Network Working Group O. Finkelman
Internet-Draft Qwilt
Intended status: Standards Track S. Mishra
Expires: August 16, 2018 Verizon
February 12, 2018
CDNI SVA Request Routing Extensions
draft-finkelman-cdni-rr-sva-extensions-00
Abstract
The Open Caching working group of the Streaming Video Alliance is
focused on the delegation of video delivery requests from commercial
CDNs to a caching layer at the ISP. In that aspect, Open Caching 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).
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
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
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This Internet-Draft will expire on August 16, 2018.
Copyright Notice
Copyright (c) 2018 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
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 2
2. Redirect Targets Capability Object . . . . . . . . . . . . . 3
2.1. Redirect Target Address . . . . . . . . . . . . . . . . . 4
3. uCDN fallback metadata . . . . . . . . . . . . . . . . . . . 5
3.1. Fallback Address . . . . . . . . . . . . . . . . . . . . 6
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
4.1. CDNI Payload Types . . . . . . . . . . . . . . . . . . . 7
4.1.1. CDNI FCI RedirectTargets Payload Type . . . . . . . . 7
4.1.2. CDNI MI Fallback Payload Type . . . . . . . . . . . . 7
5. Security Considerations . . . . . . . . . . . . . . . . . . . 8
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8
7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 8
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
8.1. Normative References . . . . . . . . . . . . . . . . . . 8
8.2. Informative References . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction
This document defines objects needed for Open Caching request
routing. For that purpose it extends CDNI metadata [RFC8006] and
CDNI Footprint and Capabilities [RFC8008]. For consistency, this
document follows the CDNI notation of uCDN (the commercial CDN) and
dCDN (the ISP caching layer).
The CDNI metadata interface is described in [RFC8006].
The CDNI footprint and capability interface is described in
[RFC8008].
1.1. Terminology
This document reuses the terminology defined in [RFC6707], [RFC8006],
[RFC8007], and [RFC8008].
Additionally, the following terms are used throughout this document
and are defined as follows:
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o SVA - Streaming Video Alliance.
o OC - SVA Open Caching.
o RR - Request Router.
o CP - Content Provider (video).
2. Redirect Targets Capability Object
Open Caching uses iterative request redirect as defined in [RFC7336].
In order for the uCDN to redirect to the dCDN it requires redirect
target addresses. The redirect targets are defined as part of the
Footprint and Capabilities interface.
Use cases
* Footprint: The dCDN may want to have different targets per
footprint. Note that a dCDN may spread across multiple
geographies. This makes it easier to route client request to a
nearby request router. Though this can be achieved using a
single canonical name and geo DNS, that approach has
limitations, for example a client may be using third party DNS
resolver, making it impossible for the redirector to detect
where the client is located.
* 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 addresses the uCDN should use in order to redirect a client
to the uCDN. Targets are represented as endpoint objects as
defined in [RFC8006].
Property: target-addresses
Description: Target addresses to which the uCDN can redirect
the client, listed in order of priority.
Type: Array of target-address objects (see Section 2.1)
Mandatory-to-Specify: No. The dCDN can advertise the redirect
targets to the uCDN statically, or by some other means
Example of Redirect Target Capability object (which contains two
target-address objects) that describes which target addreses in the
dCDN the uCDN should use in order to redirect the client to the dCDN.
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{
"capabilities": [
{
"capability-type": "FCI.RedirectTargetes",
"capability-value": {
"target-addresses": [
"endpoints": [
"a.service123.dcdn.example.com",
"b.service123.dcdn.example.com"
],
"endpoints": ["c.service123.dcdn.example.com"]
]
},
"footprints": [
<Footprint objects>
]
}
]
}
2.1. Redirect Target Address
A target-address object describes the address to be used by the uCDN
when redirecting a client to the dCDN.
Endpoints within a target-address object MUST be treated as
equivalent/equal. A dCDN can specify an array of target-addresses,
ordered by preference, within a RedirectTargets capability object.
Then, for each target-address object ranked by preference, a dCDN can
specify an array of endpoints that are equivalent (e.g., a pool of
servers that are not behind a load balancer).
Property: endpoints
Description: Endpoint addresses to which the uCDN can redirect
the client. If multiple endpoints are specified, they are all
equal, i.e., the list is not ordered by preference.
Type: Array of Endpoint objects (see section 4.3.3 of
[RFC8006]).
Mandatory-to-Specify: Yes.
Example of Target Address object (which contains two endpoint
objects) that descibes which endpoint addreses in the dCDN the uCDN
should use in order to to redirect the client to the dCDN.
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"endpoints": [
"a.service123.dcdn.example.com",
"b.service123.dcdn.example.com"
]
3. uCDN fallback metadata
Open Caching requires that the uCDN should provide fallback servers
to the dCDN to be used in cases where the dCDN cannot properly handle
the request. To avoid redirect loops, the fallback servers'
addresses at the uCDN MUST be differnet than the original address at
the uCDN from which the client was redirected to the dCDN. The uCDN
MUST avoid further redirection when receiving the client request at
the fallback server address. The fallback server 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 to. This can happen
in the case of failures, or temporary network overload. In
these 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 may
resolve to redirect back to uCDN.
The Fallback metadata object is used to indicate the server
addresses the dCDN should use in order to redirect a client back
to the uCDN. Fallbacks addresses are represented as endpoint
objects as defined in [RFC8006].
Property: fallback-addresses
Description: Fallback Addresses to which the uCDN can redirect
the client, listed in order of priority.
Type: Array of fallback-address objects (see Section 3.1)
Mandatory-to-Specify: No. The dCDN can advertise the redirect
addresses to the uCDN statically, or by some other means
Example of MI.Fallback Metadata object (which contains two fallback-
address objects) that describes which hosts addreses in the uCDN the
dCDN should use in order to redirect the client back to a fallback
address at the uCDN.
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{
"generic-metadata-type": "MI.Fallback",
"generic-metadata-value":
{
"fallback-addresses": [
{
"endpoints": [
"fallback-a.service123.ucdn.example",
"fallback-b.service123.ucdn.example"
],
"protocol": "http/1.1"
},
{
"endpoints": ["fallback-c.service123.example"],
"protocol": "http/1.1"
}
]
}
}
3.1. Fallback Address
A fallback-address object describes the address to be used by the
dCDN when redirecting a client back to the dCDN due to failure,
error, or other conditions in the dCDN.
Endpoints within a fallback-address object MUST be treated as
equivalent/equal. A uCDN can specify an array of fallback-addresses,
ordered by preference, within a Fallback metadata object. Then, for
each fallback-address object ranked by preference, a uCDN can specify
an array of endpoints that are equivalent (e.g., a pool of servers
that are not behind a load balancer).
Property: endpoints
Description: Endpoint addresses to which the dCDN can redirect
the client. If multiple endpoints are specified, they are all
equal, i.e., the list is not ordered by preference..
Type: Array of Endpoint objects (see section 4.3.3 of
[RFC8006])
Mandatory-to-Specify: Yes.
Property: protocol
Description: Network protocol to use when redirecting to this
fallback server.
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Type: Protocol (see section 4.3.2 of [RFC8006])
Mandatory-to-Specify: Yes.
Example of Fallback Address object (which contains two endpoint
objects) that descibes which endpoint addreses in the uCDN the dCDN
should use in order to to redirect the client to the uCDN.
{
"endpoints": [
"fallback-a.service123.ucdn.example",
"fallback-b.service123.ucdn.example"
],
"protocol": "http/1.1"
}
4. IANA Considerations
4.1. CDNI Payload Types
This document requests the registration of the following CDNI Payload
Types under the IANA CDNI Payload Type registry [RFC7736]:
+----------------------+---------------+
| Payload Type | Specification |
+----------------------+---------------+
| FCI.RedirectTargetes | RFCthis |
| MI.Fallback | RFCthis |
+----------------------+---------------+
[RFC Editor: Please replace RFCthis with the published RFC number for
this document.]
4.1.1. CDNI FCI RedirectTargets Payload Type
Purpose: The purpose of this payload type is to distinguish
RedirectTargets FCI objects
Interface: FCI
Encoding: see Section 2
4.1.2. CDNI MI Fallback Payload Type
Purpose: The purpose of this payload type is to distinguish Fallback
MI objects (and any associated capability advertisement)
Interface: MI/FCI
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Encoding: see Section 3
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 considerations as defined in
[RFC8006] and [RFC8008] respectively.
6. Acknowledgements
TBD.
7. Contributors
TBD.
8. References
8.1. Normative References
[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>.
[RFC6707] Niven-Jenkins, B., Le Faucheur, F., and N. Bitar, "Content
Distribution Network Interconnection (CDNI) Problem
Statement", RFC 6707, DOI 10.17487/RFC6707, September
2012, <https://www.rfc-editor.org/info/rfc6707>.
[RFC7336] Peterson, L., Davie, B., and R. van Brandenburg, Ed.,
"Framework for Content Distribution Network
Interconnection (CDNI)", RFC 7336, DOI 10.17487/RFC7336,
August 2014, <https://www.rfc-editor.org/info/rfc7336>.
[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>.
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[RFC8008] Seedorf, J., Peterson, J., Previdi, S., van Brandenburg,
R., and K. Ma, "Content Delivery Network Interconnection
(CDNI) Request Routing: Footprint and Capabilities
Semantics", RFC 8008, DOI 10.17487/RFC8008, December 2016,
<https://www.rfc-editor.org/info/rfc8008>.
8.2. Informative References
[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>.
Authors' Addresses
Ori Finkelman
Qwilt
6, Ha'harash
Hod HaSharon 4524079
Israel
Phone: +972-72-2221647
Email: orif@qwilt.com
Sanjay Mishra
Verizon
13100 Columbia Pike
Silver Spring, MD 20904
USA
Email: sanjay.mishra@verizon.com
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