eb1d4785acd42231bfe"
data: },
data: { "op": "remove",
data: "path": "/cdni-fci/capabilities/2/footprints/0/
data: footprint-value/1",
data: }
data: ]
Section 3 and Section 4 describe CDNI FCI Service which can be used to enable a uCDN to get capabilities with footprints constraints from dCDNs. However, always getting full CDNI FCI resources from dCDNs is very inefficient, hence we introduce a new service named "Filtered CDNI FCI Service" to allow a client to filter a CDNI FCI resource using a client-given set of capabilities. For each entry of the CDNI FCI response, an entry will only be returned to the client if it contains at least one of the client given capabilities. The relationship between a filtered CDNI FCI resource and a CDNI FCI resource is similar to the relationship between a filtered network/cost map and a network/cost map.
A filtered CDNI FCI resource uses the same media type defined for the CDNI FCI resource in Section 3.1.
A filtered CDNI FCI resource is requested using the HTTP POST method.
The input parameters for a filtered CDNI FCI 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-cdnifcifilter+json" which is a JSON object of type ReqFilteredCDNIFCI, where:
object {
JSONString capability-type;
JSONValue capability-value;
} CDNIFCICapability;
object {
[CDNIFCICapability cdni-fci-capabilities<0..*>;]
} ReqFilteredCDNIFCI;
with fields:
None.
The resource ID of the CDNI FCI resource based on which the filtering is performed.
The response MUST indicate an error, using ALTO protocol error handling specified in Section 8.5 of the ALTO protocol [RFC7285], if the request is invalid.
Specifically, a filtered CDNI FCI request is invalid if: [RFC7285], and the "value" field of the error message SHOULD indicate this CDNI FCI capability.
When a request is invalid, the ALTO server MUST return an "E_INVALID_FIELD_VALUE" error defined in Section 8.5.2 of
The ALTO server returns a filtered CDNI FCI resource for a valid request. The format of a filtered CDNI FCI resource is the same as an full CDNI FCI resource (See Section 3.6.)
The returned CDNI FCI 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 FCI resource from which the filtered CDNI FCI resource is provided. This ensures that a single, canonical version tag is used independently of any filtering that is requested by an ALTO client.
We use the same IRD example by Section 3.7.1.
This example filters the full CDNI FCI resource in Section 3.7.2 by selecting only the http/1.1 delivery protocol capability. Only the first two BaseAdvertisementObjects in the full resource will be returned because the first object's capability is http/1.1 delivery protocol and the second object's capability is http/1.1 and https/1.1 delivery protocols which is the superset of http/1.1 delivery protocol.
POST /cdnifci/filtered HTTP/1.1
HOST: alto.example.com
Content-Type: application/cdnifilter+json
Accept: application/alto-cdnifci+json
{
"cdni-fci-capabilities": [
{
"capability-type": "FCI.DeliveryProtocol",
"capability-value": {
"delivery-protocols": [
"http/1.1"
]
}
}
]
}
HTTP/1.1 200 OK
Content-Length: XXX
Content-Type: application/alto-cdnifci+json
{
"meta" : {
"vtag": {
"resource-id": "my-default-cdnifci",
"tag": "da65eca2eb7a10ce8b059740b0b2e3f8eb1d4785"
}
},
"cdni-fci": {
"capabilities": [
{
"capability-type": "FCI.DeliveryProtocol",
"capability-value": {
"delivery-protocols": [
"http/1.1"
]
},
"footprints": [
<Footprint objects>
]
},
{
"capability-type": "FCI.DeliveryProtocol",
"capability-value": {
"delivery-protocols": [
"https/1.1",
"http/1.1"
]
},
"footprints": [
<Footprint objects>
]
}
]
}
}
In this example, the ALTO client only cares about the updates of one Delivery Protocol object whose value is "http/1.1". So it adds its limitation of capabilities in "input" field of the POST request.
POST /updates/cdnifci HTTP/1.1
Host: fcialtoupdate.example.com
Accept: text/event-stream,application/alto-error+json
Content-Type: application/alto-updatestreamparams+json
Content-Length: ###
{ "add": {
"my-fci-stream": {
"resource-id": "my-filtered-cdnifci",
"input": {
"cdni-fci-capabilities": [
{
"capability-type": "FCI.DeliveryProtocol",
"capability-value": {
"delivery-protocols": [
"http/1.1"
]
}
}
]
}
}
}
}
HTTP/1.1 200 OK
Connection: keep-alive
Content-Type: text/event-stream
event: application/alto-updatestreamcontrol+json
data: {"control-uri":
data: "http://alto.example.com/updates/streams/3141592653590"}
event: application/alto-cdnifci+json,my-fci-stream
data: { ... full filtered CDNI FCI resource ... }
event: application/merge-patch+json,my-fci-stream
data: {
data: "meta": {
data: "vtag": {
data: "tag": "dasdfa10ce8b059740bddsfasd8eb1d47853716"
data: }
data: },
data: {
data: "capability-type": "FCI.DeliveryProtocol",
data: "capability-value": {
data: "delivery-protocols": [
data: "http/1.1"
data: ]
data: },
data: "footprints": [
data: <All footprint objects in http/1.1>
data: ]
data: }
data: }
event: application/json-patch+json,my-fci-stream
data: [
data: {
data: "op": "replace",
data: "path": "/meta/vtag/tag",
data: "value": "a10ce8b059740b0b2e3f8eb1d4785acd42231bfe"
data: },
data: { "op": "add",
data: "path": "/cdni-fci/capabilities/0/footprints/-",
data: "value": "ipv4:192.0.2.0/24"
data: }
data: ]
Besides 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, the most natrual way to satisfy this requirement is to use the ALTO property map defined in [I-D.ietf-alto-unified-props-new]. In this section, we describe how ALTO clients look up properties for individual footprints. We firstly describe how to represent footprint objects as entities in the ALTO property map. And then we provide examples of the full property map and the filtered property map supporting CDNI capabilities, and their incremental updates.
A footprint object has two properties: footprint-type and footprint-value. A footprint-value is an array of footprint values conforming to the specification associated with the registered footprint type ("ipv4cidr", "ipv6cidr", "asn", and "countrycode"). Considering each ALTO entity defined in [I-D.ietf-alto-unified-props-new] also has two properties: entity domain type and domain-specific identifier, a straightforward approach to represent a footprint as an ALTO entity is to regard its footprint-type as an entity domain type, and its footprint value as a domain-specific identifier. 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. 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 as a set of entities in the ALTO property map.
{"footprint-type": "ipv4cidr", "footprint-value": ["192.0.2.0/24", "198.51.100.0/24"]} --> "ipv4:192.168.2.0/24", "ipv4:198.51.100.0/24"
The ASN domain associates property values with Autonomous Systems in the Internet.
asn
The entity identifiers of entities in an asn domain is encoded as a string consisting of the characters "as" (in lowercase) followed by the Autonomous System Number [RFC6793].
There is no hierarchy or inheritance for properties associated with ASN.
The COUNTRYCODE domain associates property values with countries.
countrycode
The entity identifiers of entities in a countrycode domain is encoded as an ISO 3166-1 alpha-2 code [ISO3166-1] in lowercase.
There is no hierarchy or inheritance for properties associated with country codes.
We use the same IRD example given by Section 3.7.1.
This example shows a full property map in which entities are footprints and entities' property is "cdni-fci-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: ###
Content-Type: application/alto-propmap+json
{
"property-map": {
"meta": {
"dependent-vtags": [
{"resource-id": "my-default-cdnifci",
"tag": "7915dc0290c2705481c491a2b4ffbec482b3cf62"}
]
},
"countrycode:us": {
"my-default-cdnifci.cdni-fci-capabilities": [
{"capability-type": "FCI.DeliveryProtocol",
"capability-value": {"delivery-protocols": ["http/1.1"]}}]
},
"ipv4:192.0.2.0/24": {
"my-default-cdnifci.cdni-fci-capabilities": [
{"capability-type": "FCI.DeliveryProtocol",
"capability-value": {"delivery-protocols": ["http/1.1"]}}]
},
"ipv4:198.51.100.0/24": {
"my-default-cdnifci.cdni-fci-capabilities": [
{"capability-type": "FCI.DeliveryProtocol",
"capability-value": {"delivery-protocols": ["http/1.1"]}}]
},
"ipv6:2001:db8::/32": {
"my-default-cdnifci.cdni-fci-capabilities": [
{"capability-type": "FCI.DeliveryProtocol",
"capability-value": {"delivery-protocols": ["http/1.1"]}}]
},
"asn:as64496": {
"my-default-cdnifci.cdni-fci-capabilities": [
{"capability-type": "FCI.DeliveryProtocol",
"capability-value": {"delivery-protocols": ["http/1.1",
"https/1.1"]}}]
}
}
}
In this example, we use filtered property map service to get "pid" and "cdni-fci-capabilities" properties for two footprints "ipv4:192.0.2.0/24" and "ipv6:2001:db8::/32".
POST /propmap/lookup/cdnifci-pid HTTP/1.1
HOST: alto.example.com
Content-Type: application/alto-propmapparams+json
Accept: application/alto-propmap+json,application/alto-error+json
Content-Length:
{
"entities": [
"ipv4:192.0.2.0/24",
"ipv6:2001:db8::/32"
],
"properties": [ "my-default-cdnifci.cdni-fci-capabilities",
"my-default-networkmap.pid" ]
}
HTTP/1.1 200 OK
Content-Length: ###
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-fci-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-fci-capabilities": [
{"capability-type": "FCI.DeliveryProtocol",
"capability-value": {"delivery-protocols": ["http/1.1"]}}],
"my-default-networkmap.pid": "pid3"
}
}
}
In this example, here is a client want to request updates for the properties "cdni-fci-capabilities" and "pid" for two footprints "ipv4:192.0.2.0/24" and "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: ###
{ "add": {
"property-map-including-capability-property": {
"resource-id": "filtered-cdnifci-property-map",
"input": {
"properties": [ "my-default-cdnifci.cdni-fci-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: "http://alto.example.com/updates/streams/1414213562373"}
event: application/alto-cdnifci+json,my-fci-stream
data: { ... full filtered unified property map ... }
event: application/merge-patch+json,my-fci-stream
data: {
data: "property-map":
data: {
data: "meta": {
data: "dependent-vtags": [
data: {"resource-id": "my-default-cdnifci",
data: "tag": "2beeac8ee23c3dd1e98a73fd30df80ece9fa5627"},
data: {"resource-id": "my-default-networkmap",
data: "tag": "7915dc0290c2705481c491a2b4ffbec482b3cf63"}
data: ]
data: },
data: "ipv4:192.0.2.0/24":
data: {
data: "my-default-cdnifci.cdni-fci-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,my-fci-stream
data: {[
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: }
data: ]}
As proposed in Section 7.2 of [RFC8006], "CDNI Metadata Footprint Types" registry is requested. A new footprint type is to be registred, listed in Table 1.
| Footprint Type | Description | Specification |
|---|---|---|
| altopid | A list of PID-names | Section 4 of RFCthis |
[RFC Editor: Please replace RFCthis with the published RFC number for this document.]
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 2.
| Identifier | Entity Address Encoding | Hierarchy & Inheritance |
|---|---|---|
| asn | See Section 6.1.1.2 | None |
| countrycode | See Section 6.1.2.2 | None |
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 registred, listed in Table 3.
| Identifier | Intended Semantics |
|---|---|
| cdni-fci-capabilities | An array of CDNI FCI capability objects |
As an extension of the base ALTO protocol [RFC7285], this document fits into the architecture of the base protocol, and hence the Security Considerations (Section 15) of the base protocol fully apply when this extension is provided by an ALTO server.
In the context of CDNI FCI, 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 FCI 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, dCDNs can provide a uCDN with limited capabilities and smaller footprint coverage so that dCDNs can avoid transferring traffic for a uCDN which they should have to transfer.
For confidentiality 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).
For availability of ALTO services, an attacker may get the potential huge full CDNI FCI resources from an ALTO server in a dCDN continuously to unnecessarily consume bandwidth resources of that ALTO server or may query filtered CDNI FCI services with complex capabilities to unnecessarily consume computation resources of an ALTO server.
Protection strategies described in RFC 7285 can solve problems mentioned above, however, the isolation of full/filtered CDNI FCI resources should also be considered.
If a dCDN signs agreements with multiple uCDNs, it must isolate full/filtered CDNI FCI resources for different uCDNs in that uCDNs will not redirect requests which should not have to be served by this dCDN to this dCDN and it may not disclose extra information to uCDNs.
To avoid this risk, a dCDN could consider generating URIs of different full/filtered CDNI FCI resources by hashing its company ID, a uCDN's company ID as well as their agreements. A dCDN SHOULD avoid expoing all full/filtered CDNI FCI resources in one of its IRDs.
The authors would like to thank Daryl Malas, Matt Caulfield for their timely reviews and invaluable comments.
Jan Seedorf is partially supported by the GreenICN project (GreenICN: Architecture and Applications of Green Information Centric Networking), a research project supported jointly by the European Commission under its 7th Framework Program (contract no. 608518) and the National Institute of Information and Communications Technology (NICT) in Japan (contract no. 167). The views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of the GreenICN project, the European Commission, or NICT.
| [I-D.ietf-alto-incr-update-sse] | Roome, W. and Y. Yang, "ALTO Incremental Updates Using Server-Sent Events (SSE)", Internet-Draft draft-ietf-alto-incr-update-sse-17, July 2019. |
| [I-D.ietf-alto-path-vector] | Gao, K., Lee, Y., Randriamasy, S., Yang, Y. and J. Zhang, "ALTO Extension: Path Vector", Internet-Draft draft-ietf-alto-path-vector-08, July 2019. |
| [I-D.ietf-alto-unified-props-new] | Roome, W., Randriamasy, S., Yang, Y., Zhang, J. and K. Gao, "Unified Properties for the ALTO Protocol", Internet-Draft draft-ietf-alto-unified-props-new-09, September 2019. |
| [I-D.jenkins-alto-cdn-use-cases] | Niven-Jenkins, B., Watson, G., Bitar, N., Medved, J. and S. Previdi, "Use Cases for ALTO within CDNs", Internet-Draft draft-jenkins-alto-cdn-use-cases-03, June 2012. |