Frame concatenation with drop precedence assignment

• US 20080192747A1
• Filed: 02/08/2007
• Published: 08/14/2008
• Est. Priority Date: 02/08/2007
• Status: Active Grant

• Current Assignee: Orckit IP LLC (Orckit-Corrigent )
• Original Assignee: Corrigent Systems Ltd. (Orckit-Corrigent )
• Inventors: Ram, Rafi, Bruckman, Leon
• Granted Patent: US 7,697,532 B2
• Time in Patent Office: Days
• US Class Current: 370/393
• CPC Class Codes: H04L 12/437 Ring fault isolation or reconfiguration for SDH/SONET ring networks H04J3/085
• CPC Class Codes: H04L 12/4633 Interconnection of networks using encapsulation techniques, e.g. tunneling
• CPC Class Codes: H04L 2012/5665 Interaction of ATM with other protocols
• CPC Class Codes: H04L 2212/00 Encapsulation of packets
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/32 by discarding or delaying data units, e.g. packets or frames
• CPC Class Codes: H04L 47/36 by determining packet size, e.g. maximum transfer unit [MTU]

Abstract

A method for communication includes encapsulating multiple data packets, which carry data and have respective drop precedence (DP) values selected from a range of possible DP values, to produce a concatenated frame of a transport protocol. A composite drop precedence (CDP) value is assigned from the range to the concatenated frame using a pseudo-random assignment function that depends on a distribution of the DP values of the data packets in the concatenated frame. The concatenated frame is transported through a communication network using the transport protocol, in accordance with the pseudo-randomly assigned CDP value.

Claims

1. A method for communication, comprising:

encapsulating multiple data packets, which carry data and have respective drop precedence (DP) values selected from a range of possible DP values, to produce a concatenated frame of a transport protocol;

assigning a composite drop precedence (CDP) value from the range to the concatenated frame using a pseudo-random assignment function that depends on a distribution of the DP values of the data packets in the concatenated frame; and

transporting the concatenated frame through a communication network using the transport protocol, in accordance with the pseudo-randomly assigned CDP value.

2. The method according to claim 1, wherein the transport protocol comprises a Multiprotocol Label Switching (MPLS) protocol.

3. The method according to claim 1, wherein the data packets comprise Asynchronous Transfer Mode (ATM) cells.

4. The method according to claim 1, wherein the data packets comprise Ethernet frames.

5. The method according to claim 1, wherein the communication network comprises a ring network.

6. The method according to claim 1, wherein the pseudo-random assignment function is defined such that a likelihood of assigning a certain CDP value from the range is proportional to a relative amount of the data in the concatenated frame, which is carried by the data packets whose DP value equals the certain CDP value.

7. The method according to claim 6, wherein assigning the CDP value comprises generating a pseudo-random number that is greater than zero and is distributed between zero and unity, assigning the concatenated frame a first CDP value when the pseudo-random number is no greater than the relative amount of the data, and assigning the concatenated frame a second CDP value, which indicates a higher drop precedence with respect to the first CDP value, when the pseudo-random number is greater than the relative amount of the data.

8. The method according to claim 6, wherein assigning the CDP value comprises reading the relative amount of the data from a Look-Up Table (LUT).

9. The method according to claim 1, wherein the pseudo-random assignment function is defined such that a likelihood of assigning a certain CDP value from the range depends on a number of the data packets, which are encapsulated in the concatenated frame and whose DP value equals the certain CDP value.

10. The method according to claim 1, wherein assigning the CDP value comprises generating the pseudo-random assignment function using a Linear Feedback Shift Register (LFSR).

11. A network node, comprising:

A network interface, which is arranged to communicate with a communication network; and

a processor, which is arranged to encapsulate multiple data packets, which carry data and have respective drop precedence (DP) values selected from a range of possible DP values, so as to produce a concatenated frame of a transport protocol, to assign a composite drop precedence (CDP) value from the range to the concatenated frame using a pseudo-random assignment function that depends on a distribution of the DP values of the data packets in the concatenated frame, and to send the concatenated frame to the communication network using the network interface, so as to transport the concatenated frame through the communication network using the transport protocol, in accordance with the pseudo-randomly assigned CDP value.

12. The node according to claim 11, wherein the transport protocol comprises a Multiprotocol Label Switching (MPLS) protocol.

13. The node according to claim 11, wherein the data packets comprise Asynchronous Transfer Mode (ATM) cells.

14. The node according to claim 11, wherein the data packets comprise Ethernet frames.

15. The node according to claim 11, wherein the communication network comprises a ring network.

16. The node according to claim 11, wherein the pseudo-random assignment function is defined such that a likelihood of assigning a certain CDP value from the range is proportional to a relative amount of the data in the concatenated frame, which is carried by the data packets whose DP value equals the certain CDP value.

17. The node according to claim 16, wherein the processor is arranged to generate a pseudo-random number that is greater than zero and is distributed between zero and unity, to assign the concatenated frame a first CDP value when the pseudo-random number is no greater than the relative amount of the data, and to assign the concatenated frame a second CDP value, which indicates a higher drop precedence with respect to the first CDP value, when the pseudo-random number is greater than the relative amount of the data.

18. The node according to claim 16, wherein the processor is arranged to read the relative amount of the data from a Look-Up Table (LUT).

19. The node according to claim 11, wherein the pseudo-random assignment function is defined such that a likelihood of assigning a certain CDP value from the range depends on a number of the data packets, which are encapsulated in the concatenated frame and whose DP value equals the certain CDP value.

20. The node according to claim 11, wherein the processor is arranged to generate the pseudo-random assignment function using a Linear Feedback Shift Register (LFSR).

21. A computer software product used in a network node, the product comprising a computer-readable medium, in which program instructions are stored, which instructions, when read by a processor, cause the processor to encapsulate multiple data packets, which carry data and have respective drop precedence (DP) values selected from a range of possible DP values, so as to produce a concatenated frame of a transport protocol, to assign a composite drop precedence (CDP) value from the range to the concatenated frame using a pseudo-random assignment function that depends on a distribution of the DP values of the data packets in the concatenated frame, and to send the concatenated frame to a communication network, so as to transport the concatenated frame through the communication network using the transport protocol, in accordance with the pseudo-randomly assigned CDP value.