digraph G {
	rankdir=LR;
	edge [arrowhead=none];
	scale=2;

	"osmo-nitb"

	subgraph cluster_bts {
		bts
		pcu
	}

	bts -> "osmo-nitb" [label="Abis"]

	sgsn [label="osmo-sgsn"]
	pcu -> sgsn
	{"osmo-nitb",sgsn} -> "osmo-hlr" [label="GSUP"]
}