What is it? Network Link Conditioner is a new utility in OS X Lion (via the free Xcode 4.1 app) that will allow you to simulate less than desirable network conditions, such as a bad 3G connection or Edge with “Good Connectivity”. This is an especially useful utility for those developing apps and sites that highly rely on network connectivity, whether it’s a multiplayer game or just an animation heavy web app.
The utility couldn’t be any easier to use… After you’ve installed Xcode 4.1 via the Mac App Store, launch Network Link Conditioner from your Utilities folder and select one of the predefined network conditions from the pane on the left. You can also set custom bandwidth profiles to define a specific set of conditions for dropped packets, DNS delay, and uplink and downlink bandwidth. This is definitely a great tool to have and a welcomed addition as part of the improvements made to Xcode for Lion.
(via OS X Daily)