ervice element, the model of Fig. 5.18 does not work. That is when a mechanism for association handling must be implemented as part of the integrator. Association handling is also the only way that multiple service elements can be handled in a logical node when a connection-less CSP is used. Figure 5.19 provides a logical node model with association handling for the CNL-CSP case. The proper- ties of this model are as follows: The logical node comprises service elements of different types (A and B). All service elements have a temporary existence. The logical node is connected to the CSP over a CNL-SAP. There is no support from the CNL-CSP for level 1 discrimination. The integrator in the node is a protocol element that consists of a discriminator and an association handler (ASH). The permanent part of the logical node proto- col consists of an association protocol and a discrimination protocol. The function of the ASH is to negotiate associations between its own service elements and service elements in remote logical nodes. The ASH might support translation between names and addresses (as in the CC case). When no associations are established, no service elements exist in the node (they might, however, exist on the node platform, i.e. in the P-dimension, but not in the DC-plane). 5.3 Discrimination The ASH establishes (internal) association endpoint identifiers (AEid), between the discriminator and service elements, and an external association identifier (Aid), to be used by the discriminator. Associations between service elements are temporary (association endpoints x1 and x2 in the model) and must be ordered and removed over the association pro- tocol. Logical node type B type A Integrator Association protocol Discrimination Aid userData Discriminator protocol x0,x1,x2 Association endpoint identifier (AEid) Aid Association identifier ASH Association handler CNL-CSP Fig. 5.19 The association-handling model for a logical node Associations between peer-ASHs are permanent (association endpoint x0 in the model). One 