Multicast Oif Mapping Case; Figure 15: Multicast Oif Mapping - Juniper JUNOSE 11.2.X MULTICAST ROUTING Configuration Manual

JunosE 11.2.x Multicast Routing Configuration Guide

Multicast OIF Mapping Case

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NOTE: For additional information about how to configure OIF mapping, see "Configuring
Group Outgoing Interface Mapping" on page 51.
The following sections provide two possible configuration cases for using multicast QoS
adjustment.
NOTE: For additional information about QoS adjustment, see Parameter Definition
Attributes for QoS Administrators Overview .
Multicast OIF mapping enables the router to decrease the inefficiencies associated with
replicating streams of multicast traffic. Using OIF maps, MLD joins that the router receives
on a subscriber interface can be mapped to a special interface for forwarding. This special
interface can be on a different physical port or line module from that of the join interface.
Using this mapping function, the router can send a single copy of each multicast stream
over the special interface and the access nodes are configured to perform any final
replication to the subscribers and merge unicast and multicast data flows onto the
subscriber interfaces as necessary. See Figure 15 on page 152.

Figure 15: Multicast OIF Mapping

One disadvantage to using multicast OIF mapping is that the multicast traffic bypasses
any QoS treatment that is applied to subscriber interfaces. Configuring QoS adjustment
resolves this problem. (See Parameter Definition Attributes for QoS Administrators
Overview for additional information about configuring QoS adjustment.) With QoS
adjustment configured, when a subscriber requests to receive a multicast stream (or,
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