Reliable data transfer: getting started We'll D incrementally develop sender, receiver sides of reliable data transfer protocol (rdt) O consider only unidirectional data transfer o but control info will flow on both directions O use finite state machines(FSm) to specify sender receiver event causing state fransition actions taken on state transition state: when in this state next state state state uniquely determined event 2 by next event actions 3: Transport Layer 3a-123: Transport Layer 3a-12 Reliable data transfer: getting started We’ll:  incrementally develop sender, receiver sides of reliable data transfer protocol (rdt)  consider only unidirectional data transfer  but control info will flow on both directions!  use finite state machines (FSM) to specify sender, receiver state 1 state 2 event causing state transition actions taken on state transition state: when in this “state” next state uniquely determined by next event event actions