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Cisco Content Delivery Engine 205/220/250/280/285/420/460/475 Hardware Installation Guide
Chapter 1 Overview of the Content Delivery Engines
Cisco CDA Visual Quality Experience Application Overview
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A Vault Array consisting of one or more Vault servers. The Vault Array is responsible for ingest and
reliable storage of VoD content. The number of Vault servers in the Vault Array is driven by the
amount of content that the system offers and the degree of redundancy.
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One or more Streamer Arrays, each consisting of one or more Streamer servers. The Streamer Array
is responsible for personalizing and streaming content in response to user requests. The number of
Streamer servers and Streamer Arrays is determined by the number of streams deployed and by the
topology that best suits your individual network and redundancy requirements.
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One or more Cache Arrays, consisting of one or more Caching Nodes are optional. The Caching
Nodes provide more flexibility in designing a multi-tiered Virtual Video Infrastructure by acting as
a content cache tier between the Vaults and the Streamers. The Caching Nodes facilitate content
distribution and reduce distribution traffic from the network backbone.
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A CDSM server. The Content Delivery System Manager is used to manage the Streamer, Vault and
Cache servers, collect event logs, and provide reporting tools.
Note
In smaller systems, the Integrated Streamer-Vault (ISV) configuration can be used, where the Vault and
Streamer functionalities exist on a single CDE.
Cisco CDA Visual Quality Experience Application Overview
Cisco CDA Visual Quality Experience (VQE) Application offers service providers a set of technologies
and products associated with the delivery of Internet Protocol television (IPTV) video services. VQE is
designed to improve the quality of IPTV services and viewing experiences of the subscriber. VQE is part
of a Cisco end-to-end solution that builds video awareness into the network infrastructure. VQE
technology is intended for wireline operators who offer managed broadcast (multicast) IPTV services
using xDSL.
IPTV subscribers expect high video quality. Because many subscribers are migrating from existing
analog or digital cable services, their quality expectation has already been set.
VQE addresses the issue of video quality from both a network infrastructure and a video technology
perspective. VQE provides the linkage to optimize video delivery over next-generation carrier networks.
Based on industry standards, including Real-Time Transport Protocol (RTP) and RTP Control Protocol
(RTCP), Cisco VQE provides these functions to help in delivering entertainment-grade services to
subscribers:
Unicast Retransmission
—Optimized, selective retransmission of dropped IPTV packets caused by
noisy DSL lines or errors in the home network caused by poor-quality wiring. The set-top box (STB)
receiver, the VQE Client (VQE-C), sends non-acknowledgement (NACK) packets to the VQE-S to
request retransmission of the lost packets.
Forward Error Correction (FEC)
—Extra information is sent along with the video data at the
application layer. The additional information is used by the VQE-C on the STB to detect and correct lost
packets.
Rapid Channel Change (RCC)
—When the subscriber requests a channel change, the VQE-C on the
STB sends the VQE-S a request for the IPTV packets of the new channel. The VQE-S sends the VQE-C
an optimized unicast burst of IPTV packets and other channel information for the new channel from the
cached video data of the VQE-S. This greatly reduces the time needed to display the new channel.
IPTV Packet Loss Monitoring
—Facilities such as VQE-S RTCP Exporter help operators measure,
baseline, and pinpoint problem areas of the video infrastructure, including transmission lines and home
networks.
