# US 7,613,183 B1 · System and method for router data aggregation and delivery

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- Number: US 7,613,183 B1
- Document ID: US7613183B1
- Status: Granted
- Kind: B1
- Application number: 09/703,038
- Filed: 2000-10-31
- Granted: 2009-11-03
- Earliest claimed: 2000-10-31
- Assignees: Foundry Networks, Inc.
- Inventors: Tony M. Brewer; Harry C. Blackmon; Chris Davies; Harold W. Dozier; Thomas C. McDermott, III; Steven J. Wallach; Dean E. Walker; Lou Yeh
- Web page: https://patentgrep.com/patent/US7613183B1

## CPC

- H04L 45/00: Routing or path finding of packets in data switching networks (routing or path finding in wireless networks H04W40/00)
- H04J 3/0605: {Special codes used as synchronising signal}
- H04L 1/0083: {Formatting with frames or packets; Protocol or part of protocol for error control}
- H04L 1/004: {by using forward error control (H04L1/0618 takes precedence; coding, decoding or code conversion, for error detection or correction H03M13/00)}
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)
- H04J: MULTIPLEX COMMUNICATION (transmission in general H04B; peculiar to transmission of digital information H04L5/00; systems for the simultaneous or sequential transmission of more than one television signal H04N7/08; in exchanges H04Q11/00; stereophonic systems H04S)

## Abstract

A chunk format for a large-scale, high data throughput router includes a preamble that allows each individual chunk to have clock and data recovery performed before the chunk data is retrieved. The format includes a chunk header that contains information specific to the entire chunk. A chunk according to the present format can contain multiple packet segments, with each segment having its own packet header for packet-specific information. The format provides for a scrambler seed which allows scrambling the data to achieve a favorable zero and one balance as well as minimal run lengths. There are forward error correction (FEC) bytes as well as a chunk cyclical redundancy check (CRC) to detect and/or correct any errors and also to insure a high degree of data and control integrity. Advantageously, a framing symbol inserted into the chunk format itself allows the receiving circuitry to identify or locate a particular chunk format. “Break Bytes” and “Make Bytes” fields located at the beginning of a chunk preamble precondition an optical receiver to a proper state before the actual chunk arrives at the receiver.

## Claims

### Claim 1

A method of passing received Internet Protocol (IP) data packets through a network device, said method comprising:
constructing within said network device a chunk with a payload that is sized to fit more than one of said IP data packets;
formatting said chunk to include at least one of:
a forward error correction (FEC) code; and
a cyclical redundancy check (CRC) code;
filling said payload of said chunk with a portion of at least one said IP data packet;
including a framing symbol in each said chunk; and
passing said chunk through a switch fabric of said network device.

### Claim 2 (depends on 1)

The method of claim 1 further comprising inserting said framing symbol adjacent to the trailing end of said chunk.

### Claim 3 (depends on 1)

The method of claim 1 wherein said passing comprises using said framing symbol to determine uniquely within a stream of bits the beginning and the trailing end of said chunk.

### Claim 4 (depends on 1)

The method of claim 1 further comprising using said FEC encoded in each said chunk to detect and correct errors in said chunk.

### Claim 5 (depends on 4)

The method of claim 4 further comprising using said CRC encoded in each said chunk to determine that the entire said chunk has a proper CRC value.

### Claim 6 (depends on 1)

The method of claim 1 further comprising:
formatting said chunk to include a scrambler seed, and wherein said formatting comprises using said scrambler seed in said chunk to balance zeroes and ones and to minimize run lengths of zeroes and ones by scrambling bits across said chunk.

### Claim 7 (depends on 1)

The method of claim 1 further comprising:
formatting said chunk to include a “Break Bytes” field and a “Make Bytes” field, said fields configured to precondition an optical receiver prior to the arrival of said chunk.

### Claim 8 (depends on 7)

The method of claim 7 wherein said “Break Bytes” field and said “Make Bytes” field are programmable in length.

### Claim 9 (depends on 7)

The method of claim 7 wherein said passing comprises using said “Break Bytes” and said “Make Bytes” field to precondition on optical receiver prior to the arrival of a chunk.

### Claim 10 (depends on 9)

The method of claim 9 wherein “Make Bytes” field reestablishes a decision threshold level of a limiting amplifier within a burst mode optical receiver.

### Claim 11 (depends on 1)

The method of claim 1 further comprising: formatting said chunk to include adding a chunk header.

### Claim 12 (depends on 11)

The method of claim 11 wherein said chunk header includes identification of chunk type.

### Claim 13 (depends on 11)

The method of claim 11 wherein said chunk header includes a header parity.

### Claim 14 (depends on 11)

The method of claim 11 wherein said chunk header includes an indication that said chunk is a master chunk.

### Claim 15 (depends on 11)

The method of claim 11 wherein said chunk header includes a sequence number.

### Claim 16 (depends on 15)

The method of claim 15 further comprising:
performing error detection and correction using said sequence number in said chunk header for alarming and for alerting that a chunk potentially was corrupted.

### Claim 17 (depends on 16)

The method of claim 16 wherein a re-initialize bit is used to enable reinitialization of said sequence number, such that said alarming is avoided.

### Claim 18 (depends on 1)

The method of claim 1 wherein said chunk contains multiple data packets.

### Claim 19 (depends on 1)

The method of claim 1 wherein said sized chunk contains a segment of a data packet, said data packet having a length greater than the size of said chunk.

### Claim 20

An Internet Protocol (IP) packet router, said router comprising:
at least one chunk having a payload comprising a plurality of IP data packets and a framing symbol; and
a switch fabric through which said chunk passes;
wherein a respective chunk includes at least one of:
a forward error correction (FEC) code, and
a cyclical redundancy check (CRC) code.

### Claim 21 (depends on 20)

The IP packet router of claim 20 wherein said framing symbol is located adjacent the trailing end of each said chunk.

### Claim 22 (depends on 20)

The IP packet router system of claim 20 wherein said FEC coding is located adjacent to and following said framing symbol.

### Claim 23 (depends on 20)

The IP packet router claim 20 wherein each said chunk is formatted to include a chunk header.

### Claim 24 (depends on 23)

The IP packet router of claim 23 wherein said chunk header includes identification of chunk type.

### Claim 25 (depends on 23)

The IP packet router claim 23 wherein said switch fabric is partitioned into a plurality of working subplanes.

### Claim 26 (depends on 25)

The IP packet router claim 25 wherein said chunk header includes identification of a specific routing subplane through said switch fabric.

### Claim 27 (depends on 23)

The IP packet router of claim 23 wherein said chunk header includes a header parity.

### Claim 28 (depends on 23)

The IP packet router of claim 23 wherein said chunk header includes identification of an input of said switch fabric and an output of said optical switch fabric for said chunk.

### Claim 29 (depends on 23)

The IP packet router system of claim 23 wherein said chunk header includes a master chunk bit.

### Claim 30

An Internet Protocol (IP) packet router system, said system comprising:
at least one chunk having a payload comprising a plurality of data packets and a framing symbol; and
an IP packet router, including:
a switch fabric through which said chunk passes; and,
a first electrical switch stage at an input side of said switch fabric and a second electrical switch stage at an output side of said switch fabric,
wherein each said chunk is formatted to include a chunk header and at least one of:
a forward error correction (FEC) code, and
a cyclical redundancy check (CRC) code, and
wherein said chunk header includes a sequence number.

### Claim 31 (depends on 20)

The IP packet router system of claim 20 wherein said payload of said at least one chunk further comprises at least one packet segment and an associated packet header.

### Claim 32

A method of information flow through an IP packet network system device, said method comprising:
encapsulating within said network device input IP data packets from a plurality of source ports into chunks, wherein a respective chunk includes at least one of:
a forward error correction (FEC) code, and
a cyclical redundancy check (CRC) code;
formatting overhead information onto each of said chunks, said overhead including a framing symbol;
sending said chunks to a switch plane of said IP network device.

### Claim 33 (depends on 32)

The method of claim 32 further comprising:
converting said directed chunks into electrical signals;
sending said chunks from said switch plane;
performing error detection and error correction on said chunk;
removing said overhead information from said chunks; and
reassembling said input data packets out of said chunks.

### Claim 34 (depends on 32)

The method of claim 32 wherein all information flows through said switch plane in said chunks.

### Claim 35 (depends on 32)

The method of claim 32 further comprising:
formatting said chunks to include a chunk header.

### Claim 36 (depends on 35)

The method of claim 35 wherein said appropriate switch plane is one of a plurality of subplanes comprising a portioned switch fabric.

### Claim 37 (depends on 36)

The method of claim 36 wherein said chunk header includes identification of a specific routing subplane through said switch fabric.

### Claim 38 (depends on 37)

The method of claim 37 wherein said directing comprises using said identification in said chunk header of a specific routing subplane to route said chunks through said switch fabric.

### Claim 39 (depends on 35)

The method of claim 35 wherein said chunk header includes identification of an input of said appropriate switch plane and an output of said appropriate switch plane for said chunk.

### Claim 40 (depends on 39)

The method of claim 39 wherein said directing comprises using said identification in said chunk header of said input and said output to route said chunks through said switch plane.

### Claim 41 (depends on 39)

The method of claim 39 further comprising:
performing error detection and correction using said identification in said chunk header of said input and said output to verify the route of said chunks from said input and said output.

### Claim 42 (depends on 35)

The method of claim 35 wherein said chunk header includes identification of chunk type.

### Claim 43 (depends on 42)

The method of claim 42 wherein said directing comprises using said identification of chunk type in said chunk header to enable guaranteed bandwidth chunks to pass ahead of best effort chunks through said switch plane.

### Claim 44 (depends on 32)

The method of claim 32 wherein said switch plane is part of a switch fabric.

### Claim 45 (depends on 32)

The method of claim 32 wherein said sending comprises using said framing symbol in each said chunk to determine uniquely within a stream of bits a beginning and a trailing end of each said chunk.

### Claim 46 (depends on 1)

The method of claim 1, further comprising:
stripping said IP data packets from said chunk within said network device.

### Claim 47 (depends on 20)

The IP packet router of claim 20, further comprising:
a first stage at an input side of said switch fabric and a second stage at an output side of said switch fabric,
wherein said first stage is operable to construct said chunk, and said second stage is operable to strip said data packets from said chunk.