Administrator Guide

Table Of Contents
multicast traffic flows only from the RP to the receivers. Once a receiver receives traffic from the RP, PM-SM switches to SPT
to forward multicast traffic, which connects the receiver directly to the source.
You can configure PIM to switch over to the SPT when the router receives multicast packets at or beyond a specified rate.
Table 65. Configuring PIM to Switch Over to the SPT
Configuring PIM to Switch Over to the SPT Command Mode
IPv4 Configure PIM to switch over to the SPT when the
multicast packet rate is at or beyond a specified rate. The
keyword infinity directs PIM to never switch to the SPT.
ip pim spt-threshold {|
infinity}
CONFIGURATION
IPv6 Configure PIM to switch over to the SPT when the
multicast packet rate is at or beyond a specified rate. The
keyword infinity directs PIM to never switch to the SPT.
ip pim spt-threshold {|
infinity}
CONFIGURATION
Preventing a Source from Registering with the RP
To prevent the PIM source DR from sending register packets to route processor (RP) for the specified multicast source and
group, use the following command. If the source DR never sends register packets to the RP, no hosts can ever discover the
source and create a shortest path tree (SPT) to it.
Prevent a source from transmitting to a particular group.
CONFIGURATION mode
ip pim register-filter
In the following example, Source 1 and Source 2 are both transmitting packets for groups 239.0.0.1 and 239.0.0.2. R3 has a PIM
register filter that only permits packets destined for group 239.0.0.2. An entry is created for group 239.0.0.1 in the routing table,
but no outgoing interfaces are listed. R2 has no filter, so it is allowed to forward both groups. As a result, Receiver 1 receives
only one transmission, while Receiver 2 receives duplicate transmissions.
Multicast Features
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