A set of measurement tools was developed to measure the end-to-end UDP throughput, loss, and delay. Similar tools are available in the public domain (e.g. netspec and netpref). However, the set of tools being developed will also later be used to simulate UDP video traffic, and have been designed to provide flexibility for our specific requirements and a range of network topologies (e.g. 100/10 Mbps networks).
The tools are capable of generating UDP unicast and multicast traffic to saturate either a 10 Mbps or 100 Mbps network connection. The packets can be generated using multiple packet sources (this overcomes the general limitation of per socket rate). A number of command line parameters are provided for the user to configure the generated traffic, such as offered load to the network, and to limit of the number of hops through which traffic can be forwarded (important for multicast traffic).
The throughput measurement tools consist of a traffic generator and a sink.
The traffic generator sends IP packets using a BSD socket to access the UDP protocol. These are injected into the network at a user-specified rate. The traffic generator may also be used as a UDP traffic simulator for the next part of the study (loss analysis in the ATM WAN). The tool is capable of generating uniformly spaced packets or bursts of packets and is called "burst_gen_udp".
ivatt 44 > burst_gen_udp
usage: burst_gen_udp [options] internet address
options are:
-l<bursts length (Number of packets sources) (1..10)>
-b<bit rate in Kbps>
-e<enable delay measurement>
-m<message size>
-s<smooth mode (no bursts)>
-n<number of packets>
-x<multicast used>
-t<ttl value for multicasting>
-z<socket level buffer size>
ivatt 45 >
UDP Packet Sink
The packet sink receives these packets, checks the time stamps and sequence numbers and then discards them. In addition the sink program takes the required measurements to calculate the throughput. The data is stored in RAM and copied to disc at the end of each experiment (this minimises disc activity).
ivatt 45 > sink_udp_burst
usage: sink_udp [options] destination address [filename]
options are:
-i<No of iterations>
-e<enable delay measurement>
-s<No of samples per iterations>
-l<bursts length (Number of packets) (1..10)>
-m<message size>
-n<multicast>
-d<enable eating messages>
-z<socket level buffer size>
ivatt 46 >
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