Testing Network Conditions with WANem: A Free WAN Emulator

When preparing for a new internal project, I encountered the need to simulate various networking conditions and scenarios. Specifically, I wanted to test how our vCenter Client would perform over high latency satellite links with varying bandwidth availability and even packet loss. To do this, I turned to WANem, a free WAN emulator that allows me to control various networking characteristics in a controlled environment.

WANem is a virtual appliance that can be run as a VMware virtual machine. Setting it up is straightforward, and I may write a HOWTO post on it if there’s enough demand. Once the WANem Virtual Appliance is running, all you need to do is route your traffic through it.

In my test environment, I decided to route all traffic between my local computer and my vCenter Server through the WANem appliance. To do this, I opened a command prompt on my local computer with administrator privileges and used the route command to force traffic through WANem:

“`

route add {destination IP} mask 255.255.255.255 {WANem IP}

“`

For example, if I wanted to add a latency of 500ms and a packet loss of 25% for all traffic to the vCenter Server, I would use the following command:

“`

route add 192.168.1.1 mask 255.255.255.255 192.168.10.1

“`

This will add a latency of 500ms and a packet loss of 25% to all traffic between my local computer and the vCenter Server.

The WANem admin page allows you to tune the network properties of the traffic going through it. The advanced tab is where you can specify things like latency, jitter, and packet loss. Here are some screenshots of the advanced tab:

As you can see, you can easily add latency, jitter, and packet loss to your traffic, as well as specify the direction of the traffic (i.e., whether it’s a one-way or two-way simulation).

If you need to test how your applications or networking infrastructure will perform in less than ideal network conditions, WANem is an easy and free solution. It allows you to simulate a wide range of networking scenarios without the need for expensive hardware or complex setup procedures.

In conclusion, WANem is a powerful tool for testing network conditions and simulating various scenarios. With its ease of use and flexibility, it’s an excellent choice for anyone looking to test their applications or infrastructure in a controlled environment.