Research - Bandwidth


Broadband speeds are generally required for a satisfactory user experience.

To reduce the bandwidth required consider
  • which regions you visit in virtual worlds - avoid those with large prim counts or excessive scripts running
  • reducing the requirement to travel to new regions
  • selecting the option to disable streamed media if it's not required
  • using text chat instead of voice
  • the nature of the tasks to be done - tasks such as building often do not require much bandwidth
  • viewer settings - see videos below and Second Life Wiki - Reducing Lag
  • hardware requirements - see Second Life - System Requirements
  • the time of day and other demands on a network

Because there are so many factors that affect user experience in immersive worlds such as Second Life or reaction Grid it is not possible to make recommendations about how many users can be online at the same time nor what bandwidth is required for an institution. Some institutions have had up to 25 students in one computer lab successfully use Second Life or Reaction Grid while others struggle to get even a few running.

Sometimes the use of virtual worlds isn't considered possible in an educational institution because required Data volumes are thought to be very high however this is often over-estimated for students engaged in learning tasks at one location in a virtual world.

Access using a USB broadband wireless modem is a viable possibility provided the above options for reducing required bandwidth are observed.
For high speed USB broadband wireless modems (eg Telstra Turbo) it is even possible to network a few laptops from a travel router such as the Netcomm 3G Travel Router.

Viewer Tools


A better approach is to use some of the tools built into viewers to determine the possible causes of poor performance for particular locations - physical and virtual.
Even so interpreting the data can be difficult. One institution regularly had indicators that went red but the user experience was OK for most tasks most of the time when the quality and performance slider (see below) was moved to the left.

The Lag Meter (Help --> Lag Meter) is a very good place to start. Second Life Wiki - Reducing Lag

lagmeter.PNG
The Client indicator may go red when the avatar teleports or looks around a location but should come back to green.
Ping times above 300msec are not necessarily a problem if they don't persist.
Server indicator may be red for Reaction Grid but that is not necessarily a problem.

Videos:
Learn the Lag Meter - Second Life
Second Life: How to easily boost viewer performance

Graphics settings can be easily altered to change client quality and performance (this is done automatically on login but is worth checking if there are performance issues or the graphics card was unknown to the viewer).
graphics.PNG

Statistics Bar (View --> Statistic Bar) See Second Life Wiki - Statistics Bar Guide
This gives more information for those who like to delve deeper :-)
statistics.PNG
Bandwidth used will rise after a teleport and will then reduce as the scene appears.
Packet loss may indicate network issues.

See also Testing speeds


Recommendations for possible Guidelines/Standards


  • Design learning activities to suit available bandwidth.
  • Use existing viewer tools to improve quality and performance.
  • Consider implementing a local (inside firewall) instance of OpenSim (with possible Hypergid access to external virtual worlds).
  • Consider desktop or USB instances of OpenSim for building and design tasks not requiring multi-user access.