1. ESLEA Bits&Bytes, Manchester, 7-8 Dec 2006, R. Hughes-Jones Manchester 1 Protocols DCCP and dccpmon. Richard Hughes-Jones The University of Manchester www.hep.man.ac.uk/~rich/ then “Talks” www.hep.man.ac.uk/~rich/

2. ESLEA Bits&Bytes, Manchester, 7-8 Dec 2006, R. Hughes-Jones Manchester 2 UDPmon: The Measurements (1) uLatency uRound trip times measured using Request-Response UDP frames uLatency as a function of frame size Slope gives sum of individual data transfer rates end-to-end Mem copy + pci + Gig Ethernet + pci + mem copy Intercept indicates processing times + HW latencies uHistograms of ‘singleton’ measurements uTells us about: Behavior of the IP stack The way the HW operates Performance of the LAN / MAN / WAN

3. ESLEA Bits&Bytes, Manchester, 7-8 Dec 2006, R. Hughes-Jones Manchester 3 UDPmon: The Measurements (2) uUDP Throughput uSend a controlled stream of UDP frames spaced at regular intervals uVary the frame size and the frame transmit spacing uAt the receiver record The time of first and last frames received The number packets received, the number lost, number out of order The received inter-packet spacing is histogramed The time each packet is received  provides packet loss pattern CPU load, Number of interrupts Packets in/out on each interface /proc/snmp IP and UDP counters uUse the CPU cycle counter for times and delay Few lines of user code – fast & precise uTells us about: Behavior of the IP stack The way the HW operates Capacity and Available Throughput of the LAN / MAN / WAN

4. ESLEA Bits&Bytes, Manchester, 7-8 Dec 2006, R. Hughes-Jones Manchester 4 UDPmon: The Works uHow it works: The ‘Zero_stats’ request also provides an interlock against concurrent tests. Zero stats / tsync OK done ●●● Get remote statistics Send statistics Send data frames at regular intervals ●●● Time to send Time to receive Inter-packet time Signal end of test OK done n bytes Number of packets Wait time time 

5. ESLEA Bits&Bytes, Manchester, 7-8 Dec 2006, R. Hughes-Jones Manchester 5 DCCP: The Application View uStephen & Richard with help from Andrea uPorted udpmon to dccpmon Some system calls don’t work getsockopt(*soc, SOL_DCCP, DCCP_SOCKOPT_CHANGE_L, &dccp_features, &len); uHad problems with Fedora Core 6 using kernel 2.6.19-rc1 DCCP data packets never reached the receiving TSAP ! Verify with tcpdump Using development “patches” kernel 2.6.19-rc5-g73fd2531-dirty udccpmon tests Plateau ~990 Mbit/s wire rate No packet Loss Receive system crashed! uIperf tests 940Mbps, back-to-back uNeed more instrumentation in DCCP Eg a line in /proc/sys/snmp

6. ESLEA Bits&Bytes, Manchester, 7-8 Dec 2006, R. Hughes-Jones Manchester 6 DCCP: Latest Kernel uKernel 2.6.19_pktd-plus - ~2 weeks old udccpmon tests Receive system crashed even faster ! Just 1 or 2 1000,000 packet tests uIperf tests OK short runs 940Mbps, back-to-back Hangs longer runs

7. ESLEA Bits&Bytes, Manchester, 7-8 Dec 2006, R. Hughes-Jones Manchester 7 DCCP: dccpmon crash

8. ESLEA Bits&Bytes, Manchester, 7-8 Dec 2006, R. Hughes-Jones Manchester 8 DCCP: ccid-VLBI Discussion uInput from Haystack: Internet2 & Australia NRN view Protect network from high bandwidth UDP flow DoS Concerns uVLBI view Want to send CBR data Don’t want to drop throughput if just lost a packet due to error – tcpdelay results DO want to know it there is congestion / packet loss Don’t want SlowStart – DCCP RFC says use a ramp up phase VLBI profile eg Ack Ratio =10 No Send Ack Vector ? API ?

9. ESLEA Bits&Bytes, Manchester, 7-8 Dec 2006, R. Hughes-Jones Manchester 9 Any Questions?

10. ESLEA Bits&Bytes, Manchester, 7-8 Dec 2006, R. Hughes-Jones Manchester 10 Backup Slides