In this paper we show how to build a fully secure and efficient group communication service between several sites. This service is built on top of a VPN environment where IPSec tunnels are created, on-demand, between the various sites that need to communicate. This paper is a follow-up of previous work on group communications in a VPN environment and on application-level multicast. We show that these proposals naturally fit with one-another and lead to the concept of Virtual Private Routed Network, or VPRN. This concept enables us to largely improve the data distribution efficiency, and in particular reduces the physical link stress. We are convinced that security is critical in many situations and must be the primary concern of a group communication service.