Fnlag is an acronym for Forced Network LAG. It is a network latency simulator designed to alter the network behavior between hosts. Often referred to as a “software lag switch”, fnlag allows the user to introduce delay to and drop network packets at a configurable cycle.

A distinctive functionality of fnlag is that it is bi-directionally dynamic. Meaning it can cause network latency to either the upstream or downstream or both at the same time. Fnlag is also configurable. You can adjust the loss and/or delay and/or cycle at any combination and at either stream.

Fnlag was born because there did not exist any simple, inexpensive software solutions to simulate real network latency. For example, by introducing network lag between clients and servers during game development, fnlag allows developers to simulate network delay for programmatic mitigation, with the overall goal of improving the gaming experience for all players.

Fnlag is for:

  • anyone that designs/develops/tests network applications such as games, voice over IP,  peer to peer, etc…
  • network researchers
  • network enthusiasts