Stateful routing enables a server (MPE or MRA) to keep the information on each and every session as long as that session lasts. This type of routing enables you to control the information on a transaction. The trade off for this control is speed and space. Speed is compromised by how many transactions per second (tps) the server can handle in a given time interval and space is limited by the amount of RAM needed to control the number of sessions that can be in-progress at any given time. For example, a server running stateful routing can process 200K TPS is still limited in that all sessions have to stop when the RAM is full.