Latency, Jitter, and Packet Loss: A Plain English Explanation For Non-Geeks

latency, jitter, and packet loss in plain English

If you’ve read your managed service provider’s SLA (service level agreement) and wondered if you need an advanced degree in engineering to understand it all, don’t worry – you are not alone. Read on to get a plain English definition of these terms, and you’ll be speaking like a networking geek in no time!

Let’s take a look at three important network performance metrics, and learn why they matter to the successful deployment of your VoIP or unified communications service.

Latency

Latency is the time it takes a data packet to travel from point-to-point on the network. Each step your traffic takes through the network will add to its latency. Latency higher than 150 milliseconds (ms) will cause unnatural delays in an audio conversation. On a video call, high latency could create a disconnect between the audio and the video (which I like to call the “badly dubbed movie” effect). If latency becomes too high, you could experience periods of no audio or video at all.

Jitter

You may know jitter as that feeling you get when you drink too much coffee – if so, you might want to consider switching to decaf. The jitter we’re talking about here is an inconsistent arrival of packets between two endpoints. Jitter of more than 20 ms will cause delays in packet arrival which, like high latency, will result in delays in your audio or video.

Packet Loss

Packet loss happens when a packet does not arrive, arrives out of order, or arrives too late. Lost packets don’t go into a “packet lost and found,” though – they’re just discarded. Packet loss over a network will cause choppy, poor-quality audio and video. The good news is that you’d have to have a pretty high level of packet loss for the service to degrade to that state. Even if you lost 3% of all VoIP packets coming in, your audio quality would still be better than what you’d hear on a cell phone.

By the way, the Bandwidth Speed Test on the TPx website will measure the latency (ping) and jitter of your current Internet connection, in addition to your download and upload speeds. Remember, though, that a test like this one is just a snapshot of a moment in time. Try running the test several times, particularly during the times of day when you know your network is busy, and you’ll get a better picture of your network’s VoIP readiness.

Are there any other strange networking terms that have you stumped? If so, just let us know – we’re always happy to help.