What Is Packet Loss and What is Jitter? A Guide to ISP Metrics

When selecting an internet service provider (ISP), packet loss and jitter are two key metrics to check in your service level agreement (SLA) before signing up.

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Ginger Woolridge

Nov 12, 2021


Honestly, most salespeople aren't out to actively deceive us. But when charged with unloading a sub-prime product, some may try to dazzle us with one attractive feature (like speed) in the hopes we won't notice any other shortcomings—until it's too late. And while technologies have advanced, salesmanship hasn't, so it's wise to keep a lookout for lemons, whether you're shopping for a used car or business internet.

Pre-COVID-19, internet service providers (ISPs) were falling all over each other to provide businesses with the speediest of “high-speed” internet. However, with changing demands on business internet in a post-COVID world, packet loss and jitter are the metrics that matter when vetting ISPs. But what is packet loss, and what is jitter? Here, we’ll define these metrics and unpack why speed should no longer be the only item on your checklist when shopping around for the right business internet.

Avoiding the Speed Trap: Why Yesterday's Performance Metrics Matter Less

The business world's seismic shift to remote-first work as the COVID-19 pandemic swept the globe flipped what we need from service providers on its head. Digital adoption by consumers and businesses leapt ahead five years in roughly eight weeks. More employees than ever are working from home offices and kitchen tables. And data from a recent Gallup survey suggests this shift will last, as 75% of online “first-timers” plan to keep using digital channels post-COVID.

It should be noted, despite the sea of change we're now experiencing in the use of technology, business owners in the U.S. and rural communities in general still struggle to access online service that's fast enough to support remote working. In these situations, speed still is an important factor. And while the COVID-19 pandemic is shining a brighter light on equity issues that exist with respect to internet speed and access, we have some work to do before we can even agree on what should actually be accessible.

Despite this, the fact is that more of us are demanding more internet to do more things more of the time. This brings us to packet loss and jitter and why they're now key to spotting a lemon when shopping for the right ISP.

What Is Packet Loss (and Why Speed Can't Lap It)?

No matter how fast the internet could theoretically become or how much bandwidth could be added, it will always be more efficient to break down data and transmit it in pieces (i.e., packets) than sending things whole. But when all that important information is broken down, sent over the web, and reassembled, things can get a little wonky in the process—and a high-speed connection won't make a bit of difference there. So, what is packet loss in this case? It’s where Transmission Control Protocols (TCPs) come in to play.

One TCP (at point A) does the work of parsing data to be sent into efficient packets. Much like what happens at an Amazon or UPS warehouse, each packet is labeled with a number and its destination address (another TCP at point B). This is important, as not every packet takes the same route to its destination. And, once they've all arrived, Point B TCP reassembles the packets into their original form.Unless it can’t.

Packet loss is the term for when some packets don’t make it from point to point during the trip. Business-side issues, like software bugs and old or outdated hardware, can cause this to happen. Fortunately, on-site IT can mitigate these problems or, ideally, prevent them entirely. But packet loss can also occur when an ISP's network is clogged during peak-use times and/or if the network itself is old or outdated.

And, unfortunately, no amount of speed can overcome service-side causes like these. Think of a delivery truck whose packages keep falling out of the back. Does it matter if we get it to its destination faster if half of what's being carried goes AWOL during the trip? This problem is then compounded over time, as each packet that fails to arrive must be re-sent, causing a backlog until the transfer is completed (or canceled).

Now, back in the good ol’ days where all we cared about was download speeds, packet loss was simply an inconvenience. In fact, significant packet loss (10–20%) would only increase the time needed to download a file by mere seconds. But, as stated above, post-COVID business means doing a lot more than downloading Chumbawomba MP3s from Napster (unfortunately). And for day-to-day necessities like real-time voice and video, service with packet loss of just 2% can cause significant quality issues during video meetings.

This is why, while packet loss of 3–5% was considered "acceptable" pre-COVID, current business needs could already be rendering that threshold obsolete.

What Is Jitter (and Why You Can't Horsepower Through It)?

Packet loss isn't the only notable problem now found in transit. The ability to communicate online in real time isn't determined by how fast your packets can travel. Instead, a digital experience conducive to effective communication is the result of each packet being spaced apart equally while in transit.

What is jitter? Well, when that spacing fluctuates all over the place, you've got jitter. (Note: An overarching delay in all packets arriving at their destination is instead referred to as latency.) Like packet loss, jitter can be caused and/or amplified by business-side problems. But most stem from the infrastructure of the internet itself, which is a grand, funky patchwork of intercrossing copper, fiber, and switching stations that (now) span the globe.

As data packets are sent from one point to another, congestion and dead ends can cause packets to be rerouted. While all may eventually arrive at their destination (barring packet loss), they can arrive at their destination TCP at varying intervals. On a business-by-business basis, jitter can frustrate or impede real-time day-to-day business communication. But big picture, jitter along with packet loss directly contributes to the $700 billion dollars lost to unreliable internet each year.

And here we have another problem speed alone can’t solve. Thinking back to our delivery truck example before, what good does tricking out the engine do if said truck was marooned in a traffic jam? There are, however, acceptable thresholds for jitter, too.

Currently, for real-time communication, a round trip between two points should not exceed 300 milliseconds. Ah, but that's latency. Jitter is measured by adding up and averaging the varying spaces between each packet during a given trip. As of 2018, jitter of more than 30 milliseconds was considered unacceptable, which certainly means that's far less is acceptable today.

Getting What You Pay For: Mean Opinion Score and Negotiating Vendor Contracts

So, let's say (above insights in hand) you hone in on an ISP that, based on the window sticker, looks like it'll deliver exactly what your business needs. How do you drive it off the lot, so to speak, confident that it will perform the way you want? Or what if you’ve already made the choice?

This used to be a murky proposition. Large ISPs have earned a reputation for being less-than-forthcoming about the quality of the service they're providing (even with regard to speed). More forward-thinking oversight should improve our ability to make better internet buying decisions in the near future. But for those wondering about the quality of their current service, fortunately, there is a standardized rating system known Mean Opinion Score (MOS), which can help you gauge the quality of your current service.

Originally devised over 150 years ago by the International Telecommunication Union (ITU) to standardize the quality of nascent telegraph services expanding worldwide, today's ITU is an internationally recognized arm of the United Nations. And its simple 1–5 MOS rating makes it much easier to answer the question, "Is my Internet any good?"But for those currently or soon-to-be vetting ISPs the first time around, the best way to avoid a lemon is to ensure you don't experience the jitters when negotiating your service level agreement (SLA).

With regard to avoiding (or at least minimizing) the negative aspects of packet loss and jitter for your business, get comfortable with the following before you sit down with a vendor to hash things out:

  1. Make sure you understand the specific Internet needs of your business

  2. Familiarize yourself with what an SLA covers

  3. Understand the proper protocols that need to be taken if your SLA is breached

(Looking for more detail? Here’s a nice primer on internet SLAs.)

Turning Potential Lemons into Savvier Decisions

Faced with both new challenges and exciting opportunities, business will be anything but usual moving forward. One silver lining, though, could be that the pace at which organizations will need to adapt and evolve may force service providers to embrace transparency and true performance innovations if they want to remain viable.

Still, supply will never evolve as quickly as demand and it's clear how the COVID-19 pandemic compounded this. That's why IT leadership needs to self-educate more than ever before. It's crucial to stay up to date on which metrics matter most as business needs continue to adapt in a post-pandemic world, and leverage existing resources in the industry in order to keep an edge when navigating the convoluted and competitive world of internet service providers.

Now that you’re familiar with some of the crucial metrics needed to vet ISPs, lean on Lightyear to help you find the right ISPs for your business internet needs in a snap.

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