Specifications

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Cisco TV CDS 2.5 ISA Software Configuration Guide
OL-24788-01
Chapter 2 Network Design
CDS Workflow
HTTP Streamers
HTTP can be used for communication between the Caching Nodes and the Streamers. The HTTP
Streamer communicates with a proxy for locating a fill source and pulling content.
A locate service serves as a proxy for a group of Caching Nodes and Vaults. The service is accessed
through a highly available virtual IP address hosted by the Caching Node. The virtual IP address is bound
to a fill port (Locate Port).
HTTP Streamers request content by HTTP GET requests to the proxy service (the server with the locate
service). The proxy server checks its own storage and peer fill sources (servers in the same group) for
the content using extended-CCP. If the content is found, the best source is chosen based on capacity and
a redirect response is sent to the chosen server. If the content is not found, a cache-fill request is sent to
the remote servers.
After the best server is chosen to send the content to the HTTP Streamer, a single cache-fill port on that
server is chosen for the HTTP transfer of the content. This is different from CCP transfers, which could
potentially use all cache-fill ports to deliver the content.
HTTP Locate Port
With respect to resiliency, the Locate Port service is similar to the Setup and Control servers,. The
primary server of the Locate Port service has the locate port IP address bound to an interface. The backup
server becomes the primary if the primary fails.
Peer Caching Nodes advertise among themselves about the ability to host the HTTP Locate Port service;
this includes primary, backup, available, and not usable states. Available means the Caching Node can
be either a primary or backup if needed. Not usable means that the server cannot host the service; for the
HTTP Locate Port this typically means that there are no usable network ports for the service.
A dedicated network port on the Caching Node is used solely for the HTTP Locate Port service. The
primary server determines service availability based on the link status of the dedicated network port.
Failover of the service occurs if the network port loses link status. A reestablished link results in the
server becoming available.
CCP Streamers
The CCP Streamers use CCP to communicate with the Caching Nodes. They do not use the proxy
address. CCP Streamers load-balance locate requests across fill sources.
The Streamer or Caching Node sends a locate-and-request message from the proxy server. The Proxy
server sends a message to the best source to fill the request.
Streamers or Caching Nodes needing content first query peer sources (servers within the same group).
Streamers also query local Streamers, if the content is not found, then a request to the remote sources is
sent. Remote sources are queried based on a preference list. Sources are grouped and preferences are
assigned for each group.
Vault Workflow
The Vaults ingest content using three different methods:
• FTP pull
• FTP push
• Live capture of MPEG-2 transport streams over UDP