D-Link DES-3326SR User Manual page 253

DES-3326SR Layer 3 Fast Ethernet Switch User's Guide
State <Disabled>
PIM-DM Settings
The Protocol Independent Multicast – Dense Mode (PIM-DM)
protocol should be used in networks with a low delay (low
latency) and high bandwidth as PIM-DM is optimized to
guarantee delivery of multicast packets, not to reduce
overhead.
The PIM-DM multicast routing protocol is assumes that all
downstream routers want to receive multicast messages and
relies upon explicit prune messages from downstream routers
to remove branches from the multicast delivery tree that do not
contain multicast group members.
PIM-DM has no explicit 'join' messages. It relies upon periodic
flooding of multicast messages to all interfaces and then either
waiting for a timer to expire (the Join/Prune Interval) or for
the downstream routers to transmit explicit 'prune' messages
indicating that there are no multicast members on their
respective branches. PIM-DM then removes these branches
('prunes' them) from the multicast delivery tree.
Because a member of a pruned branch of a multicast delivery
tree may want to join a multicast delivery group (at some point
in the future), the protocol periodically removes the 'prune'
information from its database and floods multicast messages to
all interfaces on that branch. The interval for removing 'prune'
information is the Join/Prune Interval.
This field can be toggled between
Enabled and Disabled and enables or
disables DVMRP for the IP interface.
The default is Disabled.
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