Network processor which defines virtual paths without using logical path descriptors

• US 7,069,557 B2
• Filed: 05/23/2002
• Issued: 06/27/2006
• Est. Priority Date: 05/23/2002
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Alferness, Merwin Herscher
• Primary Examiner(s): An, Meng-Al T.
• Assistant Examiner(s): To, Jennifer N.
• Application Number:
  US10/153,995
• Publication Number:
  US 20030220959A1
• Time in Patent Office: 1,496 Days
• Field of Search: 718 1-108, 712/6, 712/16, 709230-236, 370230-413
• US Class Current: 718/102
• CPC Class Codes: H04L 12/5601 Transfer mode dependent, e.g. ATM
• CPC Class Codes: H04L 2012/5679 Arbitration or scheduling
• CPC Class Codes: H04L 47/50 Queue scheduling
• CPC Class Codes: H04L 47/566 Deadline varies as a function of time spent in the queue
• CPC Class Codes: H04L 49/901 using storage descriptor, e.g. read or write pointers

Abstract

A virtual path feature in which several virtual channels share an assigned amount of bandwidth is implemented in a network processor. The network processor maintains a schedule indicative of respective times at which a plurality of virtual channels are to be serviced. An entry is read from the schedule. The entry corresponds to a current transmit cycle and includes a pointer to a channel descriptor for a virtual channel to be serviced in the current transmit cycle. A data cell for the virtual channel to be serviced in the current cycle is transmitted. An entry is added to the schedule to point to a channel descriptor that is pointed to by the channel descriptor for the virtual channel serviced in the current transmit cycle.

Claims

1. A method of operating a network processor, the method comprising:

(a) maintaining a schedule indicative of respective times at which a plurality of virtual channels are to be serviced;

(b) reading an entry from the schedule, the entry corresponding to a current transmit cycle and including a pointer to a channel descriptor for a virtual channel to be serviced in the current transmit cycle;

(c) transmitting a data cell for the virtual channel to be serviced in the current transmit cycle;

(d) adding to the schedule an entry which points to a channel descriptor that is pointed to by the channel descriptor for the virtual channel serviced in the current transmit cycle; and

(e) writing to the channel descriptor pointed to by the channel descriptor for the virtual channel serviced in the current transmit cycle a time stamp indicative of a scheduled time for servicing a virtual channel which corresponds to the channel descriptor pointed to by the channel descriptor for the virtual channel serviced in the current transmit cycle.

2. A network processor, comprising:

means for maintaining a schedule indicative of respective times at which a plurality of virtual channels are to be serviced;

means for reading an entry from the schedule, the entry corresponding to a current transmit cycle and including a pointer to a channel descriptor for a virtual channel to be serviced in the current transmit cycle;

means, responsive to the means for reading, for transmitting a data cell for the virtual channel to be serviced in the current transmit cycle;

means for adding to the schedule an entry which points to a channel descriptor that is pointed to by the channel descriptor for the virtual channel serviced in the current transmit cycle; and

means for writing to the channel descriptor pointed to by the channel descriptor for the virtual channel serviced in the current transmit cycle a timestamp indicative of a scheduled time for servicing a virtual channel which corresponds to the channel descriptor pointed to by the channel descriptor for the virtual channel serviced in the current transmit cycle.

3. The network processor of claim 2, wherein the means for maintaining, the means for reading, and the means for adding are part of a cell scheduling component of the network processor.

4. A computer program product comprising:

a medium, other than a carrier wave signal, readable by a computer, the computer readable medium having program code adapted to;

maintain a schedule indicative of respective times at which a plurality of virtual channels are to be serviced;

read an entry from the schedule, the entry corresponding to a current transmit cycle and including a pointer to a channel descriptor for a virtual channel to be serviced in the current transmit cycle;

transmit a data cell for the virtual channel to be serviced in the current transmit cycle;

add to the schedule an entry which points to a channel descriptor that is pointed to by the channel descriptor for the virtual channel serviced in the current transmit cycle; and

write to the channel descriptor pointed to by the channel descriptor for the virtual channel serviced in the current transmit cycle a timestamp indicative of a scheduled time for servicing a virtual channel which corresponds to the channel descriptor pointed to by the channel descriptor for the virtual channel serviced in the current transmit cycle.