Thomas Kunz
Systems and Computer Engineering
388
Link Level Retransmissions
nSelective repeat protocols can deliver packets out of order
nSignificantly out-of-order delivery can trigger TCP fast retransmit
–Redundant
retransmission from TCP sender
–Reduction
in congestion window
nExample: Receipt of packets
3,4,5 triggers dupacks
6
2
5
2
3
4
1
Lost packet
Retransmitted packet