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Sometimes when using VoIP I experience disruptions. I would like to check if the problems could be caused by my internet provider.

How could I best test the quality of my bandwidth (throughput and latency)?

Until now, I have used a script which sends 3600 pings per hour and saves min/max/avg., but I am not sure how representative ICMP packets are.

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ICMP packets are very unrepresentative as they are often given special treatment by routers which either boost or lower their priority depending on what the marketers want to look good on the sales literature. –  msw Aug 21 '13 at 21:37
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3 Answers

up vote 2 down vote accepted

MTR is probably the tool you're looking for. I've been using it for a long time and it's helped me troubleshoot a lot of network connectivity problems. It's like traceroute, but it runs continuously and shows you detailed info of every hop along the way.

From the wiki:

MTR relies on ICMP Time Exceeded (type 11, code 0) packets coming back from routers, or ICMP Echo Reply packets when the packets have hit their destination host.

Good luck! VoIP can be a headache to troubleshoot.

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The ICSI Netalyzr is a Java application that tests different aspects of your network. It can also check for the buffering behaviour. The drawbacks are that it requires Java enabled in the browser and that it is closed source software.

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Diagnosing where in the 20+ hops between you and your VoIP partner you're seeing the loss is really difficult because you can't talk to the intermediate devices.

You are testing it in the most direct way, by using your VoIP application, and you've proven that someone is dropping stuff somewhere.

In my experience (debugging carrier networks from the inside) it is most often the case that your ISP has over-subscribed their upstream connection, but they won't tell you if they are seeing loss there, nor can you do much to determine if this is true.

Try changing your VoIP codex to something that uses less bits (hence reducing quality). If your application can use a different IP port number, try that as telcos sometimes throttle VoIP traffic because it competes with their voice services.

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