Method and apparatus for discarding data packets through the use of descriptors

• US 6,977,894 B1
• Filed: 05/19/1999
• Issued: 12/20/2005
• Est. Priority Date: 05/20/1998
• Status: Expired due to Fees

• Current Assignee: RPX Clearinghouse LLC (RPX Corporation)
• Original Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Inventors: Manor, Larry, Gallo, Paul, Pearson, Terry, Achilles, Heather
• Primary Examiner(s): Rao, Seema S.
• Assistant Examiner(s): MOORE JR, MICHAEL J
• Application Number:
  US09/314,566
• Time in Patent Office: 2,407 Days
• Field of Search: 370229-238, 370/412
• US Class Current: 370/235
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/12 Avoiding congestion; Recovering from congestion
• CPC Class Codes: H04L 47/2408 for supporting different services, e.g. a differentiated services [DiffServ] type of service
• CPC Class Codes: H04L 47/32 by discarding or delaying data units, e.g. packets or frames
• CPC Class Codes: H04L 49/205 Quality of Service based
• CPC Class Codes: H04L 49/505 Corrective measures

Abstract

A method, apparatus and article of manufacture for discarding a data packet. The data packet is classified according to a type of service (TOS) indicator and modified with an internal service class (ISC) indicator according to the TOS indicator. The data packet is modified with a watermark (WM) indicator according to the availability of a system resource. The ISC, WM and a drop preference (DP) indicator of the data packet are compared to a committed information rate (CIR). The packet is discarded if the DP exceeds the CIR.

Claims

1. A method for discarding a data packet comprising:

classifying the data packet including a type of service (TOS) indicator in order to produce an internal class service (ISC) indicator and a drop preference (DP) indicator;

modifying the data packet with a watermark (WM) indicator according to an availability of a system resource;

concatenating the ISC indicator, the WM indicator and the DP indicator of the data packet to produce a key value;

comparing recovered data using the key value to a committed information rate (CIR); and

discarding the data packet based on a result of a comparison of the recovered data and the CIR.

2. The method of claim 1 wherein the comparing of the recovered data to the CIR comprises:

finding an entry in a congestion clip table (CCT) using the key value being a concatenation of the ISC indicator, the WM indicator and the DP indicator; and

comparing data recovered from the entry to the CIR.

3. The method of claim 1 wherein the classifying of the data packet comprises:

analyzing a field of the data packet to determine a packet characteristic; and

assigning the TOS indicator based upon the packet characteristic.

4. A computer usable medium having computer readable program code embodied in the medium executed by a route switch processor, the program code comprising:

a first program code for causing a computer to classify a data packet including a type of service (TOS) indicator in order to produce an internal class service (ISC) indicator and a drop preference (DP) indicator;

a second program code embodied in the computer usable medium for causing the computer to modify the data packet with a watermark (WM) indicator;

a third program code embodied in the computer usable medium for causing the computer to concatenate the ISC indicator, the WM indicator and the DP indicator of the data packet to produce a key value;

a fourth program code embodied in the computer usable medium for causing the computer to compare data recovered using the key value to a committed information rate (CIR); and

a fifth program code embodied in the computer usable medium for causing a computer to discard the data packet based on a result of the comparison of the data recovered and the CIR.

5. The computer usable medium of claim 4 wherein the fourth program code embodied in the computer usable medium is further configured to:

finding an entry in a congestion clip table (CCT) using the key value.

6. The computer usable medium of claim 4, wherein the first program code comprises:

computer readable program code to analyze a field of the data packet to determine a packet characteristic; and

computer readable program code to assign the TOS indicator based upon the packet characteristic.