Command Usage - SMC Networks SMC6724L3 Management Manual

C
ONFIGURING THE

Command Usage

Broadcasting periodically floods the
network with traffic from any active
multicast server. If IGMP snooping is
disabled, multicast traffic is flooded to all
ports on the router. However, if IGMP
snooping is enabled, then the first packet
for any source group pair is flooded to all
DVMRP downstream neighbors. If a
packet is received through an interface that
the router determines to be the shortest
path back to the source (based on interface
metrics), then the router forwards the
packet on all interfaces except for the
incoming interface.
The router will transmit a prune message
back out the receiving interface (i.e., the
parent interface) to its upstream
neighboring router if there are no group
members on its child interfaces. A prune
message tells the upstream router to stop
forwarding packets for a particular
source-group pair for the prune lifetime.
If the router that previously sent a prune
message now discovers a new group
member on one of its connections, it sends
a graft message to the upstream router.
When an upstream router receives this
message, it cancels the prune message. If
necessary, graft messages are propagated
back toward the source until reaching the
nearest live branch in the multicast tree.
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S
WITCH
source
flooding
potential
hosts
source
source
grafting
pruning