Two stage internet protocol header compression

A method of performing header compression in a communications network, the method comprising:

• receiving, in a network node, a packet having an uncompressed header and belonging to a flow;
• identifying a context identifier (CID) associated with the flow;
• morphing the uncompressed header into a pseudo-compressed header, the pseudo-compressed header including the CID associated with the flow;
• determining whether the packet should be transmitted with a compressed header, a full header, or an uncompressed header;
• removing the pseudo-compressed header and adding a compressed header to the packet to form an outgoing packet when the packet should be transmitted with a compressed header;
• modifying the pseudo-compressed header into a full header to form an outgoing packet when the packet should be transmitted with a full header;
• restoring the uncompressed header to form an outgoing packet when the packet should be transmitted with an uncompressed header;
• and
• transmitting the outgoing packet over the communications network.

A network device for offloading a portion of work performed by a header compression device, the network device comprising;

• a flow lookup table that associates each flow of a plurality of flows with an assigned context identifier (CID);
• a receiver that receives a packet having an uncompressed header;
• a flow identification module that identifies a flow to which the packet belongs;
• a flow-CID lookup module that uses the flow lookup table to identify a CID assigned to the flow;
• a pseudo-compression module that morphs the uncompressed header into a pseudo-compressed header, the pseudo-compressed header including the CID and an indication that the header is a pseudo-compressed header;
• and
• a transmitter that transmits the packet having the pseudo-compressed header to the header compression device.