1. DTNperf_3: a Performance Evaluation tool for DTN 3rd major release Carlo Caini University of Bologna, Italy; mail: ccaini@arces.unibo.it Credits: Piero Cornice, Marco Livini, Rosario Firrincieli

2. DTNperf in a nutshell Is an evaluation tool to assess DTN Bundle protocol performance Goodput Status report logs (from release 2.x, i.e. Dtnperf_2) Inspired by Iperf, largely used for TCP/UDP protocols evaluation Many similarities but also some important specific features Included in the DTN2 package Latest release (2.8), downloadable from the “bleeding edge” DTN2 code repository DTNperf is regularly updated and improved A new major release, DTNperf_3 is on development DTN2 & ION compatible New! 2

3. DTNperf_2 vs. Iperf Similarities Well-known client-server approach Client transmits, server receives Two sending modes Time mode (dummy data) Data mode (dummy data or File) Specific characteristics Logs The client collects all BP status reports File transfer File segmentation in bundles of wanted size at client side; bundle reordering at server side. 3

4. Other DTNperf_2 features Can be set/enabled: Bundle size, time to live, priority Custody option Reports: custody, forwarded, received Congestion control Tx Window (on the client) No more than W bundle “in flight” the reception of a new “delivered” triggers the transmission of a new bundle. 4

5. Logs 5

6. DTNperf_3 design

7. DTNperf_3 General Modes Client Bundle source From: Server Bundle destination To: External monitor (optional) New! Report collection Report to: If the external monitor is not present, report colection is performed by the client, as in DTNperf_2 7

8. DTNperf_3 Monitor Rationale Problems to solve: In the presence of disruption or intermittent link availability, status reports are not timely received by the client in space applications the delay can be of hours! In “one-way” transfers, status reports are never received. When to close the DTNperf client&monitor node ? The client should not be closed before the reception of all status reports (difficult to determine) External monitor: Decouples the Tx and log functions (from:/reply to:) Very useful in testbed environments DTN nodes connected to monitor through dedicated “control” links Real time reception of status reports Real time logs Difficult (or impossible) to insert in real environments This is why it is optional! 8

9. DTNperf_3 Sending Modes Time Transmit for “t” seconds Data Transmit “D” dummy bytes Send a File Options As in DTNperf_2 9

10. DTNperf_3 Congestion Control Window based (ACKed) Fixed window No more than W bundles “in flight” Transmit W bundles, then wait for ACK One new bundle for each ACK Rate based (no ACKs) New! Transmit “Br” bit/s (or bundle/s) per second Useful in a wide variety of applications (e.g. CGR testing) 10

11. DTNperf_3 new “ACKs” DTNperf_2 Delivered status reports Sent by the BP of the destination node Problems Are necessarily sent to the “report to” DTN node the client (“from”) must coincide with the “report to” node Low priority DTNperf_3 DTNperf Server bundle ACKs (DSA) Sent by DTNperf application New! Much more flexibility Can be sent both to DTNperf client and monitor Can be sent at high priority 11

12. Start and stop: criteria Client With external monitor Stops after sending the last bundle Otherwise Stops after reception of last “ACK” from server Server Always on Monitor Always on 12

13. Start and stop: details The client informs the monitor with DTNperf bundle “Tx start” DTNperf bundle “Tx stop” Monitor Tx start triggers the opening of a new log file Tx stop informs the monitor of the last bundle sent and triggers a closing timer File closing triggered either by reception of all DSAs from the server by expiration of closing timer Bundle reports must be timely written in the log file By default Monitor functions are performed by the client node 13

14. Conclusions Motivation: To design a flexible tool for DTN performance evaluation DTNperf_3 new features in short: Compatibility: DTN2 & ION General Modes Client, Server, Monitor Congestion control Window based, rate based ACKs Sent by DTNperf server, nomore by BP Others ? Your comments and suggestions are welcome! 14