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Chapter 10
Configuring Multicast
IP PIM sparse-dense mode is enabled using ip pim sparse-dense-mode
on the interface command line. Here is an example:
RouterA#conf t
Enter configuration commands, one per line. End with
CNTL/Z.
RouterA(config)#interface FastEthernet3/0
RouterA(config-if)#ip pim sparse-dense-mode
RouterA(config-if)#^Z
RouterA#
Again, here is what the interface looks like once the preceding lines have
been entered:
!
interface FastEthernet3/0
ip address 172.16.21.4 255.255.255.0
no ip directed-broadcast
ip pim sparse-dense-mode
!
In summary, when using the sparse-dense mode configuration on an inter-
face, you need to understand that there are three criteria that will activate the
interface and place it into the multicast forwarding table. The first criterion
applies to either sparse or dense mode; the others will cause the interface to
operate specifically for sparse or dense mode. Look at Table 10.2 for the
details.
T A B L E 1 0 . 2
Interface Activation Criteria for Sparse-Dense Mode Interfaces
Criteria
Mode of Operation
Directly connected group members or DVMRP
neighbors
Sparse and dense
Non-pruned PIM neighbors
Dense
Join request received
Sparse
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