A communication apparatus that couples to a core network in a network system including a first access network coupled to the core network via a first relay, and a second access network coupled to the core network via a second relay, the communication apparatus including: a processor to store, when a first packet is transmitted to a first destination address included in a first address range and not included in a second address range, cache information regarding the second address range to a memory, the first address range being assigned to the first access network and the second address range being assigned to the second access network and being included in the first address range, and a transmitter to transmit, when a second packet for a second address included in the second address range is generated, the second packer to the second apparatus based on the cache information.