Games Modems Play -- Bandwidth vs. Latency The Role of Latency in Internet Connection Speeds Ron Pacchiano
Internet connection speeds are not determined by bandwidth alone. Bandwidth combined with latency is what determines how quickly a Web page loads or how fast a file transfers.
Lately, when playing games on Xbox Live, I've been experiencing very high networking delays. A few people suggested that I might not have enough upstream bandwidth, but when I checked my throughput rates using the speed test at DSL Reports, it came back with a rating of 344 Kbps on the upstream and 747 Kbps on the downstream. This should be more than sufficient. Nevertheless, the network delays continue, and I don't understand why. Do you think increasing the DSL bandwidth will improve the performance of Xbox Live? If not, what else can I do?
It never fails to amaze me how many people work under the assumption that speed and capacity are the same thing. This is one of the most commonly misunderstood concepts in networking today — at least for the casual user. Once people switch from dial-up to broadband service the most common question they ask is "How fast is your connection?" Most people answer this question by saying something along the lines of 600 Kbps - 1Mbps. This is incorrect.
These answers are actually referring to the bandwidth or capacity of the service, not the speed of the service itself.
Again (for emphasis), the 600 Kbps - 1Mbps figure doesn't refer to the speed of the service, but rather to its capacity or bandwidth. Bandwidth is normally expressed in bits per second and refers to the total amount of data that can be transferred within one second. What we're talking about in this question has to do with speed or technically what's referred to as latency.
Latency is normally expressed in milliseconds. One of the most common methods to measure latency is to use a PING utility. The utility sends a small packet of data, typically 32 bytes in size, to a host server, and then measures the time it takes for the packet to leave the source host, travel to the destination host, and return back to the source host. This measurement is known as the Round-Trip-Time or RTT.
Here's a common example of how to think about latency versus bandwidth:
Imagine water running through a pipe. The pressure is latency. The width of the pipe is bandwidth. If you have a wide pipe but low pressure, you can move more water through the pipe, but at a slower rate. If you have a narrow pipe but high pressure, you can move less water but at a faster rate.
So as you can see, latency and bandwidth are two very separate things. I guess the reason that so many people use bandwidth numbers as a speed rating can be largely blamed on service providers. All of those advertisements for "High Speed Access" are somewhat misleading. Technically speaking, it should be referred to as "High Capacity Access," but I guess that just doesn't sound sexy enough. The term "High-Speed" is more identifiable. Notice the word "Broadband." It refers to how wide the pipe is, not how fast.
In any case, the combination of latency and bandwidth is what determines how quickly a Web page loads or how fast a file transfers.
Solving bandwidth problems is much easier than solving latency issues. To increase bandwidth performance all you need to do is aggregate more pipes to your existing line. For example, back in the days of analog modems it was possible to increase your bandwidth by bonding together two or more modems.
So if you had three 28.8 modems bonded together you ended up with an 86.4 kbps pipe. In fact, this was the method ISDN used to achieve its then impressive 128K bandwidth.
So to answer your question, yes, increasing your bandwidth would help to relieve the network latency you're experiencing — but only if the latency is due to the fact that you've topped out your network's bandwidth.
If the bandwidth is saturated, congestion occurs and the latency increases. However, if the bandwidth of a circuit is not at peak, then adding more bandwidth won't have any affect on the latency at all.
Circuit Type
Speed (in Milliseconds)
Ethernet
.3ms
Analog Modem
100-200ms
ISDN
15-30ms
DSL/Cable
10-20ms
Stationary Satellite
500ms, mostly due to high orbital elevation
DS1/T1
2-5ms
Unfortunately, there aren't many ways to decrease latency in this situation. Latency is a byproduct of the electrical characteristics of the circuit and is also affected by the routing that an ISP sets (i.e., if your data packet has to travel further, latency increases). The chart above shows average latencies speeds for some of the more common circuit types:
To sum up, there are many factors that could be causing your problem. Unfortunately, though, there is not all that much you can do about it on your own. The latency could be coming from your network, your ISP, or from the Xbox Live network itself. I suggest that you do some testing on your own first to see if your network speed stays consistent all the time. This will help you figure out who to call next.
For example, when Xbox Live is slow, are your PCs slow as well? If not, the problem might be with Xbox Live. If all of your PCs are slow, then it might be a problem with your ISP. Does latency increase depending on the time of day you're using the Internet, or is it the same all the time? Have you checked your system for viruses? Certain viruses (like Code Red for example) can cause a tremendous amount of latency on a broadband connection. Do a thorough scan of your system for viruses or spyware.
These are just a few of the things that could be contributing to your problem. I know it's not much, but I hope this at least gives you a better understanding of the problem and that you find some of these suggestions helpful. Good Luck resolving your issue.
Lately, when playing games on Xbox Live, I've been experiencing very high networking delays. A few people suggested that I might not have enough upstream bandwidth, but when I checked my throughput rates using the 
It never fails to amaze me how many people work under the assumption that speed and capacity are the same thing. This is one of the most commonly misunderstood concepts in networking today — at least for the casual user. Once people switch from dial-up to broadband service the most common question they ask is "How fast is your connection?" Most people answer this question by saying something along the lines of 600 Kbps - 1Mbps. This is incorrect.
