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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

Tool Input Measurement Output
    Active /
Functions Time Scope Aggregate Scope  
bing compare RTTs from ICMP/ECHO reply of different size pkts active raw bandwidth real-time none raw capacity (bps)
{b|c}probe ICMP/ECHO reply active bandwidth, congestion real-time none text
clink UDP w/limited TTL to unused port; ICMP err response or ICMP/ECHO reply active bandwidth real-time none text
netperf UDP w/limited TTL; ICMP time exceeded active uni-directional throughput, end-to-end latency real-time > 60 secs text
nettimer pkt collection; pkt tailgating both pkt capture server, pkt capture client, active probe (tailgater) real-time two phases for pkt tailgating: entire path scanned once; active probes in tailgating phase until confidence interval reached for measuring link chars records; space delimited fields in ns trace file format
pathchar UDP; ICMP both bandwidth, throughput, latency, loss, queue chars real-time various GUI
pathrate UDP based, running from client to sink active absolute capacity (bottleneck bandwidth) real-time not applicable absolute capacity (range between a low and high estimate)
pchar UDP; ICMP both bandwidth, throughput, latency, loss, queue chars real-time various GUI
TReno UDP w/limited TTL to unused port; ICMP err response or ICMP/ECHO reply both bandwidth real-time none gnuplot and ppmtogif graphs
ttcp and nttcp load generator active throughput real-time none text

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: Fri Aug-22-2014 11:22:59 PDT
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