Multicast routing [3]
l
Networks with no
group members
pruned from tree
l
Must somehow allow
tree to re-grow
l
Soft-state:
–
timeout – re-flood
–
downstream nodes
prune again
l
Explicit
graft
:
–
downstream nodes join
tree
•
Third refinement:
•
pruning
•
need to refresh tree –
soft-state
•
reverse path multicasting (RPM)