Impairment Combination Standard Test Cases

5.2Impairment Combination Standard Test Cases

• 
  Well-Managed Network (Profile A) – a network with no over-committed links that employs QoS edge routing. The well-managed test cases include managed voice and video services.
  
• 
  Partially Managed Network (Profile B) – a network that minimizes over-committed links and has one or more links without QoS edge routing. The partially managed test cases include a mixture of managed voice and video services, and unmanaged / best-effort data and over-the-top video services
  
• 
  Unmanaged Network (Profile C) – an unmanaged network such as the Internet that includes over-committed links and has one or more links without QoS edge routing. The unmanaged test cases include unmanaged data and over-the-top video services.
  

The specific core network parameters, interferers, and access network parameters for each test case were selected so that the simulation results align with the impairment level requirements of section 5.1, with an adjustment to account for the fact that the simulations only cover the core-to-LAN topology. The interferers represent a realistic mix of typical traffic. The test cases span a range of impairment severities from mild to severe within each Service Test Profile.

• 
  The first character is either D for DSL or G for GPON. The access rates and impairments chosen represent typical values in 2010. (The single core-only test case, lacking an access network portion, is labeled simply “Core.”)
  
• 
  The second character is one of the following:
  
  • 
    w for well-managed profile A, highlighted in green in Table .
    
  • 
    p for partially managed profile B, highlighted in yellow in Table .
    
  • 
    u for unmanaged profile C, highlighted in red in Table .
    
  • 
    c for the core-only case, highlighted in blue in Table .
    
• 
  The third character is an ordinal digit, where a higher value generally corresponds to a higher severity (more difficult) test case.
  

Table : Well-Managed Service Test Profile A Test Cases

• 
  Bandwidth utilization is stable.
  
• 
  Packet loss is low.
  
• 
  Jitter is low.
  

Figure : Aggregate Bit Rate over Time for DSL Well-Managed Profile A

Figure shows the aggregate bit rate over time for the DSL partially managed profile. Test Profile B has the following characteristics:

• 
  Bandwidth can vary significantly.
  
• 
  Packet loss is medium to high for the subset of unmanaged services.
  
• 
  Jitter is medium to high for the subset of unmanaged services.
  

Figure : Aggregate Bit Rate over Time for DSL Partially Managed Profile B

• 
  Bandwidth can vary significantly.
  
• 
  Packet loss is high.
  
• 
  Jitter is high.
  

Figure : Aggregate Bit Rate over Time for DSL Unmanaged Profile C

6Using the Network Model

The network model can be used in two ways:

1. 
   Evaluate a test stream using the simulator.
   
2. 
   Run a test stream through a real-time hardware emulator.
   

6.1Using the Simulator

The simulator can be used in a number of ways:

• 
  Select a standard test case.
  
• 
  Generate a test pcap file that includes payload. The test stream should correspond to an existing standard pcap file included in the test case.
  
• 
  Replace an existing pcap file with the test pcap file by editing a simulator parameter file. See Annex A section 6.4.1.1.1.1.5.
  
• 
  Run the simulation, which results in a .out file and a set of output pcap files.
  
• 
  Evaluate the test output pcap file to assess network effects on the payload under this test condition.
  

6.2Using a Real-Time Hardware Emulator

Figure shows an example of a lab test setup using a video stream played between a server and set-top box through a network emulator.


Figure : Hardware Emulator Test Setup

The emulator could be used as follows:

• 
  Select a standard test case that includes a technology similar to the test stream.
  
• 
  Configure the emulator with the standard .out file from 6.4.1.1.1.4 for the selected test case.
  
• 
  Run the test stream through the emulator, and evaluate the effect of the network impairments on the stream.
  

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