Traffic Testing Tools

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• If you cannot observer poor performance directly, use testers to simulate traffic loads

Info

• This test can have substantial impact on performance
• schedule when the network is unused

Throughput Testers

• simple way to measure network throughput:
  • transfer a large file between hosts (copy)
  • to calculate
  • e.g., transfer 1 GB in 30 minutes
    • 1 gigabyte = 1,024x1,024x1,024 bytes (1,073,741,824 bytes or 8,589,934,592 bits)
    • 8,589,934,592 bits in 1,800 seconds = 4,772,186 bits per second or 4.55 Mbps
  • derives a value that is different from the nominal data rate
    • bc Application layers handle the file transfer,
      • intervening layers add complexity and inaccuracy (retransmission)
• tools can automate this
  • iperf
  • Ttcp
  • BWPing
• how it works
  • the tool is installed on two network hosts
  • tools measure the throughput achieved between the sender and listener

Top Talkers/Listeners

Top talkers are the interfaces generating the most outgoing traffic (in terms of bandwidth).

Top Listeners are the interfaces receiving the most incoming traffic.

• identify these hosts and their routes help:
  • identify and eliminate performance bottlenecks
• most network analyzers come with filters or built-in reporting to identify these

Bandwidth Speed Testers

Bandwidth speed tester is a hosted utility used to measure actual speed obtained by an Internet link to a representative server or to measure the response times of websites from different locations on the Internet.

• two classes:
  • broadband speed tester
    • tests speed of the local broadband link to the Internet
    • designed for SOHO use
    • how it works:
      • tests downlink and uplink speeds
      • tests latency using ping
      • can compare the results with neighboring properties and other users of same ISP
  • website performance checkers
    • query a nominated website to test how quickly pages load
    • advantage of online tool:
      • can test site’s response times from the perspective of customers in different countries