Dynamic payload header suppression extensions for IPV6
In a communications system (such as cable modem communications), dynamic payload header suppression (DPHS) is applied to a data stream to reduce header overhead. DPHS allows the suppression of static fields as well as fields that change in a predictable manner (i.e., predictably dynamic fields). To suppress predictably dynamic fields, delta encoding is utilized to enable a cable modem to replace a dynamic field with information indicating how the field is different from the same field in a previous packet in the data stream. DPHS constructs a suppression mask by using a special packet called a “learn” packet. The “learn” packet is a copy of the original packet with extra bytes that guide the suppression process. It indicates that both the sending and receiving entities are to take a full copy of a packet header, which is then used as a reference to reconstruct the suppressed fields.
1 . A method for transmitting data streams from a source to a destination within a communications network, comprising:
receiving from a data stream a first data packet for transmission to the destination;
detecting a session change based on the first data packet;
appending a first control value to the first data packet to produce a learn packet, wherein the learn packet includes information that enables suppression of fields within data packets;
transmitting the learn packet;
receiving from the data stream a second data packet;
suppressing one or more dynamic header fields within the second data packet to thereby produce a suppressed packet having a suppressed header; and
transmitting the suppressed packet.
2 . The method according to claim 1 , wherein said suppressing step comprises:
producing a delta value indicating a change in at least one of said one or more dynamic header fields from a corresponding header field in a previously transmitted data packet;
suppressing the at least one changed dynamic field; and
including the delta value in the suppressed header.
3 . The method according to claim 2 , wherein the said delta value comprises a Delta Sequence value, a Delta Acknowledgement value or both a Delta Sequence value and a Delta Acknowledgement value.
4 . The method according to claim 1 , wherein said suppressing step comprises:
suppressing at least one of said one or more dynamic header fields;
appending a second control value to the second data packet that, when received at the destination, enables recalculation of the suppressed at least one dynamic header field; and
including the second control value in the suppressed header.
5 . The method according to claim 1 , wherein said suppressing step comprises:
suppressing one or more dynamic header fields that conform to Version 6 of the Internet Protocol (IPv6).
6 . The method according to claim 1 , wherein said suppressing step comprises:
suppressing one or more header fields that conform to Version 2 of the Ethernet protocol (DIX).
7 . The method according to claim 1 , wherein said suppressing step comprises:
suppressing a dynamic header field in a data packet that conforms to a protocol selected from the group consisting of IPv6/DIX, TCP/IPv6/DIX, TCP/IPv4/DIX, and RTP/UDP/IPv4.
8 . The method according to claim 1 , further comprises the step of:
suppressing a static header field within the second packet to produce the suppressed packet.
9 . The method according to claim 1 , wherein said communications network is a wireline network, wireless network or a network that includes wireline and wireless network elements.
10 . The method according to claim 1 , wherein said source is a cable modem and wherein said destination is a cable modem termination system.
11 . A method for receiving data streams by a destination from a source within a communications network, comprising:
receiving a learn packet, wherein the learn packet includes header information and information that enables suppression of header fields within data packets within a data stream;
storing header information contained within the learn packet;
following the storing of header information contained within the learn packet, receiving a data packet within the data stream, wherein one or more dynamic header fields within the data packet are suppressed;
reconstructing the suppressed dynamic header fields within the data packet to create a reconstructed header; and
placing the reconstructed header on the received data within the received data packet to create a reconstructed data packet, wherein the reconstructed data packet includes data contained within the received data packet and the reconstructed header.
12 . The method according to claim 11 , wherein reconstructing the suppressed dynamic header fields within the data packet to create a reconstructed header is based on information in control bytes received within the data packet and the stored header template.
13 . The method according to claim 11 , further comprising updating changed fields in the stored header information after receipt of the data packet.
14 . The method according to claim 11 , wherein the step of reconstructing the suppressed dynamic header fields within the data packet to create a reconstructed header further includes recalculating an IP total length field within the reconstructed data packet and calculating a new IP header checksum for the updated fields in the template header.
15 . The method according to claim 11 , wherein said reconstructing step comprises:
reconstructing one or more dynamic header fields that conform to Version 6 of the Internet Protocol (IPv6).
16 . The method according to claim 11 , wherein said reconstructing step comprises:
reconstructing one or more header fields that conform to Version 2 of the Ethernet protocol (DIX).
17 . The method according to claim 11 , wherein said reconstructing step comprises:
reconstructing a dynamic header field in a data packet that conforms to a protocol selected from the group consisting of IPv6/DIX, TCP/IPv6/DIX, TCP/IPv4/DIX, and RTP/UDP/IPv4.
18 . The method according to claim 11 , wherein said communications network is a wireline network, wireless network or a network that includes wireline and wireless network elements.
19 . The method according to claim 11 , wherein said source is a cable modem and wherein said destination is a cable modem termination system.