Multicast

Multicast fails silently. No ICMP unreachable, no log message, no down interface: the stream just is not there. The good

Standard PIM sparse mode scales beautifully for a handful of sources and thousands of receivers. Push it the other direction,

Everything hard about PIM sparse mode traces back to one assumption: receivers do not know who the sources are. Drop

Unicast routing looks forward: where is this packet going? Multicast routing looks backward: did this packet arrive from the right

PIM sparse mode is where multicast stops being theory and becomes state machines. It is the protocol that turns "

IGMP is the only part of multicast a host ever speaks. Before PIM builds a single tree, before an RP