• Related Topics
• Configuring Multicast Routing Over IP Demux Interfaces
• Junos Subscriber Access Configuration Guide

Configuring Multicast Outgoing Interface Mapping

Multicast outgoing interface (OIF) mapping enables you to map multicast output to different interfaces. You can use this feature to enable the router to decrease the inefficiencies associated with replicating streams of multicast traffic by directing multicast streams (data packets) to a different interface than the one used for multicast control packets (used for IGMP and MLD joins and leaves). If multiple control interfaces all request the same stream and are mapped to the same output interface, only one copy of the stream is transmitted. Once an OIF map has been configured, you can apply it to an IGMP interface, enabling it to use a different output interface for multicast data forwarding.

Note: OIF mapping and reverse OIF mapping are not supported on the same customer or shared interface.

Configuring OIF mapping on a multicast interface requires the following general steps:

1. Configuring an OIF Map
2. Associating OIF Maps with Interfaces
3. Disabling QoS Adjustment
4. Configuring Passive Mode for IGMP or MLD

Configuring an OIF Map

The OIF map is a routing policy statement that can contain multiple terms. When creating OIF maps, keep the following in mind:

• If you specify a physical interface as the map-to-interface statement value (for example, ge-0/0/0), a ".0" is appended to the interface to create a logical interface (for example, ge-0/0/0.0).
• Configure a routing policy for each logical system. You cannot configure routing policies dynamically. As part of the policy, you must configure the map-to-interface statement statically.
• To use OIF mapping, you must also have IGMP, MLD, or PIM configured.
• You cannot map to a mapped interface.
• To use call admission control (CAC) with a mapped interface, you must configure it using the maximum-bandwidth statement (see the existing documentation for details about this statement).
• We recommend that you configure policy statements for IGMP and MLD separately.

To specify an OIF map:

1. Access the [edit policy-options] hierarchy.
   [edit]user@host# edit policy-options
2. Specify the policy that you want to use as an OIF map.
   [edit policy-options]user@host# edit policy-statement map1
3. Include any desired terms and specify any from or then clauses within them. The from clause in each term can select multicast flows based on the multicast group (using the route-filter keyword) and the source address (with the source-address-filter keyword). The then clause must accept or reject the term.
   [edit policy-options policy-statement map1]user@host# set from family inetuser@host# set then accept

   Note: For detailed information about how to create policies, see the Junos Policy Framework Configuration Guide.

4. Access the policy statement term.
   [edit policy-options policy-statement map1]user@host# edit term term1
5. Include a then action for the map-to-interface statement. The map-to-interface statement sets a value similar to the existing metric or tag actions and requires that you specify either a logical interface (that is, any interface that multicast currently supports) or the keyword self.
   [edit policy-options policy-statement map1 term term1]user@host# edit then map-to-interface
6. Specify either a logical interface (that is, any logical interface that multicast currently supports) or the keyword self. The self keyword specifies that multicast data packets be sent on the same interface as the control packets and that no mapping occur. If no term matches, then no multicast data packets are sent.
   [edit policy-options policy-statement map1 term term1 then map-to-interface]user@host# set self

   Note: For additional information about how to configure the map-to-interface statement, see “Configuring Actions in Routing Policy Terms” in the Junos Policy Framework Configuration Guide.

Associating OIF Maps with Interfaces

For OIF mapping to function, you must associate the configured OIF map with a logical interface. The OIF map is then applied to all IGMP or MLD requests received on the configured interface.

Note: If an OIF map is already configured on an interface, the new OIF map is added to the policy.

To associate an OIF map with a logical interface:

1. Access the IGMP or MLD interface.
   [edit]user@host# edit protocols igmp interface ge-1/0/0.1

   or

   [edit]user@host# edit protocols mld interface ge-1/0/0.2

2. Configure the OIF map that you want to associate with the interface as follows:

   • For IGMP interfaces, include the IGMP oif-map statement.
   • For MLD interfaces, include the MLD oif-map statement.
   [edit protocols igmp interface ge-1/0/0.1]user@host# set oif-map MAP1
   or
   [edit protocols mld interface ge-2/0/0.1]user@host# set oif-map MAP2

   Note: You can dynamically associate OIF maps with IGMP interfaces using dynamic profiles. For detailed information about creating dynamic profiles, see the Junos Subscriber Access Configuration Guide.

Disabling QoS Adjustment

QoS adjustment decreases the available bandwidth on the client interface by the amount of bandwidth consumed by the multicast streams that are mapped from the client interface to the shared interface. This action always occurs unless it is explicitly disabled.

You can optionally disable QoS adjustment. If you do so, available bandwidth is not reduced on the customer interface when multicast streams are added to the shared interface.

To disable QoS adjustment:

1. Access the multicast interface hierarchy.
   [edit]user@host# edit routing-options multicast interface ge-1/0/1
2. Include the no-qos-adjust statement to disable QoS adjustment.
   [edit routing-options multicast interface ge-1/0/1]user@host# set no-qos-adjust

   Note: You can dynamically disable QoS adjustment for IGMP interfaces using dynamic profiles. For more detailed information about creating dynamic profiles, see the Junos Subscriber Access Configuration Guide.

Configuring Passive Mode for IGMP or MLD

You can optionally define either IGMP or MLD to use passive mode.

Note: The OIF map interface should not typically pass IGMP or MLD control traffic and should be configured as passive. However, the OIF map implementation does support running IGMP or MLD on an interface (control and data) in addition to mapping data streams to the same interface. In this case, you should configure IGMP or MLD normally (that is, not in passive mode) on the mapped interface.

By default, specifying the passive statement means that no general queries, group-specific queries, or group-source-specific queries are sent over the interface and that all received control traffic is ignored by the interface. However, you can selectively activate up to two out of the three available options for the passive statement while keeping the other functions passive (inactive). These options include the following:

• send-general-query—When specified, the interface sends general queries.
• send-group-query—When specified, the interface sends group-specific and group-source-specific queries.
• allow-receive—When specified, the interface receives control traffic.

To configure passive mode for IGMP or MLD interfaces:

1. Access the IGMP or MLD interface.
   [edit]user@host# edit protocols igmp interface ge-1/0/0.1

   or

   [edit]user@host# edit protocols mld interface ge-1/0/0.2

2. Configure the interface to use passive mode as follows:

   • For IGMP interfaces, include the IGMP passive statement.
   • For MLD interfaces, include the MLD passive statement.
   [edit protocols igmp interface ge-1/0/0.1]user@host# set passive
   or
   [edit protocols mld interface ge-2/0/0.1]user@host# set passive

   Note: You can dynamically define IGMP interfaces as passive. For more detailed information about creating dynamic profiles, see the Junos Subscriber Access Configuration Guide.