US Patent 7567505 VRRP technology keeping VR confidentiality

In a packet transmission router used in a VRRP (Virtual Router Redundancy Protocol) network having a VR (Virtual Router) function, when virtual routers VR are realized by the VRRP, the routing control information that each VR manages is prevented from being mixed with that of other VR. When an active packet transmission router transmits a VRRP packet to a standby packet transmission router, an identifier indicating which virtual router belongs to the VRRP packet is added to the VRRP packet before the transmission of the VRRP packet.