Thomas Kunz
Systems and Computer Engineering
12
Reliable BCAST
nEach node keeps cache of recently transmitted packets (FIFO, small)
nEach node, upon receiving packet X from sender S, checks
whether it received packet X-1 from
that sender
ØIf not, broadcast retransmission request (NACK) to 1-hop
neighbors
ØNeighbors listen to overhear other retransmission and
cancels theirs
nFirst set of experiments revealed that under high
traffic load, too many NACKs
were issued, flooding the network and
resulting in overall worse performance (70% PDR for 10 sender scenarios)
nAdded feature: NACK throttle