 of this common agent layer changes the original layer structure according to Fig. 4.9. Common agent layer Interlayer protocol *) Metaprimitives are: r-invokeOrd(...,sendReq(...),...) I-invokeRep(...,recRep(...),... Fig. 4.9 The effect of introducing interlayer protocols on the layer structure The existence of actor-agent interfaces in this model does not tell that it repre- sents a separation of a control structure from a connectivity structure, since LA through Lc still are layers interconnected over connectivity layer interfaces. The new layers only define a way for some layer interface of realizing these layer inter- faces (which we applied on node n11 in Fig. 4.8). Be aware of that the distinction between inter- and intralayer protocols is never made in standardized layer structures. Furthermore, protocol relations are always drawn horizontally in models, which further hides this distinction (see Fig. 4.10). Intralayer Interlayer Interlayer Intralayer The corresponding OSI RM model Fig. 4.10 The OSI RM way of modeling hides the intra- and interlayer protocol distinction 4.3 Horizontal Partitioning The upper model is equivalent to the one to the right in Fig. 4.8. Below the cor- responding model drawn the "OSI RM way": logical nodes and routes are not defined and the actor-agent separation is not shown. Consequently, the model does not tell if protocols are for inter- or intralayer distribution. 4.3.3 Horizontally-Partitioned Logical-Network Structures In this chapter we will discuss how realization of layer interfaces as interlayer pro- tocols affects logical-network structures. Let's start by looking at a scenario in the original model of Fig. 4.7 and how this scenario changes when the model is refined. Figure 4.11 shows a scenario in the original model on network level 1, where layer element B receives a message. n1.2.1 n1.4.1 n1.2.1 nw1.2 n1.4.2 n1.3.1 nw1.2 n1.3.2 .,APi,..} n1.3.3 n1.2.2 {...,ap1,...} nw1.2 E (nw1.1) n1.2.2 E (nw1.1) T-RE(n1.3.1): n1.3.2->(NA(nw1.2), APi(nw1.2)); n1.3.3->{NA(nw1.2), APi(