is indicated in Fig. 3.7. Note that a hosted node (such as n11) may be hosted by more than one hosting node (n11 is hosted by both n011 and n021). 3.2 Logical Networks Logical network nw1: Route Hosting network {n11,n12} Legend: {n11,n13} {n11,n14} Logical node symbol {n11,n15} Route {n13,n14} Route-endpoint symbol n0111 Logical-network structure: Hosting node Hosted nodes All layer elements that exist in node n11 w01 stratum nw02 stratum element element Fig. 3.7 A logical network. n NN=node name; nw ,NWi=logical network identifier To be able to handle a logical network separately in configuration activities, all nodes are assigned node names. These names belong to a known or implied num- bering system that may be unique to the particular logical network. A layer element in a node must identify a remote node with address parame- ters, (AddrPar) that are defined by the hosting network, see Fig. 3.8. REdef Functions that manage Hosting AddrPar nw1 resources nw01AddrPar(n12) Routes realized Route realized by nw02 by nw01 nw01AddrPar(n12) Legend: n12->{nw01, nw01AddrPar(n12)) nw01 stratum stratum is an instance of the translation element REi->REdef, where REdef= {NWi, AddrPar} Fig. 3.8 Route identification and addressing in logical networks The nodes n11 and n12 are logical nodes of the logical network nw1. In this sce- nario, n11 wants to send something to n12. n11 therefore must refer the route to n12 by the endpoint on n11. We say that n12 is the route-endpoint identifier, REi, in the scenario. However, in this scenario, the hosting network nw01 is assumed to know nothing about how nodes are identified in nw1. It is therefore necessary (in this case) to store information in n11 about how to refer its route endpoints in com- munication with hosting nodes. We call this information route-endpoint defini- tion (REdef). 3 Node Structures Thus, in general, a route endpoint in a logical network is defined by an REi (which is equivalent to a node name in the very logical network) and an REi-RE- def translation. Translatio