of the same type in parallel. A typical application is a logical node in a process control system that handles the setup, release and supervision of call/connections. The logical node can still handle different functions, but only on discrimina- tion level 2. This means that the service elements must include a level 2 discrim- inator, which slows down the communication between service elements. It is the responsibility of the CC to establish an internal connection endpoint. The scenario may look as shown in Fig. 5.18. The model shows only the scenario in the initiating node. 1. A service element (SE) requests from the CC to establish a connection to a remote protocol element, identified by name (destGT). The SE or the CC may select the intCEI (here it is assumed that the SE does that). 2. The CC translates the name to an address that is recognized by the CON-CSP. 3. The CC requests a connection from the CON-CSP. The CC or the CON-CSP may select the extCEI (CON-CSP is assumed here). 4. The CON-CSP confirms the connection, which means that, in the remote logical node, there exist san SE that is associated to the SE in the initiating logical node. 5. The CC provides the SAH with CEI-translation information. 5 Protocol Network Modelling 6. The CC confirms the connection to the SE. Events in the scenario: iConnReq(destGT, intCEI) Find SAPI for destGT! 3 eConnReq(destSAPI) intCEI eConnCnf(destSAPI, extCEI) useOrd(intCEI, extCEI) iConnCnf(destGT, intCEI) 7 sendConOrder(SDU) sendConOrder(extCEI, SDU) extCEI CON-CSP Fig. 5.18 Connection handling scenario in a logical node 7. The SE sends an SDU to the SAH over the intCEI. 8. The SAH sends the SDU to the CON-CSP, referring the extCEI. Every time the logical node is offered a connection from a calling party, the CC will instantiate a new service element. That implies that a service element cannot request a connection to an existing service element in another node. Thus, if one needs to create a connection to a remote service element of a particular type, or to an existing s