Internet transport-layer protocols reliable,in-order application delivery (TCP) network data link network physical o congestion control data link og ork physical o flow control network o connection setup end data link nd physical network data link unreliable,unordered physical delivery:UDP o no-frills extension of "best-effort"IP application ransport network services not available: data link physical o delay guarantees o bandwidth guarantees Transport Layer 3-6
Transport Layer 3-6 Internet transport-layer protocols reliable, in-order delivery (TCP) congestion control flow control connection setup unreliable, unordered delivery: UDP no-frills extension of “best-effort” IP services not available: delay guarantees bandwidth guarantees application transport network data link physical application transport network data link physical network data link physical network data link physical network data link physical network data link network physical data link physical
Chapter 3 outline 3.1 Transport-layer 3.5 Connection-oriented services transport:TCP 3.2 Multiplexing and o segment structure demultiplexing o reliable data transfer ▣3.3 Connectionless o flow control transport:UDP o connection management ▣3.4 Principles of ▣3.6 Principles of reliable data transfer congestion control 3.7 TCP congestion control Transport Layer 3-7
Transport Layer 3-7 Chapter 3 outline 3.1 Transport-layer services 3.2 Multiplexing and demultiplexing 3.3 Connectionless transport: UDP 3.4 Principles of reliable data transfer 3.5 Connection-oriented transport: TCP segment structure reliable data transfer flow control connection management 3.6 Principles of congestion control 3.7 TCP congestion control
Multiplexing/demultiplexing Demultiplexing at rcy host: Multiplexing at send host: delivering received segments gathering data from multiple to correct socket sockets,enveloping data with header (later used for demultiplexing) socket process application P3 P1 application P2 application transport transport transport network network network link link physical physical physical host 1 host 2 host 3 Transport Layer 3-8
Transport Layer 3-8 Multiplexing/demultiplexing application transport network link physical P1 application transport network link physical application transport network link physical P3 P2 P4 P1 host 1 host 2 host 3 = socket = process delivering received segments to correct socket Demultiplexing at rcv host: gathering data from multiple sockets, enveloping data with header (later used for demultiplexing) Multiplexing at send host:
How demultiplexing works host receives IP datagrams o each datagram has source 32 bits IP address,destination IP address source port dest port o each datagram carries 1 transport-layer segment other header fields o each segment has source, destination port number host uses IP addresses port application numbers to direct segment to data appropriate socket (message) TCP/UDP segment format Transport Layer 3-9
Transport Layer 3-9 How demultiplexing works host receives IP datagrams each datagram has source IP address, destination IP address each datagram carries 1 transport-layer segment each segment has source, destination port number host uses IP addresses & port numbers to direct segment to appropriate socket source port # dest port # 32 bits application data (message) other header fields TCP/UDP segment format
Connectionless demultiplexing Create sockets with port When host receives UDP numbers: segment: DatagramSocket mySocketl new o checks destination port DatagramSocket(12534); number in segment DatagramSocket mySocket2 new o directs UDP segment to DatagramSocket(12535); socket with that port UDP socket identified by number two-tuple: IP datagrams with (dest IP address,dest port number) different source IP addresses and/or source port numbers directed to same socket Transport Layer 3-10
Transport Layer 3-10 Connectionless demultiplexing Create sockets with port numbers: DatagramSocket mySocket1 = new DatagramSocket(12534); DatagramSocket mySocket2 = new DatagramSocket(12535); UDP socket identified by two-tuple: (dest IP address, dest port number) When host receives UDP segment: checks destination port number in segment directs UDP segment to socket with that port number IP datagrams with different source IP addresses and/or source port numbers directed to same socket