Technique for packet compression in an application level multicast

A data compression apparatus, comprising:

• an input interface for receiving data packets attributable to a plurality of data packet flows destined for different devices, respectively, in an application level multicast (ALM) of material to be shared with the different devices;
• a memory unit for recording a plurality of payloads of selected ones of the data packets;
• and
• a processing unit configured to determine whether the memory unit has therein a record of an identical version of a payload of a received data packet;
• an output interface for sending a data packet derived from the received data packet, the derived data packet including the payload of the received data packet and an indication that the derived data packet is in uncompressed form if it is determined that the memory unit has therein no record of an identical version of the payload, and the derived data packet including a representation of the payload of the received data packet and an indication that the derived data packet is in compressed form if it is determined that the memory unit has therein a record of an identical version of the payload.

A method for use in a data compression device which includes a memory unit, comprising:

• receiving data packets attributable to a plurality of data packet flows destined for different devices, respectively, in an application level multicast (ALM) of material to be shared with the different devices;
• recording in the memory unit a plurality of payloads of selected ones of the data packets;
• and
• determining whether the memory unit has therein a record of an identical version of a payload of a received data packet;
• recording the payload of the received data packet in the memory unit if it is determined that the memory unit has therein no record of an identical version of the payload;
• and
• replacing the payload of the received data packet with a representation of the payload if it is determined that the memory unit has therein a record of an identical version of the payload.