Source: http://www.google.com/patents/US6049527?dq=4182933
Timestamp: 2017-06-28 04:12:00
Document Index: 352249553

Matched Legal Cases: ['art 11', 'art 11', 'art 13', 'art 11', 'art 13', 'art 11', 'art 11', 'art 11', 'art 13', 'art 11', 'art 13', 'art 11', 'art 13', 'art 11', 'art 11', 'art 11', 'art 11', 'art 11']

Patent US6049527 - Cell discard control system for an ATM cell buffer - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inPatentsThe present invention is to provide a cell discard control system for an ATM (asynchronous transfer mode) cell buffer capable of preventing useless cells which are not restored to an original packet from being transmitted to an ATM network and minimize a discarded number of packets which should not be...http://www.google.com/patents/US6049527?utm_source=gb-gplus-sharePatent US6049527 - Cell discard control system for an ATM cell bufferAdvanced Patent SearchTry the new Google Patents, with machine-classified Google Scholar results, and Japanese and South Korean patents.Publication numberUS6049527 APublication typeGrantApplication numberUS 08/824,051Publication dateApr 11, 2000Filing dateMar 21, 1997Priority dateMar 22, 1996Fee statusPaidPublication number08824051, 824051, US 6049527 A, US 6049527A, US-A-6049527, US6049527 A, US6049527AInventorsKazuhiko Isoyama, Toshiya AramakiOriginal AssigneeNec CorporationExport CitationBiBTeX, EndNote, RefManPatent Citations (2), Non-Patent Citations (4), Referenced by (34), Classifications (15), Legal Events (6) External Links: USPTO, USPTO Assignment, EspacenetCell discard control system for an ATM cell buffer
US 6049527 AAbstract
The present invention is to provide a cell discard control system for an ATM (asynchronous transfer mode) cell buffer capable of preventing useless cells which are not restored to an original packet from being transmitted to an ATM network and minimize a discarded number of packets which should not be discarded. It comprises a cell receiving section 11 having a packet identifier adding part 11a for adding a packet identifier for identifying being cellulated from the same packet for an input cell and a cell discard part 11b for discarding cells, a cell buffer 12 for buffering cells transferred from the cell receiving section 11, the cell transmitting section 13 for transmitting cells transferred from the cell buffer 12 to an ATM network and transmitting idle cells instead of discarded cell which have been discarded by a cell discard part 13a, and buffer controller 14 for detecting a packet identifier added to a cell being discarded due to over flow of the cell buffer 12 and instructing the cell receiving section 11 and the cell transmitting section 13 to discard cells having the same packet identifier being detected.
1. A cell discard control system for an ATM (asynchronous transfer mode) cell buffer being provided at a line transmitting section of an ATM apparatus, comprising:a cell receiving section for receiving a flow of AAL5 type ATM cells, for adding a packet identifier to each cell for identifying cells associated with the same packet, for detecting number of cells consisting each packet, and for discarding cells in accordance with instructions and outputting cells with the packet identifier; a cell buffer for buffering a cell transferred from said cell receiving section; a cell transmitting section for transmitting a cell transferred from said cell buffer to an ATM network; and a buffer controller for monitoring a queue length of said cell buffer available for storing cells, detecting a packet identifier added to a cell being stored at the end of a queue of said cell buffer when the queue length is shorter than a predetermined threshold value and instructing said cell receiving section to discard cells consisting a packet having a different packet identifier being detected except for a packet comprising a smaller number of cells than a remaining queue length available in said cell buffer. Description
The present invention relates to a cell discard control system for an ATM (Asynchronous Transfer Mode) cell buffer, particularly to a cell discard control system when the ATM cell buffer overflow occurs, e.g. due to input of unexpected traffic volume, for transferring an AAL5 (ATM adaptation layer type 5) cell at a cell transmitting section of an ATM apparatus.
As this type of the cell discard control system for an ATM cell (AAL5 cell), the following cell discard control systems have been disclosed in the technical report, title of "Buffer Management for Best Effort Traffic in ATM Networks", of IEICE (Institute of Electronics, Information, and Communication Engineers) Research Conference SSE94-94, 1994 so far: a partial packet discard system and an early packet discard system.
FIG. 6 is an illustration schematically showing operations of the partial packet discard system which is a conventional cell discard control system. As shown in FIG. 6, in the case of the partial packet discard system, when cell 46e in a certain packet, which consists of cells 46a, 46b, . . . , and 46h, is discarded due to overflow of cell buffer 42, the packet without the cell 46e cannot be restored any more at the receiving end even though the rest of cells being transmitted and therefore, control is performed so as to discard all the following cells 46f, . . . , and 46h in the same packet. Thereby, the partial packet discard system makes it possible to decrease a useless number of cells to be transmitted to an ATM network.
FIG. 7 is an illustration schematically showing operations of the early packet discard system which is a conventional cell discard control system. As shown in FIG. 7, in the case of the early packet discard system, when the first cell 56a of a certain packet, consisting of cells 56a, 56b, 56c and 56d, reaches cell buffer 52, if the number of cells in cell buffer 52 exceeds a predetermined threshold at that point of time, control is performed so as to discard all cells 56a, . . . , and 56d in the packet. Thereby, the early packet discard system makes it possible to do away with useless cells to be transmitted to an ATM network.
However, the above-described partial packet discard system has a problem that cells 46a, . . . , and 46d of the same packet already being input to cell buffer 42 are transferred to the ATM network even though control is performed so as to discard all the following cells 46f, . . . , and 46h of the same packet when one cell 46e of those is discarded due to buffer overflow.
Moreover, the above described early packet discard system has a problem that any reached packet is discarded only the condition when the number of cells in the cell buffer exceeds a threshold. It means that a packet which can be saved is also discarded because all cells in a reached packet are discarded even if the number of cells in the packet is smaller than a remaining queue length of the cell buffer 52.
Therefore, the present invention is made to solve the above problems and its object is to provide a cell discard control system for an ATM (asynchronous transfer mode) cell buffer capable of preventing useless cells which are not restored to an original packet from being transmitted to an ATM network and minimize a discarded number of packets which should not be discarded.
To achieve the above object, the present invention provides a cell discard control system for an ATM cell buffer at a cell transmitting section of an ATM apparatus, which comprises a cell receiving section which receives a flow of AAL5 type ATM cells, adds a packet identifier to each cell for identifying being cellulated from the same packet, and outputs cells with the packet identifier, a cell buffer for buffering a cell transferred from the cell receiving section, a cell transmitting section which transmits a cell transferred from the cell buffer to an ATM network, discards cells in accordance with instructions and transmits idle cells instead of cells being discarded to the ATM network, and a buffer controller which detects a packet identifier added to a cell being discarded due to over flow of the cell buffer and instructs the cell transmitting section to discard cells having the same packet identifier being detected.
Moreover, in the case of a cell discard control system of the present invention, it is preferable that the cell receiving section is further provided with means for discarding cells and the buffer controller instructs both of the cell transmitting section and the cell receiving section to discard cells having the same packet identifier as the cell having been discarded due to overflow of the cell buffer.
In another aspect of a cell discard control system of the present invention, a buffer controller monitors queue length of the cell buffer available for storing cells and detects a packet identifier added to a cell being stored at the end of queue of the cell buffer when queue length becoming shorter than predetermined threshold value. At this time, the buffer controller instructs the cell receiving section to discard cells consisting a packet having the different packet identifier being detected.
In this case, a cell receiving section may detect number of cells consisting each packet, and the buffer controller may instruct the cell receiving section to discard cells consisting a packet having the different packet identifier being detected except for a packet comprising smaller number of cells than queue length available in the cell buffer.
FIG. 1 is a block diagram showing a structure of first embodiment of a cell discard control system of the present invention;
FIG. 2 is an illustration schematically showing the state in which a packet identifier is added to each cell by a packet identifier adding part of an embodiment of the present invention;
FIG. 3 is an illustration for explaining operations of an embodiment of a cell discard control system of the present invention;
FIG. 4 is a block diagram showing a structure of second embodiment of a cell discard control system of the present invention;
FIG. 5 is a block diagram showing a structure of third embodiment of a cell discard control system of the present invention;
FIG. 6 is an illustration schematically showing operations of a partial packet discard system which is a conventional cell discard control system; and
FIG. 7 is an illustration schematically showing operations of an early packet discard system which is a conventional cell discard control system.
The embodiments of the present invention are described below by referring to the accompanying drawings.
FIG. 1 is a block diagram showing the structure of first embodiment of a cell discard control system of the present invention. As shown in FIG. 1, the cell discard control system of this embodiment comprises a cell receiving section 11, a cell buffer 12, a cell transmitting section 13, and a buffer controller 14.
The cell receiving section 11 comprises a packet identifier adding part iia for adding a packet identifier to each of input AAL5 cells for identifying cells associated with the same packet and a cell discard part 11b for discarding a cell in accordance with an instruction from the buffer controller 14, and the cell transmitting section 13 also includes a cell discard part 13a for discarding a cell in accordance with an instruction from the buffer controller 14.
FIG. 2 is an illustration schematically showing the state in which a packet identifier is added to each of cells consisting of the same packet by the packet identifier adding part 11a. As shown in FIG. 2, the same packet identifier "1" is added to each of cells 21a, 21b, . . , and 21c obtained by segmenting packet 21. Similarly, packet identifiers "2" and "N" are added to cells 22a, 22b, . . . , and 22c and cells 23a, 23b, . . . , and 23c obtained by segmenting packet 22 and packet 23 respectively. The packet identifier adding part 11a can discriminate corresponding between the packet identifier and a cell to which the packet identifier is to be added by VCI (virtual channel identifier) and EOM (end of message) cell information contained in a cell header of each cell flowing into the cell receiving section 11. That is a bunch of cells between two EOM cells having the same VCI are regarded as cells segmenting the same packet.
Cells thus added with a packet identifier are input to the cell buffer 12. When a cell discarding occurs due to overflow of the cell buffer 12, buffer controller 14 instructs both of the cell receiving section 11 and the cell transmitting section 13 to discard cells having the same packet identifier as the discarded cell.
Then, operations of the cell discard control system of this embodiment are described below. FIG. 3 is an illustration for explaining operations of a cell discard control system of the present invention.
In FIG. 3, when cell 36e is discarded due to overflow of the cell buffer 12, packet identifier "N" being added to the cell 36e is stored in the buffer controller 14. The buffer controller 14 controls the cell discard part 11b of the cell receiving section 11 so as to discard continuously input cells 36f, . . . , and 36h having the same packet identifier "N". Moreover, the buffer controller 14 controls the cell discard part 13a of the cell transmitting section 13 so as to discard cells 36a, . . . , and 36d, input from the cell buffer 12 and having the same packet identifier "N", and controls the cell transmitting section 13 to output idle cells instead of discarded cells to the ATM network.
Therefore, the cell discard control system of this embodiment makes it possible, by discarding cells having the same packet identifier as a cell discarded due to buffer overflow, to prevent useless cells, which are unable to be restored to an original packet, from being transmitted to the ATM network, and also prevent extra cells regarded as useless cells from being input to the cell buffer.
FIG. 4 is a block diagram showing the structure of a second embodiment of the cell discard control system of the present invention. As shown in FIG. 4, the cell discard control system of this embodiment comprises a cell receiving section 11 having a packet identifier adding part 11a for adding a packet identifier to each of input AAL5 cells for identifying cells associated with the same packet, a cell buffer 12, a buffer controller 14, and a cell transmitting section 13 having a cell discard part 13a for discarding a cell in accordance with an instruction from the buffer controller 14.
A packet identifier is added to each of cells consisting of the same packet by the packet identifier adding part 11a as already having been explained. Cells thus added with a packet identifier are input to the cell buffer 12. When a cell discarding occurs due to overflow of the cell buffer 12, buffer controller 14 instructs the cell transmitting section 13 to discard cells having the same packet identifier as the discarded cell.
The buffer controller 14 controls the cell discard part 13a of the cell transmitting section 13 so as to discard cells which are input from the cell buffer 12 and having the same packet identifier as the discarded cell due to the cell buffer overflow, and controls the cell transmitting section 13 to output idle cells instead of discarded cells to the ATM network.
Therefore, the cell discard control system of this embodiment makes it possible, by discarding cells having the same packet identifier as a cell discarded due to buffer overflow, to prevent useless cells, which are unable to be restored to an original packet, from being transmitted to the ATM network.
FIG. 5 is a block diagram showing the structure of a third embodiment of the cell discard control system of the present invention, and this embodiment is the improved type of the early packet discard system. As shown in FIG. 5, the cell discard control system of this embodiment comprises a cell receiving section 11 having a packet identifier adding part 11a, a cell discard part 11b and a packet length monitor 11c, a cell buffer 12, a cell transmitting section 13, and a buffer controller 14 having a buffer length monitor 14a and controller 14b.
A packet identifier is added to each of cells consisting of the same packet by the packet identifier adding part 11a as already having been explained. Cells thus added with a packet identifier are input to the cell buffer 12.
The buffer controller 14 monitors aqueue length remained by the buffer length monitor 14a, and when the number of cells in the cell buffer 12 exceeds a predetermined threshold at that point of time, the buffer controller 14 informs the cell receiving section 11 of the packet identifier of the cell being stored at the end of queue of the cell buffer 12 and queue length available for storing more cells. When such information is transferred from the buffer controller 14, the cell receiving section 11 performs the control of cell discarding as follows.
The cell discard part 11b allows cells, having the same packet identifier as informed by the buffer controller 14, to pass to the cell buffer 12, and discards all next incoming cells having different packet identifier except for the following condition. That is a number of cells consisting of a packet (packet length) is counted by the packet length monitor 11c, and if the packet length of the next packet is short enough to be stored in the cell buffer 12 comparing with queue length available informed by the buffer controller 14, cells of the next packet are also allowed to pass to the cell buffer 12.
Therefore, the cell discard control system of this embodiment makes it possible, to save a reached packet if the number of cells in the packet is smaller than a remaining queue length of the cell buffer.
The embodiments of the present invention are described above. However, the present invention is not restricted to the embodiments. Various embodiments following the principle of the present invention are included.
For example, in the case of first and second embodiments of the present invention above described, cell buffer 12 detects overflow of its own and communicates the identifies of discarded cells to buffer controller 14. However, it is also possible to detect overflow of cell buffer 12 by cell discard part 11b and communicate the identifiers of discarded cells to buffer controller 14 from cell receiving section 11.
Patent CitationsCited PatentFiling datePublication dateApplicantTitleJPH0766807A * Title not availableJPH03135248A * Title not available* Cited by examinerNon-Patent CitationsReference1"Buffer Management for Best Effort Traffic in ATM Networks", IEICE(Institute for Electronics, Information, and Communication Engineers) Research Conference SSE94-94, 1994, pp. 21-26.2 *Buffer Management for Best Effort Traffic in ATM Networks , IEICE ( Institute for Electronics, Information, and Communication Engineers ) Research Conference SSE94 94, 1994, pp. 21 26.3K. Noritake et al., "A study on selective cell discard control in ATM-CL network", pp. 43-48, Technical Report of IEICE, vol. 94, No. 95, Jun. 1994.4 *K. Noritake et al., A study on selective cell discard control in ATM CL network , pp. 43 48, Technical Report of IEICE, vol. 94, No. 95, Jun. 1994.* Cited by examinerReferenced byCiting PatentFiling datePublication dateApplicantTitleUS6219339 *Feb 20, 1998Apr 17, 2001Lucent Technologies Inc.Method and apparatus for selectively discarding packetsUS6304552 *Sep 11, 1998Oct 16, 2001Nortel Networks LimitedMemory and apparatus for input based control of discards in a lossy packet networkUS6487211 *Mar 8, 2000Nov 26, 2002Fujitsu LimitedData packet switching apparatusUS6711126 *Jan 3, 2000Mar 23, 2004AlcatelCongestion control of AAL2 connectionsUS6847612 *Feb 26, 1999Jan 25, 2005Siemens AktiengesellschaftMethod for removing ATM cells from an ATM communications deviceUS6925056 *Jul 25, 2000Aug 2, 2005Sun Microsystems, Inc.System and method for implementing a routing scheme using intention packets in a computer networkUS6937607Jan 16, 2002Aug 30, 2005AlcatelRandom early discard for cell-switched data switchUS6947996Jan 29, 2001Sep 20, 2005Seabridge, Ltd.Method and system for traffic controlUS6950396Mar 20, 2001Sep 27, 2005Seabridge Ltd.Traffic control method and systemUS6990115Feb 26, 2001Jan 24, 2006Seabridge Ltd.Queue control method and systemUS7072976Jan 4, 2001Jul 4, 2006Sun Microsystems, Inc.Scalable routing scheme for a multi-path interconnection fabricUS7130269 *Dec 17, 2001Oct 31, 2006Infineon Technologies AgMethod for timing the output of data packets from network nodes, a network node, and a networkUS7145907 *Mar 8, 1999Dec 5, 2006Siemens AktiengesellschaftMethod for removing ATM cells from an ATM communications deviceUS7324442 *Feb 14, 2001Jan 29, 2008The Board Of Trustees Of The Leland Stanford Junior UniversityActive queue management toward fair bandwidth allocationUS7401161Dec 18, 2000Jul 15, 2008Sun Microsystems, Inc.High performance storage array interconnection fabric using multiple independent pathsUS7486939Jun 21, 2005Feb 3, 2009Motorola, Inc.Apparatus for removing distortions created by an amplifierUS7872969 *Mar 21, 2003Jan 18, 2011Ciena CorporationMethod and apparatus for auto detection of AAL5 type frames for VCC and VPC switchesUS8774191Oct 1, 2010Jul 8, 2014Ciena CorporationMethod and apparatus for auto detection of AAL5 type frames for VCC and VPC switchesUS20020018474 *May 31, 2001Feb 14, 2002Seabridge Ltd.Efficient packet transmission over ATMUS20020110137 *Dec 17, 2001Aug 15, 2002Xiaoning NieMethod for timing the output of data packets from network nodes, a network node, and a networkUS20020116522 *Feb 22, 2001Aug 22, 2002Orckit Communications Ltd.Network congestion control in a mixed traffic environmentUS20020147829 *Jan 29, 2001Oct 10, 2002Seabridge Ltd.Method and system for traffic controlUS20020147841 *Jan 4, 2001Oct 10, 2002Lee Whay S.Scalable routing scheme for a multi-path interconnection fabricUS20020163885 *Feb 26, 2001Nov 7, 2002Seabridge Ltd.Queue control method and systemUS20020176358 *Mar 20, 2001Nov 28, 2002Seabridge, Ltd.Traffic control method and systemUS20030002534 *Jan 16, 2002Jan 2, 2003Hoof Werner VanRandom early discard for cell-switched data switchUS20030202481 *Mar 21, 2003Oct 30, 2003Pillar John FrankMethod and apparatus for auto detection of AAL5 type frames for VCC and VPC switchesUS20030221018 *Dec 18, 2000Nov 27, 2003Lee Whay S.High performance storage array interconnection fabric using multiple independent pathsUS20070010215 *Jun 21, 2005Jan 11, 2007Porco Ronald LApparatus for removing distortions created by an amplifierUS20080298271 *Aug 4, 2008Dec 4, 2008Fujitsu LimitedCommunication-quality measuring apparatus, communication-quality measuring method, and computer programUS20110019545 *Oct 1, 2010Jan 27, 2011Ciena CorporationMethod and apparatus for auto detection of aal5 type frames for vcc and vpc switchesEP1271859A1 *Jun 20, 2002Jan 2, 2003Alcatel internetworkingRandom early discard for cell-switched data switchWO2007001721A2 *May 26, 2006Jan 4, 2007Motorola, Inc.System and method for discarding packetsWO2007001721A3 *May 26, 2006Mar 29, 2007Ronald T CrockerSystem and method for discarding packets* Cited by examinerClassifications U.S. Classification370/235, 370/395.65, 370/429International ClassificationH04L12/911, H04L12/927, H04L12/801, H04L12/823, H04L12/851, H04Q11/04, H04Q3/00Cooperative ClassificationH04L2012/5648, H04L2012/5658, H04L2012/5682, H04Q11/0478European ClassificationH04Q11/04S2Legal EventsDateCodeEventDescriptionMar 21, 1997ASAssignmentOwner name: NEC CORPORATION, JAPANFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:ISOYAMA, KAZUHIKO;ARAMAKI, TOSHIYA;REEL/FRAME:008625/0946Effective date: 19970317Sep 15, 2003FPAYFee paymentYear of fee payment: 4Feb 15, 2005ASAssignmentOwner name: JUNIPER NETWORKS, INC., CALIFORNIAFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:NEC CORPORATION;REEL/FRAME:016274/0345Effective date: 20050117Oct 11, 2007FPAYFee paymentYear of fee payment: 8Oct 22, 2007REMIMaintenance fee reminder mailedOct 11, 2011FPAYFee paymentYear of fee payment: 12RotateOriginal ImageGoogle Home - Sitemap - USPTO Bulk Downloads - Privacy Policy - Terms of Service - About Google Patents - Send FeedbackData provided by IFI CLAIMS Patent Services