The node number serves administration and routing purposes. The numbers are allocated by the network configurator and must be unique network-wide. The Node number for a system is configured in every individual node with the AMO ZAND, Parameter PNNO. This applies to both open and closed numbering schemes. A distinction is made between a physical and virtual (fictitious) node numbers . For this function (LCR) an originating node number (ONNO) and an destination node number (DNNO) were defined. These always describe entry and end-points of a connection (not the transit nodes!)

Node number parameters are specified in the following AMOs:

ZAND, RICHT, KNMAT, TACSU, TDCSU, TSCSU, LDAT, KNFOR, WABE (display only), ACSU, KNDEF, KNLCR, KNTOP and SDAT.