The ISA FCC server is supported within an IES or VPRN service context as applicable to the platform. VPRN services are not supported on the 7450 ESS.
Whether the FCC server is active for a specific multicast channel is defined in the multicast information policy where channels are defined. The channel configuration for the FCC server within the policy is an explicit enable/disable of the local FCC server (that is, whether the channel should be buffered) and a channel type PIP, SD or HD. When FCC is enabled, three (3) GOPs are stored in the buffer. The channel also defines an optional FCC tuning parameter called the FCC Minimum Duration which is used by the FCC server to determine which GOP to start the FCC unicast session. If there are too few frames of the current GOP stored in the FCC server buffer (based on number of milliseconds of buffering), the FCC server starts the FCC session from the previous GOP.
In an IES or VPRN service, up to 16 IP addresses can be assigned to a video interface.
The Video Policy within the multicast information policy defines the characteristics for the how the FCC server should respond to FCC requests received on an IP address. The different characteristics defined in an FCC server ‟profile” are for each channel type (PIP, SD and HD):
enable/disable for the FCC server (for example, should the requests be serviced or dropped)
the FCC mode (burst, dent or hybrid)
the burst rate (as a percentage above the nominal channel rate) for PIP, SD and HD channel types
the multicast handover rate (as a percentage of the nominal channel rate) used by the server after it has signaled the client to join the main multicast channel
Different FCC rates are allowed for each of the channel types because the channel types have different nominal bandwidths. For example, the last mile may only be able to reliably send a 25% burst (above nominal) for HD whereas the equivalent bit rate for SD is a 75% burst. The profiles are designed to provide flexibility.
The IP address of the FCC server is defined in the unicast service instance, whereas the UDP port for the FCC server is defined in the ‟default” bundle in the multicast information policy. The same UDP port is used for all FCC server IP addresses that use the particular multicast information policy.
The ISA FCC server supports the network model where there are separate service instances for unicast and multicast traffic that are cross-connected and multicast replicated downstream in the network. If there are separate multicast and unicast service instances, the unicast and multicast services must use the same multicast information policy.