Now a day's Low Earth orbit satellite networks are used for IP based services. Satellite networks are required to support multimedia services. Delivering QoS guarantees to the users of LEO satellite networks is complicated since footprints of LEO satellites move as the satellites traverse their orbits, and thus, causing frequent user handovers between the satellites. In LEO satellite networks the traffic on the inter-satellite links (ISLs) also change with changes in the user-to-satellite traffic (which in turn changes due to the mobility of the satellites).Hence, traditional terrestrial routing protocols cannot be applied to broadband LEO satellite networks. To improve robustness and for load balancing in Low Earth orbit satellite networks a Cross-layer design and Ant-colony optimization based Load-balancing routing algorithm (CAL-LSN) is designed and implemented. CAL-LSN can utilize the information of the physical layer to make routing decision during the route construction phase. CAL-LSN uses mobile agents called ants for gathering the information of the nodes. ACO is well adapted to decentralized systems such as constellations of satellites because of the delays incurred by signalling information as it propagates through the network. Using CAL-LSN LEO satellite network performance is improved by balancing traffic load and increasing the packet delivery rate. Meanwhile, the end-to-end delay and delay jitter performance can meet the requirement of video transmission.