Internet DRAFT - draft-seedorf-i2aex-alto-cdni-perpective
draft-seedorf-i2aex-alto-cdni-perpective
Content Delivery Networks J. Seedorf
Interconnection NEC
Internet-Draft March 5, 2012
Intended status: Informational
Expires: September 6, 2012
Infrastructure-to-application information exposure from an ALTO-CDNI
Perspective
draft-seedorf-i2aex-alto-cdni-perpective-00
Abstract
Recently, there has been a discussion on "Infrastructure-to-
Application Information Exposure" and the related communications
requirements in fully controlled (e.g. data centers) or partially
controlled environments (e.g. CDN). One possibility to expose
infrastructure information to applications in the aforementioned
environments is to use yet-to-be-defined ALTO extensions. This draft
discusses requirements for such ALTO extensions for a specific use
case: Request Routing in CDN Interconnection (CDNI).
Status of this Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Useful Extensions to ALTO to facilitate CDNI Request
Routing with ALTO . . . . . . . . . . . . . . . . . . . . . . 4
3. Security Considerations . . . . . . . . . . . . . . . . . . . 6
4. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . 7
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 8
6. Informative References . . . . . . . . . . . . . . . . . . . . 9
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 10
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1. Introduction
Recently, there has been a discussion on "Infrastructure-to-
Application Information Exposure" and the related communications
requirements in fully controlled (e.g. data centers) or partially
controlled environments (e.g. CDNs) [I-D.marocco-alto-next]. One
possibility to expose infrastructure information to applications in
the aforementioned environments is to use ALTO
[I-D.ietf-alto-protocol], or rather extension to ALTO which are yet
to be investigated and specified [I-D.marocco-alto-next].
Network Service Providers (NSPs) are currently considering to deploy
Content Delivery Networks (CDNs) within their networks. As a
consequence of this development, there is a need for interconnecting
these local CDNs. The necessary interfaces for inter-connecting CDNs
are currently being defined in the Content Delivery Networks
Interconnection (CDNI) WG [I-D.ietf-cdni-requirements]
[I-D.ietf-cdni-problem-statement] [I-D.ietf-cdni-use-cases]. Among
other protocols, ALTO has been suggested to facilitate downstream CDN
selection in the context of CDNI request routing [refs.altocdni],
i.e. ALTO is currently a candidate protocol for "Footprint and
Capabilities Advertisment" within CDNI Request Routing.
This document discusses what extensions to ALTO would be useful in
case ALTO is used as a protocol within CDNI request routing, and in
particular within the "Footprint and Capabilities Advertisment" part
of the CDNI request routing interface. The discussion is based on
the suggested extensions to ALTO proposed in [I-D.marocco-alto-next]
and the examples of how ALTO could be used for downstream CDN
selection within CDNI request routing in [refs.altocdni].
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2. Useful Extensions to ALTO to facilitate CDNI Request Routing with
ALTO
In the following, we assume the following scenario of using ALTO for
selecting a downstream CDN [refs.altocdni]: Each downstream CDN
provider hosts an ALTO server which provides ALTO information (i.e.
ALTO network maps and ALTO cost maps [I-D.ietf-alto-protocol]) to an
ALTO client at the upstream CDN provider. A network map provided by
each of several candidate downstream CDNs can provide information to
the upstream CDN provider regarding the geopgraphical coverage, the
location of "surrogates", or similar. In addition, an ALTO cost map
can provide an upstream CDN provider information about the ''cost''
of delivering certain content via the downstream CDN which provided
such a cost map. ''Cost'' in this context is a generic term; many
types of costs are possible and can be useful in the context of CDNI
request routing, e.g. average link load, expected delay, or monetary
costs.
As an example, an upstream CDN (uCDN) receives a request from an end
user. Based on the IP-address of the end user, uCDN determines that
it is possible to deliver the content from one of several candidate
downstream CDNs (dCDN-a, dCDN-b, and dCDN-c). Assume that only the
ALTO network maps provided by dCDN-a and dCDN-c indicate that these
downstream CDNs can deliver content for the location of the end user
requesting content. In this case, the ALTO costs maps provide useful
information to the upstream CDN, uCDN, in order to make a selection
decision regarding either dCDN-a or dCDN-c.
From the perspective of the given scenario and example, the following
proposed extensions to ALTO would be beneficial to facilitate CDNI
request routing with ALTO:
o Server-initiated Notifications and Incremental Updates: In case
the footprint or the capabilities of a downstream CDN change
abruptly (i.e. unexpectedly from the perspective of an upstream
CDN), server initiated notifications would enable a dCDN to
directly inform an upstream CDN about such changes. Consider the
case where - due to failure - part of the footprint of the dCDN is
not functioning, i.e. the CDN cannot serve content to such clients
with reasonable QoS. Without server-initiated notifications, the
uCDN might still use a very recent network and cost map from dCDN,
and therefore redirect request to dCDN which it cannot serve.
Similarly, the possibility for incremental updates would enable
efficient conveyance of the aforementioned (or similar) status
changes by the dCDN to the uCDN.
o Content Availability on Hosts: A dCDN might want to express CDN
capabilties in terms of certain content types (e.g. codecs/
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formats, or content from certain content providers). A new
endpoint property for ALTO that would be able to express such
"content availability" would enable a dCDN to make available such
information to an upstream CDN. This would enable a uCDN to
determine if a given dCDN actually has the capabilities for a
given request with respect to the type of content requested.
o Resource Availability on Hosts or Links: The capabilities on links
(e.g. maximum bandwidth) or caches (e.g. average load) might be
useful information for an upstream CDN for optimized dowmstream
CDN selection. For instance, if a uCDN receives a streaming
request for content with a certain bitrate, it needs to know if it
is likely that a dCDN can fulfill such stringent application-level
requirements (i.e. can be expected to have enough consistent
bandwidth) before it redirects the request. In general, if ALTO
could convey such information via new endpoint properties, it
would enable more sophisticated means for downstream CDN selection
with ALTO.
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3. Security Considerations
Security Considerations will be discussed in a future version of this
document.
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4. Conclusion
Recently, there has been a discussion on "Infrastructure-to-
Application Information Exposure" and the related communications
requirements in fully controlled (e.g. data centers) or partially
controlled environments (e.g. CDN). One possibility to expose
infrastructure information to applications in the aforementioned
environments is to use yet-to-be-defined ALTO extensions. This draft
considered requirements for such ALTO extensions for a specific use
case: Request Routing in CDN Interconnection (CDNI). This document
discussed useful extensions to ALTO in this context, i.e. what
extensions would be beneficial from the CDNI perspective and why.
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5. Acknowledgements
Jan Seedorf is partially supported by the COAST project (COntent
Aware Searching, retrieval and sTreaming, http://www.coast-fp7.eu), a
research project supported by the European Commission under its 7th
Framework Program (contract no. 248036). The views and conclusions
contained herein are those of the authors and should not be
interpreted as necessarily representing the official policies or
endorsements, either expressed or implied, of the COAST project or
the European Commission.
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6. Informative References
[I-D.ietf-alto-protocol]
Penno, R., Alimi, R., and Y. Yang, "ALTO Protocol",
draft-ietf-alto-protocol-10 (work in progress),
October 2011.
[I-D.ietf-cdni-problem-statement]
Niven-Jenkins, B., Faucheur, F., and N. Bitar, "Content
Distribution Network Interconnection (CDNI) Problem
Statement", draft-ietf-cdni-problem-statement-03 (work in
progress), January 2012.
[I-D.ietf-cdni-requirements]
Leung, K. and Y. Lee, "Content Distribution Network
Interconnection (CDNI) Requirements",
draft-ietf-cdni-requirements-02 (work in progress),
December 2011.
[I-D.ietf-cdni-use-cases]
Gilles, B., Watson, G., Ma, K., Eardley, P., Emile, S.,
and T. Burbridge, "Use Cases for Content Delivery Network
Interconnection", draft-ietf-cdni-use-cases-03 (work in
progress), January 2012.
[I-D.marocco-alto-next]
Marocco, E. and V. Gurbani, "Extending the Application-
Layer Traffic Optimization (ALTO) Protocol",
draft-marocco-alto-next-00 (work in progress),
January 2012.
[refs.altocdni]
Seedorf, J., "ALTO for CDNi Request Routing",
draft-seedorf-cdni-request-routing-alto-00 (work in
progress), March 2012.
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Author's Address
Jan Seedorf
NEC Laboratories Europe, NEC Europe Ltd.
Kurfuersten-Anlage 36
Heidelberg 69115
Germany
Phone: +49 (0) 6221 4342 221
Email: jan.seedorf@neclab.eu
URI: http://www.neclab.eu
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