High latency and low bandwidth can cause all kinds of problems. A few years ago, I was on a project experiencing difficulties with SQL Server replication over a satellite link. Many retail outlets use satellite links to communicate with corporate data centers. Offshore drilling rigs almost exclusively use satellites for communication. I frequently talk about the need for test environments to be both valid and complete. If your test environment is complete with all of the servers and client applications in place, it's not a valid environment until it matches the network characteristics of the real world instead of the test lab.
Communication satellites are in geostationary orbits about 35,790 km above the earth. A signal must travel from the earth to the satellite and back to earth covering a total distance of approximately 71,580 km while traveling at the speed of light (299,792,458 meters/sec). This introduces a one way latency of 419 milliseconds. A round trip, such as a ping, has a latency of at least 838 milliseconds.
To simulate satellite latency in my test environment, I used a product from www.shunra.com called VE Desktop. It is a simple to use application providing programmatic tweaks to the network adapter. I installed it in a Hyper-V virtual machine running 32 bit Windows XP SP3.
A ping from a client machine to a server was done to establish a baseline before starting the Shunra VE Desktop software.
C:\>ping w2008x64
Pinging w2008x64 [169.254.114.53] with 32 bytes of data:
Reply from 169.254.114.53: bytes=32 time<1ms TTL=128
Reply from 169.254.114.53: bytes=32 time<1ms TTL=128
Reply from 169.254.114.53: bytes=32 time<1ms TTL=128
Reply from 169.254.114.53: bytes=32 time<1ms TTL=128
Ping statistics for 169.254.114.53:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 0ms, Maximum = 0ms, Average = 0ms
Next, a latency of 419 msec was introduced by clicking the Begin Test button. Another ping was done.
C:\>ping w2008x64
Pinging w2008x64 [169.254.114.53] with 32 bytes of data:
Reply from 169.254.114.53: bytes=32 time=843ms TTL=128
Reply from 169.254.114.53: bytes=32 time=833ms TTL=128
Reply from 169.254.114.53: bytes=32 time=819ms TTL=128
Reply from 169.254.114.53: bytes=32 time=828ms TTL=128
Ping statistics for 169.254.114.53:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 819ms, Maximum = 843ms, Average = 830ms
Test results are more meaningful when test conditions match the real world as closely as possible. The VE Desktop product can even introduce packet loss into your testing scenarios. Shunra also has a hardware based product with additional features.