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Internet Engineering Task Force (IETF) O. Finkelman
Request for Comments: 8804 Qwilt
Category: Standards Track S. Mishra
ISSN: 2070-1721 Verizon
September 2020
Content Delivery Network Interconnection (CDNI) Request Routing
Extensions
Abstract
Open Caching architecture is a use case of Content Delivery Network
Interconnection (CDNI) in which the commercial Content Delivery
Network (CDN) is the upstream CDN (uCDN) and the ISP caching layer
serves as the downstream CDN (dCDN). This document defines
extensions to the CDNI Metadata Interface (MI) and the Footprint &
Capabilities Advertisement interface (FCI). These extensions are
derived from requirements raised by Open Caching but are also
applicable to CDNI use cases in general.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc8804.
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 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.
Table of Contents
1. Introduction
1.1. Terminology
1.2. Requirements Language
2. Redirect Target Capability
2.1. DNS Redirect Target
2.2. HTTP Redirect Target
2.3. Properties of Redirect Target Capability Object
2.4. DnsTarget Object
2.4.1. DnsTarget Example
2.5. HttpTarget Object
2.5.1. HttpTarget Example
2.6. Usage Example
3. Fallback Target Server Address
3.1. Properties of Fallback Target Generic Metadata Object
3.2. Usage Example
3.3. uCDN Addressing Considerations
4. IANA Considerations
4.1. CDNI Payload Types
4.1.1. CDNI FCI RedirectTarget Payload Type
4.1.2. CDNI MI FallbackTarget Payload Type
5. Security Considerations
5.1. Confidentiality and Privacy
6. References
6.1. Normative References
6.2. Informative References
Acknowledgements
Authors' Addresses
1. Introduction
The Streaming Video Alliance [SVA] is a global association that works
to solve streaming video challenges in an effort to improve end-user
experience and adoption. The Open Caching Working Group [OCWG] of
the Streaming Video Alliance [SVA] is focused on the delegation of
video delivery requests from commercial CDNs to a caching layer at
the ISP's network. Open Caching architecture is a specific use case
of CDNI where the commercial CDN is the upstream CDN (uCDN) and the
ISP caching layer is the downstream CDN (dCDN). The Open Caching
Request Routing Functional Specification [OC-RR] defines the Request
Routing process and the interfaces that are required for its
provisioning. This document defines the CDNI metadata object
[RFC8006] and the CDNI Footprint and Capabilities object [RFC8008]
that are required for Open Caching Request Routing:
* Redirect Target Capability (for dCDN advertising redirect target
address)
* Fallback Target Metadata (for uCDN configuring fallback target
address)
This document also registers CDNI Payload Types [RFC7736] for these
defined objects.
For consistency with other CDNI documents, this document follows the
CDNI convention of uCDN (upstream CDN) and dCDN (downstream CDN) to
represent the commercial CDN and ISP caching layer, respectively.
1.1. Terminology
The following terms are used throughout this document:
FQDN Fully Qualified Domain Name
CDN Content Delivery Network
Additionally, this document reuses the terminology defined in
[RFC6707], [RFC7336], [RFC8006], [RFC8007], and [RFC8008].
Specifically, we use the following CDNI acronyms:
FCI Footprint & Capabilities Advertisement interface (see
[RFC8008])
MI Metadata Interface (see [RFC8006])
uCDN Upstream CDN (see [RFC7336])
dCDN Downstream CDN (see [RFC7336])
RT Redirection Target. Endpoint for redirection from uCDN to
dCDN.
RR Request Router. An element responsible for routing user
requests, typically using HTTP redirect or DNS CNAME,
depending on the use case.
1.2. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2. Redirect Target Capability
Iterative CDNI Request Redirection is defined in Section 1.1 of
[RFC7336] and elaborated by examples in Sections 3.2 and 3.4 of
[RFC7336]. A Redirection Target (RT) is defined in Section 2 of
[RFC7975] for Recursive Request Redirection as:
| The endpoint to which the User Agent is redirected. In CDNI, an
| RT may point to a number of different components, some examples
| include a surrogate in the same CDN as the request router, a
| request router in a dCDN, or a surrogate in a dCDN.
In this document, we adopt the same definition of the RT for the
Iterative Request Redirect use case. This use case requires the
provisioning of the RT address to be used by the uCDN in order to
redirect to the dCDN. RT addresses can vary between different
footprints (for example, between different regions), and they may
also change over time (for example, as a result of network problems).
Given this variable and dynamic nature of the redirect target
address, it may not be suitable to advertise it during bootstrap. A
more dynamic and footprint-oriented interface is required.
Section 4.3 of [RFC7336] suggests that it could be one of the roles
of the FCI [RFC8008]. Following this suggestion, we have therefore
chosen to use the CDNI Footprint & Capabilities Advertisement
interface for redirect target address advertisement.
Use cases:
* Footprint: The dCDN may want to have a different target per
footprint. Note that a dCDN may spread across multiple
geographies. This makes it easier to route client requests to a
nearby request router. Though this can be achieved using a single
canonical name and "Geo DNS", such that in different geographies
the same hostname is resolved to different IP address, that
approach has limitations; for example, a client may be using a
third-party DNS resolver, making it impossible for the redirector
to detect where the client is located, or Geo DNS granularity may
be too rough for the requirement of the application.
* Scaling: The dCDN may choose to scale its Request Routing service
by deploying more request routers in new locations and advertise
them via an updatable interface like the FCI.
The Redirect Target capability object is used to indicate the target
address the uCDN should use in order to redirect a client to the
dCDN. A target may be attached to a specific uCDN host, attached to
a list of uCDN hosts, or used globally for all the hosts of the uCDN.
When a dCDN is attaching the redirect target to a specific uCDN host
or a list of uCDN hosts, the dCDN MUST advertise the hosts within the
Redirect Target capability object as "redirecting-hosts". In this
case, the uCDN can redirect to that dCDN address, only if the User
Agent request was to one of these uCDN hosts.
If the Redirect Target capability object does not contain a target or
the target is empty, the uCDN MUST interpret it as "no target
available for these uCDN hosts for the specified footprint". In case
such a target was already advertised in a previous FCI object, the
uCDN MUST interpret it as an update that deletes the previous
redirect target.
2.1. DNS Redirect Target
A redirect target for DNS redirection is an FQDN used as an alias in
a CNAME record response (see [RFC1034]) of the uCDN DNS router. Note
that DNS routers make routing decisions based on either the DNS
resolver's IP address or the client IP subnet when EDNS0 client-
subnet (ECS) is used (see [RFC7871]). The dCDN may choose to
advertise redirect targets and footprints to cover both cases, such
that the uCDN resolution would route the DNS query to different dCDN
CNAMEs according to client subnet or dCDN resolver IP address. This
method further allows the dCDN DNS to optimize the resolution by
localizing the target CNAMEs. A uCDN implementation SHOULD prefer
routing based on client IP subnet when the ECS option is present. A
dCDN implementation using the ECS option MUST be aware of the privacy
drawbacks listed in Section 2 of [RFC7871] and SHOULD follow the
guidelines provided in Section 11.1 of [RFC7871].
2.2. HTTP Redirect Target
A redirect target for HTTP redirection is the URI to be used as the
value for the Location header of an HTTP redirect 3xx response,
typically a 302 (Found) (see Section 7.1.2 of [RFC7231] and
Section 6.4 of [RFC7231]).
2.3. Properties of Redirect Target Capability Object
The Redirect Target capability object consists of the following
properties:
Property: redirecting-hosts
Description: One or more uCDN hosts to which this redirect target
is attached. A redirecting host SHOULD be a host that was
published in a HostMatch object by the uCDN as defined in
Section 4.1.2 of [RFC8006].
Type: A list of Endpoint objects (see Section 4.3.3 of [RFC8006])
Mandatory-to-Specify: No. If absent or empty, the redirect
target applies to all hosts of the redirecting uCDN.
Property: dns-target
Description:
Target CNAME record for DNS redirection.
Type:
DnsTarget object (see Section 2.4)
Mandatory-to-Specify:
No. If the dns-target is absent or empty, the uCDN MUST
interpret it as "no dns-target available".
Property: http-target
Description:
Target URI for an HTTP redirect.
Type:
HttpTarget object (see Section 2.5)
Mandatory-to-Specify:
No. If the http-target is absent or empty, the uCDN MUST
interpret it as "no http-target available".
The following is an example of a Redirect Target capability object
serialization that advertises a dCDN target address that is attached
to a specific list of uCDN "redirecting-hosts". A uCDN host that is
included in that list can redirect to the advertised dCDN redirect
target. The capabilities object is serialized as a JSON object as
defined in Section 5.1 of [RFC8008].
{
"capabilities": [
{
"capability-type": "FCI.RedirectTarget",
"capability-value": {
"redirecting-hosts": [
"a.service123.ucdn.example.com",
"b.service123.ucdn.example.com"
],
"dns-target": {
"host": "service123.ucdn.dcdn.example.com"
},
"http-target": {
"host": "us-east1.dcdn.example.com",
"path-prefix": "/cache/1/",
"include-redirecting-host": true
}
},
"footprints": [
<Footprint objects>
]
}
]
}
2.4. DnsTarget Object
The DnsTarget object gives the target address for the DNS response to
delegate from the uCDN to the dCDN.
Property: host
Description: The host property is a hostname or an IP address,
without a port number.
Type: Endpoint object as defined in Section 4.3.3 of [RFC8006],
with the limitation that it SHOULD NOT include a port number
and, in case a port number is present, the uCDN MUST ignore it.
Mandatory-to-Specify: Yes.
2.4.1. DnsTarget Example
The following is an example of the DnsTarget object:
{
"host": "service123.ucdn.dcdn.example.com"
}
The following is an example of a DNS query for uCDN address
"a.service123.ucdn.example.com" and the corresponding CNAME
redirection response:
Query:
a.service123.ucdn.example.com:
type A, class IN
Response:
NAME: a.service123.ucdn.example.com, TYPE: CNAME, CLASS: IN,
TTL: 120, RDATA: service123.ucdn.dcdn.example.com
2.5. HttpTarget Object
The HttpTarget object gives the necessary information to construct
the target Location URI for HTTP redirection.
Property: host
Description: Hostname or IP address and an optional port, i.e.,
the host and port of the authority component of the URI as
described in Section 3.2 of [RFC3986].
Type: Endpoint object as defined in Section 4.3.3 of [RFC8006].
Mandatory-to-Specify: Yes.
Property: scheme
Description: A URI scheme to be used in the redirect response
location construction. When present, the uCDN MUST use the
provided scheme in for HTTP redirection to the dCDN.
Type: A URI scheme as defined in Section 3.1 of [RFC3986],
represented as a JSON string. The scheme MUST be either "http"
or "https".
Mandatory-to-Specify: No. If this property is absent or empty,
the uCDN request router MUST use the same scheme as was used in
the original request before redirection.
Property: path-prefix
Description: A path prefix for the HTTP redirect Location header.
The original path is appended after this prefix.
Type: A prefix of a path-absolute as defined in Section 3.3 of
[RFC3986]. The prefix MUST end with a trailing slash to
indicate the end of the last path segment in the prefix.
Mandatory-to-Specify: No. If this property is absent or empty,
the uCDN MUST NOT prepend a path-prefix to the original content
path, i.e., the original path MUST appear in the Location URI
right after the authority component.
Property: include-redirecting-host
Description: A flag indicating whether or not to include the
redirecting host as the first path segment after the path-
prefix. If set to true and a "path-prefix" is used, the uCDN
redirecting host MUST be added as a separate path segment after
the path-prefix and before the original URL path. If set to
true and there is no path-prefix, the uCDN redirecting host
MUST be prepended as the first path segment in the redirect
URL.
Type: Boolean.
Mandatory-to-Specify: No. Default value is False.
2.5.1. HttpTarget Example
The following is an example of the HttpTarget object with a "scheme",
a "path-prefix", and "include-redirecting-host" properties:
{
"host": "us-east1.dcdn.example.com",
"scheme": "https",
"path-prefix": "/cache/1/",
"include-redirecting-host": true
}
The following is an example of an HTTP request for content at uCDN
host "a.service123.ucdn.example.com" and the corresponding HTTP
response with a Location header, used for redirecting the client to
the dCDN, constructed according to the HttpTarget object from the
above example:
Request:
GET /vod/1/movie.mp4 HTTP/1.1
Host: a.service123.ucdn.example.com
Response:
HTTP/1.1 302 Found
Location: https://us-east1.dcdn.example.com/cache/1/
a.service123.ucdn.example.com/vod/1/movie.mp4
2.6. Usage Example
Before requests can be routed from the uCDN to the dCDN, the CDNs
must exchange service configurations between them. Using the MI, the
uCDN advertises out-of-band its hosts to the dCDN; each host is
designated by a hostname and has its own specific metadata (see
Section 4.1.2 of [RFC8006]). Using the FCI, the dCDN advertises
(also out-of-band) the redirect target address defined in Section 2.3
for the relevant uCDN hosts. The following is a generalized example
of the message flow between a uCDN and a dCDN. For simplicity, we
focus on the sequence of messages between the uCDN and dCDN and not
on how they are passed.
dCDN uCDN
+ +
| |
(1) | MI: host: s123.ucdn.example.com |
| host-metadata: < metadata > |
<-------------------------------------------------------+
| |
(2) | FCI: capability-type: FCI.RedirectTarget |
| redirecting-hosts: s123.ucdn.example.com |
| target host: us-east1.dcdn.example.com |
+------------------------------------------------------->
| |
| |
+ +
Figure 1: Redirect Target Address Advertisement
Explanation:
(1) The uCDN advertises a host (s123.ucdn.example.com) with the host
metadata.
(2) The dCDN advertises its FCI objects to the uCDN, including a
Redirect Target capability object that contains the redirect
target address (us-east1.dcdn.example.com) specified for that
uCDN host.
Once the redirect target has been set, the uCDN can start redirecting
user requests to the dCDN. The following is a generic sequence of
redirection using the host and redirect target that were advertised
in Figure 1.
End User dCDN uCDN RR
+ + +
| | |
(1) | Request sent s123.ucdn.example.com |
+-----------------------+----------------------->
| | |
(2) | Redirect to us-east1.dcdn.example.com |
<-----------------------+-----------------------+
| | |
(3) | Request us-east1.dcdn.example.com |
+-----------------------> |
| | |
(4) | Response | |
<-----------------------+ |
| | |
+ + +
Figure 2: Generic Request Redirection Sequence
Explanation:
(1) The End User sends a request (DNS or HTTP) to the uCDN Request
Router (RR).
(2) Using the previously advertised Redirect Target, the uCDN
redirects the request to the dCDN.
(3) The End User sends a request to the dCDN.
(4) The dCDN either sends a response or reroutes it, for example, to
a dCDN surrogate.
3. Fallback Target Server Address
Open Caching requires that the uCDN provides a fallback target server
to the dCDN to be used in cases where the dCDN cannot properly handle
the request. To avoid redirect loops, the fallback target server's
address at the uCDN MUST be different from the original uCDN address
from which the client was redirected to the dCDN. The uCDN MUST
avoid further redirection when receiving the client request at the
fallback target. The Fallback Target is defined as a generic
metadata object (see Section 3.2 of [RFC8006]).
Use cases:
* Failover: A dCDN request router receives a request but has no
caches to which it can route the request. This can happen in the
case of failures or temporary network overload.
* No coverage: A dCDN request router receives a request from a
client located in an area inside the footprint but not covered by
the dCDN caches or outside the dCDN footprint coverage. In such
cases, the router may choose to redirect the request back to the
uCDN fallback address.
* Error: A cache may receive a request that it cannot properly
serve, for example, some of the metadata objects for that service
were not properly acquired. In this case, the cache's "default
action" may be to "redirect back to uCDN".
The Fallback Target metadata object is used to indicate the target
address the dCDN should redirect a client to when falling back to the
uCDN. The fallback target address is represented as an Endpoint
object as defined in Section 4.3.3 of [RFC8006].
In DNS redirection, a CNAME record is used as the fallback target
address.
In HTTP redirection, a hostname is used as the fallback target
address.
When using HTTP redirect to route a client request back to the uCDN,
it is the dCDN's responsibility to use the original URL path as the
client would have used for the original uCDN request, stripping, if
needed, the dCDN path-prefix and/or the uCDN hostname from the
redirect URL that may have been used to request the content from the
dCDN.
3.1. Properties of Fallback Target Generic Metadata Object
The MI.FallbackTarget generic metadata object consists of the
following two properties:
Property: host
Description: Target address to which the dCDN can redirect the
client.
Type: Endpoint object as defined in Section 4.3.3 of [RFC8006],
with the limitation that in case of DNS delegation, it SHOULD
NOT include a port number, and in case a port number is
present, the dCDN MUST ignore it.
Mandatory-to-Specify: Yes.
Property: scheme
Description: A URI scheme to be used in the redirect response
location construction. When present, the dCDN MUST use this
scheme in case of HTTP redirection to the uCDN fallback
address.
Type: A URI scheme as defined in Section 3.1 of [RFC3986],
represented as a JSON string. The scheme MUST be either "http"
or "https".
Mandatory-to-Specify: No. In case of HTTP redirection to
fallback, if this property is absent or empty, the dCDN
redirecting entity MUST use the same scheme as in the request
received by the dCDN.
The following is an example of an MI.FallbackTarget generic metadata
object that designates the host address the dCDN should use as
fallback address to redirect back to the uCDN:
{
"generic-metadata-type": "MI.FallbackTarget",
"generic-metadata-value":
{
"host": "fallback-a.service123.ucdn.example",
"scheme": "https"
}
}
3.2. Usage Example
The uCDN advertises out-of-band the fallback target address to the
dCDN, so that the dCDN may redirect a request back to the uCDN in
case the dCDN cannot serve it. Using the MI, the uCDN advertises its
hosts to the dCDN, along with their specific host metadata (see
Section 4.1.2 of [RFC8006]). The Fallback Target generic metadata
object is encapsulated within the "host-metadata" property of each
host. The following is an example of a message flow between a uCDN
and a dCDN. For simplicity, we focus on the sequence of messages
between the uCDN and dCDN, not on how they are passed.
dCDN uCDN
+ +
| |
(1) | MI: host: s123.ucdn.example.com |
| host-metadata: |
| < metadata objects > |
| < MI.FallbackTarget |
| host: fallback-a.service123.ucdn.example > |
| < metadata objects > |
<-------------------------------------------------------+
| |
(2) | FCI: capability-type: FCI.RedirectTarget |
| redirecting-hosts: s123.ucdn.example.com |
| target host: us-east1.dcdn.example.com |
+------------------------------------------------------->
| |
| |
+ +
Figure 3: Advertisement of Host Metadata with Fallback Target
Explanation:
(1) The uCDN advertises a host (s123.ucdn.example.com) with the host
metadata. The host-metadata property contains an
MI.FallbackTarget generic metadata object.
(2) The dCDN advertises its FCI objects to the uCDN, including a
Redirect Target capability object that contains the redirect
target address (us-east1.dcdn.example.com) specified for that
uCDN host.
The following is a generic sequence of redirection using the
configurations that were advertised in Figure 3. In this case, the
dCDN redirects back to the uCDN fallback target address.
End User dCDN uCDN fallback uCDN RR
+ + + +
| | | |
(1) | Request sent s123.ucdn.example.com | |
+-------------------+-------------------+------------------->
| | | |
(2) | Redirect to us-east1.dcdn.example.com | |
<-------------------+-------------------+-------------------+
| | | |
(3) | Request us-east1.dcdn.example.com | |
+-------------------> | |
| | | |
(4) | Redirect back to fallback-a.service123.ucdn.example |
<-------------------+ | |
| | | |
(5) | Request fallback-a.service123.ucdn.example |
+---------------------------------------> |
| | | |
(6) | Response | | |
<-------------------+-------------------+ |
| | | |
+ + + +
Figure 4: Redirection to Fallback Target
Explanation:
(1) The End User sends a request (DNS or HTTP) to the uCDN Request
Router (RR).
(2) Using the previously advertised Redirect Target, the uCDN
redirects the request to the dCDN.
(3) The End User sends a request to the dCDN.
(4) The dCDN cannot handle the request and therefore redirects it
back to the uCDN fallback target address.
(5) The End User sends the request to the uCDN fallback target
address.
(6) The uCDN either sends a response or reroutes it, for example, to
a uCDN surrogate.
3.3. uCDN Addressing Considerations
When advertising fallback addresses to the dCDN, the uCDN SHOULD
consider the failure use cases that may lead the dCDN to route
requests to uCDN fallback. In extreme dCDN network failures or under
denial-of-service (DoS) attacks, requests coming from a large segment
or multiple segments of the dCDN may be routed back to the uCDN. The
uCDN SHOULD therefore design its fallback addressing scheme and its
available resources accordingly. A favorable approach would be for
the uCDN to use a different fallback target address for each uCDN
host, enabling it to load balance the requests using the same methods
as it would for its original hosts. See Sections 4.1.2 and 4.1.3 of
[RFC8006] for a detailed description of how to use GenericMetadata
objects within the HostMatch object advertised in the HostIndex of
the uCDN.
4. IANA Considerations
4.1. CDNI Payload Types
IANA has registered the following CDNI Payload Types in the "CDNI
Payload Types" registry defined in [RFC7736]:
+====================+===============+
| Payload Type | Specification |
+====================+===============+
| FCI.RedirectTarget | RFC 8804 |
+--------------------+---------------+
| MI.FallbackTarget | RFC 8804 |
+--------------------+---------------+
Table 1
4.1.1. CDNI FCI RedirectTarget Payload Type
Purpose: The purpose of this payload type is to distinguish FCI
advertisement objects for redirect target.
Interface: FCI
Encoding: See Section 2.3.
4.1.2. CDNI MI FallbackTarget Payload Type
Purpose: The purpose of this payload type is to distinguish
FallbackTarget MI objects (and any associated capability
advertisement).
Interface: MI/FCI
Encoding: See Section 3.1.
5. Security Considerations
This specification defines extensions to the CDNI Metadata Interface
(MI) and the Footprint & Capabilities Advertisement interface (FCI).
As such, it is subject to the security and privacy considerations
defined in Section 8 of [RFC8006] and in Section 7 of [RFC8008],
respectively.
5.1. Confidentiality and Privacy
The Redirect Target capability object potentially reveals information
about the internal structure of the dCDN network. A third party
could intercept the FCI transactions and use the information to
attack the dCDN. The same is also true for the Fallback Target
generic metadata object, as it may reveal information about the
internal structure of the uCDN, exposing it to external exploits.
Implementations of the FCI and MI MUST therefore use strong
authentication and encryption and strictly follow the directions for
securing the interface as defined for the Metadata Interface in
Section 8.3 of [RFC8006].
6. References
6.1. Normative References
[RFC1034] Mockapetris, P., "Domain names - concepts and facilities",
STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987,
<https://www.rfc-editor.org/info/rfc1034>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, DOI 10.17487/RFC3986, January 2005,
<https://www.rfc-editor.org/info/rfc3986>.
[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>.
[RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Semantics and Content", RFC 7231,
DOI 10.17487/RFC7231, June 2014,
<https://www.rfc-editor.org/info/rfc7231>.
[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>.
[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>.
[RFC8007] Murray, R. and B. Niven-Jenkins, "Content Delivery Network
Interconnection (CDNI) Control Interface / Triggers",
RFC 8007, DOI 10.17487/RFC8007, December 2016,
<https://www.rfc-editor.org/info/rfc8007>.
[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>.
6.2. Informative References
[OC-RR] Finkelman, O., Ed., Hofmann, J., Klein, E., Mishra, S.,
Ma, K., Sahar, D., and B. Zurat, "Open Cache Request
Routing Functional Specification", Version 1.1, November
2016, <https://www.streamingvideoalliance.org/books/open-
cache-request-routing-functional-specification/>.
[OCWG] Streaming Video Alliance, "Open Caching",
<https://www.streamingvideoalliance.org/technical-groups/
open-caching/>.
[RFC7736] Ma, K., "Content Delivery Network Interconnection (CDNI)
Media Type Registration", RFC 7736, DOI 10.17487/RFC7736,
December 2015, <https://www.rfc-editor.org/info/rfc7736>.
[RFC7871] Contavalli, C., van der Gaast, W., Lawrence, D., and W.
Kumari, "Client Subnet in DNS Queries", RFC 7871,
DOI 10.17487/RFC7871, May 2016,
<https://www.rfc-editor.org/info/rfc7871>.
[SVA] "Streaming Video Alliance",
<https://www.streamingvideoalliance.org>.
Acknowledgements
The authors thank Nir B. Sopher for reality checks against production
use cases; his contribution is significant to this document. The
authors also thank Ben Niven-Jenkins for his review and feedback and
Kevin J. Ma for his guidance throughout the development of this
document, including his regular reviews.
Authors' Addresses
Ori Finkelman
Qwilt
6, Ha'harash
Hod HaSharon 4524079
Israel
Email: ori.finkelman.ietf@gmail.com
Sanjay Mishra
Verizon
13100 Columbia Pike
Silver Spring, MD 20904
United States of America
Email: sanjay.mishra@verizon.com