See also The Wide Area Network EMulator

https://code.google.com/p/wanbridge/

WAN-Bridge is a live-CD open-source WAN-Emulation alternative that doesn't require complex routing when testing the behavior of applications and network protocols over WAN.

WAN-Bridge can run as a virtual machine or on a standard PC.

With WAN-Bridge it is easy to create fully virtualized or mixed test environments, and benefit from advanced network monitoring and charting capabilities.