Method and apparatus for supporting the forwarding of received data packets in a router (402,702) of a packet-switched network. A forwarding table (706a) is configured in the router based on aggregating router keys and associated aggregation related instructions received from a key manager (400,700). Each aggregating router key represents a set of destinations. When a data packet (P) is received comprising an ingress tag derived from a sender key or router key, the ingress tag is matched with entries in the forwarding table. An outgoing port is selected for the packet according to a found matching table entry that further comprises an associated aggregation related instruction. An egress tag is then created according to the aggregation related instruction, and the packet with the created egress tag attached is sent from the selected outgoing port to a next hop router.