Apparatus and method for hardware creation of a header

• US 20080089342A1
• Filed: 08/17/2007
• Published: 04/17/2008
• Est. Priority Date: 09/27/2001
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Lansing, Shane, Avakian, Heratch
• Granted Patent: US 7,738,460 B2
• Time in Patent Office: Days
• US Class Current: 370/392
• CPC Class Codes: H04L 69/12 Protocol engines
• CPC Class Codes: H04L 69/22 Parsing or analysis of headers
• CPC Class Codes: H04L 69/324 in the data link layer [OSI layer 2], e.g. HDLC
• CPC Class Codes: H04N 21/42676 for modulating an analogue carrier signal to encode digital information or demodulating it to decode digital information, e.g. ADSL or cable modem
• CPC Class Codes: H04N 21/437 Interfacing the upstream path of the transmission network, e.g. for transmitting client requests to a VOD server flow control in data networks H04L47/10; streaming protocols, e.g. RTP or RTCP, H04L65/65; scheduling or organising the servicing of application requests in data packet switching networks H04L67/60
• CPC Class Codes: H04N 7/17318 Direct or substantially direct transmission and handling of requests

Abstract

A media access controller (MAC) is configured with a header creator circuit. The header creator circuit is configured with logic for receiving a data packet and determining whether the received data packet has an existing packet header prepended thereto. The header creator circuit is further configured to determine if the length of the received data packet includes a cyclic redundancy code. Still further, the header creator circuit is configured to determine a packet header length field value for the received data packet. If the header creator circuit determines that a cyclic redundancy code needs to be included with the received data packet, then the header creator circuit is able to generate a CRC flag. If the data packet needs to be encrypted, then the header creator circuit will generate an encryption flag if it is determined that the received data packet should be encrypted. Finally, the header creator circuit generates a packet header having a plurality of fields.

Claims

1. A hardware-implemented packet header generation circuit configured to receive data packets and information associated with descriptor words that were previously prepended to the data packets, the descriptor words indicating tasks to be performed by the packet header generation circuit, the hardware-implemented packet header generation circuit comprising:

an input node;

a plurality of descriptor registers having one or more corresponding information inputs coupled to the input node, and configured to capture and store the information associated with the descriptor words;

a control signal generator circuit configured to receive the data packets from the input node and the information associated with the descriptor words from the plurality of registers, and configured to generate the packet headers using the information associated with the descriptor words;

a data encryption flag generator circuit configured to receive a first set of one or more control signals from the control signal generator; and

a cyclic redundancy code (“

CRC”

) flag generator circuit configured to receive a second set of one or more control signals from the control signal generator;

whereby the control signal generator is configured to control the data encryption flag generator circuit to generate an encryption flag for a data packet when the corresponding information associated with the descriptor words indicates that the data packet is to be encrypted;

whereby the control signal generator is configured to control the CRC flag generator circuit to generate a CRC flag for the data packet when the corresponding information associated with the descriptor words indicates that the data packet is to include a CRC; and

whereby the data packets and corresponding headers are forwarded for potential CRC processing and/or encryption, and thereafter for transmission over a wireless communication network.

2. The packet header generation circuit according to claim 1, wherein the plurality of descriptor registers are configured to capture and store one or more of the following types of information:

control information for CRC generation;

control information for payload header suppression processing; and

control information for encryption.

3. The packet header generation circuit according to claim 1, wherein the plurality of descriptor registers are configured to capture and store one or more of the following types of information:

information indicating a first packet size value; and

information indicating a packet header size value.

4. The packet header generation circuit according to claim 1, wherein the plurality of descriptor registers are configured to capture and store an encryption key.

5. The packet header generation circuit according to claim 1, wherein the control signal generator is configured to add bytes to a data packet when the information associated with descriptor words indicate that the length of the data packet does not include a cyclic redundancy code, wherein the added bytes can be used by a CRC generator to insert the CRC.

6. The packet header generation circuit according to claim 1, wherein the plurality of descriptor registers are configured to capture frame control information, media access control information, packet header length information, and header check sequence information.

7. The packet header generation circuit according to claim 6, wherein the plurality of descriptor registers are configured to capture extended header information.

8. The packet header generation circuit according to claim 6, wherein the control signal generator circuit is configured to generate the packet header for a data packet after a determination is made that the data packet does not have an existing packet header.

9. The packet header generation circuit according to claim 6, wherein the control signal generator circuit is configured to include the packet header length information into the packet header.

10. The packet header generation circuit according to claim 6, further comprising a data encryption standard/header check sequence/cyclic redundancy code (DES/HCS/CRC) circuit coupled to an output of the packet header generation circuit and configured to generate cyclic redundancy codes, encrypt data packets, and generate header check sequences, in accordance with flags within the generated packet headers.

11. The packet header generation circuit according to claim 10, further comprising a data encryption standard key fetching circuit coupled to the DES/HCS/CRC circuit.

12. The packet header generation circuit according to claim 1, wherein the control signal generator circuit is configured to compare generated packet headers to corresponding information associated with descriptor words, and configured to determine whether packet sizes associated with the information, and at least a subset of the information, correspond to information within the generated packet headers and packet sizes associated with the generated packet headers.

13. The packet header generation circuit according to claim 12, wherein the plurality of descriptor registers are configured to capture length information, and wherein the control signal generator circuit is configured to compare the length information with corresponding generated packet headers.