[networking] Network tools that simulate slow network connection

I would like to visually evaluate web pages response time for several Internet connections types (DSL, Cable, T1, dial-up etc.) while my browser and web server are on the same LAN or even on the same machine. Are there any simple network tools or browser plug-ins that slow down network bandwidth to simulate different real-world connection scenarios.

I appreciate any input on that.

For Linux or OSX, you can use ipfw.

From Quora (http://www.quora.com/What-is-the-best-tool-to-simulate-a-slow-internet-connection-on-a-Mac)

Essentially using a firewall to throttle all network data:

Define a rule that uses a pipe to reroute all traffic from any source address to any destination address, execute the following command (as root, or using sudo):

$ ipfw add pipe 1 all from any to any

To configure this rule to limit bandwidth to 300Kbit/s and impose 200ms of latency each way:

$ ipfw pipe 1 config bw 300Kbit/s delay 200ms

To remove all rules and recover your original network connection:

$ ipfw flush

My work uses this tool, and it seems quite good: http://www.dallaway.com/sloppy/

Best of luck.

I am resurrecting this thread because I had the same need recently. Amazingly, I discovered that Fiddler can be used to do that by customizing the rules and adding this line oSession["response-trickle-delay"] = "150"; in the section OnBeforeResponse.

Fiddler is really amazing.

You can also try WANem which is an open source Wide Area Network emulator. You can download the image (ISO, Knoppix live CD) or VMWare virtual appliances.

In case you need to simulate network connection quality when developing for Windows Phone, you might give a try to a Visual Studio built-in tool called Simulation Dashboard (more details here http://msdn.microsoft.com/en-us/library/windowsphone/develop/jj206952(v=vs.105).aspx):

You can use the Simulation Dashboard in Visual Studio to test your app for these connection problems, and to help prevent users from encountering scenarios like the following:

• High-resolution music or videos stutter or freeze while streaming, or take a long time to download over a low-bandwidth connection.
• Calls to a web service fail with a timeout.
• The app crashes when no network is available.
• Data transfer does not resume when the network connection is lost and then restored.
• The user’s battery is drained by a streaming app that uses the network inefficiently.
• Mapping the user’s route is interrupted in a navigation app.

...

In Visual Studio, on the Tools menu, open Simulation Dashboard. Find the network simulation section of the dashboard and check the Enable Network Simulation check box.

I love Charles.

The free version works fine for me.

Throttling, rerwiting, breakpoints are all awesome features.

I've successfully used TMnetSim (bottom of the page, under “Other Tools” - the link says something like “ZIP: TMnetSim Network Simulator version 2.4 32-bit (600KB)”

It's not just for websites - you can slow connections to any TCP port. I was using it to simulate a slow SQL Server (port 1433).

A simple mac GUI program is

https://www.macupdate.com/app/mac/28072/entonnoir/ which can limit the speed

Mac OS X has now an integrated tool able to simulate slow and bad networks : http://9to5mac.com/2011/08/10/new-in-os-x-lion-network-link-conditioner-utility-lets-you-simulate-internet-and-bandwidth-conditions/

DummyNet

Try this FreeBSD based VMWare image. It also has an excellent how-to, purely free and stands up in 20 minutes.

Update: DummyNet also supports Linux, OSX and Windows by now

If you use Apache, you can use mod_bandwith.

See here for configuration parameters.

You can use dummynet ofcourse, There is extension of dummynet called KauNet. which can provide even more precise control of network conditions. It can drop/delay/re-order specific packets (that way you can perform more in-depth analysis of dropping key packets like TCP handshake to see how your web pages digest it). It also works in time domain. Usually most the emulators are tuned to work in data domain. In time domain you can specify from what time to what time you can alter the network conditions.

If you'd like a hardware solution, Netgear has a series of cheap ($50 or so) switches that do bandwidth limiting. Netgear Prosafe GS105E and similar switches are worth investigating.

On Linux, see netem: the kernel already contains support for traffic shaping, and can simulate high latency, low bandwidth, packet losses, and all sort of other adverse conditions, even on a loopback device (so you don't need a real, physical network to test across).

Try Microsoft's NEWT, it worked perfect for me. It supplies customized latency, packet drop techniques and more :)

http://blog.mrpol.nl/2010/01/14/network-emulator-toolkit/

Update 1:

Here is a good video tutorial for NEWT - Network Emulator For Windows Toolkit Tutorial (Credits to Jimmery)