This question was cobbled together from several common e-mails this week.

Hey, Inetdaemon,  Doesn’t bandwidth solve all network problems with [Skype, Facetime, Vonage, NetFlix, Hulu, YouTube, World of Warcraft (WoW)…], and push my frame rates through the roof in [choose any FPS/MMORPG]?

Answer:  Not so!

Engineers use a measurement called “latency” to measure delay between endpoints in communications systems, including the Internet.  High latency is bad, low latency is good.  High latency indicates a problem between endpoints. This could be you and a friend across Skype, Facetime, Vonage or  anything else.  Problems with ‘delay’ are the real causes of ‘slowness’ and communications problems. More bandwidth will only fix issues with congestion and over-subscription, and only if you can add more bandwidth along the entire path from end-to-end.   More bandwidth can’t do anything about the actual delay from the communications systems, routers, switches and the infrastructure supporting it or delay from the server.  Moreover, if the “internet pipe” at the far end serving the person or site you’re trying to reach is full, their router is busy, or their servers are overloaded, there’s no benefit to upgrading your own service to higher bandwidth.  Given the nature of the Internet, everyone else would also have to upgrade thier Internet connection to make your services faster to every site you use frequently.

Sources of Latency

Latency is the measure of end-to-end delay. Delay is caused by the distance and by the air, fibers and wires, by the network components and network devices, and by the computers and terminals at each end.  Sources of latency include:

  • Physcial distance
  • Propagation delay of the physical media
  • Media Converters (Conversion and Transcoding)
  • Network device packet & frame forwarding delay
  • Application delay:  Encryption and Compression
  • Server CPU time & interrupts
  • Network Device CPU time & interrupts
  • and more…

You cannot ‘drive down’ latency with more bandwidth, but you CAN reduce it with:

  • Reducing the physical distance (reduce cable-length, eliminate back-hauls to common switchpoints)
  • Installing faster equipment
  • Eliminating encryption and compression

 

Why “More Speed” (Bandwidth) Doesn’t Help

The time it takes a that first single bit (a zero or one) to move from one end of the communications path to the other cannot be improved by widening the ‘internet pipe’.  Bandwidth will shorten the time between when the first bit and the very last bit of your YouTube video arrive, but the time it takes any given bit within the video stream to travel over the entire end-to-end path is always the same. To put it another way, the speed limit on many American highways is 55 mph. No matter what you do, it will take you the same time to drive the same distance at 55 mph as long as the highway is uncongested. Widening the highway (adding more bandwidth) only helps if the highway has too much traffic and none of the cars can go any faster. Putting in a new, more direct highway with high-speed interchanges reduces the delay. Similarly, upgrading or eliminating intervening network equipment and making direct connections wherever possible will reduce network latency.

Reducing Latency

Things that can reduce the delay and thus the latency:

  • Reducing the total distance between the endpoints
  • Switching from a relatively slow electrical transmission to a faster fiber transmission
  • Eliminating equipment between the endpoints
  • Upgrading network equipment between the endpoints
  • Upgrading the endpoints themselves

Latency and Video Display Frame Rates

Network Latency has zero impact on local Frame Rates on your computer.  It does have an impact on how quickly the server can inform your computer that something that triggers a screen update has occurred and the actual function that performs frame rate calculations within the game may, or may not take this into account, depending on how the developers wrote the code.

What WILL affect your game’s “frame rate” is the speed and power of your computer’s video processor and that has nothing to do with network latency or bandwidth.

 

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