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Center for Applied Internet Data Analysis
Bandwidth Estimation: Issues and Approaches

Proposal for a Bandwidth Estimation Testbed

Bandwidth estimation is a problematic measurement where accuracy is difficult to achieve, particularly in high-speed networks. Several tools are available that use various strategies for estimating bandwidth, and some have been tested. However, more testing is needed to fully understand the impact of using different tools in particular configurations or contexts.

Bandwidth / Throughput Measurement Tools

  Active /
FunctionsTime ScopeAggregate Scope 
bingcompare RTTs from ICMP/ECHO reply of different size pktsactiveraw bandwidthreal-timenoneraw capacity (bps)
{b|c}probeICMP/ECHO replyactivebandwidth, congestionreal-timenonetext
clinkUDP w/limited TTL to unused port; ICMP err response or ICMP/ECHO replyactivebandwidthreal-timenonetext
netperfUDP w/limited TTL; ICMP time exceededactiveuni-directional throughput, end-to-end latencyreal-time> 60 secstext
nettimerpkt collection; pkt tailgatingbothpkt capture server, pkt capture client, active probe (tailgater)real-timetwo phases for pkt tailgating: entire path scanned once; active probes in tailgating phase until confidence interval reached for measuring link charsrecords; space delimited fields in ns trace file format
pathcharUDP; ICMPbothbandwidth, throughput, latency, loss, queue charsreal-timevariousGUI
pathrateUDP based, running from client to sinkactiveabsolute capacity (bottleneck bandwidth)real-timenot applicableabsolute capacity (range between a low and high estimate)
pcharUDP; ICMPbothbandwidth, throughput, latency, loss, queue charsreal-timevariousGUI
TRenoUDP w/limited TTL to unused port; ICMP err response or ICMP/ECHO replybothbandwidthreal-timenonegnuplot and ppmtogif graphs
ttcp and nttcpload generator activethroughputreal-timenonetext

Talks and Papers


nettimer uses a technique called 'packet tailgating' to actively measure link bandwidths.

  • Kevin Lai and Mary Baker. "Measuring Link Bandwidths Using a Deterministic Model of Packet Delay"
    Packet tailgating sends an order of magnitude fewer packets, while maintaining approximately the same accuracy as previous bandwidth estimation methods. It does not rely on consistent behavior of routers handling ICMP packets, and does not rely on timely delivery of acknowledgements. Advantages of this technique are its speed, unobtrusiveness, robustness, and ability to handle multiple channels. Disadvantages are its need to send packets back-to-back on the first link, its inability to measure a very fast link after a very slow link, the fact that queuing anywhere along the path disrupts the measurement of all links on the path, and the accumulation of errors in the calculation. Additionally, although nettimer gets timing information directly from the kernel using libpcap instead of the application level, this technique couldn't be extended accross many different NIC drivers. Thus, while the application-kernel node can be removed from the measured path, bridges remain invisible and are not taken into account. This paper includes a comparison of results from four bandwidth estimation tools: nettimer, pathchar, clink, and pchar. Results from both short path (3 hops) and long path (10 hops) measurements are given for each tool on channels of known physical bandwidth.


Pathchar (written by Van Jacobon) is a tool that infers (estimates) the characteristics of links along an Internet path.



  Last Modified: Tue Oct-13-2020 22:21:55 UTC
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