Ping Connectivity Testing–Why Source Matters

The ping command is a pervasive troubleshooting tool used by network administrators and engineers. One important, but sometimes overlooked, detail is the source that is used by the traffic it creates. By default ping uses the IP address of the outgoing interface as the source of ICMP Echo messages. When this command is issued from a router with multiple interfaces, a positive response may not necessarily confirm the expected connectivity between two networks.

The video below outlines the scenario in detail and demonstrates why it is sometime important to specify the source when attempting to validate connectivity.

About Paul Stewart, CCIE 26009 (Security)

Paul is a Network and Security Engineer, Trainer and Blogger who enjoys understanding how things really work. With over 15 years of experience in the technology industry, Paul has helped many organizations build, maintain and secure their networks and systems.
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4 Responses to Ping Connectivity Testing–Why Source Matters

  1. Marek says:

    Hello Paul,
    great video with a great explanation. Can you please share which software you are using to record the video?

    Thanks.

    Marek

    • I’m pretty much a n00b when it comes to video and appreciate the comment. I’m going to continue to work on my technique. I used QuickTime Player to record the screen and applied a noise filter with iMovie. I also used Keynote and iTerm. All of these are free or part of Mac OSX (well I guess you pay when you buy the hardware). I have also been looking at a product for $99 called Screenflow. It looks awesome.

  2. Marek says:

    Thank you for the response. The recording was from my point of view in a very good quality.

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