There is described a method and apparatus for sending data through one or more packet data networks. A stripped-down packet is sent from a packet sending node towards a cache node, the stripped down packet including in its payload a pointer to a payload data segment stored in a file at the cache node. When the stripped-down packet is received at the cache node, the pointer is used to identify the payload data segment from data stored at the cache node. The payload data segment is inserted into the stripped-down packet in place of the pointer so as to generate a full size packet, which is sent from the cache node towards a client.