Multi-length packet format including check sequence(s)
First Claim
1. Apparatus for generating a packet including at least a transport word, i.e., header, comprising:
- means for generating said transport word including a predetermined number of groups of bit positions each including a predetermined number of bit positions, predetermined ones of said transport word bit positions forming a packet length indicator field, a predetermined number of said transport word bit positions forming an at least one prescribed parity check field and a predetermined number of said transport word bit positions forming an at least second prescribed parity check field;
means for obtaining the length of said packet;
means for inserting bits representative of said packet length in bit positions of said packet length indicator field;
means for generating an at least first prescribed parity check from bits in predetermined bit positions of said transport word;
means for generating an at least second prescribed parity check from bits in predetermined bit positions of said transport word;
means for inserting a number of bits representative of said at least first prescribed parity check into said number of bit positions of said at least one prescribed parity check field; and
means for inserting a number of bits representative of said at least second prescribed parity check in said number of bit positions of said at least second partiy check field, said at least first prescribed parity check, said at least second prescribed parity check and said packet length indicator being employed to delimit said packet.
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Accused Products
Abstract
A unique packet transport word, i.e., header, format is disclosed which is advantageously employed to delimit the corresponding packet and to verify data fields in the transport word. An at least first parity check is employed in conjunction with a packet length indicator to delimit the corresponding packet. The at least first parity check is formed by computing a predetermined number of parity check bits from bits in predetermined bit positions of the transport word. These parity check bits are inserted into predetermined bit positions in the transport word. Similarly, bits representing the packet length indicator are also inserted into predetermined bit positions of the transport word. In a specific embodiment, a plurality of parity checks is employed to achieve increased robustness. The plurality of parity checks is formed such that each of the bits in predetermined bit positions of the transport word is used in computing at least two different parity check bits. In one embodiment, a first prescribed parity check is formed by computing parity over bits from predetermined bit positions in one or more groups of bit positions in the transport word and a second prescribed parity check is formed by computing parity over bits from predetermined similar bit positions in the groups of bit positions in the transport word. In one example the transport word includes a plurality of bytes each of which includes a predetermined number of bit positions forming columns and rows. Parity check bits forming the first prescribed parity check are obtained by computing parity from bits in predetermined bit positions in the transport word columns and parity check bits forming the second prescribed parity check are obtained by computing parity from bits in predetermined bit positions in the transport word rows. In this example, the first and second parity checks are obtained by so-called "group" processing and are adequate to both delimit the packets and verify the transport word data fields. These verified fields include, among others, the packet length and necessary information for delivery and "billing" of the packet.
60 Citations
19 Claims
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1. Apparatus for generating a packet including at least a transport word, i.e., header, comprising:
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means for generating said transport word including a predetermined number of groups of bit positions each including a predetermined number of bit positions, predetermined ones of said transport word bit positions forming a packet length indicator field, a predetermined number of said transport word bit positions forming an at least one prescribed parity check field and a predetermined number of said transport word bit positions forming an at least second prescribed parity check field; means for obtaining the length of said packet; means for inserting bits representative of said packet length in bit positions of said packet length indicator field; means for generating an at least first prescribed parity check from bits in predetermined bit positions of said transport word; means for generating an at least second prescribed parity check from bits in predetermined bit positions of said transport word; means for inserting a number of bits representative of said at least first prescribed parity check into said number of bit positions of said at least one prescribed parity check field; and means for inserting a number of bits representative of said at least second prescribed parity check in said number of bit positions of said at least second partiy check field, said at least first prescribed parity check, said at least second prescribed parity check and said packet length indicator being employed to delimit said packet. - View Dependent Claims (2, 3, 4, 5, 6, 14, 15, 16, 17, 18)
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7. Apparatus for generating a packet including at least a transport word, i.e., header, comprising:
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means for generating said transport word including a predetermined number of groups of bit positions each including a predetermined number of bit positions wherein each of said predetermined number of groups of bit positions forms a byte, predetermined ones of said transport word bit positions forming a packet length indicator field and a predetermined number of said transport word bit positions forming an at least one prescribed parity check field, wherein said means for generating said transport word generates each said byte in parallel and wherein said transport word bit positions form a predetermined number of columns of bit positions and a predetermined number of rows of bit positions; means for obtaining the length of said packet; means for inserting bits representative of said packet length in bit positions of said packet length indicator field; means for generating an at least first prescribed parity check from bits in predetermined bit positions of said transport word; and means for inserting a number of bits representative of said at least first prescribed parity check into said number of bit positions of said at least one prescribed parity check field, said at least one prescribed parity check and said packet length indicator being employed to delimit said packet. - View Dependent Claims (8, 9, 10, 11, 12, 13)
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19. Apparatus for generating a packet including at least a transport word, i.e., header, comprising:
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means for generating said transport word including a predetermined number of groups of bit positions each including a predetermined number of bit positions, predetermined ones of said transport word bit positions forming a plurality of parity check fields and predetermined others of said transport word bit positions forming data fields; means for generating a plurality of prescribed parity checks from bits in predetermined bit positions of said transport word, wherein each of said bits from said predetermined bit positions in said transport word is used to compute at least two different parity check bits which form said plurality of prescribed parity checks; and means for inserting said computed parity check bits into bit positions in said plurality of parity check fields in said transport word, wherein said plurality of prescribed parity checks are employed to verify said transport word data fields.
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Specification