Even though the previous sections discussed the RET server and FCC server as separate entities, the ISA can support RET and FCC servers at the same service at the same time. Therefore, the configuration commands and operational commands for the services are intermingled. If both the RET server and FCC server are enabled for a specific channel, a single buffer is used for caching of the channel.
A maximum bandwidth limit for all server requests can be defined for a specific ‟subscriber” which is equated with the source IP address. Before an ISA server processes a request, the ISA calculates the bandwidth to the subscriber required, and drops the request if the subscriber bandwidth limit is exceeded.
The ISA services RET and FCC requests on a first in, first out (FIFO) basis. Before servicing any request, the ISA calculates whether its egress bandwidth can handle the request. If there is insufficient egress bandwidth to handle the service request, the request is dropped. Near the ISA’s egress limits, RET requests generally continue to be serviced whereas FCC requests are dropped because RET sessions are generally a fairly small percentage of the nominal rate and FCC sessions are slightly below to above the nominal channel rate.