A system, comprising: a plurality of terminals ; a gateway computer , programmed to: distribute an encryption key, in a unicast mode, to the plurality of terminals ; receive traffic data from a remote computer ; and multicast the received traffic data to the plurality of terminals by: encrypting the received traffic data with the encryption key; and multicasting the received traffic data encrypted with the encryption key to the plurality of terminals ; wherein each of the plurality of terminals include: a terrestrial communication interface ; a satellite communication interface , for satellite communication with the gateway computer via a satellite link , wherein the terrestrial and satellite communication interfaces are configured to communicate traffic data; and a computer communicatively linked to the terrestrial and satellite communication interfaces , wherein the computer determines that encrypted multicast data is received, wherein the computer executes instructions, to determine that the traffic data, communicated via the terrestrial communication interface , exceeds a threshold; and based on the determination, route at least a portion of traffic data via the satellite communication interface in accordance with a traffic data load-balancing scheme. a plurality of terminals ; a gateway computer , programmed to: distribute an encryption key, in a unicast mode, to the plurality of terminals ; receive traffic data from a remote computer ; and multicast the received traffic data to the plurality of terminals by: encrypting the received traffic data with the encryption key; and multicasting the received traffic data encrypted with the encryption key to the plurality of terminals ; distribute an encryption key, in a unicast mode, to the plurality of terminals ; receive traffic data from a remote computer ; and multicast the received traffic data to the plurality of terminals by: encrypting the received traffic data with the encryption key; and multicasting the received traffic data encrypted with the encryption key encrypting the received traffic data with the encryption key; and multicasting the received traffic data encrypted with the encryption key to the plurality of terminals ; wherein each of the plurality of terminals include: a terrestrial communication interface ; a satellite communication interface , for satellite communication with the gateway computer via a satellite link , wherein the terrestrial and satellite communication interfaces are configured to communicate traffic data; and a computer communicatively linked to the terrestrial and satellite a terrestrial communication interface ; a satellite communication interface , for satellite communication with the gateway computer via a satellite link , wherein the terrestrial and satellite communication interfaces are configured to communicate traffic data; and a computer communicatively linked to the terrestrial and satellite communication interfaces , wherein the computer determines that encrypted multicast data is received, wherein the computer executes instructions, to determine that the traffic data, communicated via the terrestrial communication interface , exceeds a threshold; and based on the determination, route at least a portion of traffic data via the satellite communication interface in accordance with a traffic data load-balancing scheme. determine that the traffic data, communicated via the terrestrial communication interface , exceeds a threshold; and based on the determination, route at least a portion of traffic data via the satellite communication interface in accordance with a traffic data load-balancing scheme. <EOS>