Reliable data transfer: getting started rdt send(: called from above deliver data(): called by (e.g, by app. ) Passed data to rdt to deliver data to upper deliver to receiver upper layer rdt send()Idata data Deliver data() send reliable data reliable data receive transfer protocol transfer protocol side (sending side 〔 receiving side) side udt send( packet packet rat rcv unreliable channel udt send(: called by rdt rdt rcv(): called when packet to transfer packet over arrives on rcv-side of channel unreliable channel to receiver 3: Transport Layer 3a-113: Transport Layer 3a-11 Reliable data transfer: getting started send side receive side rdt_send(): called from above, (e.g., by app.). Passed data to deliver to receiver upper layer udt_send(): called by rdt, to transfer packet over unreliable channel to receiver rdt_rcv(): called when packet arrives on rcv-side of channel deliver_data(): called by rdt to deliver data to upper