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Interfering Stream Files [Les]
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4.4Interfering Stream Files [Les]The network traffic files used by the simulator are all of a standard packet capture format commonly known as pcap, as defined in file pcap.h (version 2.4) of libpcap. See http://wiki.wireshark.org/Development/LibpcapFileFormat . Usually the files have been captured at the endpoints of the network at client devices. The goal of these files is that they be used as traffic sources for input into the simulation model. These files have been anonymously captured by a variety of researchers and from a variety of sources as real examples of representative types of packet traffic. The actual sources of the data cannot always be disclosed. In general, the files are a reflection of the traffic patterns observed and have had the payloads stripped to protect the privacy and rights of the actual content as well as to keep the overall file size small. Note that even though the traffic source files omit the payloads, size information is maintained so that the full traffic is modeled by the simulation. The simulator does pass payload data, if present in the pcap file. In addition to payload stripping, the pcap files have had a number of processing steps:
[we probably want figures of the bandwidth of the "reference files". i probably already have this. it's actually several related groups since the BW ranges between kbits and ~15Mbit] Quality of service QoS [xx] is a critical part of real networks and of each simulation scenario. Traffic flows are assigned a priority that is essential in practical access networks to ensure that higher priority traffic from managed services is carried in preference to lower priority traffic. The simulator has 7 priority levels and no per-class bandwidth reservation. The simulation test cases are set as follows: 1: (highest priority) Managed voice traffic 2: Managed IPTV-type video traffic 3: Unused 4: Unused 5: Unused 6: Unused 7: (lowest priority) Best effort, OTT video, VoIP, P2P
[how described by time series, PDV histogram] [impairment severity is a function of pcap statistics, number and rate of streams] [where they came from] [remember to include telepresence files from Phil H] [how selected] [bidirectional] [how processed: strip payload (or not), optionally scaled, optionally smoothed] [how described by time series, PDV histogram] [QoS assigned as managed or residual bandwidth (or does that belong elsewhere in the Standard?)] [impairment severity is a function of pcap statistics, number and rate of streams] [files provided on disk] 4.5Simulation InputsInput to the simulator is in the form of PCAP files. These files are driven into the simulation as specified by the timestamps in PCAP files. The payload of the PCAP files, if present, is carried along with the packets in the simulation and placed in the output files. The simulation parameter settings can adjust the timing of the packets driven into the simulation, for example to speed up or slow down the playback, or to smooth out unintended burstiness. A full list of the adjustable parameters for the PCAP packet generator is given in [Annex]. [network topology input] [where pcap files are inserted: artificially all at the start] Table : Network Model Simulation Input Parameters
Directory: TR-30 -> TR-30.3 -> Public Public -> Ansi/tia-921-b network Model for Evaluating Multimedia Transmission Performance Over the Internet Protocol TR-30 -> Document submitted to Download 182.84 Kb. Share with your friends:
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