a number of hosted networks. Layer elements of a particular hosted net- work are identified by SAPIs. When LAPD is used in the context of another net- work system, the assignment of a SAPI to a particular hosted network is defined in that context. For example, when LAPD is used in ISDN, SAPI=0 identifies the ISDN call-handling layer, SAPI=63 identifies the LAPD layer-management layer. When LAPD is used in GSM, assignment of SAPI values is different (see the dis- cussion at the end of this chapter). Hosted nodes in terminals terminate a single LAPD route. Since the hosting net- work (i.e., LAPD) is non-switching, and since the layer APi method is used for dis- crimination, hosted nodes in terminals need no REi or REdef for this route, i.e., no T-RE table. However, since the route is multichannelled, a hosting node must deliver a con- nection identifier (Ci) to the LAPD layer element at sending. LAPD uses the name TEI ("terminal identifier") for Ci. The range for the TEI is 0 through 127. These connections are not created on-demand, but by a special LAPD management net- work (that has hosted nodes in every terminal and in the network) when a terminal initially connects to the network. This network is (normally) hosted on SAPI=63. The connection identifier TEI=127, a broadcast connection that exist for every SAPI, is the only connection that need not be assigned by the management net- work. Since LAPD was initially defined for the ISDN application, the range 0 through 126 of TEI values is shared between a number of terminals on a terminal site. This is why a particular hosting node has access only to a subset of the total number of TEIs. For example, the model in Fig. 3.22, shows that the hosted node on SAPI=0 uses a LAPD route with two connections, denoted as te5 and te9 (besides the broadcast connection te 127). The indicated scenario shows the hosted SAPI=0 node in the terminal sending on te5. Note that the LAPD network does not know 3 Node Structures how a hosting network uses connections. It just delivers the T