HP ProCurve 6200yl Multicast And Routing Manual page 58

PIM-DM (Dense Mode)
PIM-DM Operation
These multicast switches support
the state refresh feature but must
handle periodic flood-prune cycles
for the downstream routers that
lack this feature.
Video
Server
Video
Server
Video
Server
These multicast switches support
the state refresh feature and do not
require periodic flood-prune cycles
for a given multicast group, which
frees up bandwidth for other uses.
Figure 3-2. Example of Bandwidth Conservation in Switches with PIM-DM State Refresh
3-8
5400zl #4
Multicast
Multicast
5400zl #1
ProCurve
5400zl #3
5400zl #2
Other
Router
Other
Router
These multicast routers do
not have the state refresh
feature and thus require
periodic flood-prune
cycles to advertise active
multicast group. In this
case it may be better to
group these routers on the
same multicast tree to
avoid the additional flood/
prune cycles on the routers
that do support state
refresh.
Indicates Paths Requiring
Periodic Flood-Prune Cycles
for a Given Multicast Group