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[video] Observing The Impact Multiple Default Gateways With Wireshark

Posted by Tony Fortunato on 2/16/17 8:00 AM

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Wireshark with Tony FortunatoI was speaking with a client the other day and they were asking me how Microsoft behaves if a device has two default gateways.

One thing I have to say about my job and clients, I always get interesting scenarios and questions to figure out.

He mentioned that they did some research online for a few hours and found many articles contradicted one another. They became frustrated and thought they would ask me. I searched around as well and understood their point.

I asked if they simply tried it in their lab, capture some packets while rebooting one of the routers to see what happens. I figure that it would take more time to setup the lab, than capturing and reviewing the packets.

In this video, I show you how I tested their question, how I used Wireshark and what I found out.

As I went through this example, I realized that I can go through the process of playing with metric settings but then remembered the client wanted to know how it behaved with default settings.  I also wondered if I left the test computer alone for a longer period, if it would eventually go back to the first router.  All things that I can go back and observe. That’s the nice thing of having a methodology, its easy to go back and try your ‘what if scenarios.’

I always recommend you start by documenting and understanding default behavior. Then you can confirm if any tuning parameters help.

 

Want more? Download the Network TAPs 101 - The Networking User Guide, where we discuss the connectivity strategy of the various TAP modes, as well as environmental considerations such as passive or active, and media conversion.

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Topics: Network TAPs, Network Visibility/Monitoring, Wireshark