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What are causes of Jitter in gaming and how to find and deal with it


Posted Date: 11-May-2012  Last Updated:   Category: Performance & Optimization    
Author: Member Level: Platinum    Points: 100


You’ve checked jour download speed and PING, but those aren’t the only factors that online garners should consider. There is another important variable — jitter. Find out more about Jitter in the following article.



A cursory glance at the PC games chart reveals the importance of online gaming for the PC. In fact, EA claims that Battlefield 3 is the fastest-selling game it's ever made. While single-player titles such as Skyrim and Alan Wake are undoubtedly pulling in crowds, many PC garners also love to pretend they're soldiers on a virtual battlefield filled with real- Life players. However, with huge maps, veritable armies of players and servers with more slots than a Vegas casino, online multiplayer gaming can be very demanding, and herein lies the problem.

It's no secret that many parts of the world don't even have access to a stable 2Mb/sec broadband connection, but raw download speed isn't the only problem. Arguably, the bigger problem for on line gamers is latency. You may already know about checking your PING to check latency, but there's another factor that often curiously goes unmentioned. This is jitter, and in this article, we're going to have look at the causes of jitter and what you can potentially do about it.

Let's start with a definition —what actually is jitter?
It's range between which an average latency score fluctuates. Latency is the average delay an internet packet experiences while going from point A to point B (and back again). Like
a car in a traffic jam, a packet might alternate its speed depending the traffic it is in. Sometimes a packet can be on the motorway; sometimes it can be crawling along in rush hour. This range between which an average Latency score fluctuates is what we call jitter.

This differs from PING, a term that's used either as another way of saying latency or a tool to measure latency. Jitter is the variation in latency, and it's a problem because it makes the experience unpredictable. It's also one that's very rarely mentioned. For most Internet users, download speeds or latency are the key factors, since normal web browsing or file downloading aren't affected as much by jitter. It's also not an important factor for online games that don't require quick reactions, but it's a big deal for players of multiplayer first-person shooter games.

Jitter or more accurately, latency fluctuation, manifests itself during games through choppy gameplay. You're running around, and suddenly the world freezes. Once it unfreezes, everything has changed, as if time had stood still for you and then caught up suddenly. Even if this is just half a second, you'll probably notice this stuttery gameplay. Jitter causes the latency to change rapidly, for example from l0 ms to 80ms and back. In such a situation, it's very difficult for game servers to provide a fair environment for all players, which can be very frustrating.

What are the causes of jitter? Why does latency fluctuate in this way?


This can be attributed to a huge range of causes from the host end. Electromagnetic interference, congested or flapping Internet links, unstable routing (traffic changing between different paths constantly) and sometimes a high CPU or fabric load in network devices.

Avoid jitter in gaming by having strong network connection


To avoid jitter, you need predictable and constant routing, free space on your links and have redundant paths available. Also, jitter and latency are inseparable. As such, physical distances between the host server and end user are important.

However, the need for predictable and constant routing can also be helped at the gamer's side of the connection. The 54 Mb/sec 802.11 g wireless connection you receive from an average home wireless router might theoretically look like overkill in terms of bandwidth, but the unpredictability of a wireless connection can introduce latency and, again, fluctuation in latency.

In general, an Ethernet cable is a much better way to connect with your router if latency and jitter are important for you. A cable offers high capacity (at least 100Mb/sec, and usually 1 Gb/sec, and is nearly immune to disturbances. WiFi offers lower speeds, higher latency and is very sensitive to any interferences. WiFi networks can sometimes be fast, but they usually limit their speed to the capabilities of the slowest device connected.

It is also better to research details about your router before you make a purchase, to see if it suffers from 'bufferbloat', As its name suggests, this phenomenon is caused by the router performing excessive buffering, creating a queue of packets waiting to be sent to your machine, even though they've already turned up from the host, which in turn increases latency and jitter.

Of course, a router manufacturer isn't going to List 'bufferbloat'in its specs, but it's worth Googling the names and models of various routers to see what other gamers are saying about their performance and latency on tech forums.

If you want to check your own router, you can run the ICSI Netalyzr test (http://netalyzr. icsi.berkeley.edu) - this in-browser Java applet will test your Net connection and tell you if you're suffering from bufferbloat —just check the buffer measurements in Network Access Link Properties.

Have a high speed internet connection to avoid jitter in gaming


You can also generalize about the causes of jitter based on the speed of your broadband connection. For example low-speed connections of 1 Mb/sec or 2 Mb/sec make it likely for jitter to occur on your uplink, particularly if your connection is shared among other people and devices at home. All it takes is one other person to start a large upload or download, and the latency (and fluctuation in latency) will then increase. However, if you have a decent high-speed connection then jitter is more likely to be caused by congestion on your ISP's network, or on your chosen gaming server.

Avoid DSL connection to avoid Jitter in gaming


There's another potential problem, of course, which is that many of the low-speed connections are based on ADSL rather than cable, which again introduces another variable into the mix. Is an ADSL line more susceptible to jitter than a cable connection?

It isn't as black and white as that, but DSL connections are indeed slower latency-wise and offer lower throughput, making it much easier to congest them, in turn causing problems for online gaming. In some areas, the telecommunication infrastructure used by DSL connections is so old that even bad weather and rainfall may affect the speed too.

Use PING service to check Jitter


Beyond making sure you have the most stable connection possible, and connecting to a decent router via a cable, the rest is down to your ISP and server host, You can effectively measure jitter by performing long-term tests of your PING — a great app for this is PingPlotter (www.pingplotter.com), although there are plenty of other tools available, including some console commands in some games.

Using an app such as PingPlotter, you can plot a graph of the round trip it takes for data to travel from your game server to your PC, and it also tells you at what stages latency is introduced, by IP address, You can just type in the IP address of your game server, hit the Trace button and it will then start plotting a graph. Try this over time, while playing online games, and see how your Latency fluctuates. You can simply subtract the lowest result from the highest result to give you the measure of fluctuation, or jitter. Once you have an idea of your problem's location, you can then start informing the right people, arid making them aware of the problems.

The hardware of ISPs shouldn't cause any delays by itself, even during the peaks of CPU usage or disk operations. That's why ISPs should use stable network equipment, and make sure they have high redundancy and a quality network, so that Internet lines don't become congested when part of its hardware breaks.

Concluding remarks about Jitter problem


Due to the nature of a system with several machines in different locations communicating, jitter isn't always a simple problem to sort out, and doing so will involve work for several people. Everybody has to do their part. The gamer has to research which home ISP has the best results for their region and check the location of their preferable game servers. The home ISP needs to make sure that it has a good network, checking the available paths to every destination, while considering new peering relationships if possible. Online gaming companies have to ensure they host with a provider that has a first-class global network.

Is this a problem that's likely to disappear as our broadband connections gradually become quicker and more efficient? Jitter will always remain one of the parameters to describe the quality of an Internet connection. However, as our capacities increase and network devices become smarter, we hope that jitter will become less of an issue. We also hope that manufacturers of small office and home office routers will provide new boxes that aren't affected by bufferbloat, but it will be a very long time before latency and jitter will be significantly reduced.

If you're experiencing regular stuttering in online games, don't just check your download and upload speeds and your PING, but also check the variation in PING overtime. You could be experiencing jitter, and depending on your setup, it could be relatively easy to sort out. Check your router's abilities, connect to it using an Ethernet cable, make sure you have a reliable, preferably cable-based broadband connection and, if all else fails, log your jitter time and send the information to your ISP and server host as appropriate.


Read related articles: Gaming    Jitter in Gaming    

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