Packet tag for support of remote network function/ packet classification
View Patent ↗A method and system for creating an ethernet-formatted packet from an upstream DOCSIS packet. The upstream packet is first received along with packet characteristic data that is contained in physical layer prepend data and in the packet header. A packet tag is then created, based on the packet characteristic data. The packet characteristic data includes identifiers for the transmitting remote device and the channel over which the transmission is sent. Packet characteristic data also includes information about the physical characteristics of the transmission signal, such as the power level and time offset. The packet characteristic data also includes administrative information, such as the minislot count at which the packet is received and whether the packet was received in contention. The packet tag is appended to the payload of the upstream packet. Also appended to the payload is an encapsulation tag, and source and destination address headers. The result is a packet in an ethernet format. The resulting packet can therefore be sent using the ethernet protocol. The packet includes information that characterizes a DOCSIS packet. In a distributed cable modem termination system, this additional characterizing information can be used by processes further upstream, such as packet classification. An analogous operation can take place with respect to packets going downstream. Here, a DOCSIS packet is formed at an intermediate node, on the basis of a received ethernet-formatted packet.
1. A method of creating and transmitting an ethernet-formatted packet, based on an upstream DOCSIS packet, comprising the steps of:
receiving the upstream DOCSIS packet from a cable modem, comprising an upstream header and a payload;
appending a source address header, a destination address header including an ethernet destination address and a DOCSIS encapsulation tag (DET) in a type/length field of an ethernet encapsulation header to the payload to generate the ethernet-formatted packet; wherein the DET identifies the ethernet-formatted packet as a DOCSIS packet encapsulated in an ethernet-format; and
transmitting the ethernet-fomatted packet to a cable modern termination system (CMTS).
2. The method of claim 1 , further comprising:
receiving physical layer data that comprises information indicating physical characteristics of the upstream DOCSIS packet, and that comprises physical layer prepend data;
appending a packet header, based on the physical layer data and on an upstream packet header, to the payload of the upstream DOCSIS packet; and
appending an encapsulation tag to the payload of the upstream DOCSIS packet;
wherein the physical layer prepend data includes information indicating burst power, a burst frequency, a time offset, and equalizer coefficients.
3. The method of claim 1 , further comprising:
receiving packet characteristic data for the DOCSIS packet, the packet characteristic data including at least one of: identifiers for the cable modem that generated the DOCSIS packet, the channel over which the DOCSIS packet was transmitted, the minislot count for the DOCSIS packet and whether the DOCSIS packet was received in contention.
4. A system to create and transmit an ethernet formatted packet, based on an upstream DOCSIS packet, comprising:
a physical layer (PHY) interface configured to receive, from a cable modem, the upstream DOCSIS packet and physical layer data that comprises information indicating physical characteristics of the upstream packet, said information comprising a PHY prepend;
a header processor configured to extract additional packet characteristic data from an upstream header of the upstream DOCSIS packet; and
an upstream packet port egress module configured to encapsulate a payload of the upstream DOCSIS packet with tag information based on said upstream header and on said physical layer data, to form the ethernet-formatted packet and transmit the ethernet formatted packet to a cable modem termination system (CMTS).
5. The system of claim 4 , wherein the system is incorporated in a point-to multi-point communications system.
6. The system of claim 5 , wherein said point-to multi-point communications system comprises wireless communications media.
7. The system of claim 5 , wherein said point-to multi-point communications system comprises satellite communications media.
8. The system of claim 5 , wherein said point-to multi-point communications system comprises fiber optic communications media.
9. The system of claim 4 , wherein the upstream packet port egress module is configured to append a DOCSIS encapsulation tag (DET) in a type/length field of an ethernet encapsulation header to the payload to generate the ethernet-formatted packet; wherein the DET identifies the ethernet-formatted packet as a DOCSIS packet encapsulated in an ethernet-format.
10. A method of creating and transmitting a DOCSIS packet, based on a downstream ethernet packet, comprising the steps of:
receiving the downstream ethernet packet from a cable modern termination system (CMTS), wherein the downstream ethernet packet includes a DOCSIS encapsulation tag (DET) in a type/length field of an ethernet encapsulation header;
creating a downstream DOCSIS header for the ethernet packet and appending the DOCSIS header to the ethernet packet to create the DOCSIS packet; and
transmitting the DOCSIS packet to a cable modem.
11. The method of claim 10 , further comprising the step of:
mapping the DOCSIS packet into an MPEG stream.
12. The method of claim 10 , further comprising the step of:
extracting a packet tag from the downstream ethernet packet, wherein the packet tag comprises a packet length.
13. The method of claim 10 , further comprising the step of
extracting a packet tag from the downstream ethernet packet, wherein the packet tag comprises a header length,
14. The method of claim 10 , further comprising the step of:
extracting a packet tag from the downstream ethernet packet, wherein the packet tag comprises an indication of whether the CRC is to be generated.
15. The method of claim 10 , further comprising:
extracting a packet tag from the downstream ethernet packet;
reading a payload header suppression (PHS) rule from a memory location indicated by the packet tag and performing PHS according to the PHS rule if PHS is indicated by a flag in the packet tag;
generating a cyclic redundancy check (CRC) if indicated by the packet tag;
encrypting the downstream ethernet packet if indicated by the packet tag;
generating a header check sequence (HCS); and
formatting the MAP message in a MAP FIFO format to create the DOCSIS packet if the downstream ethernet packet contains a MAP message.
16. A system for creating a DOCSIS-formatted packet based on a downstream ethernet packet, comprising:
a packet port ingress engine configured to receive the downstream ethernet packet from a cable modem termination system (CMTS), wherein the downstream ethernet packet includes a DOCSIS encapsulation tag (DET) in a type/length field of an ethernet encapsulation header; and
a header creation module for creating a DOCSIS header on the basis of a packet descriptor format and appending said DOCSIS header to a payload of the downstream ethernet packet to generate the DOCSIS-formatted packet.
17. The system of claim 16 , further comprising an encapsulation module for mapping said DOCSIS-formatted packet into an MPEG stream.
18. The system of claim 16 , wherein the system is incorporated in a point-to multi-point communications system.
19. The system of claim 18 , wherein said point-to multi-point communications system comprises wireless communications media.
20. The system of claim 18 , wherein said point-to multi-point communications system comprises satellite communications media.
21. The system of claim 18 , wherein said point-to multi-point communications system comprises fiber optic communications media.
22. The system of claim 16 , wherein the packet port ingress engine is further configured to extract a tag from the downstream ethernet packet, and convert the tag to a packet descriptor format.
23. The system of claim 22 , further comprising:
a payload header suppression (PHS) module configured to perform PHS when indicated by a flag in said tag.