draft-ietf-cdni-request-routing-extensions-07.txt   draft-ietf-cdni-request-routing-extensions-08.txt 
Network Working Group O. Finkelman Network Working Group O. Finkelman
Internet-Draft Qwilt Internet-Draft Qwilt
Intended status: Standards Track S. Mishra Intended status: Standards Track S. Mishra
Expires: March 26, 2020 Verizon Expires: May 23, 2020 Verizon
September 23, 2019 November 20, 2019
CDNI Request Routing Extensions CDNI Request Routing Extensions
draft-ietf-cdni-request-routing-extensions-07 draft-ietf-cdni-request-routing-extensions-08
Abstract Abstract
Open Caching is a use case of Content Delivery Networks Open Caching architecture is a use case of Content Delivery Networks
Interconnetion (CDNI) in which the commercial Content Delivery Interconnection (CDNI) in which the commercial Content Delivery
Network (CDN) is the upstream CDN (uCDN) and the ISP caching layer Network (CDN) is the upstream CDN (uCDN) and the ISP caching layer
serves as the downstream CDN (dCDN). The extensions specified in serves as the downstream CDN (dCDN). The extensions specified in
this document to the CDNI Metadata and FCI interfaces are derived this document to the CDNI Metadata Interface (MI) and the Footprint
from requirements raised by Open Caching but are also applicable to and Capabilities Interface (FCI) are derived from requirements raised
CDNI use cases in general. by Open Caching but are also applicable to CDNI use cases in general.
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 Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
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This Internet-Draft will expire on March 26, 2020. This Internet-Draft will expire on May 23, 2020.
Copyright Notice Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. Redirect Target Capability . . . . . . . . . . . . . . . . . 3 1.2. Requirements Language . . . . . . . . . . . . . . . . . . 3
2.1. Properties of Redirect Target Capability Object . . . . . 5 2. Redirect Target Capability . . . . . . . . . . . . . . . . . 4
2.2. DnsTarget . . . . . . . . . . . . . . . . . . . . . . . . 6 2.1. DNS Redirect Target . . . . . . . . . . . . . . . . . . . 5
2.3. HttpTarget . . . . . . . . . . . . . . . . . . . . . . . 7 2.2. HTTP Redirect Target . . . . . . . . . . . . . . . . . . 5
2.4. Usage Example . . . . . . . . . . . . . . . . . . . . . . 9 2.3. Properties of Redirect Target Capability Object . . . . . 5
3. Fallback Target Address Metadata . . . . . . . . . . . . . . 10 2.4. DnsTarget Object . . . . . . . . . . . . . . . . . . . . 7
3.1. Properties of Fallback Target Address Metadata Object . . 11 2.4.1. DNS Target Example . . . . . . . . . . . . . . . . . 7
3.2. Usage Example . . . . . . . . . . . . . . . . . . . . . . 12 2.5. HttpTarget Object . . . . . . . . . . . . . . . . . . . . 8
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14 2.5.1. HTTP Target Example . . . . . . . . . . . . . . . . . 9
4.1. CDNI Payload Types . . . . . . . . . . . . . . . . . . . 14 2.6. Usage Example . . . . . . . . . . . . . . . . . . . . . . 10
4.1.1. CDNI FCI RedirectTarget Payload Type . . . . . . . . 14 3. Fallback Target Address Metadata . . . . . . . . . . . . . . 11
4.1.2. CDNI MI FallbackTarget Payload Type . . . . . . . . . 14 3.1. Properties of Fallback Target Address Metadata Object . . 12
5. Security Considerations . . . . . . . . . . . . . . . . . . . 14 3.2. Usage Example . . . . . . . . . . . . . . . . . . . . . . 13
5.1. Confidentiality and Privacy . . . . . . . . . . . . . . . 15 3.3. uCDN addressing considerations . . . . . . . . . . . . . 15
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 15 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 15 4.1. CDNI Payload Types . . . . . . . . . . . . . . . . . . . 16
7.1. Normative References . . . . . . . . . . . . . . . . . . 15 4.1.1. CDNI FCI RedirectTarget Payload Type . . . . . . . . 16
7.2. Informative References . . . . . . . . . . . . . . . . . 16 4.1.2. CDNI MI FallbackTarget Payload Type . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16 5. Security Considerations . . . . . . . . . . . . . . . . . . . 17
5.1. Confidentiality and Privacy . . . . . . . . . . . . . . . 17
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 17
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 17
7.1. Normative References . . . . . . . . . . . . . . . . . . 17
7.2. Informative References . . . . . . . . . . . . . . . . . 18
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19
1. Introduction 1. Introduction
The Open Caching working group of the Streaming Video Alliance (SVA) The Streaming Video Alliance [SVA] is a global association that works
is focused on the delegation of video delivery requests from to solve streaming video challenges in an effort to improve end-user
commercial CDNs to a caching layer at the Internet Service Provider's experience and adoption. The Open Caching Working Group [OCWG] of
(ISP) network. Open Caching is a specific use case of CDNI where the the Streaming Video Alliance [SVA] is focused on the delegation of
commercial CDN is the upstream CDN (uCDN) and the ISP caching layer video delivery requests from commercial CDNs to a caching layer at
is the downstream CDN (dCDN). This document defines and registers the Internet Service Provider's (ISP) network. Open Caching
CDNI generic metadata object [RFC8006] and CDNI Footprint and architecture is a specific use case of CDNI where the commercial CDN
Capabilities object [RFC8008] that are required for Open Caching is the upstream CDN (uCDN) and the ISP caching layer is the
request routing. For consistency with other CDNI documents this downstream CDN (dCDN). The Open Caching Request Routing
document follows the CDNI convention of uCDN (upstream CDN) and dCDN Specification [OC-RR] defines the Request Routing process and the
(downstream CDN) to represent the commerical CDN and ISP caching interfaces that are required for its provisioning. This document
layer respectively. defines and registers CDNI metadata object [RFC8006] and CDNI
Footprint and Capabilities object [RFC8008] that are required for
Open Caching Request Routing. 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.
This document also registers CDNI Payload Types [RFC7736] for the This document also registers CDNI Payload Types [RFC7736] for the
defined objects: defined objects:
o Redirect Target Capability (for dCDN advertising redirect target o Redirect Target Capability (for dCDN advertising redirect target
address) address)
o Fallback Target Metadata (for uCDN configuring fallback target o Fallback Target Metadata (for uCDN configuring fallback target
address) address)
1.1. Terminology 1.1. Terminology
The following terms are used throughout this document: The following terms are used throughout this document:
o FQDN - Fully Qualified Domain Name o FQDN - Fully Qualified Domain Name
o CDN - Content Delivery Network o CDN - Content Delivery Network
Additionaly, this document reuses the terminology defined in Additionally, this document reuses the terminology defined in
[RFC6707], [RFC7336], [RFC8006], [RFC8007], and [RFC8008]. [RFC6707], [RFC7336], [RFC8006], [RFC8007], and [RFC8008].
Specifically, we use the following CDNI acronyms: Specifically, we use the following CDNI acronyms:
o FCI - Footprint and Capability Interface (see [RFC8008]) o FCI - Footprint and Capability Interface (see [RFC8008])
o MI - Metadata Interface (see [RFC8006]) o MI - Metadata Interface (see [RFC8006])
o uCDN, dCDN - Upstream CDN and Downstream CDN respectively (see o uCDN, dCDN - Upstream CDN and Downstream CDN respectively (see
[RFC7336]) [RFC7336])
o RT - Redirection Target. Endpoint for redirection from uCDN to o RT - Redirection Target. Endpoint for redirection from uCDN to
dCDN. dCDN.
o RR - Request Router. An element responsible for routing user o RR - Request Router. An element responsible for routing user
requests. 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 2. Redirect Target Capability
Iterative request redirection is defined in Section 1.1 of [RFC7336] Iterative request redirection is defined in Section 1.1 of [RFC7336]
and elaborated by examples in Sections 3.2 and 3.4 of [RFC7336]. A 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 Redirection Target (RT) is defined in Section 2 of [RFC7975] for
Recursive Request Redirection as: Recursive Request Redirection as:
"The endpoint to which the User Agent is redirected. In CDNI, a "The endpoint to which the User Agent is redirected. In CDNI, a
RT may point to a number of different components, some examples RT may point to a number of different components, some examples
include a surrogate in the same CDN as the request router, a include a surrogate in the same CDN as the request router, a
request router in a dCDN, or a surrogate in a dCDN". request router in a dCDN, or a surrogate in a dCDN".
In this document we adopt the same defintion of the RT for the In this document we adopt the same definition of the RT for the
Iterative Request Redirect use case. This use case requires 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 provisioning of the RT address to be used by the uCDN in order to
redirect to the dCDN. RT addresses can vary between different redirect to the dCDN. RT addresses can vary between different
footprints, for example, between different regions, and they may also footprints, for example, between different regions, and they may also
change over time, for example as a result of network problems. Given change over time, for example as a result of network problems. Given
this variable and dynamic nature of the redirect target address, it this variable and dynamic nature of the redirect target address, it
may not be suitable to advertise it during bootstrap. A more dynamic may not be suitable to advertise it during bootstrap. A more dynamic
and footprint oriented interface is required. Section 4.3 of and footprint oriented interface is required. Section 4.3 of
[RFC7336] suggests that it could be one of the roles of the FCI [RFC7336] suggests that it could be one of the roles of the FCI
[RFC8008]. Following this suggestion we have, therefore, chosen to [RFC8008]. Following this suggestion, we have therefore, chosen to
use the CDNI Footprint and Capabilities interface for redirect target use the CDNI Footprint and Capabilities interface for redirect target
address advertisement. address advertisement.
Use cases Use cases
o Footprint: The dCDN may want to have a different target per o Footprint: The dCDN may want to have a different target per
footprint. Note that a dCDN may spread across multiple footprint. Note that a dCDN may spread across multiple
geographies. This makes it easier to route client requests to a geographies. This makes it easier to route client requests to a
nearby request router. Though this can be achieved using a single nearby request router. Though this can be achieved using a single
canonical name and Geo DNS, that approach has limitations; for canonical name and "Geo DNS", such that in different geographies
example a client may be using a third party DNS resolver, making the same hostname is resolved to different IP address, that
it impossible for the redirector to detect where the client is approach has limitations; for example a client may be using a
located, or Geo DNS granularity may be too rough for the third party DNS resolver, making it impossible for the redirector
requirement of the application. to detect where the client is located, or Geo DNS granularity may
be too rough for the requirement of the application.
o Scaling: The dCDN may choose to scale its request routing service o Scaling: The dCDN may choose to scale its request routing service
by deploying more request routers in new locations and advertise by deploying more request routers in new locations and advertise
them via an updatable interface like the FCI. them via an updatable interface like the FCI.
The Redirect Target capability object is used to indicate the target The Redirect Target capability object is used to indicate the target
address the uCDN should use in order to redirect a client to the address the uCDN should use in order to redirect a client to the
dCDN. A target may be attached to a specific uCDN host, a list of dCDN. A target may be attached to a specific uCDN host, a list of
uCDN hosts, or used globally for all the hosts of the uCDN. 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 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 or a list of uCDN hosts, the dCDN MUST advertise the hosts within the
Redirect Target capability object as "redirecting-hosts". In this Redirect Target capability object as "redirecting-hosts". In this
case, the uCDN can redirect to that dCDN address, only if the User case, the uCDN can redirect to that dCDN address, only if the User
Agent request was to one of these uCDN hosts. Agent request was to one of these uCDN hosts.
A redirect target for DNS redirection is an IPv4 address used as an A
record response, an IPv6 address used as an AAAA record response or a
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
address when EDNS0 client-subnet is used (see [RFC7871]). The dCDN
may choose to advertise redirect targets and footprints to cover both
cases. A uCDN DNS router implemenation SHOULD prefer routing based
on client IP address when it is available.
A redirect target for HTTP redirection is the URI to be used as the
value for the Location header of a HTTP redirect 3xx response,
typically a 302 (Found) (see Section 7.1.2 of [RFC7231] and section
6.4 of [RFC7231]).
If the redirect target capability object does not contain a target or If the redirect target capability object does not contain a target or
the target is empty, the uCDN MUST interpret it as "no target the target is empty, the uCDN MUST interpret it as "no target
available for these uCDN hosts for the specified footprint". In case available for these uCDN hosts for the specified footprint". In case
such a target was already advertised in a previous FCI object, the such a target was already advertised in a previous FCI object, the
uCDN MUST interperet it as an update that deletes the previous uCDN MUST interpret it as an update that deletes the previous
redirect target. redirect target.
2.1. Properties of Redirect Target Capability Object 2.1. DNS Redirect Target
A redirect target for DNS redirection is a 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 a different
dCDN CNAMEs according 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 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 a 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 The Redirect Target capability object consists of the following
properties: properties:
Property: redirecting-hosts Property: redirecting-hosts
Description: One or more uCDN hosts to which this redirect Description: One or more uCDN hosts to which this redirect
target is attached. A redirecting host SHOULD be a host that target is attached. A redirecting host SHOULD be a host that
was published in a HostMatch object by the uCDN as defined in was published in a HostMatch object by the uCDN as defined in
Section 4.1.2 of [RFC8006]. Section 4.1.2 of [RFC8006].
Type: A list of Endpoint objects (see Section 4.3.3 of Type: A list of Endpoint objects (see Section 4.3.3 of
[RFC8006]) [RFC8006])
Mandatory-to-Specify: No. If not present, or empty, the Mandatory-to-Specify: No. If not present, or empty, the
redirect target applies to all hosts of the redirecting uCDN. redirect target applies to all hosts of the redirecting uCDN.
Property: dns-target Property: dns-target
Description: Target address for a DNS A record, AAAA record or Description: Target CNAME record for DNS redirection.
CNAME record.
Type: DnsTarget object (see Section 2.2) Type: DnsTarget object (see Section 2.4)
Mandatory-to-Specify: No. If the dns-target is not present or Mandatory-to-Specify: No. If the dns-target is not present or
empty the uCDN MUST interpret it as "no dns-target available". empty the uCDN MUST interpret it as "no dns-target available".
Property: http-target Property: http-target
Description: Target URI for a HTTP redirect. Description: Target URI for a HTTP redirect.
Type: HttpTarget object (see Section 2.3) Type: HttpTarget object (see Section 2.5)
Mandatory-to-Specify: No. If the http-target is not present or Mandatory-to-Specify: No. If the http-target is not present or
empty the uCDN MUST interpret it as "no http-target available". empty the uCDN MUST interpret it as "no http-target available".
The following is an example of a Redirect Target capability object The following is an example of a Redirect Target capability object
serialization that advertises a dCDN target address that is attached serialization that advertises a dCDN target address that is attached
to a specific list of uCDN "redirecting-hosts". A uCDN host that is to a specific list of uCDN "redirecting-hosts". A uCDN host that is
included in that list can redirect to the advertised dCDN redirect included in that list can redirect to the advertised dCDN redirect
target. The capabilities object is serialized as a JSON object as target. The capabilities object is serialized as a JSON object as
defined in Section 5 of [RFC8008] defined in Section 5.1 of [RFC8008]
{ {
"capabilities": [ "capabilities": [
{ {
"capability-type": "FCI.RedirectTarget", "capability-type": "FCI.RedirectTarget",
"capability-value": { "capability-value": {
"redirecting-hosts": [ "redirecting-hosts": [
"a.service123.ucdn.example.com", "a.service123.ucdn.example.com",
"b.service123.ucdn.example.com" "b.service123.ucdn.example.com"
], ],
"dns-target": { "dns-target": {
skipping to change at page 6, line 46 skipping to change at page 7, line 29
"include-redirecting-host": true "include-redirecting-host": true
} }
}, },
"footprints": [ "footprints": [
<Footprint objects> <Footprint objects>
] ]
} }
] ]
} }
2.2. DnsTarget 2.4. DnsTarget Object
The DnsTarget object gives the target address for the DNS response to The DnsTarget object gives the target address for the DNS response to
delegate from the uCDN to the dCDN. delegate from the uCDN to the dCDN.
Property: host Property: host
Description: The host property is a hostname or an IP address, Description: The host property is a hostname or an IP address,
without a port number. without a port number.
Type: Endpoint object as defined in Section 4.3.3 of [RFC8006] Type: Endpoint object as defined in Section 4.3.3 of [RFC8006]
with the limitation that it SHOULD NOT include a port number with the limitation that it SHOULD NOT include a port number
and, in case a port number is present, the uCDN MUST ignore it. and, in case a port number is present, the uCDN MUST ignore it.
Mandatory-to-Specify: Yes. Mandatory-to-Specify: Yes.
2.4.1. DNS Target Example
The following is an example of DnsTarget object: The following is an example of DnsTarget object:
{ {
"host": "service123.ucdn.dcdn.example.com" "host": "service123.ucdn.dcdn.example.com"
} }
The following is an example of a DNS query for uCDN address The following is an example of a DNS query for uCDN address
"a.service123.ucdn.example.com" and the corresponding CNAME "a.service123.ucdn.example.com" and the corresponding CNAME
redirection response: redirection response:
Query: Query:
a.service123.ucdn.example.com: a.service123.ucdn.example.com:
type A, class IN type A, class IN
Response: Response:
a.service123.ucdn.example.com: NAME: a.service123.ucdn.example.com, TYPE: CNAME, CLASS: IN,
type CNAME, class IN, cname service123.ucdn.dcdn.example.com TTL: 120, RDATA: service123.ucdn.dcdn.example.com
2.3. HttpTarget 2.5. HttpTarget Object
The HttpTarget object gives the necessary information to construct The HttpTarget object gives the necessary information to construct
the target Location URI for HTTP redirection. the target Location URI for HTTP redirection.
Property: host Property: host
Description: Hostname or IP address and an optional port, i.e., Description: Hostname or IP address and an optional port, i.e.,
the host and port of the authority component of the URI as the host and port of the authority component of the URI as
described in Section 3.2 of [RFC3986]. described in Section 3.2 of [RFC3986].
Type: Endpoint object as defined in Section 4.3.3 of [RFC8006]. Type: Endpoint object as defined in Section 4.3.3 of [RFC8006].
Mandatory-to-Specify: Yes. 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 Property: path-prefix
Description: A path prefix for the HTTP redirect Location Description: A path prefix for the HTTP redirect Location
header. The original path is appended after this prefix. header. The original path is appended after this prefix.
Type: A prefix of a path-absolute as defined in Section 3.3 of Type: A prefix of a path-absolute as defined in Section 3.3 of
[RFC3986]. The prefix MUST end with a trailing slash, to [RFC3986]. The prefix MUST end with a trailing slash, to
indicate the end of the last path segment in the prefix. indicate the end of the last path segment in the prefix.
Mandatory-to-Specify: No. If this property is absent or empty, Mandatory-to-Specify: No. If this property is absent or empty,
skipping to change at page 8, line 29 skipping to change at page 9, line 29
redirecting host MUST be added as a separate path segment after redirecting host MUST be added as a separate path segment after
the path-prefix and before the original URL path. If set to the path-prefix and before the original URL path. If set to
true and there is no path-prefix, the uCDN redirecting host true and there is no path-prefix, the uCDN redirecting host
MUST be prepended as the first path segment in the redirect MUST be prepended as the first path segment in the redirect
URL. URL.
Type: Boolean. Type: Boolean.
Mandatory-to-Specify: No. Default value is False. Mandatory-to-Specify: No. Default value is False.
Example of HttpTarget object with a path-prefix and include- 2.5.1. HTTP Target Example
redirecting-host:
Example of HttpTarget object with a "scheme", a "path-prefix", and
"include-redirecting-host" properties:
{ {
"host": "us-east1.dcdn.example.com", "host": "us-east1.dcdn.example.com",
"scheme": "https",
"path-prefix": "/cache/1/", "path-prefix": "/cache/1/",
"include-redirecting-host": true "include-redirecting-host": true
} }
Example of a HTTP request for content at uCDN host Example of a HTTP request for content at uCDN host
"a.service123.ucdn.example.com" and the corresponding HTTP response "a.service123.ucdn.example.com" and the corresponding HTTP response
with Location header used for redirecting the client to the dCDN with a Location header, used for redirecting the client to the dCDN,
using the the http-target in the above example: constructed according to the HttpTarget object from the above
example:
Request: Request:
GET /vod/1/movie.mp4 HTTP/1.1 GET /vod/1/movie.mp4 HTTP/1.1
Host: a.service123.ucdn.example.com Host: a.service123.ucdn.example.com
Response: Response:
HTTP/1.1 302 Found HTTP/1.1 302 Found
Location: http://us-east1.dcdn.example.com/cache/1/ Location: https://us-east1.dcdn.example.com/cache/1/
a.service123.ucdn.example.com/vod/1/movie.mp4 a.service123.ucdn.example.com/vod/1/movie.mp4
2.4. Usage Example 2.6. Usage Example
Before requests can be routed from the uCDN to the dCDN the CDNs must Before requests can be routed from the uCDN to the dCDN the CDNs must
exchange service configurations between them. Using the MI the uCDN exchange service configurations between them. Using the MI, the uCDN
advertises out-of-band its hosts to the dCDN, each host is designated advertises out-of-band its hosts to the dCDN, each host is designated
by a host name and has its own specific metadata (see Section 4.1.2 by a hostname and has its own specific metadata (see Section 4.1.2 of
of [RFC8006]. The dCDN, using the FCI, advertises, also out-of-band, [RFC8006]. The dCDN, using the FCI, advertises, also out-of-band,
the redirect target address object defined in Section 2.1 for the the redirect target address object defined in Section 2.3 for the
relevant uCDN hosts. The following is a generalized example of the relevant uCDN hosts. The following is a generalized example of the
message flow between an upstream CDN and a downstream dCDN. For message flow between an upstream CDN and a downstream dCDN. For
simplicity, we focus on the sequence of messages between the uCDN and simplicity, we focus on the sequence of messages between the uCDN and
dCDN and not on how they are passed. dCDN and not on how they are passed.
dCDN uCDN dCDN uCDN
+ + + +
| | | |
(1) | MI: host: s123.ucdn.example.com | (1) | MI: host: s123.ucdn.example.com |
| host-metadata: < metadata > | | host-metadata: < metadata > |
<-------------------------------------------------------+ <-------------------------------------------------------+
| | | |
(2) | FCI: capability-type: FCI.RedirectTarget | (2) | FCI: capability-type: FCI.RedirectTarget |
| redirecting-hosts: us-east1.dcdn.example.com | | redirecting-hosts: s123.ucdn.example.com |
| target host: s123.ucdn.example.com | | target host: us-east1.dcdn.example.com |
+-------------------------------------------------------> +------------------------------------------------------->
| | | |
| | | |
+ + + +
Figure 1: Redirect target address advertisement Figure 1: Redirect target address advertisement
1. The uCDN advertises a host (s123.ucdn.example.com) with the host 1. The uCDN advertises a host (s123.ucdn.example.com) with the host
metadata. metadata.
2. The dCDN adveritses its FCI objects to the uCDN including a 2. The dCDN advertises its FCI objects to the uCDN including a
FCI.RedirectTarget object that contains the redirect target FCI.RedirectTarget object that contains the redirect target
address (us-east1.dcdn.example.com) specified for that uCDN host. address (us-east1.dcdn.example.com) specified for that uCDN host.
Once the redirect target has been set, the uCDN can start redirecting Once the redirect target has been set, the uCDN can start redirecting
user requests to the dCDN. The following is a generic sequence of user requests to the dCDN. The following is a generic sequence of
redirection using the host and redirect target that were advertised redirection using the host and redirect target that were advertised
in Figure 1 above. in Figure 1 above.
End User dCDN uCDN RR End User dCDN uCDN RR
+ + + + + +
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case of failures or temporary network overload. case of failures or temporary network overload.
o No coverage: A dCDN request router receives a request from a o No coverage: A dCDN request router receives a request from a
client located in an area inside the footprint but not covered by client located in an area inside the footprint but not covered by
the dCDN caches or outside the dCDN footprint coverage. In such the dCDN caches or outside the dCDN footprint coverage. In such
cases, the router may choose to redirect the request back to the cases, the router may choose to redirect the request back to the
uCDN fallback address. uCDN fallback address.
o Error: A cache may receive a request that it cannot properly o Error: A cache may receive a request that it cannot properly
serve, for example, some of the metadata objects for that service serve, for example, some of the metadata objects for that service
were not properly acquired. In this case, the cache may resolve were not properly acquired. In this case, the cache's "default
to redirect back to uCDN. action" may be to "redirect back to uCDN".
The Fallback target metadata object is used to indicate the target The Fallback target metadata object is used to indicate the target
address the dCDN should use in order to redirect a client back to the address the dCDN should redirect a client to when falling back to the
uCDN. Fallback target is represented as endpoint objects as defined uCDN. Fallback target address is represented as an endpoint object
in section 4.3.3 of [RFC8006]. as defined in Section 4.3.3 of [RFC8006].
The uCDN fallback target address may be used as a DNS A record, AAAA In DNS redirection a CNAME record is used as the fallback target
record or CNAME record in case of DNS redirection or a hostname for address.
HTTP redirect.
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, 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 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 client would have used for the original uCDN request, stripping, if
needed, the dCDN path-prefix and/or the uCDN hostname from the 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 redirect URL that may have been used to request the content from the
dCDN. dCDN.
3.1. Properties of Fallback Target Address Metadata Object 3.1. Properties of Fallback Target Address Metadata Object
skipping to change at page 11, line 49 skipping to change at page 13, line 7
Description: Target address to which the dCDN can redirect the Description: Target address to which the dCDN can redirect the
client. client.
Type: Endpoint object as defined in Section 4.3.3 of [RFC8006] Type: Endpoint object as defined in Section 4.3.3 of [RFC8006]
with the limitation that in case of DNS delegation it SHOULD with the limitation that in case of DNS delegation it SHOULD
NOT include a port number and, in case a port number is NOT include a port number and, in case a port number is
present, the dCDN MUST ignore it. present, the dCDN MUST ignore it.
Mandatory-to-Specify: Yes. 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.
Example of a MI.FallbackTarget Metadata object that designates the Example of a MI.FallbackTarget Metadata object that designates the
host address the dCDN should use as fallback address to redirect back host address the dCDN should use as fallback address to redirect back
to the uCDN. to the uCDN.
{ {
"generic-metadata-type": "MI.FallbackTarget", "generic-metadata-type": "MI.FallbackTarget",
"generic-metadata-value": "generic-metadata-value":
{ {
"host": "fallback-a.service123.ucdn.example" "host": "fallback-a.service123.ucdn.example",
"scheme": "https"
} }
} }
3.2. Usage Example 3.2. Usage Example
The uCDN advertises out-of-band the fallback target address to the 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 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 case the dCDN cannot serve it. Using the MI the uCDN advertises its
hosts to the dCDN, along with their specific host metadata (see hosts to the dCDN, along with their specific host metadata (see
Section 4.1.2 of [RFC8006]. The Fallback Target generic metadata Section 4.1.2 of [RFC8006]. The Fallback Target generic metadata
skipping to change at page 12, line 38 skipping to change at page 14, line 17
| | | |
(1) | MI: host: s123.ucdn.example.com | (1) | MI: host: s123.ucdn.example.com |
| host-metadata: | | host-metadata: |
| < metadata objects > | | < metadata objects > |
| < MI.FallbackTarget | | < MI.FallbackTarget |
| host: fallback-a.service123.ucdn.example > | | host: fallback-a.service123.ucdn.example > |
| < metadata objects > | | < metadata objects > |
<-------------------------------------------------------+ <-------------------------------------------------------+
| | | |
(2) | FCI: capability-type: FCI.RedirectTarget | (2) | FCI: capability-type: FCI.RedirectTarget |
| redirecting-hosts: us-east1.dcdn.example.com | | redirecting-hosts: s123.ucdn.example.com |
| target host: s123.ucdn.example.com | | target host: us-east1.dcdn.example.com |
+-------------------------------------------------------> +------------------------------------------------------->
| | | |
| | | |
+ + + +
Figure 3: Advertisement of host metadata with Fallback Target Figure 3: Advertisement of host metadata with Fallback Target
1. The uCDN advertises a host (s123.ucdn.example.com) with the host 1. The uCDN advertises a host (s123.ucdn.example.com) with the host
metadata. The host-metadata property contains a metadata. The host-metadata property contains a
MI.FallbackTarget object. MI.FallbackTarget object.
2. The dCDN adveritses its FCI objects to the uCDN including a 2. The dCDN advertises its FCI objects to the uCDN including a
FCI.RedirectTarget object that contains the redirect target FCI.RedirectTarget object that contains the redirect target
address (us-east1.dcdn.example.com) specified for that uCDN host. address (us-east1.dcdn.example.com) specified for that uCDN host.
The following is a generic sequence of redirection using the The following is a generic sequence of redirection using the
configurations that were advertised in Figure 3 above. In this case configurations that were advertised in Figure 3 above. In this case
the dCDN redirects back to the uCDN fallback target address. the dCDN redirects back to the uCDN fallback target address.
End User dCDN uCDN fallback uCDN RR End User dCDN uCDN fallback uCDN RR
+ + + + + + + +
| | | | | | | |
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4. The dCDN cannot handled the request and, therefore, redirects it 4. The dCDN cannot handled the request and, therefore, redirects it
back to the uCDN fallback target address. back to the uCDN fallback target address.
5. The End User sends the request to the uCDN fallback target 5. The End User sends the request to the uCDN fallback target
address. address.
6. The uCDN either sends a response or reroutes it, for example, to 6. The uCDN either sends a response or reroutes it, for example, to
a uCDN surrogate. 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 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. IANA Considerations
4.1. CDNI Payload Types 4.1. CDNI Payload Types
This document requests the registration of the following CDNI Payload This document requests the registration of the following CDNI Payload
Types under the IANA "CDNI Payload Types" registry defined in Types under the IANA "CDNI Payload Types" registry defined in
[RFC7736]: [RFC7736]:
+--------------------+---------------+ +--------------------+---------------+
| Payload Type | Specification | | Payload Type | Specification |
skipping to change at page 14, line 33 skipping to change at page 16, line 39
[RFC Editor: Please replace RFCthis with the published RFC number for [RFC Editor: Please replace RFCthis with the published RFC number for
this document.] this document.]
4.1.1. CDNI FCI RedirectTarget Payload Type 4.1.1. CDNI FCI RedirectTarget Payload Type
Purpose: The purpose of this payload type is to distinguish Purpose: The purpose of this payload type is to distinguish
RedirectTarget FCI objects RedirectTarget FCI objects
Interface: FCI Interface: FCI
Encoding: see Section 2.1 Encoding: see Section 2.3
4.1.2. CDNI MI FallbackTarget Payload Type 4.1.2. CDNI MI FallbackTarget Payload Type
Purpose: The purpose of this payload type is to distinguish Purpose: The purpose of this payload type is to distinguish
FallbackTarget MI objects (and any associated capability FallbackTarget MI objects (and any associated capability
advertisement) advertisement)
Interface: MI/FCI Interface: MI/FCI
Encoding: see Section 3.1 Encoding: see Section 3.1
skipping to change at page 15, line 7 skipping to change at page 17, line 15
5. Security Considerations 5. Security Considerations
This specification is in accordance with the CDNI Metadata Interface This specification is in accordance with the CDNI Metadata Interface
and the CDNI Request Routing: Footprint and Capabilities Semantics. and the CDNI Request Routing: Footprint and Capabilities Semantics.
As such, it is subject to the security and privacy considerations as As such, it is subject to the security and privacy considerations as
defined in Section 8 of [RFC8006] and in Section 7 of [RFC8008] defined in Section 8 of [RFC8006] and in Section 7 of [RFC8008]
respectively. respectively.
5.1. Confidentiality and Privacy 5.1. Confidentiality and Privacy
The redirect Target FCI object potentially exposes information about The Redirect Target FCI object potentially reveals information about
the internal strcture of the dCDN network. A third party could the internal structure of the dCDN network. A third party could
intercept the FCI transactions and use the information to attack the intercept the FCI transactions and use the information to attack the
dCDN. An implemenation of the FCI MUST therefore use strong dCDN. The same is also true for the Fallback Target Metadata object
authentication and encryption and strictly follow the directions for as it may reveal information about the internal structure of the
securing the interface as defined for the Metadata Interface in uCDN, exposing it to external exploits. Implementations of the FCI
Section 8.3 of [RFC8006]. 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. Acknowledgements 6. Acknowledgements
The authors thank Nir B. Sopher for reality checks against production The authors thank Nir B. Sopher for reality checks against production
use cases, his contribution is significant to this document. The use cases, his contribution is significant to this document. The
authors also thank Ben Niven-Jenkins for his review and feedback and authors also thank Ben Niven-Jenkins for his review and feedback and
Kevin J. Ma for his guidance throughout the development of this Kevin J. Ma for his guidance throughout the development of this
document including his regular reviews. document including his regular reviews.
7. References 7. References
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(CDNI) Request Routing: Footprint and Capabilities (CDNI) Request Routing: Footprint and Capabilities
Semantics", RFC 8008, DOI 10.17487/RFC8008, December 2016, Semantics", RFC 8008, DOI 10.17487/RFC8008, December 2016,
<https://www.rfc-editor.org/info/rfc8008>. <https://www.rfc-editor.org/info/rfc8008>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
7.2. Informative References 7.2. Informative References
[OC-RR] Finkelman, O., Ed., Hofmann, J., Klein, E., Mishra, S.,
Ma, K., Sahar, D., and B. Zurat, "Open Caching - Request
Routing Functional Specification", Version 1.1, October
2019, <https://www.streamingvideoalliance.org/books/open-
cache-request-routing-functional-specification/>.
[OCWG] "Open Caching Home Page",
<https://www.streamingvideoalliance.org/technical-groups/
open-caching/>.
[RFC7736] Ma, K., "Content Delivery Network Interconnection (CDNI) [RFC7736] Ma, K., "Content Delivery Network Interconnection (CDNI)
Media Type Registration", RFC 7736, DOI 10.17487/RFC7736, Media Type Registration", RFC 7736, DOI 10.17487/RFC7736,
December 2015, <https://www.rfc-editor.org/info/rfc7736>. December 2015, <https://www.rfc-editor.org/info/rfc7736>.
[RFC7871] Contavalli, C., van der Gaast, W., Lawrence, D., and W. [RFC7871] Contavalli, C., van der Gaast, W., Lawrence, D., and W.
Kumari, "Client Subnet in DNS Queries", RFC 7871, Kumari, "Client Subnet in DNS Queries", RFC 7871,
DOI 10.17487/RFC7871, May 2016, DOI 10.17487/RFC7871, May 2016,
<https://www.rfc-editor.org/info/rfc7871>. <https://www.rfc-editor.org/info/rfc7871>.
[SVA] "Streaming Video Alliance Home Page",
<https://www.streamingvideoalliance.org>.
Authors' Addresses Authors' Addresses
Ori Finkelman Ori Finkelman
Qwilt Qwilt
6, Ha'harash 6, Ha'harash
Hod HaSharon 4524079 Hod HaSharon 4524079
Israel Israel
Email: ori.finkelman.ietf@gmail.com Email: ori.finkelman.ietf@gmail.com
Sanjay Mishra Sanjay Mishra
Verizon Verizon
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