A novel multicast communication model using a RingNet hierarchy is proposed. The RingNet hierarchy consists of 4 tiers: border router tier, access gateway tier, access proxy tier and mobile host tier. Within the hierarchy, the upper 2 tiers are dynamically organized into logical rings with network entities. A novel hierarchical secure access control scheme on key management is proposed based on the RingNet model. Network entities within the multicast hierarchy belong to different privileged local groups. Network entities of the higher-privileged local groups have the right to derive the keys held by network entities of the lower-privileged local groups, and the reverse operation is not allowed. With the key management approach, any insertion and changing of local group key will not affect other local groups. The analytical result shows that the scheme has higher security than Lin’s.