classDiagram
    RelayServerA <-- ClientX : Raed/Write
    RelayServerA <-- ClientY : Raed/Write    
    RelayServerB <-- ClientX : Raed/Write
    RelayServerB <-- ClientY : Raed/Write
    RelayServerB <-- ClientZ : Raed/Write
    RelayServerC <-- ClientX : Raed/Write    
    RelayServerC <-- ClientZ : Raed/Write
    RelayServerD <-- ClientZ : Raed/Write
    RelayServerD <-- ClientY : Raed/Write

    namespace Internet {
      class RelayServerA{
      }
      class RelayServerB{
      }
      class RelayServerC{
      }
      class RelayServerD{
      }
    }
    class ClientX{

    }
    class ClientY{

    }
    class ClientZ{

    }

classDiagram
    ServerA <|--|> ServerB : coodinate
    ServerA <|--|> ServerC : coodinate
    ServerA <|--|> ServerD : coodinate
    ServerB <|--|> ServerC : coodinate
    ServerB <|--|> ServerD : coodinate
    ServerA <-- ClientA : Raed/Write
    ServerB <-- ClientB : Read/Write
    ServerC <-- ClientC : Read/Write
    ServerD <-- ClientD : Read/Write(VPN)
    namespace Internet {
      class ServerA{
      }
      class ServerB{
      }
    }
    namespace NW-C____________ {
      class ServerC{
      }
      class ClientC{
      }      
    }
    namespace NW-D______________ {
      class ServerD{
      }
    }
    namespace NW-A {
      class ClientA{
      }
    }
    namespace NW-B_________ {
      class ClientB{
      }
    }
    namespace NW-X_________ {
      class ClientD{      
      }
    }