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It could be considered as: Performance versus Functional test.

For Channel Zapping the key metric is the max number of channels/subscribers supported. While Verification focuses more on whether the correct Channel is received for each subscriber (uses all 32 bits instead of just 2 for the Analyzer Filters). Although from a performance perspective they both can support the same channel change rates and/or "zap and view."

• Used to monitor zapping characteristics for a large number of clients and groups (virtually unlimited)
• Only verifies that a channel was changed successfully
• Only verifies using the last two bits of the IP multicast address

• Used to monitor zapping characteristics for a limited:
  • number of clients and groups (32,768 total when multiplying the two); and
  • number of IPTV viewers (1024 per port for package A and 4096 per port for package B)
• Fully verifies that a channel change was successful using all 32 bits of the multicast IP address

added 2/25/15

There are two configurable test types. The main difference between them is the way the IPTV host-side Analyzer filters are configured.  The two tests are:

• Channel Verification Test
  • IPTV host-side Analyzer filter
    • 1 substream programmed into the analyzer for each (mc group, IPTV client).
    • Example 10 IPTV clients zapping over 12 channels = 120 substreams programmed into the Analyzer.
  • Useage
    • This test will verify each channel is received by each IPTV host. Each substream will be able to capture the first and last multicast data packet for a host/channel pair. All possible host/channel pairs will be programmed into the analyzer filter prior to running the test. The IPTV/Mcast daemons will be given the substream list in order to capture the first and last timestamp for each host/channel pair.
  • Limitations
    • Package A = 1024 IPTV hosts/port
    • Package B = 4096 IPTV hosts/port
    • numClients * numChannels <= 32K
       
• Channel Zapping Test
  • IPTV host-side Analyzer filter
    • 4 substreams programmed into the analyzer for each IPTV client vlan. 
      • Basically the 4 substreams use filters on the last 2 bits of the mc group.  This creates 4 buckets and hence doesn't verify that the correct data is being received on each channel change.
    • Example 10 IPTV clients zapping over 12 groups = 40 substreams programmed into the Analyzer.
  • Useage
    • This test is used to monitor zapping characteristics for a large number of hosts. The list of channels will be aggregated down to four or more substream filters. Every time a channel is switched on a given host, the channel changed from and the channel changed to will have different assigned substream. This test does not take into account the case where a channel is incorrectly switched to a channel that is in the same substream aggregate group, but that behavior should be tested for with the first test.
  • Limitations
    • Package A = 1024 IPTV hosts/port
    • Package B = 4096 IPTV hosts/port
    • Requires number of channels zapped to is a multiple of 4

So one might use the Channel Verification Test to do deep analysis of a smaller number of hosts and channel ranges.  As the SUT is characterized higher scale tests can be achieved by using the Channel Zapping Test.