OPTICAL PACKET SWITCHING APPARATUS AND METHODS

• US 20090129775A1
• Filed: 01/27/2008
• Published: 05/21/2009
• Est. Priority Date: 09/04/2001
• Status: Active Grant

• Current Assignee: F Poszat Hu LLC (Intellectual Ventures LLC)
• Original Assignee: Rondel Technology Facility LLC (Intellectual Ventures LLC)
• Inventors: Handelman, Doron
• Granted Patent: US 7,720,379 B2
• Time in Patent Office: Days
• US Class Current: 398/47
• CPC Class Codes: H04J 14/08 Time-division multiplex systems
• CPC Class Codes: H04Q 11/0005 Switch and router aspects
• CPC Class Codes: H04Q 11/0066 Provisions for optical burst or packet networks
• CPC Class Codes: H04Q 2011/0015 using splitting combining
• CPC Class Codes: H04Q 2011/0035 using miscellaneous components, e.g. circulator, polarisation, acousto/thermo optical
• CPC Class Codes: H04Q 2011/005 Arbitration and scheduling
• CPC Class Codes: H04Q 2011/0064 Arbitration, scheduling or medium access control aspects
• CPC Class Codes: H04Q 2011/0075 Wavelength grouping or hierarchical aspects
• CPC Class Codes: H04Q 2011/0084 Quality of service aspects

Abstract

An optical packet switch switches optical packets according to bit-rates at which the optical packets are provided. For example, optical packets that are received at similar bit-rates may be routed to a destination at separate time slots over a single channel wavelength, and optical packets that are received at different bit-rates may be routed to the destination over separate channel wavelengths. When optical packets are provided at different bit-rates on a plurality of input paths, optical packets provided at low bit-rates may be compacted before switching to the destination. Alternatively or additionally, the bit-rates of the optical packets may be balanced before switching to the destination. Bandwidth contention among optical packets may be resolved by polarizing optical packets originating from separate input paths in different polarization directions, and merging optical packets having different polarization directions onto a single switched channel wavelength. Compaction of optical packets may alternatively be employed for resolution of bandwidth contention. Related apparatus and methods are also described.

Claims

1. An optical packet switching method for use at a switching node that receives a first optical packet on a first input path at a first bit-rate and a second optical packet on a second input path at a second bit-rate, the method comprising:

routing the first optical packet to a destination over a first channel wavelength and the second optical packet to the destination over a second channel wavelength if a magnitude of a difference between the first bit-rate and the second bit-rate exceeds a bit-rate difference threshold, and

routing the first optical packet and the second optical packet to the destination at a separate time slots over a single channel wavelength if the magnitude of a difference between the first bit-rate and the second bit-rate does not exceed the bit-rate difference threshold.

2. The method according to claim 1 wherein each of the first optical packet and the second optical packet comprises at least one of

a fixed-length optical packet or a variable-length optical packet or any combination thereof.

3. The method according to claim 1 and also comprising determining the magnitude of a difference between the first bit-rate and the second bit-rate prior to the routing.

4. The method according to claim 3 and wherein the determining comprises:

obtaining a first bit-rate identifier associated with the first optical packet by analyzing a first header associated with the first optical packet;

obtaining a second bit-rate identifier associated with the second optical packet by analyzing a second header associated with the second optical packet; and

comparing the first bit-rate identifier with the second bit-rate identifier to obtain the magnitude of a difference between the first bit-rate and the second bit-rate.

5. The method according to claim 4 wherein each of the first bit-rate identifier and the second bit-rate identifier comprises at least one of the following:

a source identifier;

a label;

or an overhead byte or any combination thereof.

6. The method according to claim 1 and wherein the bit-rate difference threshold is about zero.

7. An optical packet switching method for use at a switching node that receives a first optical packet on a first input path at a first bit-rate and a second optical packet on a second input path at a second bit-rate, the method comprising:

determining a magnitude of a difference between the first bit-rate and the second bit-rate; and

if the magnitude of a difference between the first bit-rate and the second bit-rate exceeds a bit-rate difference threshold;

switching the first optical packet to a destination via a first optical communication switch that is operatively associated with the destination and the second optical packet to the destination via a second optical communication switch that is operatively associated with the destination.

8. The method according to claim 7 and wherein each of the first optical packet and the second optical packet comprises one of the following:

a fixed-length optical packet;

or a variable-length optical packet.

9. An optical packet switching method for use at a switching node that receives N series of optical packets on N input paths at N bit-rates respectively, where N is an integer greater than two, the method comprising:

arranging the N series optical packets as K groups of series of optical packets, where K≦

N and the K groups are characterized in that each group includes series of optical packets having substantially similar bit-rates, and bit-rates of series in each group differ from bit-rates of series in other groups; and

routing optical packets in each K group to a destination on a respective channel wavelength.

10. The method according to claim 9 and wherein each optical packet in the N series of optical packets comprises one of the following:

a fixed-length optical packet; and

a variable-length optical packet.

11. The method according to claim 9 and wherein the arranging comprises determining the N bit-rates by obtaining a bit-rate identifier from a header associated with at least one optical packet in each of the N series.

12-33. -33. (canceled)

34. A method of switching or routing optical packets, comprising:

receiving a first optical packet on a first input path at a first bit-rate;

receiving a second optical packet on a second input path at a second bit-rate;

determining a magnitude of a difference between the first bit-rate and the second bit-rate; and

routing the first optical packet to a destination over a first channel wavelength and the second optical packet to the destination over a second channel wavelength in response to the difference between the first bit-rate and the second bit-rate exceeding a particular value.

35. The method according to claim 34 wherein the act of determining a difference between the first bit-rate and the second bit-rate comprises obtaining a first bit-rate identifier associated with the first optical packet by analyzing a first header associated with the first optical packet and obtaining a second bit-rate identifier associated with the second optical packet by analyzing a second header associated with the second optical packet, and comparing the first bit-rate identifier with the second bit-rate identifier to obtain the magnitude of a difference between the first bit-rate and the second bit-rate.

36. The method according to claim 34 wherein the first optical packet and the second optical packet comprises at least one of a fixed-length optical packet or a variable-length optical packet or any combination thereof.

37. The method according to claim 34 wherein the first channel wavelength and the second channel wavelength are in the same wavelength band.

38. The method according to claim 34 wherein each of the first channel wavelength and the second channel wavelength comprises a wavelength in a wavelength band on the order of tens of nanometer (nm).

39. The method according to claim 38 wherein the wavelength band is approximately at least one of 780 nm, 980 nm, 1310 nm, 1480 nm, 1510 nm, 1550 nm, or 1620 nm.

40. The method according to claim 34 further comprising:

obtaining a first bit-rate identifier associated with the first optical packet by analyzing a first header associated with the first optical packet; and

obtaining a second bit-rate identifier associated with the second optical packet by analyzing a second header associated with the second optical packet.

41. The method according to claim 34 wherein the act of determining a magnitude of a difference between the first bit-rate and the second bit-rate comprises comparing the first bit-rate identifier with the second bit-rate identifier to obtain the magnitude of a difference between the first bit-rate and the second bit-rate.