Internet DRAFT - draft-ietf-cdni-request-routing-extensions
draft-ietf-cdni-request-routing-extensions
Network Working Group O. Finkelman
Internet-Draft Qwilt
Intended status: Standards Track S. Mishra
Expires: May 23, 2020 Verizon
November 20, 2019
CDNI Request Routing Extensions
draft-ietf-cdni-request-routing-extensions-08
Abstract
Open Caching architecture is a use case of Content Delivery Networks
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). The extensions specified in
this document to the CDNI Metadata Interface (MI) and the Footprint
and Capabilities Interface (FCI) are derived from requirements raised
by Open Caching but are also applicable to CDNI use cases in general.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on May 23, 2020.
Copyright Notice
Copyright (c) 2019 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
Finkelman & Mishra Expires May 23, 2020 [Page 1]
Internet-Draft CDNI Request Routing Extensions November 2019
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 . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
1.2. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. Redirect Target Capability . . . . . . . . . . . . . . . . . 4
2.1. DNS Redirect Target . . . . . . . . . . . . . . . . . . . 5
2.2. HTTP Redirect Target . . . . . . . . . . . . . . . . . . 5
2.3. Properties of Redirect Target Capability Object . . . . . 5
2.4. DnsTarget Object . . . . . . . . . . . . . . . . . . . . 7
2.4.1. DNS Target Example . . . . . . . . . . . . . . . . . 7
2.5. HttpTarget Object . . . . . . . . . . . . . . . . . . . . 8
2.5.1. HTTP Target Example . . . . . . . . . . . . . . . . . 9
2.6. Usage Example . . . . . . . . . . . . . . . . . . . . . . 10
3. Fallback Target Address Metadata . . . . . . . . . . . . . . 11
3.1. Properties of Fallback Target Address Metadata Object . . 12
3.2. Usage Example . . . . . . . . . . . . . . . . . . . . . . 13
3.3. uCDN addressing considerations . . . . . . . . . . . . . 15
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16
4.1. CDNI Payload Types . . . . . . . . . . . . . . . . . . . 16
4.1.1. CDNI FCI RedirectTarget Payload Type . . . . . . . . 16
4.1.2. CDNI MI FallbackTarget Payload Type . . . . . . . . . 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
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 Internet Service Provider's (ISP) 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
Specification [OC-RR] defines the Request Routing process and the
interfaces that are required for its provisioning. This document
defines and registers CDNI metadata object [RFC8006] and CDNI
Finkelman & Mishra Expires May 23, 2020 [Page 2]
Internet-Draft CDNI Request Routing Extensions November 2019
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
defined objects:
o Redirect Target Capability (for dCDN advertising redirect target
address)
o Fallback Target Metadata (for uCDN configuring fallback target
address)
1.1. Terminology
The following terms are used throughout this document:
o FQDN - Fully Qualified Domain Name
o 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:
o FCI - Footprint and Capability Interface (see [RFC8008])
o MI - Metadata Interface (see [RFC8006])
o uCDN, dCDN - Upstream CDN and Downstream CDN respectively (see
[RFC7336])
o RT - Redirection Target. Endpoint for redirection from uCDN to
dCDN.
o 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.
Finkelman & Mishra Expires May 23, 2020 [Page 3]
Internet-Draft CDNI Request Routing Extensions November 2019
2. Redirect Target Capability
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
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, a
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 and Capabilities interface for redirect target
address advertisement.
Use cases
o 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.
o 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, a list of
uCDN hosts, or used globally for all the hosts of the uCDN.
Finkelman & Mishra Expires May 23, 2020 [Page 4]
Internet-Draft CDNI Request Routing Extensions November 2019
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 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
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].
Finkelman & Mishra Expires May 23, 2020 [Page 5]
Internet-Draft CDNI Request Routing Extensions November 2019
Type: A list of Endpoint objects (see Section 4.3.3 of
[RFC8006])
Mandatory-to-Specify: No. If not present, 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 not present or
empty the uCDN MUST interpret it as "no dns-target available".
Property: http-target
Description: Target URI for a HTTP redirect.
Type: HttpTarget object (see Section 2.5)
Mandatory-to-Specify: No. If the http-target is not present 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]
Finkelman & Mishra Expires May 23, 2020 [Page 6]
Internet-Draft CDNI Request Routing Extensions November 2019
{
"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. DNS Target Example
The following is an example of DnsTarget object:
{
"host": "service123.ucdn.dcdn.example.com"
}
Finkelman & Mishra Expires May 23, 2020 [Page 7]
Internet-Draft CDNI Request Routing Extensions November 2019
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.
Finkelman & Mishra Expires May 23, 2020 [Page 8]
Internet-Draft CDNI Request Routing Extensions November 2019
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. HTTP Target Example
Example of 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
}
Example of a 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:
Finkelman & Mishra Expires May 23, 2020 [Page 9]
Internet-Draft CDNI Request Routing Extensions November 2019
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]. The dCDN, using the FCI, advertises, also out-of-band,
the redirect target address object defined in Section 2.3 for the
relevant uCDN hosts. The following is a generalized example of the
message flow between an upstream CDN and a downstream 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
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
FCI.RedirectTarget 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
Finkelman & Mishra Expires May 23, 2020 [Page 10]
Internet-Draft CDNI Request Routing Extensions November 2019
redirection using the host and redirect target that were advertised
in Figure 1 above.
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 requests redirection sequence
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 Address Metadata
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
Finkelman & Mishra Expires May 23, 2020 [Page 11]
Internet-Draft CDNI Request Routing Extensions November 2019
o 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.
o 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.
o 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. 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 Address Metadata Object
The MI.FallbackTarget Metadata object consists of the following
single property:
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.
Finkelman & Mishra Expires May 23, 2020 [Page 12]
Internet-Draft CDNI Request Routing Extensions November 2019
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
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 an
upstream CDN and a downstream dCDN. For simplicity, we focus on the
sequence of messages between the uCDN and dCDN, not on how they are
passed.
Finkelman & Mishra Expires May 23, 2020 [Page 13]
Internet-Draft CDNI Request Routing Extensions November 2019
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
1. The uCDN advertises a host (s123.ucdn.example.com) with the host
metadata. The host-metadata property contains a
MI.FallbackTarget object.
2. The dCDN advertises its FCI objects to the uCDN including a
FCI.RedirectTarget 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 above. In this case
the dCDN redirects back to the uCDN fallback target address.
Finkelman & Mishra Expires May 23, 2020 [Page 14]
Internet-Draft CDNI Request Routing Extensions November 2019
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
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 handled 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
Finkelman & Mishra Expires May 23, 2020 [Page 15]
Internet-Draft CDNI Request Routing Extensions November 2019
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
4.1. CDNI Payload Types
This document requests the registration of the following CDNI Payload
Types under the IANA "CDNI Payload Types" registry defined in
[RFC7736]:
+--------------------+---------------+
| Payload Type | Specification |
+--------------------+---------------+
| FCI.RedirectTarget | RFCthis |
| MI.FallbackTarget | RFCthis |
+--------------------+---------------+
[RFC Editor: Please replace RFCthis with the published RFC number for
this document.]
4.1.1. CDNI FCI RedirectTarget Payload Type
Purpose: The purpose of this payload type is to distinguish
RedirectTarget FCI objects
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
Finkelman & Mishra Expires May 23, 2020 [Page 16]
Internet-Draft CDNI Request Routing Extensions November 2019
5. Security Considerations
This specification is in accordance with the CDNI Metadata Interface
and the CDNI Request Routing: Footprint and Capabilities Semantics.
As such, it is subject to the security and privacy considerations as
defined in Section 8 of [RFC8006] and in Section 7 of [RFC8008]
respectively.
5.1. Confidentiality and Privacy
The Redirect Target FCI 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 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. 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.
7. References
7.1. 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>.
Finkelman & Mishra Expires May 23, 2020 [Page 17]
Internet-Draft CDNI Request Routing Extensions November 2019
[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>.
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/>.
Finkelman & Mishra Expires May 23, 2020 [Page 18]
Internet-Draft CDNI Request Routing Extensions November 2019
[OCWG] "Open Caching Home Page",
<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 Home Page",
<https://www.streamingvideoalliance.org>.
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
USA
Email: sanjay.mishra@verizon.com
Finkelman & Mishra Expires May 23, 2020 [Page 19]
