IGMP channel zapping time

Description

This test measures zapping times (in ms) when switching between different IPTV channels. An IGMP channel zapping consists of two IGMP messages: an IGMP join and an IGMP leave.

The IGMP zapping test lets you monitor and test channel change times, that is, how long it takes from the customer switching channels until the new channel is received.

When you start the test, the Netrounds Test Agent starts zapping between the selected multicast channels. It waits a specified length of time for each zapping to complete (i.e. to receive traffic on the new channel). The Test Agent performs a given number of zapping cycles over the channels. At the end of the test, the Test Agent reports the minimum, maximum, and average zapping times (the maximum will be limited to the timeout setting).

Please note that it does not make sense to perform an IGMP zapping test on a channel where the same Test Agent is already running an IPTV monitoring on the same interface. (If this is the case, the Test Agent will not leave the channel on IGMP leave, since the IPTV monitoring stipulates that the channel should be received continuously. In other words, because of the way multicast works, the IPTV monitoring will interfere with the IGMP zapping.)

Setting up a test or monitoring

Decide upon your network topology and follow these steps (jump forward if done):

To run IGMP channel zapping measurements you need to have at least one Netrounds Test Agent installed. If you haven't already done the installation, consult our quick start guides for various types of Test Agents in the section Netrounds Test Agents.

Also make sure that you have prepared Netrounds with your IPTV channel list.

Then create a new IGMP channel zapping test or monitoring and fill in the mandatory parameters below:

Parameters

Tests only

  • Duration (seconds): The duration of this test step in seconds. Min: 30 s. Max: 604800 s. Default: 60 s.
  • Fail threshold (seconds): The maximum number of errored seconds (ES) that may occur without triggering a fail for this test step. Default: 0.
  • Wait for ready: Time to wait before starting the test. The purpose of inserting a wait is to allow all Test Agents time to come online and acquire good time sync. Min: 1 min. Max: 24 hours. Default: "Don't wait", i.e. zero wait time.

General

  • Clients: Test Agents to use in the test or monitoring.
  • Channels: Select the IPTV channels to monitor from the preset IPTV channel list.
  • Min wait time between zapping: The minimum time a client will wait between IGMP join/leave messages. Min: 0 ms. Default: 2000 ms.
  • Max wait time between zapping: The maximum time a client will wait between IGMP join/leave messages. Min: 0 ms. Default: 2000 ms. Note: If you have a difference between Min wait time... and Max wait time...the joins/leaves will be randomized within the specified interval.

Thresholds for errored seconds (ES)

  • Threshold for join delay: The join delay is the time it takes from when the client issues an IGMP join message for a multicast group until the first packet is received for that multicast group. An errored second (ES) is triggered if the join delay threshold is exceeded. The default value is set to 500 ms in accordance with ETSI TS 102 034 (2009-08). Min: 0 ms. Default: 1000 ms.
  • Threshold for leave delay: The leave delay is the time it takes from when the client issues an IGMP leave message for a multicast group until the last packet is received for that multicast group. An errored second (ES) is triggered if the leave delay threshold is exceeded. The default value is set to 500 ms in accordance with ETSI TS 102 034 (2009-08). Min: 0 ms. Default: 1000 ms.

Advanced

  • Delayed start (s): (Tests only) Time by which to delay the start of the test within a test step. Default: 0 s.

SLA thresholds (monitorings only)

  • SLA Good: Threshold for good fulfillment of service level agreement. Default: 99.95%.
  • SLA Acceptable: Threshold for acceptable fulfillment of service level agreement. Default: 99.5%.

Result metrics

  • Average join delay (ms): Average delay from sending an IGMP join until the stream arrives.
  • Minimum join delay (ms): Minimum delay from sending an IGMP join until the stream arrives.
  • Maximum join delay (ms): Maximum delay from sending an IGMP join until the stream arrives.
  • Failed joins: Number of failed IGMP joins. A join fails if the stream does not arrive before an IGMP leave is sent.
  • Average leave delay (ms): Average delay from sending an IGMP leave until the stream is stopped.
  • Minimum leave delay (ms): Minimum delay from sending an IGMP leave until the stream is stopped.
  • Maximum leave delay (ms): Maximum delay from sending an IGMP leave until the stream is stopped.
  • Failed leaves: Number of failed IGMP leaves. A leave fails if the stream is not stopped before a new IGMP join is sent.
  • ES join: Number of errored seconds triggered by a failed IGMP join occurring during the second.
  • ES leave: Number of errored seconds triggered by a failed IGMP leave occurring during the second.
  • ES total: Aggregated errored second percentage, taking into account all types of error.
  • SLA: Service level agreement fulfillment for the test or monitoring: equal to (100 – ES total) %.
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