Schwarzimmulation vs Riemulation
(brought to you by the proud author of "Kinki Japanese")
WAN emulators are devices that are inserted between client and server on a local network and replicate the conditions of the wide-area network. The WAN emulator manipulates the stream of packets flowing through it so they end up with the same bandwidth constraints, latency, and packet loss as if the client and server were communicating across a WAN. Applications behave exactly as if they are physically separated, and actual performance can be measured for a range of conditions.
Testing with WAN emulators is done in real time, using actual clients and servers running real applications on a live local network – only the conditions of the network between client and server are emulated to convert a local gigabit (or ten gig) network into a low speed, high-latency testbed.