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 an ethernet-formatted packet, based on an upstream packet, comprising the steps of:
(a) receiving the upstream packet, comprising an upstream header and a payload;
(b) receiving physical layer prepend data that comprises information indicating burst power, a burst frequency, a time offset, and equalizer coefficients;
(c) appending a packet header, based on the physical layer prepend data and on an upstream packet header, to the payload of the upstream packet;
(d) appending an encapsulation tag to the payload of the upstream packet; and
(e) appending a source address header and a destination address header to the payload.
2. The method of claim 1 , wherein the upstream packet is a DOCSIS-formatted packet.
3. The method of claim 1 , wherein the physical layer prepend data comprises physical characterization of the upstream packet.
4. A system for creating an ethernet-formatted packet, based on an upstream packet, comprising:
a physical layer (PHY) interface for receiving the upstream packet and physical layer prepend data that comprises information indicating burst power, a burst frequency, a time offset, and equalizer coefficients;
a header processor for extracting packet characteristic data from an upstream header of the upstream packet; and
an upstream packet port egress module for encapsulating a payload of the upstream packet with tag information based on said upstream header and
on said physical layer prepend data, to form the ethernet-formatted packet.
5. A method of creating a DOCSIS packet, based on a downstream packet, comprising the steps of:
(a) receiving the downstream packet;
(b) extracting a packet tag from the downstream packet;
(c) performing header suppression when indicated by the packet tag;
(d) creating a downstream header;
(e) generating a cyclic redundancy check (CRC) when indicated by the packet tag;
(f) encrypting the downstream packet when indicated by the packet tag;
(g) generating a header check sequence (HCS); and
(h) if the downstream packet contains a MAP message, formatting the MAP message in a MAP FIFO format.
6. The method of claim 5 , further comprising the step of:
(j) mapping the DOCSIS-formatted packet into an MPEG stream.
7. The method of claim 5 , wherein the packet tag comprises a packet length.
8. The method of claim 5 , wherein the packet tag comprises a header length.
9. The method of claim 5 , wherein the packet tag comprises an indication of whether a CRC is to be generated.
10. A system for creating a DOCSIS-formatted packet based on a downstream packet, comprising:
a packet port ingress engine for receiving the downstream packet from said packet port, extracting a tag from the downstream packet, and
converting said tag to a packet descriptor format;
a header suppression module for receiving a packet descriptor and performing header suppression if necessary; and
a header creation module for creating a DOCSIS header on the basis of said packet descriptor and appending said DOCSIS header to a payload of the downstream packet.
11. The system of claim 10 , further comprising an encapsulation module for mapping said DOCSIS-formatted packet into an MPEG stream.