Networking Terms Explained: Bandwidth, Latency, Jitter, and Flapping

It’s 2017 and Internet in America still isn’t as good as it could be. A large contributor to this may be that consumers don’t really understand networking or what to expect. Even the “tier one” support representatives at major ISPs (Internet service providers) don’t fully know what to look for when you’re having an issue.

If you’ve ever called your ISP because things don’t seem to be working as expected, odds are they’ve had you run a speed test; and if the results are within a few megabits per second of what you’re paying for, they’ve sent you on your merry way, had you reset your modem/router combo unit, or offered to have someone come and “take a look.” Problem is, a speed test isn’t conclusive and there’s a good chance the problem may be something within your control.

This article will attempt to explain some basic networking terms and concepts to help you know what to do the next time your streaming-movie or online multiplayer game doesn’t function the way you expect.

Bandwidth

What is bandwidth? Let’s start with the basics. Many people refer to bandwidth as speed. This isn’t really right or wrong. A better way to describe bandwidth is capacity.

Think of having two large soft drinks in front of you, one has a big wide straw and the other has a smaller skinny straw. Because the larger straw can transport more liquid at a time, the drink will likely be consumed quicker.

A lot of bandwidth means more data can be transported simultaneously. Most devices support up to 1 Gbps (gigabit per second) although some are less (10/100 Mbps). If you have a 10 Mbps connection and try to stream three HD videos on Netflix at about 5 Mbps each you will fail since you don’t have enough bandwidth for the data to be transported simultaneously.

In this case it has nothing to do with speed and everything to do with capacity.

Latency

So what terminology do we use to refer to speed? In networking we use the term “latency” to refer to how long it takes data to travel from on location to the next. These locations are physical routers that make up the Internet referred to as “hops.” The standard set by ISPs is less than 100 ms. The closer to zero the better, especially when it comes to realtime traffic such as VoIP (voice over Internet protocol) calls, video calls (like Skype or FaceTime), or online gaming.

Bandwidth vs. Latency

When thinking in terms of bandwidth and latency it helps to imagine driving down a highway. There are many factors that will determine how fast you drive and how many cars can be on the highway at once. The amount of lanes can be seen as how much bandwidth is available. The amount of cars will affect congestion. The distance you go will affect latency. And all of these things, including speed limits (some servers are slower than others) will affect your overall speed.

In other words, latency and bandwidth both contribute to your connection speed.

Jitter and Flapping

When a network isn’t working as expected it’s easy to blame your bandwidth and in some cases this may be the cause. But what do you do when you have plenty of bandwidth for what you are trying to do but still experiencing issues? Well it depends, if sites simply aren’t loading you may want to check your browser settings, your computer’s connection, or your router’s configuration. But if you’re experiencing choppy call quality on your video call or your VoIP phone, or your character is jumping around in your online game, you may be experiencing an unstable connection.

Network stability often utilizes the terms jitter and flapping. These refer to issues with your network latency. It may be happening on your local network or it may be happening along one of the hops along the route your connection takes.

Jitter refers to variations in latency. When sending and receiving data to and from a specific location the amount of time should be pretty consistent. If it’s not it can cause data packets to arrive late or out of order.

Flapping refers to large spikes in latency that can cause packet loss (when data times out and doesn’t make it) or issues with data arriving heavily delayed.

If you notice choppy quality with your realtime data it may indicate poor network stability likely caused by jitter or flapping.

Troubleshoot Your Network

Troubleshooting network issues can be difficult, but here are some helpful steps that can help you avoid a call to the ISP or help you better isolate the cause of the issue:

• Check what devices on your network are consuming data and make sure they’re not using more than what your network is capable of. Again, if you pay for 20 Mbps and a device on your network is trying to stream a 4K Netflix movie, it’s probably not going to work. Netflix recommends a minimum of 25 Mbps for UHD (ultra high definition) streaming. Even if you have 25 Mbps, remember it needs to be shared with all the devices on your network.
• Try unplugging your modem and router for about two minutes or more. Some SOHO (small home/home office) and ISP provided equipment build up static electricity overtime, leaving them unplugged for a few minutes can help with this and also serves as a reboot.
• If you’re not using more data than you have capacity or available bandwidth for, now is the time to run a speed test. net is a great choice for this. If you’re showing significantly less than what you pay for, it might be a good time to call your ISP.
• If you’re experiencing choppy real time data (such as a video call or gaming), run some ping tests to Google’s primary DNS server (8.8.8.8) to test latency. This can be done by typing “ping 8.8.8.8” in a Terminal window on your Mac or Linux machine and pressing enter. Alternatively you can run a ping test in Windows’ Command Prompt by typing “ping 8.8.8.8 -t”. This will send a series of pings, they should for the most part be less than 100 ms and shouldn’t vary by more than 10 or 15 ms for optimal stability. The closer to zero the better. Ideally, you shouldn’t see any packet loss.
• If your ping tests are high or show a lot of jitter (variations in latency) you may want to run a ping test to your router’s IP address to see if the issue is internal or not. Internal pings are usually less than 1 or 2 ms. Ideally you shouldn’t see any packet loss. If you see packet loss or high pings this could indicate faulty cabling or equipment (router, modem, wireless access point (WAP), port, or switch). Before replacing things you may want to try rebooting your device(s) and networking equipment. It’s also a good idea to make sure you’re running the latest firmware on all your devices and equipment.
• Also, wireless networks are not as stable as wired networks. For gaming and other realtime streaming a wired connection is advised as wired connections tend to provide the most stable connection. In areas with a lot of magnetic interference you may want to try STP (shielded twisted pair) Ethernet cabling.

While this article may prove useful for better understanding basic network issues and terms it isn’t meant to be a replacement for trained network professionals and may not apply to every instance. It’s intended to help you get the most out of your network and better communicate issues to your ISP. No network is perfect, but the more you understand about networking the better your home network will function as a result.