+ \draw[arrow,bend left=15,dashdotted] (cco3.west) to node {} (csi3.east);
+ \draw[arrow,bend right=15,dashdotted] (cci3.west) to node {} (cso3.east);
+ \node at (-9mm,22.5mm) {Data connection};
+\end{tikzpicture}
+% \foreach \sector in {%
+% 0, 1, 2, 3, 4, 5, 6, 7, 8, 9}%
+% {
+% \node[netdb](node\sector) at ({36 * (-\sector + .5)} : 10mm) {\sector};
+% }
+% \node at (0, 0) {netDB};
+% % client
+% \node[client](client) at (28mm, 12mm) {Server Router};
+% \node[rectangle,draw,below=0mm of client.south west] {Application};
+% \node[minimum width=7em,minimum height=4em,draw=gray](clientpc) at (25mm,9mm) {};
+% \node[above=0mm of clientpc.south] {Server's System};
+% % server
+% \node[client](server) at (-42mm, 12mm) {Client Router};
+% \node[rectangle,draw,below=0mm of server.south east] {Application};
+% \node[minimum width=7em,minimum height=4em,draw=gray](clientpc) at (-38mm,9mm) {};
+% \node[above=0mm of clientpc.south] {Client's System};
+% % client client tunnel
+% \node[chain,minimum size=6.5em,minimum height=2em,draw=gray](tunnel) at (16mm,20.5mm) {};
+% \node[above=0mm of tunnel.north] {Server's data tunnel pair};
+% % \node[tunnel,minimum width=9.5em] at (16mm, 19mm) {};
+% % \node[tunnel,minimum width=9.5em] at (16mm, 22mm) {};
+% %
+% \node[chain] (cco1) at (23mm, 19mm) {};
+% \path[arrow] ([xshift=4mm]client.north) |- (cco1.east);
+% \node[chain] (cco2) at (16mm, 19mm) {};
+% \path[arrow] (cco1.west) -- (cco2.east);
+% \node[chain] (cco3) at (9mm, 19mm) {};
+% \path[arrow] (cco2.west) -- (cco3.east);
+% \node[chain] (cci1) at (23mm, 22mm) {};
+% \path[arrow] (cci1.east) -| ([xshift=5mm]client.north);
+% \node[chain] (cci2) at (16mm, 22mm) {};
+% \path[arrow] (cci2.east) -- (cci1.west);
+% \node[chain] (cci3) at (9mm, 22mm) {};
+% \path[arrow] (cci3.east) -- (cci2.west);
+% % server client tunnel
+% \node[chain,minimum size=6.5em,minimum height=2em,draw=gray](tunnel) at (-30mm,20.5mm) {};
+% \node[above=0mm of tunnel.north] {Client's data tunnel pair};
+% % \node[tunnel,minimum width=9.5em] at (-34mm, 19mm) {};
+% % \node[tunnel,minimum width=9.5em] at (-34mm, 22mm) {};
+% %
+% \node[chain] (csi1) at (-37mm, 19mm) {};
+% \path[arrow,<-] ([xshift=-4mm]server.north) |- (csi1.west);
+% \node[chain] (csi2) at (-30mm, 19mm) {};
+% \path[arrow,<-] (csi1.east) -- (csi2.west);
+% \node[chain] (csi3) at (-23mm, 19mm) {};
+% \path[arrow,<-] (csi2.east) -- (csi3.west);
+% \node[chain] (cso1) at (-37mm, 22mm) {};
+% \path[arrow,<-] (cso1.west) -| ([xshift=-5mm]server.north);
+% \node[chain] (cso2) at (-30mm, 22mm) {};
+% \path[arrow,<-] (cso2.west) -- (cso1.east);
+% \node[chain] (cso3) at (-23mm, 22mm) {};
+% \path[arrow,<-] (cso3.west) -- (cso2.east);
+% % client exploratory tunnel
+% \node[chain,minimum size=4.5em,minimum height=2em,draw=gray](tunnel) at (-32.5mm,-3.5mm) {};
+% \node[below=0mm of tunnel.south,align=center] {Client's exploratory\\tunnel pair};
+% % \node[tunnel,minimum width=7.5em] at (-36.5mm, 0mm) {};
+% % \node[tunnel,minimum width=7.5em] at (-36.5mm, -3mm) {};
+% %
+% \node[chain] (eo1) at (-36mm, -2mm) {};
+% \path[arrow] ([xshift=-4mm]server.south) |- (eo1.west);
+% \node[chain] (ei1) at (-36mm, -5mm) {};
+% \path[arrow,<-] ([xshift=-5mm]server.south) |- (ei1.west);
+% \node[chain] (eo2) at (-29mm, -2mm) {};
+% \path[arrow] (eo1.east) -- (eo2.west);
+% \node[chain] (ei2) at (-29mm, -5mm) {};
+% \path[arrow,<-] (ei1.east) -- (ei2.west);
+% % service lookup
+% \draw[arrow,bend right=20,dashdotted] (eo2.east) to node[above=.8em,align=center] {service\\lookup} (node4.west);
+% \draw[arrow,bend right=10,<-,dashdotted] (ei2.east) to node {} ([yshift=-1mm]node4.west);
+% % data link
+% \draw[arrow,bend left=15,dashdotted] (cco3.west) to node {} (csi3.east);
+% \draw[arrow,bend right=15,dashdotted] (cci3.west) to node {} (cso3.east);
+% \node at (-9mm,20.5mm) {Data connection};
+% \end{tikzpicture}