Due to the dynamic nature of real TCP traffic, its best practice to perform a loopback reference test to determine the sum total of the application load achievable in terms of throughput and latency across the modem/CMTS environment.
With this golden reference it’s now possible to test for degradation across the devices under test and the aggregation switch environment is also quantifiable.
The results above show baseline traffic loads for HTTP and SMTP as well as overall loads upstream and downstream on the physical ports.
150 Mbps Downstream and ~20Mbps upstream is representative of a load that can be easily attained by each DOCSIS 3.0 cable modem.
By applying an appropriate load with single or multiple applications the required bandwidth in the upstream (FTP PUT, SMTP, HTTP POST VoIP call) and downstream (FTP GET, HTTP GET, Multicast/unicast stream receipt, VoIP call etc.) can be produced. The example below illustrates upstream and downstream load using a multiple application loopback reference test.