Wide area network (WAN) emulation is a technique where a local area network (LAN) acquires the properties of a WAN. This is usually accomplished through the insertion of a device partitioning the LAN such that the device may alter the packet flow between the halves. The device itself may be either a general purpose computer running software to perform the network emulation or a single purpose machine that performs the emulation, perhaps with hardware assistance. The device may emulate the network by increasing the round trip time across the link (latency), constraining the available bandwidth, or by adding packet loss. These are sometimes collectively known as packet shaping.

Broadly these break into three groups:

Free Software

  * ipfw or Dummynet runs on FreeBSD and is maintained
  * NISTnet runs an emulator on a Linux platform, but seems to be out of date (last update 2002)

Commercial Software

  * Shunra Virtual Network runs on Microsoft Windows enables bandwidth constrains, latency, and loss to be inserted

Commercial Devices

  * Packet Storm provides emulation at up to gigabit speeds
  * Network Nightmare provides low end (< 20 Mbps) emulation