A service provider's routers (PE1, P1, P2, PE2) provide connections between and share routing information with routers (CE1, CE2) of a customer virtual private network (VPN) as well as routers of other customers' VPNs, which may have overlapping address spaces. A service provider's edge router (PE1)...http://www.google.co.uk/patents/US7369556?utm_source=gb-gplus-sharePatent US7369556 - Router for virtual private network employing tag switching
