Add Latency to Localhost

On FreeBSD and OSX, you can use ipfw:<p><pre><code> sudo ipfw pipe 1 config bw 50KBytes/s delay 100ms sudo ipfw add 1 pipe 1 src-port 80 sudo ipfw add 2 pipe 1 dst-port 80 </code></pre> But don't forget to disable it!<p><pre><code> sudo ipfw delete 1 sudo ipfw delete 2</code></pre>

Mininet is a project at Stanford that provides an API to emulate a multi-node network on a single machine. It uses linux containers and namespaces for configuration/resource isolation.<p>Project page: <a href="http://www.openflowswitch.org/foswiki/bin/view/OpenFlow/Mininet" rel="nofollow">http://www.openflowswitch.org/foswiki/bin/view/OpenFlow/Mini...</a><p>Paper: <a href="http://conferences.sigcomm.org/hotnets/2010/papers/a19-lantz.pdf" rel="nofollow">http://conferences.sigcomm.org/hotnets/2010/papers/a19-lantz...</a><p>Other similar projects:<p><pre><code> * http://clownix.net/ * http://www-x.antd.nist.gov/nistnet/</code></pre>

Anyone know a good way to replicate this in Windows? Would be great to have a more user-like experience when working on my Rails app.

Do be aware that your linux loopback has an MTU an order of magnitude greater than ethernet, so your latency sensitive TCP startup times are not going to behave the same.

Could anyone explain why that would be desirable? Is it to test out a website design that you are hosting locally, and you want it to "feel" right? Something else?

qdiscs in linux have always seems something of an underdocumented dark art to me. I've used HTB to slow down packets that I mark with iptable rules, but that's about as fancy as I can get. Does anybody know of some nice documentation about this stuff that isn't a decade old? ;)

For those on FreeBSD dummynet was perhaps one of the most useful traffic shapers I've ever used. I had a router built on FreeBSD going strong for more than 3 years on an old pentium 90 that would route traffic like no ones business.

iprelay too:<p><pre><code> iprelay -b30000 8000:localhost:80</code></pre>