PEERAPP WHITE PAPER
Converged Edge Caching of
Over-the-top and Managed Content
December 2011
Copyright 2011 PeerApp Ltd. All rights reserved 2
Introduction
The debate about the impact of video on an
􀂑􀂒􀂇􀂔􀂃􀂖􀂑􀂔􀇯􀂕􀀃􀂄􀂔􀂑􀂃􀂆􀂄􀂃􀂐􀂆􀀃􀂐􀂇􀂖􀂙􀂑􀂔􀂍􀀃􀂋􀂕􀀃􀂑􀂘􀂇􀂔􀇤􀀃􀀃􀀙􀂋􀂆􀂇􀂑􀀃
consumption is outpacing every other use of
the Internet today and the growth is showing
no signs of a slowdown.
Internet video will be more than 50 percent of
consumer Internet traffic by the end of 2012
􀂃􀂅􀂅􀂑􀂔􀂆􀂋􀂐􀂉􀀃􀂖􀂑􀀃􀀆􀂋􀂕􀂅􀂑􀇯􀂕􀀃􀀙􀀑􀀌􀀃􀂕􀂖􀂗􀂆􀂛􀇤􀀃􀀃􀀓􀂇􀂇􀂔􀀄􀂒􀂒􀇯􀂕􀀃􀀘.S.
deployments regularly see Netflix alone
account for over 35% of peak traffic.
At the same time, the video delivery value
chain includes the operator as a transport
mechanism, but excludes the operator from
participation in the revenue stream. Operators
world-­‐wide are developing defensive and
offensive strategies to cope with the
tremendous consumer demand for Internet
content.
Operators are creating opportunities for direct
participation in the value chain of content
delivery as they build their own content
delivery infrastructure, the Operator CDN. The
primary drivers for operator CDN deployments
vary from operator to operator, but are
typically summarized as:
1. Revenue Generation 􀈂 product and
service revenue resulting from new
business models made possible by the
newly deployed infrastructure.
2. Network Optimization 􀈂 core network
traffic offload, infrastructure upgrade
deferment, and reduction of transit
costs.
3. Subscriber Benefit 􀈂 higher Quality of
Experience (QoE) and product
􀂕􀂖􀂋􀂅􀂍􀂋􀂐􀂇􀂕􀂕􀀃􀂖􀂑􀀃􀂖􀂊􀂇􀀃􀂑􀂒􀂇􀂔􀂃􀂖􀂑􀂔􀇯􀂕􀀃􀂑􀂙􀂐􀀃
subscribers and wholesale customers,
as well as opportunities to create
emerging value-­‐added or subscriber
􀂔􀂇􀂖􀂇􀂐􀂖􀂋􀂑􀂐􀀃􀂕􀂇􀂔􀂘􀂋􀂅􀂇􀂕􀀃􀂎􀂋􀂍􀂇􀀃􀇲􀀗􀀙􀀃Ever􀂛􀂙􀂊􀂇􀂔􀂇􀇳
PeerApp is actively engaged with a number of
content delivery partners to deliver a
converged content caching architecture that
addresses these objectives.
The converged content caching architecture
takes a holistic view of content delivery in the
operator network. The architecture provides a
balanced view of both the unmanaged over-­‐
the-­‐top (OTT) content traffic, which represents
the majority of total traffic today, and the
managed CDN content, sourced from operator
relationships direct with content owners. A
converged content caching architecture
uniquely provides the operator with a faster
time to revenue and immediate network
optimization for ALL of their content traffic.
The Role of Caching
The primary solution that meets the operator
goal of network optimization is caching.
Simply stated, by storing and serving popular
content at the edge of the network, the
number of bits transferred across the network
core and Internet transit links is reduced, and
the content delivery quality is improved. Other
network optimization techniques may be used
that include traffic shaping or prioritization.
Each of these has merit in various situations,
but caching is the only solution that provides
direct impact to the amount of traffic served
while meeting the subscriber demand for high
QoE.
Caching is used by operators for delivery of
both managed CDN content and unmanaged
OTT content. While there is a certain overlap
between CDN content delivery and OTT
transparent caching, the two diverge in their
business objectives and technical requirements.
CDN content delivery is an end-­‐to-­‐end offering
focusing on content service providers (CSPs), of
which content caching is a part. In addition to
content caching, a CDN solution typically
includes content ingestion distribution and
reporting, as well as optional functionality of
content transcoding, content protection
(DRM), and advanced analytics.
Copyright 2011 PeerApp Ltd. All rights reserved 3
The CDN is built to deliver a consistent service
level in the face of demand variations, network
congestion and faults, in a uniform way for all
content objects stored in it.
As a result, in CDN caching, the compliance
with SLAs and content business logic has
higher priority than does 􀂑􀂒􀂇􀂔􀂃􀂖􀂑􀂔􀇯􀂕􀀃network
optimization.
CDN cach􀂋􀂐􀂉􀀃􀂋􀂕􀀃􀇲􀂅􀂑􀂑􀂒􀂇􀂔􀂃􀂖􀂋􀂘􀂇􀇳􀀃􀂋􀂐􀀃􀂃􀀃􀂕􀂇􀂐􀂕􀂇􀀃􀂖􀂊􀂃􀂖􀀃
CDN caches and CDN origin servers cooperate
in delivery of pre-­‐ingested and known content
libraries of content service providers using the
CDN.
By contrast, caching of unmanaged content is
designed to achieve the widest possible
network impact for the network operator,
without pre-­‐existing knowledge of the content
or cooperation with the content service
provider. It concurrently deals with a very large
number of content services and very large
Internet content sets, and, as a result, is mostly
statistical and predictive in nature.
CDN content delivery and OTT caching
therefore, turn out to serve different and
complementary objectives. Operators looking
to holistically manage content in their networks
need to consider both types of caching and how
they can work together.
The following section describes how CDN and
OTT caching can be used together within
operator network to achieve the broadest
possible impact on the network and to enable
new business opportunities.
Caching at the Subscriber Edge
The benefits of content caching are maximized
by placing content close to subscribers within
􀂑􀂒􀂇􀂔􀂃􀂖􀂑􀂔􀂕􀇯􀀃􀂐􀂇􀂖􀂙􀂑􀂔􀂍􀇤 By caching content at the
broadband subscriber edge, operators
minimize the latency of delivery to subscribers,
resulting in the high session throughput
required to provide high Internet video quality
of experience (QoE).
The speed of content delivery is especially
critical with the delivery of adaptive bit rate
(ABR) protocols. ABR delivery is becoming the
de facto standard for Internet video delivery.
The interaction of a client and the content
source allows for constant adjustment of the
video quality to match network conditions. The
lower the latency of the connection, the higher
the quality video can be served.
Figure 1: Netflix Acceleration
Netflix, the largest content service provider in
U.S., leverages the 􀀐􀂋􀂅􀂔􀂑􀂕􀂑􀂈􀂖􀇯􀂕􀀃􀀖􀂋􀂎􀂘􀂇􀂔􀂎􀂋􀂉􀂊􀂖􀀃􀀄􀀅􀀕􀀃
delivery mechanism and all of the top global
CDN networks. An average video quality of
2.7Mbps is measured by Netflix across the best
U.S. access networks. By comparison, the
UltraBand deployed at the network edge
(CMTS), delivers sustained throughput of
4.2Mbps from the cache. This level of
sustained, high quality delivery can be directly
measured as increased QoE toward the
operator CDN goals.
Copyright 2011 PeerApp Ltd. All rights reserved 4
Defining the Subscriber Edge
Transparent caching at the network edge
allows the statistical delivery of popular
content. The edge cache reduces the impact on
Internet transit, core network transit and metro
transit. This creates a cumulative network
offload of 20-­‐40% across multiple segments of
􀂑􀂒􀂇􀂔􀂃􀂖􀂑􀂔􀇯􀂕􀀃􀂐􀂇􀂖􀂙􀂑􀂔􀂍􀇤􀀃By contrast, CDN caching
would not be as effective at the edge, since it
would address a much smaller portion of the
total traffic.
􀀓􀂇􀂇􀂔􀀄􀂒􀂒􀇯􀂕􀀃UltraBand transparent caching
platform is uniquely positioned for deployment
at the subscriber edge.
This mode of deployment features a large
number of caching elements deployed within
􀂖􀂊􀂇􀀃􀂑􀂒􀂇􀂔􀂃􀂖􀂑􀂔􀇯􀂕􀀃􀂃􀂅􀂅􀂇􀂕􀂕􀀃􀂐􀂇􀂖􀂙􀂑􀂔􀂍􀇤􀀃􀀃􀀌􀂖􀀃􀂋􀂕􀀃􀂖􀂊􀂇􀂔􀂇􀂈􀂑􀂔􀂇􀀃
critical to maintain low cost of ownership of the
solution through seamless network integration,
fully automated operation and high system
availability.
UltraBand fully meets these requirements,
while also enabling operators to scale their
caching footprint by adding computational and
storage resources as needed.
The location of the subscriber edge varies in in
different types of fixed broadband networks-­‐
from highly distributed CMTS level in MSO
networks to metro-­‐level BRAS/BNG
deployments in DSL/FTTx networks.
Figure 2: DSL network: edge deployment overview
When deploying the content caching solution in
3G wireless networks, the edge cache platform
is deployed next to GGSN at the Gi interface.
As LTE networks are deployed worldwide, the
IP edge moves closer to the network edge. This
allows the cache to be deployed at the SAE
gateway (SGW), increasing the network
optimization impacts and decreasing the
content delivery latency, to make use of full 4G
broadband speeds.
Figure 3: Mobile network: edge deployment overview
Converged Content Delivery Architecture
The utilization of operator CDNs ramps up
gradually, as subscribers adopt new service
offerings and content service providers begin to
tap new content distribution capabilities.
Because of this, the operator CDNs are
responsible for a modest share of overall
broadband network traffic today, with traffic
forecasts ranging from 15 to 30% in the next 36
months.
The operators are therefore taking centralized
rather than distributed approach to CDN
deployment. The CDN edge nodes are
deployed around the inner core network, rather
than in locations where aggregation of
subscribers creates sufficient traffic density.
In the converged architecture, the UltraBand
platform is deployed closer to the subscriber
Transparent caching improves
operator CDN economics, enables
CDN caching at the IP edge
Copyright 2011 PeerApp Ltd. All rights reserved 5
edge, where it acts as a common caching layer
for both on-­‐net operator CDN and over-­‐the-­‐top
traffic.
Figure 4: Converged content delivery architecture
The OTT content represents most of the
remaining 70-­‐90% of broadband downstream
traffic on the network.
By caching the CDN traffic at subscriber edge,
operators can capture the following benefits:
-­‐ Offload of network capacity between
subscriber edge and CDN nodes
(on-­‐net or over-­‐the-­‐top)
-­‐ Optimal handling of peak events on the
CDN
-­‐ Significant video quality improvement,
leading to customer retention,
increased content viewership and an
increase in CDN content consumption
By optimizing a much larger share of the
network, the converged architecture provides
the best economics of edge delivery. In doing
so, it enables operators to extend their CDN
footprint much deeper into the access network
while providing broadest impact to both
network optimization and subscriber quality.
The edge deployment also allows smooth
handling of peak events on the network. News
events, such as a sporting event, or a viral
effect created by social media, bring many
users to similar content in a short period of
time, creating a tremendous spike in traffic and
forcing operators to over-­‐provision their CDN
footprint. By steering resources between OTT
and CDN traffic at the subscriber edge as
needed, the converged architecture allows
operators to right-­‐size their CDNs, and enables
instantaneous provisioning of resources.
The edge caching is able to sustain delivery of
higher quality video, with throughput
improvement of 2x-­‐4x as exemplified in the
Netflix comparison (Figure 1).
With adoption of adaptive bitrate technology
for streaming of video over Internet, the
streaming client immediately takes advantage
of local cache by switching to higher quality
video bitrate. The quality improvement results
in CDN revenue increase, as end users consume
more bits per minute and in video quality
causes end users to consume more minutes of
video, with each causes end users to consume
more data per minute of view and to consume
more minute, leading in higher CDN data
consumption per minute of video as well as
larger amount of minutes consumed due to
increased customer retention.
Network Deployment
The architecture of caching deployment within
operator network may vary, depending on pre-­‐
existing caching deployment and variations in
subscriber density across the network.
In urban locations with high subscriber density
and backbone proximity transparent caching
nodes may be co-­‐located with operator CDN
nodes. In other locations off the backbone,
transparent caching nodes to offload operator
CDN traffic delivered from nearest CDN nodes.
Copyright 2011 PeerApp Ltd. All rights reserved 6
Figure 5: Network Deployment Overview
Content Delivery Logic
When an operator CDN is deployed in
conjunction with transparent caching, the CDN
effectively adopts three-­‐tier architecture,
where transparent caching acts as the first tier
(i.e. closest to the subscriber).
Figure 6: 3-­‐tier content delivery architecture
The second and third tiers of the architecture
are exclusive to the operator CDN: at the
operator backbone and CDN edge. Traffic
served from the operator CDN flows across the
network edge where it can be transparently
cached. The caching of operator CDN content
by UltraBand is done in a transparent manner,
the same way as over-­‐the-­‐top delivery. This
allows the operator CDN to retain request and
content load balancing within CDN cloud
without change.
All aspects of CDN business logic and operation
are r􀂇􀂖􀂃􀂋􀂐􀂇􀂆􀀃􀇲􀂃􀂕􀀃􀂋􀂕􀇳􀇡􀀃􀂙􀂊􀂇􀂐􀀃􀂆􀂇􀂒􀂎􀂑􀂛􀂇􀂆􀀃􀂋􀂐􀀃
conjunction with transparent caching:
-­‐ CDN request routing (DNS-­‐based, Anycast,
HTTP redirect)
-­‐ User authorization (URL token, cookie etc.)
-­‐ 􀀄􀂅􀂅􀂇􀂕􀂕􀀃􀇲􀂉􀂇􀂑-­‐􀂅􀂑􀂐􀂖􀂔􀂑􀂎􀇳􀀃
-­‐ DRM content protection
-­‐ Content adaptation for mobile platforms
-­‐ Video transcoding/transrating
The preservation of application logic is inherent
to transparent caching (hence the name).
􀀘􀂎􀂖􀂔􀂃􀀅􀂃􀂐􀂆􀇯􀂕􀀃􀂖􀂔􀂃􀂐􀂕􀂒􀂃􀂔􀂇􀂐􀂅􀂛􀀃􀂊􀂃􀂕􀀃􀂄􀂇􀂇􀂐􀀃􀂆􀂇􀂒􀂎􀂑􀂛􀂇􀂆􀀃
and proven in a very large variety of CDN and
non-­‐CDN-­‐delivered applications and services.
Integration between operator CDN and
transparent cache provides for the following
functionality:
-­‐ Reporting of content delivered by the
transparent cache back to CDN, for billing
and analytics purposes
-­‐ Cache control, allowing CDN edge to
extend caching policies and prioritization to
downstream transparent cache
Figure 7: CDN Integration interfaces
Transparent Cache
node
CDN node
End users
Transparent
cache
IP Core
CDN edge
CDN origin
External
origin
1
2
3
IP Edge
End users
Transparent
cache
IP Core
CDN
edge
CDN
management
IP Edge
Status
Transaction
reporting
Cache
Control
Copyright 2011 PeerApp Ltd. All rights reserved 7
Conclusion
Fixed and mobile operators world-­‐wide are
developing strategies enabling them to reduce
their network costs, improve subscriber
satisfaction and create new content-­‐based
revenue streams to cope with an explosion of
content in their networks. 􀀓􀂇􀂇􀂔􀀄􀂒􀂒􀇯􀂕􀀃􀀘􀂎􀂖􀂔aBand
transparent caching system enables operators
to optimize the delivery of unmanaged content
to their subscribers. The UltraBand system
integrates well with the operator CDN
architecture, enabling operators to leverage
the transparent caching layer to extend their
CDN footprint deeper into the network,
optimize their CDN deployment and deploy an
integrated caching solution at the subscriber
edge.
About PeerApp
PeerApp is the leading infrastructure provider of transparent Internet caching and content delivery
platforms, enabling network operators to control rich media content, improve network efficiency,
􀂇􀂐􀂊􀂃􀂐􀂅􀂇􀀃􀂕􀂗􀂄􀂕􀂅􀂔􀂋􀂄􀂇􀂔􀂕􀇯􀀃􀂓􀂗􀂃􀂎􀂋􀂖􀂛􀀃􀂑􀂈􀀃􀂇􀂚􀂒􀂇􀂔􀂋􀂇􀂐􀂅􀂇􀇡􀀃􀂃􀂐􀂆􀀃􀂑􀂈􀂈􀂇􀂔􀀃􀂐􀂇􀂙􀀃􀀌􀂐􀂖􀂇􀂔􀂐􀂇􀂖􀀃􀂅􀂑􀂐􀂖􀂇􀂐􀂖􀀃􀂕􀂇􀂔􀂘􀂋􀂅􀂇􀂕􀇤􀀃􀀃􀀐􀂑􀂔􀂇􀀃􀂖􀂊􀂃􀂐􀀃􀍙􀍟􀍝􀀃
operators in over 60 countries have deployed PeerApp systems. PeerApp was founded in 2004 and is
headquartered in Newton, Massachusetts, USA. For more information, visit www.peerapp.com.
Copyright 2011 PeerApp, Ltd. PeerApp, UltraBand, UBView, UBInsight and their respective logos are trademarks of PeerApp Ltd. All other
trademarks, logos and copyrights are the property of their respective owners. The information in this document is believed to be accurate in all
aspects at the time of publication and is subject to change without notice. PeerApp Ltd. is not liable for any errors that appear in this document.
December 2011-­‐A
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