Multiplex communications – Data flow congestion prevention or control
Reexamination Certificate
1997-12-23
2001-08-28
Chin, Wellington (Department: 2664)
Multiplex communications
Data flow congestion prevention or control
C370S397000
Reexamination Certificate
active
06282171
ABSTRACT:
FIELD OF THE INVENTION
The present invention is related to managing the transmission of ATM packets. More specifically, the present invention is related to managing the transmission of ATM packets by discarding cells only of a same packet when a predetermined event occurs.
BACKGROUND OF THE INVENTION
Early Packet Discard (EPD) and Partial Packet Discard (PPD) when used in conjunction with per VC queuing have proved to be an extremely effective method for providing congestion control in an ATM network while maximizing users' goodput. In order to provide for congestion control, an ATM switch will begin to discard cells when its cell buffers begin to fill past configured thresholds. Without EPD/PPD, an ATM switch might discard N cells with each cell belonging to a different user packet; this means it has effectively discarded N user packets, all of which will have to be retransmitted. With EPD/PPD, an ATM switch will only discard cells that belong to the same packets; i.e., the unit of discard is packets rather than cells. This minimizes the number of user packets that are discarded.
Unfortunately, the EPD/PPD only works for AAL5, since it uses the End of Message (EOM) bit in the ATM header. This means that in order to perform EPD/PPD, an ATM switch must have awareness of individual VCs so that it knows which VCs are using AAL5. This can cause scaling problems for ATM switches in the core of a large ATM network, because they will tremendous numbers of VCs transiting them. In addition to having to maintain state for a large number of VCs, these core ATM switches will have to process the signaling messages for all of these VCs, which puts a large burden on the processors in these switches.
Ideally, these core switches would have only VP awareness, so that they wouldn't have to maintain per VC state or process per VC signaling messages, while at the same time be capable of performing EPD/PPD. The present invention solves this problem.
SUMMARY OF THE INVENTION
The present invention pertains to a system for sending ATM cells. The system comprises an ATM network along which ATM cells travel. The system comprises source nodes connected to the ATM network which produce packets having cells and transmit the cells on the ATM network. The system comprises I input switches connected to the ATM network, where I is greater than or equal to 1 and is an integer, which receive cells from the ATM network transmitted by the source node. The system comprises M intermediate switches connected to the ATM network, where M is greater than or equal to 1, which receive signals from the ATM network transmitted by at least one input switch. The intermediate switch discards cells only of a same packet when a predetermined event occurs so the discarded cells are not transmitted by the intermediate switch. The system comprises destination nodes connected to the ATM network which receive non-discarded ATM cells from the intermediate switch.
The present invention pertains to a method for sending ATM cells. The method comprises the steps of receiving cells of ATM packets at an intermediate switch from an ATM network that have been transmitted by an input switch. Next there is the step of discarding only cells of the same ATM packet from the intermediate switch. Then there is the step of receiving non-discarded cells at a destination node from the ATM network that have been transmitted from the intermediate switch.
REFERENCES:
patent: 5689499 (1997-11-01), Hullett et al.
patent: 5764641 (1998-06-01), Lin
patent: 6032272 (2000-02-01), Soirinsuo et al.
Adams Jay
Drake, Jr. John E.
Chin Wellington
Marconi Communications Inc.
Schwartz Ansel M.
Tran Maikhanh
LandOfFree
System and method regarding early packet discard (EPD) and... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with System and method regarding early packet discard (EPD) and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and System and method regarding early packet discard (EPD) and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2548701