digraph G {
  rankdir = RL;
  CBC [color=red];
  CBE -> CBC [label="REST/JSON"];
  CBC -> BSC [label="CBSP"];
  CBC -> RNC [label="SABP"];
  CBC -> MME [label="SBc-AP"];
  CBC -> PWSIWF [label="SBc-AP"];

  PWSIWF -> AMF [label="N50"];

  BSC -> BTS [label="A-bis RSL"];
  RNC -> NodeB [label="Iub"];
  MME -> eNodeB [label="S1-AP"];
  AMF -> gNodeB [label="N2"];

  BTS -> UE [label="CBCH"];
  NodeB -> UE [label="BMC/CTCH"];
  eNodeB -> UE [label="SIB10/11/12"];
  gNodeB -> UE [label="Uu"];
}