Internet DRAFT - draft-seedorf-cdni-fci-alto
draft-seedorf-cdni-fci-alto
CDNI J. Seedorf
Internet-Draft NEC
Intended status: Informational Y. Yang
Expires: April 24, 2014 Yale
October 21, 2013
CDNI Footprint and Capabilities Advertisement using ALTO
draft-seedorf-cdni-fci-alto-00
Abstract
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. This document focuses on the CDNI
Footprint & Capabilities Advertisement interface (FCI).
Specifically, this document outlines how the solutions currently
being defined in the Application Layer Traffic Optimization (ALTO) WG
can facilitate Footprint & Capabilities Advertisement in a CDNI
context, i.e. how the CDNI FCI can be realised with the ALTO
protocol. Concrete examples of how ALTO can be integrated within
CDNI request routing and in particular in the process of selecting a
downstream CDN are given. The examples in this document are based on
the use cases and examples currently being discussed in the CDNI WG.
Status of This Memo
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This Internet-Draft will expire on April 24, 2014.
Copyright Notice
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. ALTO within CDNI Request Routing . . . . . . . . . . . . . . 3
3. Assumptions and High-Level Design Considerations . . . . . . 4
3.1. General Assumptions and Consideration . . . . . . . . . . 4
3.2. Semantics for Footprint/Capabilities Advertisment . . . . 5
4. Selection of a Downstream CDN with ALTO . . . . . . . . . . . 7
4.1. Footprint and Capabilities Advertisement using ALTO
Network Map and PID Properties . . . . . . . . . . . . . 7
4.2. Conveying additional information with ALTO Cost Maps . . 8
4.3. Example of Selecting a Downstream CDN based on ALTO Maps 9
4.4. Advantages of using ALTO . . . . . . . . . . . . . . . . 10
5. Useful ALTO extensions for CDNI Request Routing . . . . . . . 10
6. Security Considerations . . . . . . . . . . . . . . . . . . . 12
7. Summary and Outlook . . . . . . . . . . . . . . . . . . . . . 12
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 12
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 13
9.1. Normative References . . . . . . . . . . . . . . . . . . 13
9.2. Informative References . . . . . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15
1. Introduction
Many Network Service Providers (NSPs) are currently considering or
have already started to deploy Content Delivery Networks (CDNs)
within their networks. As a consequence of this development, there
is a need for interconnecting these local CDNs. Content Delivery
Networks Interconnection (CDNI) has the goal of standardizing
protocols to enable such interconnection of CDNs [RFC6707].
The CDNI problem statement [RFC6707] envisions four interfaces to be
standardized within the IETF for CDN interconnection:
o CDNI Request Routing Interface
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o CDNI Metadata Interface
o CDNI Logging Interface
o CDNI Control Interface
This document focuses solely on the CDNI Request Routing Interface,
which can be further divided into two interfaces (see [RFC6707] for a
detailed description): the CDNI Request Routing Redirection interface
(RI), and the CDNI Footprint & Capabilities Advertisement interface
(FCI). This document presents how one may use ALTO as a protocol for
CDNI Footprint & Capabilities Advertisement. Concrete examples of
how the CDNI FCI can be implemented with the ALTO protocol
[I-D.ietf-alto-protocol] are given. The examples used in this
document are based on the use cases and request routing proposals
currently being discussed in the CDNI WG [RFC6770]
[I-D.peterson-CDNI-strawman] and in the ALTO WG
[I-D.jenkins-alto-cdn-use-cases].
A previous version of this document [I-D.seedorf-alto-for-cdni]
contained detailed examples of actual request routing and surrogate
selection with ALTO, i.e. how ALTO could be used for implementing the
CDNI Request Routing Redirection interface (RI). This version solely
focuses on implementing the CDNI Footprint & Capabilities
Advertisement interface (FCI) with ALTO, i.e. the selection of a
downstream CDN and how ALTO can support such downstream CDN
selection.
Throughout this document, we use the terminology for CDNI defined in
[I-D.ietf-cdni-problem-statement].
2. ALTO within CDNI Request Routing
The main purpose of the CDNI Request Routing Interface is described
in [RFC6707] as follows: "The CDNI Request Routing interface enables
a Request Routing function in an Upstream CDN to query a Request
Routing function in a Downstream CDN to determine if the Downstream
CDN is able (and willing) to accept the delegated Content Request.
It also allows the Downstream CDN to control what should be returned
to the User Agent in the redirection message by the upstream Request
Routing function." On a high level, the scope of the CDNI Request
Routing Interface therefore contains two main tasks:
o A) Determining if the downstream CDN is willing to accept a
delegated content request
o B) Redirecting the content request coming from an upstream CDN to
the proper entry point or entity in the downstream CDN
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More precisely, in [I-D.ietf-cdni-framework] the request routing
interface is broadly divided into two functionalities:
o 1) the asynchronous advertisement of footprint and capabilities by
a dCDN that allows a uCDN to decide whether to redirect particular
user requests to that dCDN (the CDNI FCI)
o 2) the synchronous operation of actually redirecting a user
request (the CDNI RI)
Application Layer Traffic Optimization (ALTO) is an approach for
guiding the resource provider selection process in distributed
applications that can choose among several candidate resources
providers to retrieve a given resource. By conveying network layer
(topology) information, an ALTO server can provide important
information to "guide" the resource provider selection process in
distributed applications. Usually, it is assumed that an ALTO server
conveys information these applications cannot measure themselves
[RFC5693].
Originally, ALTO was motivated by the huge amount of cross-ISP
traffic generated by P2P applications [RFC5693]. Recently, however,
ALTO is also being considered for improving the request routing in
CDNs [I-D.jenkins-alto-cdn-use-cases]. In this context, it has also
been proposed to use ALTO for selecting an entry-point in a
downstream NSP's network (see section 3.4 "CDN delivering Over-The-
Top of a NSP's network" in [I-D.jenkins-alto-cdn-use-cases]). Also,
the CDNI problem statement explicitly mentions ALTO as a candidate
protocol for "algorithms for selection of CDN or Surrogate by
Request-Routing systems" [I-D.ietf-cdni-problem-statement]. Yet,
there have not been concrete proposals so far on how to use ALTO in
the context of CDN interconnection. This document tries to close
this gap by giving some examples on how ALTO could be used within
CDNI request routing.
3. Assumptions and High-Level Design Considerations
In this section we list some assumptions and design issues to be
considered when using ALTO for the CDNI Footprint and Capabilities
Advertisement interface
3.1. General Assumptions and Consideration
Below we list some general assumptions and considerations:
o As explicitly being out-of-scope for CDNI
[I-D.ietf-cdni-problem-statement], the examples used in this
document assume that ingestion of content or acquiring content
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across CDNs is not part of request routing as considered within
CDNI standardization work. The focus of using ALTO (as considered
in this document) is hence on request routing only, assuming that
the content (desired by the end user) is available in the
downstream CDN (or can be aquired by the downstream CDN by some
means).
o Federation Model: "Footprint and Capabilities Advertisement" and
in general CDN request routing depends on the federation model
among the CDN providers. Designing a suitable solution thus
depends on whether a solution is needed for different settings,
where CDNs consist of both NSP CDNs (serving individual ASes) and
general, traditional CDNs (such as Akamai). We assume that CDNI
is not designed for a setting where only NSP CDNs each serve a
single AS only.
o In this document, we assume that the upstream CDN (uCDN) makes the
decision on selecting a downstream CDN, based on information that
each downstream CDN has made available to the upstream CDN.
Further, we assume that in principle more than one dCDN may be
suitable for a given end-user request (i.e. different dCDNs may
claim "overlapping" footprints). The uCDN hence potentially has
to select among several candidate downstream CDNs for a given end
user request.
o It is not clear what kind(s) of business, contract, and
operational relationships two peering CDNs may form. For the
Internet, we see provider-customer and peering as two main
relations; providers may use different charging models (e.g.,
95-percentile, total volume) and may provide different SLAs.
Given such unknown characteristics of CDN peering business
agreements, we should design the protocol to support as much
diverse potential business and operational models as possible.
3.2. Semantics for Footprint/Capabilities Advertisment
The CDNI document on "Footprint and Capabilities Semantics"
[I-D.spp-cdni-rr-foot-cap-semantics] defines the semantics for the
CDNI FCI. It thus provides guidance on what Footprint and
Capabilities mean in a CDNI context and how a protocol solution
should in principle look like. Here we briefly summarize the key
points of the semantics of Footprint and Capabilities (for a detailed
discussion, the reader is referred to
[I-D.spp-cdni-rr-foot-cap-semantics]):
o Often, footprint and capabilities are tied together and cannot be
interpreted independently from each other. In such cases, i.e.
where capabilities must be expressed on a per footprint basis, it
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may be beneficial to combine footprint and capabilities
advertisement.
o Given that a large part of Footprint and Capabilities
Advertisement will actually happen in contractual agreements, the
semantics of CDNI Footprint and Capabilities advertisement refer
to answering the following question: what exactly still needs to
be advertised by the CDNI FCI? For instance, updates about
temporal failures of part of a footprint can be useful information
to convey via the CDNI request routing interface. Such
information would provide updates on information previously agreed
in contracts between the participating CDNs. In other words, the
CDNI FCI is a means for a dCDN to provide changes/updates
regarding a footprint and/or capabilities it has prior agreed to
serve in a contract with a uCDN.
o It seems clear that "coverage/reachability" types of footprint
must be supported within CDNI. The following such types of
footprint are mandatory and must be supported by the CDNI FCI:
* List of ISO Country Codes
* List of AS numbers
* Set of IP-prefixes
A 'set of IP-prefixes' must be able to contain full IP addresses,
i.e., a /32 for IPv4 and a /128 for IPv6, and also IP prefixes
with an arbitrary prefix length. There must also be support for
multiple IP address versions, i.e., IPv4 and IPv6, in such a
footprint.
o For all of these mandatory-to-implement footprint types,
footprints can be viewed as constraints for delegating requests to
a dCDN: A dCDN footprint advertisement tells the uCDN the
limitations for delegating a request to the dCDN. For IP prefixes
or ASN(s), the footprint signals to the uCDN that it should
consider the dCDN a candidate only if the IP address of the
request routing source falls within the prefix set (or ASN,
respectively). The CDNI specifications do not define how a given
uCDN determines what address ranges are in a particular ASN.
Similarly, for country codes a uCDN should only consider the dCDN
a candidate if it covers the country of the request routing
source. The CDNI specifications do not define how a given uCDN
determines the country of the request routing source. Multiple
footprint constraints are additive, i.e. the advertisement of
different types of footprint narrows the dCDN candidacy
cumulatively.
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o The following capabilities seem useful as 'base' capabilities,
i.e. ones that are needed in any case and therefore constitute
mandatory capabilities to be supported by the CDNI FCI:
* Delivery Protocol (e.g., HTTP vs. RTMP)
* Acquisition Protocol (for aquiring content from a uCDN)
* Redirection Mode (e.g., DNS Redirection vs. HTTP Redirection as
discussed in [I-D.ietf-cdni-framework])
* Capabilities related to CDNI Logging (e.g., supported logging
mechanisms)
* Capabilities related to CDNI Metadata (e.g., authorization
algorithms or support for proprietary vendor metadata)
4. Selection of a Downstream CDN with ALTO
Under the considerations stated in Section 3, ALTO can help the
upstream CDN provider to select a proper downstream CDN provider for
a given end user request as follows: 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. Network maps provided by each
of several candidate downstream CDNs can provide information to the
upstream CDN provider about each dCDN's "coverage/reachability" as
well as capabilities.
4.1. Footprint and Capabilities Advertisement using ALTO Network Map
and PID Properties
Conceptually, the foorprint and capabilities interface of a dCDN is
easy to specify: It is a function that given an endhost, returns if
the dCDN is willing to serve the endhost, and the capabilities
available to that endhost (e.g., "delivery-protocol":
["HTTP","RMTP"], "acquisition-protocol": ["HTTP"], "redirection-
mode": ["HTTP-redirect"], "loggin-mechanism": ["TBD"], and "meta-
capabilities": [""]).
Specifiying the preceding for each endhost can be redundant, and one
may use PIDs defined in ALTO. Specifically, an ALTO network map
contains a "set of Network Location groupings"
[I-D.ietf-alto-protocol]. The groupings are defined in the form of
so-called "PIDs". A PID is an identifier to group network location
endpoints, e.g. IP-addresses in the form of prefixes (see section 4
in [I-D.ietf-alto-protocol] for details).
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Applying the basic idea of ALTO PIDs to the preceding, abstract
mapping specification, by aggregating endhosts with the same
capabilities in the same PID, we obtain CDNi FCI using ALTO Network
Maps as simply (1) a Network Map which defines a set of PIDs, and (2)
a PID Property Map [draft-roome-alto-pid-properties ] that defines
the properties of each PID, where the properties define the
capabilities.
With the preceding Network Map and PID Property Map, the upstream CDN
provider can easily match a given end user request with the footprint
and capabilities of the downstream CDN providers. Whenever the
footprint and/or capabilities of a dCDN change, the ALTO server of
the dCDN changes its data, and the uCDN can obtain the update through
ALTO incremental updates. Future extensions to ALTO to add
notifications can be integrated when they become available.
In particular, this document does not define how a dCDN aggregates
the endhosts into PIDs, to allow flexibility in (anticipated)
updates.
In this document, we define the following PID properties, which each
must be a JSON array, to convey all mandatory capabilities (see
Section 3.2):
o delivery-protocol
o acquisition-protocol
o redirection-mode
o loggin-mechanism
o meta-capabilities
To complement the preceding capabilities mapping, we require that an
uCDN has access to ALTO Network Map(s) that can map from an endhost
to Country Code and AS Number. Such mapping may or may not be
specific to CDNI but can be a general mapping. Specifically, the
uCDN should have access to ALTO Network Map(s) with Properties
include:
o country-code
o asn
4.2. Conveying additional information with ALTO Cost Maps
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An ALTO cost map contains costs between defined groupings of a
corresponding network map (i.e. costs between PIDs): "An ALTO Cost
Map defines Path Costs pairwise amongst sets of source and
destination Network Locations" [I-D.ietf-alto-protocol]. This
concept enables the provider of a cost map to express (and quantify)
preferences of a destination network location with respect to a given
source network location.
In the context of CDNI, the ALTO cost map concept is an extensive
tool to convey additional information about the footprint or
capabilties of a downstream CDN. The cost map concept provides a
means for a downstream CDN provider to convey numeric values
associated with a PID, e.g. in order to convey metrics associated
with a footprint or a capability. This may be useful for future,
non-mandatory types of footprint or capabilties.
One way to use ALTO cost maps would have these maps of the type
N-to-m, i.e. 'costs' are expressed for each of N end user source PIDs
to m dCDN request router PIDs. Semantically, a source PID in a CDNI
ALTO cost map is thus the end user location, whereas a destination
PID is a (group of) request router(s) to which the uCDN redirects the
end user request. Note that this perspective is driven by the CDNI
request routing. An alternative way - seen from the perspective of
content retrieval - would be to have a m-to-N cost map where the
source is always the dCDN and the destination is the end user (with
the semantic "if the source dCDN would deliver content to an end user
in the destination PID, the costs would be the following). With
explicit destination PIDs reflecting different entries to the same
dCDN, the dCDN can convey shortcut or differentiaed quality of
services.
4.3. Example of Selecting a Downstream CDN based on ALTO Maps
In the following, we will outline an example of dCDN selection by a
uCDN based on ALTO maps provided by dCDNs. Consider the following
example: An upstream CDN (uCDN) has agreed on CDN interconnection
with several downstream CDNs (dCDN-a, dCDN-b, and dCDN-c). Each of
these downstream CDNs runs an ALTO server to provide aforementioned
ALTO information. Whenever the upstream CDN receives a request from
an end user and has determined that this request is best served by an
interconnected dCDN, the uCDN uses ALTO maps to make a redirection
decision. For a given request, assume that only the ALTO network
maps provided by dCDN-a and dCDN-c include the endhost. The uCDN
first looks up the PIDs of the endhost in the two network maps from
the two dCDNs, then search the PID properties to find out the
capabilities of each dCDN for the endhost. If only one dCDN supports
the required capabilities, then the uCDN chooses the dCDN.
Otherwise, if Cost Maps are available to provide additional server
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selection information (e.g., a Cost Map defining latency), the uCDN
picks the dCDN with better cost performance.
4.4. Advantages of using ALTO
The following reasons make ALTO a suitable candidate protocol for
downstream CDN selection as part of CDNI request routing and in
particular for a FCI protocol:
o CDN request routing is done at the application layer. ALTO is a
protocol specifically designed to improve application layer
traffic (and application layer connections among hosts on the
Internet) by providing additonal information to applications that
these applications could not easily retrieve themselves. For
CDNI, this is exactly the case: a uCDN wants to improve
application layer CDN request routing by using dedicated
information (provided by a dCDN) that the uCDN could not easily
obtain otherwise.
o The semantics of an ALTO network are an exact match for the needed
information to convey a footprint by a downstream CDN, in
particular if such a footprint is being expressed by IP-prefix
ranges.
o ALTO cost maps are suitable to express various types of numeric
values and can hence be used by an upstream CDN to obtain metrics
for capabilities associated with a given dCDN for a given
foorprint. Further, an ALTO cost map could also convey relevant
network topology information other than simply routing hops or
reachability. This facilitiates advanced and more sophisticated
selection of a downstream CDN based on various metrics by the
upstream CDN and increases flexibility to cover different use
cases and business models for CDN interconnection.
o Flexible granularity: The concept of the PID and ALTO network/cost
maps allows for different degrees of granularity. This enables a
dCDN to differentiate the delivery quality for serving an end user
request on a fine granularity depending on the end user location
(and not only express delivery quality e.g. on an AS-level). It
remains at the discretion of each dCDN how fine-granular the ALTO
network and cost maps are that it publishes.
o ALTO maps can be signed and hence provide inherent integrity
protection (see Section 6)
5. Useful ALTO extensions for CDNI Request Routing
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It is envisioned that yet-to-be-defined ALTO extensions will be
standardized that make the ALTO protocol more suitable and useful for
applications other than the originally considered P2P use case
[I-D.marocco-alto-next]. Some of these extensions to the ALTO
protocol would be useful for ALTO to be 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 following proposed extensions to ALTO would be beneficial to
facilitate CDNI request routing with ALTO as outlined in Section 4:
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. A proposal for server-initiated
ALTO updates can be found in [I-D.marocco-alto-ws]. A discussion
of incremental ALTO updates can be found in
[I-D.schwan-alto-incr-updates].
o Content Availability on Hosts: A dCDN might want to express CDN
capabilties in terms of certain content types (e.g. codecs/
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.
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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.
6. Security Considerations
One important security consideration is the proper authentication of
advertisement information provided by a downstream CDN. The ALTO
protocol provides a specification for a signature of ALTO maps (see
8.2.2. of [I-D.ietf-alto-protocol]. ALTO thus provides a proper
means for protecting the integrity of footprint advertisment
information.
More Security Considerations will be discussed in a future version of
this document.
7. Summary and Outlook
This document presented conrete examples of how ALTO can be used
within the downstream CDN selection of CDNI Request Routing.
Further, the document provides arguments why ALTO is a meaningful
protocol in this context. Essentially, ALTO network and cost maps
are a means to provide detailed and various types of information to
an upstream CDN, in order to facilitate well-considered downstream
CDN selection.
The intention of this document is to find consensus in the CDNI WG
that ALTO is a useful protocol for CDNI request routing, and that
ALTO has many benefits for proper selection of a downstream CDN. The
overall objective is to form agreement on how ALTO should be used
within the CDNI request routing protocol. It is the intention to
capture the outcome of such continuing discussions in future versions
of this document.
8. Acknowledgements
Jan Seedorf is partially supported by the CHANGE project (CHANGE:
Enabling Innovation in the Internet Architecture through Flexible
Flow-Processing Extensions, http://www.change-project.eu/), a
research project supported by the European Commission under its 7th
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Framework Program (contract no. 257422). 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 CHANGE project or
the European Commission.
Jan Seedorf has been 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.
9. References
9.1. Normative References
[RFC5693] Seedorf, J. and E. Burger, "Application-Layer Traffic
Optimization (ALTO) Problem Statement", RFC 5693, October
2009.
[RFC6707] Niven-Jenkins, B., Le Faucheur, F., and N. Bitar, "Content
Distribution Network Interconnection (CDNI) Problem
Statement", RFC 6707, September 2012.
[RFC6770] Bertrand, G., Stephan, E., Burbridge, T., Eardley, P., Ma,
K., and G. Watson, "Use Cases for Content Delivery Network
Interconnection", RFC 6770, November 2012.
9.2. Informative References
[I-D.peterson-CDNI-strawman]
Peterson, L. and J. Hartman, "Content Distribution Network
Interconnection (CDNI) Problem Statement", draft-peterson-
CDNI-strawman-01 (work in progress), May 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-08 (work in
progress), June 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.
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[I-D.ietf-alto-protocol]
Alimi, R., Penno, R., and Y. Yang, "ALTO Protocol", draft-
ietf-alto-protocol-20 (work in progress), October 2013.
[I-D.ietf-cdni-requirements]
Leung, K. and Y. Lee, "Content Distribution Network
Interconnection (CDNI) Requirements", draft-ietf-cdni-
requirements-11 (work in progress), October 2013.
[I-D.ietf-cdni-use-cases]
Bertrand, G., Emile, S., Burbridge, T., Eardley, P., Ma,
K., and G. Watson, "Use Cases for Content Delivery Network
Interconnection", draft-ietf-cdni-use-cases-10 (work in
progress), August 2012.
[I-D.marocco-alto-ws]
Marocco, E. and J. Seedorf, "WebSocket-based server-to-
client notifications for the Application-Layer Traffic
Optimization (ALTO) Protocol", draft-marocco-alto-ws-01
(work in progress), July 2012.
[I-D.schwan-alto-incr-updates]
Schwan, N. and B. Roome, "ALTO Incremental Updates",
draft-schwan-alto-incr-updates-02 (work in progress), July
2012.
[I-D.jenkins-alto-cdn-use-cases]
Niven-Jenkins, B., Watson, G., Bitar, N., Medved, J., and
S. Previdi, "Use Cases for ALTO within CDNs", draft-
jenkins-alto-cdn-use-cases-03 (work in progress), June
2012.
[I-D.seedorf-alto-for-cdni]
Seedorf, J., "ALTO for CDNi Request Routing", draft-
seedorf-alto-for-cdni-00 (work in progress), October 2011.
[I-D.ietf-cdni-framework]
Peterson, L. and B. Davie, "Framework for CDN
Interconnection", draft-ietf-cdni-framework-06 (work in
progress), October 2013.
[I-D.liu-cdni-cost]
Liu, H., "A Cost Perspective on Using Multiple CDNs",
draft-liu-cdni-cost-00 (work in progress), October 2011.
[I-D.spp-cdni-rr-foot-cap-semantics]
Seedorf, J., Peterson, J., Previdi, S., Brandenburg, R.,
and K. Ma, "CDNI Request Routing: Footprint and
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Capabilities Semantics", draft-spp-cdni-rr-foot-cap-
semantics-04 (work in progress), February 2013.
Authors' Addresses
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
Y.R. Yang
Yale University
51 Prospect Street
New Haven 06511
USA
Email: yry@cs.yale.edu
URI: http://www.cs.yale.edu/~yry/
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