connection identifier (connection identifiers are called "virtual channel identification" in ATM and "virtual circuit number" in X.25). The discriminator on the terminal side provides a similar SAP to the CONU, but here the subflows are identified by (local) connection endpoint identifiers. Fig- ure 3.33 is a scenario for setting up a CON connection from the CONU to another CONU (not shown in the model) that is connected to the same CON-CSP. Network Process CON-TPC Controller for VC inLink Discriminator Discriminator Control store L2-connection {inLink,inCl}<-x {outLink,outCl} VC-switch connectConReq(destSAPI) {{MTid origSetupAck}, inCl) {{MTid origSetup}, destSAPI SAPI} {{MTid control}, userData} sendLinkOrd(SDU) useOrd(inCl, cei CEI) {{MTid control}, userData} 12 connectConConf(cei) 5 recLinkRep(SDU) 13 sendConOrd(cei, SDU) connectOrd(inLink, inCl CI, outLink, outCI CI) 14 {{MTid data}, inCI, userData} 15 recConRepCnf(iCI, SDU) Fig. 3.33 An originating establishment scenario for CON connections 1. The CONU requests to be connected to the CONU with a given destination- SAPI. Note that addressing in CON networks must be completely separated from addressing in CS networks. 2. The CON-TPC creates a corresponding message (PDU). 3. CON-TPC request sending of the bits of the PDU (an SDU) from the discrimi- nator. 3 Logical Network Modelling 4. The discriminator creates a message that contains the MTid value control and the userData (the SDU, or part of it). control tells the receiving discriminator that the SDU shall be delivered to the network process controller. 5. The message arrives at the discriminator that handles the link inLink. The dis- criminator reads the MTid and delivers the SDU to the network process control- 6. The network process controller assigns a suitable connection identifier, inCl. It also performs a routing analysis and selects a suitable outgoing link (outLink) and a connection identifier, outCl, for that link. It then orders the VC switch to switch incoming packets on inLink, inCI to outgoing 