Configuring Default IGMP Parameters for AMT Interfaces

You can optionally configure default IGMP parameters for all AMT tunnel interfaces. Although, typically you do not need to change the values. To configure default IGMP attributes of all AMT relay tunnels, include the amt statement:

You can include this statement at the following hierarchy levels:

• [edit protocols igmp]
• [edit logical-systems logical-system-name protocols igmp]
• [edit routing-instances routing-instance-name protocols igmp]
• [edit logical-systems logical-system-name routing-instances routing-instance-name protocols igmp]

The IGMP statements included at the [edit protocols igmp amt relay defaults] hierarchy level have the same syntax and purpose as IGMP statements included at the [edit protocols igmp] or [edit protocols igmp interface interface-name] hierarchy levels. These statements are as follows:

• You can collect IGMP join and leave event statistics. To enable the collection of IGMP join and leave event statistics for all AMT interfaces, include the accounting statement:
  user@host# set protocols igmp amt relay defaults accounting
• After enabling IGMP accounting, you must configure the router to filter the recorded information to a file or display it to a terminal. You can archive the events file.
• To disable the collection of IGMP join and leave event statistics for all AMT interfaces, include the no-accounting statement:
  user@host# set protocols igmp amt relay defaults no-accounting
• You can filter unwanted IGMP reports at the interface level. To filter unwanted IGMP reports, define a policy to match only IGMP group addresses (for IGMPv2) by using the policy's route-filter statement to match the group address. Define the policy to match IGMP (S,G) addresses (for IGMPv3) by using the policy's route-filter statement to match the group address and the policy's source-address-filter statement to match the source address. In the following example, the amt_reject policy is created to match both the group and source addresses.
  user@host# set policy-options policy-statement amt_reject from route-filter 224.1.1.1/32 exactuser@host# set policy-options policy-statement amt_reject from source-address-filter 192.168.0.0/16 orlongeruser@host# set policy-options policy-statement amt_reject then reject
• To apply the IGMP report filtering on the interface where you prefer not to receive specific group or (S,G) reports, include the group-policy statement. The following example applies the amt_reject policy to all AMT interfaces.
  user@host# set protocols igmp amt relay defaults group-policy amt_reject
• You can change the IGMP query interval for all AMT interfaces to reduce or increase the number of host query messages sent. In AMT, host query messages are sent in response to membership request messages from the gateway. The query interval configured on the relay must be compatible with the membership request timer configured on the gateway. To modify this interval, include the query-interval statement. The following example sets the host query interval to 250 seconds.
  user@host# set protocols igmp amt relay defaults query-interval 250

  The IGMP querier router periodically sends general host-query messages. These messages solicit group membership information and are sent to the all-systems multicast group address, 224.0.0.1.

• You can change the IGMP query response interval. The query response interval multiplied by the robust count is the maximum amount of time that can elapse between the sending of a host query message by the querier router and the receipt of a response from a host. Varying this interval allows you to adjust the number of IGMP messages on the AMT interfaces. To modify this interval, include the query-response-interval statement. The following example configures the query response interval to 20 seconds.
  user@host# set protocols igmp amt relay defaults query-response-interval 20
• You can change the IGMP robust count. The robust count is used to adjust for the expected packet loss on the AMT interfaces. Increasing the robust count allows for more packet loss but increases the leave latency of the subnetwork. To modify the robust count, include the robust-count statement. The following example configures the robust count to 3.
  user@host# set protocols igmp amt relay defaults robust-count 3

  The robust count automatically changes certain IGMP message intervals for IGMPv2 and IGMPv3.

  • On a shared network running IGMPv2, when the query router receives an IGMP leave message, it must send an IGMP group query message for a specified number of times. The number of IGMP group query messages sent is determined by the robust count. The interval between query messages is determined by the last member query interval. Also, the IGMPv2 query response interval is multiplied by the robust count to determine the maximum amount of time between the sending of a host query message and receipt of a response from a host.

    For more information about the IGMPv2 robust count, see RFC 2236, Internet Group Management Protocol, Version 2.

  • In IGMPv3 a change of interface state causes the system to immediately transmit a state-change report from that interface. If the state-change report is missed by one or more multicast routers, it is retransmitted. The number of times it is retransmitted is the robust count minus one. In IGMPv3 the robust count is also a factor in determining the group membership interval, the older version querier interval, and the other querier present interval.

    For more information about the IGMPv3 robust count, see RFC 3376, Internet Group Management Protocol, Version 3.

• You can apply a source-specific multicast (SSM) map to an AMT interface. SSM mapping translates IGMPv1 or IGMPv2 membership reports to an IGMPv3 report, which allows hosts running IGMPv1 or IGMPv2 to participate in SSM until the hosts transition to IGMPv3.

  SSM mapping applies to all group addresses that match the policy, not just those that conform to SSM addressing conventions (232/8 for IPv4).

  In this example, you create a policy to match the 232.1.1.1/32 group address for translation to IGMPv3. Then you define the SSM map that associates the policy with the 192.168.43.66 source address where these group addresses are found. Finally, you apply the SSM map to all AMT interfaces.

  user@host# set policy-options policy-statement ssm-policy-example term A from route-filter 232.1.1.1/32 exactuser@host# set policy-options policy-statement ssm-policy-example term A then acceptuser@host# set routing-options multicast ssm-map ssm-map-example policy ssm-policy-exampleuser@host# set routing-options multicast ssm-map ssm-map-example source 192.168.43.66user@host# set protocols igmp amt relay defaults ssm-map ssm-map-example