UDP and CBR Internet Engineering

1 Contents Delivery Encode –Music or movie is converted to data (compress) CBR (Constant Bit Rate) –Constant bit assignment method (MPEG2) –Assign a certain amount of bits VBR (Variable Bit Rate) –Bit rate is changeable –High bit amount for strong change (moving, color) Assignment Method (MPEG2) –Assign a lot of bits for strong change in movement of color Bit rate ： Number of bits are sent every second [bps (bit per second)]. higher bit rate will give more information and better quality of picture or music

Internet Engineering 2 Protocol of transport layer Low reliability, there is no guarantee that packets will be delivered Suit for delivery of music or movie Application layer FTP, CBR HTTP, SMTP Transport layer TCPUDP Network layer IP Physic, data-link layer Ethernet UDP (User Datagram Protocol) Sending data Without considering about network state, UDP sends data according to the request from higher layer

Internet Engineering 3 Hierarchy Architecture senderreceiver data UDP header IP header Ethernet Frame Header IP Header UDP Header addition analysis Communication medium （ LAN Cable ・ Optical Cable ・ Wireless ） sendingreceiving Application layer Transport layer Network layer Physic Data-link layer

Internet Engineering 4 UDP Packet Configuration (Notice) Since UDP header is small, In NS header size is considered as 0 Source Port Number Destination Port Number Packet LengthChecksum Data UDP Header 0 31

Internet Engineering 5 CBR/UDP Simulation Data encoded by CBR UDP Agent NetworkRouter Voice ・ Movie playback UDP Agent Network Parameter ・ Packet size ・ Transmission rate

Internet Engineering 6 Throughput [Mbps] = Packet drop rate [%] = ×100 (Total of received packet)×(Packet size(including header)[bytes] (transmision time)[s] (Total of dropped packet) (Total of sent packets) Experiment CBR/UDP Bandwidth: Bw (Bottleneck link) 40Mbps