To begin the story let's assume there is the mainland named ERP world and an island - APO. The island is connected to the mainland by a multi-lane bridge. The bridge (RFC connection) has toll gates at both ends. You have tourists (transaction data) and workers (master data) who need to get over from one island to the other through coaches or buses (Integration Models). Interestingly workers (Master Data) can go from the mainland to the island only and not other way round. Tourists (Transaction Data) can go either way but they cannot go from mainland to the island till there is infrastructure built by workers (Master Data). There are designated buses/coaches to transfer workers and toursists depending on the destination (different Integration Models for different type of data) to minimise confusion and mismatch. Depending on the route number (type of master or transaction data) the buses/coaches travel in dedicated lanes of the bridge. And if one of the bus/coach breaks down (CIF queue) then that entire lane is stuck with no further bus (more followup CIF queues in WAITING status after the ERROR queue) able to travel to the other island. So here are the steps for commuting between the mainland and island. Taking cue from the above description the initial infrastructure setup to be done in respective systems is explained below. First the bridge needs to be built - this is normally done by the BASIS team who can be considered as the bridge-building engineers. Once this is done you start creating the routes and assign them to workers or tourists - Integration Model "creation". Integration Models variant are created in transaction CFM1 and saved. This is like defining who can go in the particular coach/bus. You then use the same transaction CFM1 to "generate" the Integration Model by pulling up a suitable variant and executing it (F8). Save the "generated" model. The Generated Integration Model can be considered as the bus/coach filled in with workers/tourists and waiting at the toll gate before the bridge. This Integration Model is now ready for "Activation" using transaction CFM2. This can be thought as actually starting the bus/coach and cross over the bridge to the other island and ultimately reach its destination on other side. However this may not always be so smooth. So the bridge authorities use a monitoring mechanism called SCM Queue Manager (transaction /SAPAPO/CQ) and other tools (SMQ1 - Outbound Queue and SMQ2 - Inbound Queue) to keep track of the bridge and clear any breakdowns. To compare who all toursists (transaction data only) have arrived at APO island there is another tool called Delta Report (transaction /SAPAPO/CCR). In case someone is left behind she can be resent. This is in short a story board way of explaining CIF.