WORLD INTELLECTUAL PROPERTY ORGANIZATION
`International Bureau
`
`INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT)
`(11) International Publication Number:
`W0 97l14240
`(51) International Patent Classification 5 :
`H04L 12/56, H04Q ll/04
` (43) International Publication Date:
`
`
`
`
`17 April 1997 (17.04.97)
`
`
`
`
`
`
`
`(21) International Application Number:
` (22) International Filing Date:
` Published
` (30) Priority Data:
`With international search report.
`GB
`ll October 1995 (l1.l0.95)
`
`
`PCT/CA96/00681
`
`11 October 1996 (1 1.10.96)
`
`(81) Designated States: AU, CA, JP. KR, US, European patent (AT,
`BE, CH, DE, DK, ES, FI, FR, GB, GR, IE, IT, LU, MC,
`NL. PT, SE).
`
`95208070
`
`(71) Applicant (for all designated States except US): NEWBRIDGE
`NETWORKS CORPORATION [CMCA]; 600 March Road,
`PO. Box 13600, Kanata, Ontario KZK 2E6 (CA).
`
` (72) Inventors; and
`
`(75) InventorsIApplicants (for US only):
`GIROUX, Natalie
`[CA/CA]; 8 de la Cométe, Hull, Québec J9A 2Y6 (CA).
`
`LIAO, Raymond, Rui-Feng [CA/CA]; Unit 903, 5785
`
`Yonge Street, North York, Ontario MZM 412 (CA).
`AISSAOUI, Mustapha [CA/CA]; 30 Eleanore Drive #1210,
`
`Nepean, Ontario KZE 7E5 (CA).
`
`(74) Agent: MITCHELL, Richard, 1.; Marks & Clerk, PO. Box
`957, Station B, Ottawa, Ontario KIP 557 (CA).
`
`(54) Title: FAIR QUEUE SERVICING USING DYNAMIC WEIGHTS (DWFQ)
`
`(57) Abstract
`
`In a method of fair queue servicing
`at a queuing point in a multi-service class
`packet switched network, incoming packets
`are received in buffers and outgoing packets
`are scheduled by a weighted fair queue
`scheduler. Real-time information of buffer
`usage along with the minimum bandwidth
`requirement is used to dynamically modify
`the weights of
`the weighted fair queue
`scheduler.
`
`
`
`
`
`
`
`
`
`
`Congestion
`_
`ervice
`analyser
`class
`manaer
`
`
`connection
`
`Admission
`
`
`conitcller
`Congestion
`control
`mechanisms
`
`
` Queue growth
`Monitor
`
`
`
`
`
`
`Timescale = ~ 100 cell units
`————-i>
`
`
`
`
`
`Timescale n~ milliseconds 1'C,
`
`
`
`
`
`ERICS SON EXHIBIT 1003
`
`

`
`FOR THE PURPOSES OF INFORMATION ONLY
`
`Codes used to identify States party to the PCT on the front pages of pamphlets publishing international
`applications under the PCT.
`
`AM
`AT
`AU
`BB
`BE
`BF
`BG
`BJ
`BR
`BY
`CA
`CF
`CG
`CH
`CI
`CM
`CN
`CS
`CZ
`DE
`DK
`EE
`ES
`FI
`FR
`GA
`
`Annenia
`Austria
`Australia
`Barbados
`Belgium
`Burltina Faso
`Bulgaria
`Benin
`Brazil
`Belarus
`Canada
`Central African Republic
`Congo
`Switzerland
`Cote d'Ivoire
`Cameroon
`China
`Czechoslovakia
`Czech Republic
`Genmny
`Denmark
`Estonia
`Spain
`Finland
`France
`Gabon
`
`GB
`GE
`GN
`GR
`HU
`IE
`IT
`JP
`KE
`KG
`KP
`
`KR
`KZ
`Ll
`LK
`LR
`LT
`LU
`LV
`MC
`MD
`MG
`ML
`MN
`MR
`
`United Kingdom
`Georgia
`Guinea
`Greece
`Hungary
`Ireland
`Italy
`Japan
`Kenya
`Kyrgystan
`Democratic People's Republic
`of Korea
`Republic of Korea
`Kazakhstan
`Liechtenstein
`Sri Lanka
`Liberia
`Lithuania
`Luxembourg
`Latvia
`Monaco
`Republic of Moldova
`Madagascar
`Mali
`Mongolia
`Mauritania
`
`MW
`MX
`NE
`NL
`NO
`NZ
`PL
`
`RO
`RU
`SD
`SE
`
`SK
`SN
`SZ
`
`TC
`TJ
`
`UA
`UG
`US
`UZ
`
`Malawi
`Mexico
`Niger
`Netherlands
`Norway
`New Zealand
`Poland
`Portugal
`Romania
`Russian Federation
`Sudan
`Sweden
`Singapore
`Slovenia
`Slovakia
`Senegal
`Swaziland
`Chad
`Togo
`Tajikistan
`Trinidad and Tobago
`Ukraine
`Uganda
`United States of America
`Uzbekistan
`Viet Nam
`
`

`
`W0 97/14240
`
`PCT/CA96/00681
`
`Fair Queue Servicing using dynamic weights (DWFQ)
`
`_ 1 _
`
`This invention relates to the field of telecommunications, and more particularly to
`
`a method of fair queue servicing in asynchronous data networks, such as Asynchronous
`
`Transfer Mode (ATM) networks or more generally any packet switched network that
`
`supports more than one class of service.
`
`The use of ATM by a continually increasing number of applications is driving a
`
`requirement to increase the number of service classes and to allow more flexibility in the
`
`service offerings. To support the application requirements, the ATM Forum is adding
`
`new service categories in new releases of ATM specifications. Furthermore, network
`
`providers are looking for the flexibility of defining multiple service classes for a given
`
`service category. The service classes are differentiated by their Quality-Of-Service
`
`requirements (Q08). The Q08 requirements are configurable in accordance with a bi-
`
`dimensional matrix describing loss and delay. The delay jitter is another factor which
`
`.
`needs to be bounded for some service classes.
`
`Previously. three service categories were supported on an ATM network element,
`
`namely constant bit rate (CBR), variable bit rate (VBR) and unspecified bit rate (UBR).
`
`The CBR service is the only service that guarantees a bound on delay. It is used for time
`
`sensitive data. such as voice and video.
`
`These various services can be supported by traditional exhaustive round-robin
`
`queuing among two priority queues. However, this simple technique cannot be used
`
`when the number of queues increases beyond two. because of the high potential of
`
`starvation for lower priority queues. Furthermore. the exhaustive round robin can only
`
`guarantee bounds on delay and delay variation for the highest priority queue. The support
`
`of multiple service class in an ATM switching product or multiplexer requires a minimum A
`
`ofone queue per class.
`
`A queue scheduling algorithm. Weighted Fair Queuing (WFQ). has been recently
`
`proposed in the literature (see S. Golestani, A self—clocked Fair Queuing scheme for
`
`broadband applications. INFOCOM 1994. June 1994).
`
`

`
`W0 97/14240
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`PCT/CA96/00681
`
`- 2 _
`This scheduling scheme allows any number queues (service classes) to be
`
`serviced. while providing fair and work conserving access to bandwidth. One of the key
`
`features of WFQ is that the CDV (Cell Delay Variation) is bounded for any service class,
`
`as long as it is given a minimum weight.
`
`This proposed scheme can be implemented in ATM products. However, it has not
`
`been determined how to set the servicing weights efficiently to take into account the
`
`dynamically changing bandwidth requirement of each service class (connection
`
`addition/removal. ABR flow control, Early packet Discard).
`
`An object of the invention is to provide a framework that ensures that the weights
`
`are set appropriately to guarantee the desired Quality of Service and modified in real-time
`
`to ensure that the dynamic allocation of bandwidth across the classes is optimized.
`
`According to the present invention there is provided a method of fair queue
`
`servicing at a queuing point in a multi-service class packet switched network, wherein
`
`incoming packets are received in buffers and outgoing packets are scheduled by a
`
`weighted fair queue scheduler characterized in that real-time information of buffer usage
`
`along with the minimum bandwidth requirement is used to dynamically modify the
`
`weights of the weighted fair queue scheduler.
`
`Preferably the minimum bandwidth requirement is extracted during connection
`
`admission control.
`
`The method is particularly suitable for use in ATM networks.
`
`The DWFQ (Dynamic Weighted Fair Queuing) can be implemented at any
`
`queuing point which arbitrates servicing between n queues (n22).
`
`The invention also provides a fair queue servicing arrangement in a multi-service
`
`class packet switched network, comprising a weighted fair queuing controller, and buffer
`
`means for receiving incoming packets in queues, characterized in that further comprises
`
`means for monitoring buffer usage for each queue, means for determining the bandwidth
`
`requirements of each class of service, and a service weights manager for dynamically
`
`modifying the weights of said weighted fair queuing controller means in response to said
`
`buffer usage and bandwidth requirements.
`
`

`
`W0 97/14240
`
`PCT/CA96/00681
`
`Preferably, the means for monitoring buffer usage a queue growth monitor which
`
`performs real-time estimation of the queue growth in said buffer means.
`
`_ 3 _
`
`The invention will now be described in more detail. by way of example only. with
`
`reference to the accompanying drawings, in which:-
`
`Figure 1 is a diagram depicting the high level queuing scheme at an ATM switch;
`
`Figure 2 shows the information provided by the Queue Growth Monitor;
`
`Figure 3 illustrates the data flow between the key components of the system and
`
`the action of the Service Weight Manager (SWM); and
`
`Figure 4 describes the process performed by the SWM.
`
`Referring now to Figure 1, ATM cells 2 arrive at buffer 1 and are placed in queues
`
`I ', I2,
`
`1". From there the cells are passed to a weighted fair queuing unit 3. The buffer 1
`
`is also connected to a queue growth monitor 4, which in turn is connected to congestion
`
`control unit 5. congestion analyzer 6, and connection admission controller 8, which in
`
`turn is connected to SVC & PVC (Switched Virtual Circuit and Permanent Virtual
`
`Circuit) connection handling unit 7, and service class manager 10. Queue growth monitor
`
`4. connection admission controller 8 and service class manager 9 are connected to service
`
`weights manager 9. which is connected to weighted fair queuing scheduler 3.
`
`The key element of the Dynamic Weighted Fair Queuing (DWFQ) scheme is the
`
`service weight manager (SWM) 9, which dynamically modifies the service weights to be
`
`used by the WFQ Scheduler 3. It uses real-time information from the service class
`
`manager 10. the connection admission controller 8, and the Queue growth monitor 4.
`
`The service class manager 10 configures the service classes. A service class is
`
`configured with a given value of delay (CTD - Cell Transfer Delay) and loss (CLR - Cell
`
`Ratio Loss) requirements. These parameters represent the maximum nodal delay and loss
`
`allowed in order to meet the end-to~end QoS requirements of the connection. The service
`
`classes are mapped into a priority table as exemplified in Table 1. The priority table is
`
`used later by the service weight manager to allocate remaining bandwidth. The priority
`
`table is updated when a service class definition is modified. The service class manager
`
`

`
`WO 97/14240
`
`PCT/CA96/00681
`
`also dictates which traffic descriptors are used to compute the minimum bandwidth
`
`- 4 -
`
`s
`
`required by a connection of a given class.
`
` CTD—
`
`
`
`
`
`firm
`:1
`
`Table l - Example of a Queue Service Priority Mapping.
`
`The connection admission controller (CAC) 8 computes the minimum bandwidth
`
`required for each service class. The minimum bandwidth is updated each time a
`
`connection of a given class is established or disconnected, based on its traffic descriptor.
`
`Table 2 shows a typical example of which traffic descriptors that can be used to
`
`compute the minimum bandwidth for each basic service category relative to the queue
`
`service rate (SR). The CAC 8 communicates the minimum Weight table to the SWM
`
`every time the value of the minimum weights have changed by a factor of E_,.
`
`5%
`
`
`
`j
`
`Q3
`
`RT—VBR (>3 SCR) / SR
`NRT-
`(2 SCR) / SR
`VBR
`
`
`
`Q4 _
`
`
`Table 2 - Example of minimum weight table.
`
`The CTD is further taken into account in the target queue size (TQS) table. which
`
`is the maximum queue size allowed to limit the CTD. An example ofTQSj computation
`
`is shown in Table 3, for typical service categories. A zero TQS indicates that the queue
`
`can grow without limitation. This table is computed by the CAC .
`
`

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`W0 97/14240
`
`PCT/CA96/00681
`
`
`
`Table 2 - Example of a target queue size computation.
`
`The Queue Growth Monitor (QGM) 4 performs real-time estimation of the queue
`
`growth every T5 cell slots (sampling interval). The information provided by the Queue
`
`Growth monitor 4 to the‘ SWM 9 consists of AQi, the Queue Growth Rate of output queue
`
`i during an interval of duration Ts, Qi, the length of output queue i at the sampling time,
`
`and Ai, the arrival rate during the same interval of time.
`
`The corresponding parameters: queue size Qi, queue growth AQi, number of
`
`arrivals Ai are collected or each queue by the QGM 4 for each Ts interval. From these
`
`parameters, auxiliary parameters such as average arrival rate Xi and service rate pi can be
`
`-derived by the SWM 9:
`
`Xi : average arrival rate, 7.; = A + T5
`
`u. : average service rate, pi = S. + T5, where S; = Ar — AQ; is the number of cells
`
`served during T5.
`
`Figure 2 shows the information provided by the Queue Growth Monitor 4. Using
`
`this information for the CAC 8. the service class manager 9 and the queue growth monitor
`
`4, the SWM computes the service eight for each queue ,' (W) to be used during the next
`
`sampling interval‘
`
`As can be seen in Figure 3. which shows the data flow between the key
`
`components of the system and the action of the SWM 9, the queue weights. Wi, are
`
`updated using information provided by the Queue Growth monitor 4.
`
`If )1, denotes the arrival rate of cells in queue i in the coming T5 interval, then
`
`ideally, the target service rate {II can be calculated as:
`
`-—
`
`T5 = Q — TQS_. This
`
`means at the end of next Ts interval, the queue size Qi will reach the target queue size
`
`

`
`wo 97/14240
`
`PCT/CA96/0068]
`
`TQSi. On the assumption that X, remains unchanged from 2..
`
`. the service weight
`
`W, = Q, - T, can be approximated as
`
`_ 6 -
`
`w_ =t]l-T521.-TS+Q_ —TQSl =A| +Q‘ —TQs,.
`
`However, the assumption on the stable arrival rate may not hold, and also the
`
`actual number of serviced cells Si could be less than Wi; therefore a more conservative
`
`approach is AQ. > 0, then Q,+AQ,, the predicted queue size at the end of the next Ts
`
`interval, is used to calculate the target service rate and weight. That is:
`
`([1, — 21,)-T, = Q, +AQ, — TQS, and
`
`W, ax. -rs +Q, +AQI—TQSl =A,+Q|+AQ, —TQSl.
`
`The detailed algorithm performed by the service weights manager 9 is shown in
`
`Figure 4. The queue size Q; at the end of each interval T5, the number of arrivals A during
`
`the previous interval T5, and the change in queue size AQ. are input at step 20. Step 21
`
`‘determines whether the queue growth is positive: if yes, the service weight Wi is
`
`conservatively adjusted to bring the queue size to TQSi at step 22; if no, the service
`
`weight Wi is adjusted to bring the queue size to TQSi at step 23. The difference AW is
`
`detemiined in step 24.
`
`Step 25 detemiines whether the shared weights pool is empty: if yes, Wi is set to
`
`min_Wi in step 26; if no, step 27 determines whether W5 2 AW; if yes, step 28 sets W. =
`
`min_W. + AW. and W5 = W, + AW,; ifno, step 29 sets W,= min_W; + W, and VVS = 0.
`
`Step 30 runs through all the W, in the ordered list L and step 31 updates the weight
`
`table used by the Weighted Fair Queuing scheduler 3.
`
`The described technique complies with ITU and ATM Forum standards and can
`
`be applied to any switching equipment which supports more than a single service class of
`
`service.
`
`

`
`W0 97,142“)
`
`PCT/CA96/00681
`
`Claims:
`
`_ 7 _
`
`1.
`
`A method of fair queue servicing at a queuing point in a multi—service class packet
`
`switched network, wherein incoming packets are received in buffers and outgoing packets
`
`are scheduled by a weighted fair queue scheduler characterized in that real-time
`
`information of buffer usage along with the minimum bandwidth requirement is used to
`
`dynamically modify the weights of the weighted fair queue scheduler.
`
`2.
`
`A method as claimed in claim 1, the minimum bandwidth requirement is extracted
`
`during connection admission control.
`
`3.
`
`A method as claimed in claim 1, characterized in that said weights are also
`
`modified in accordance with real-time service class information.
`
`4.
`
`A method as claimed in claim 1, characterized in that buffer usage is monitored by
`
`a queue growth monitor, which performs real-time estimation of the queue growth every
`
`sampling interval TS.
`
`. 5
`
`.
`
`A method as claimed in any of claims 1 to 4, wherein said packet switched
`
`network is an ATM network and said packets are ATM cells.
`
`

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`W0 97/ 14240
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`PCT/CA96/00681
`
`6.
`
`- 3 _
`A method as claimed in any of claims 1 to 5, wherein the weights of the weighted
`fair queue scheduler are modified in accordance with the following algorithm:
`
`
`
`
`
`From the Queue growth monitor:
`Qi : queue size at the end of Ts
`Ai : number of arrivals during previous Ts
`
`flQi: change of queue size during previous Ts
`
`
`
`Weights Re-calculations per Ts
`
`
`
`Queue Growth Positive ?
`
`N0
`——
`
`Adjust service weight to bring queue
`size to TQSi.
`
`
`
`
`
`Wi = max ((Ai + Oi - TQSi), rnin_Wi}
`
`
`
`
`
`
`
`
` Yes
`
`
`
`
`Conservatively adjust service weight to
`
`bring queue size to TOSi_
`
`Wi = max {(Ai + Qi was
`- TQSi). min_Wi}
`
`
`
`
`
`Weights Enforcements
`
`Yes Weights
`
`Pool Empty,
`
`N0
`
`Yes
`
`
`
`Remained Weigh
`Large Enough,
`wsfisws
`
`
`Ws = Ws fiNi
`
`
`
`Wi = min_Wi + Ws
`Ws = 0
`
`W: = min_Wi +flNi
`
`
`
`
`N0
`
`Go through all the Wi
` 5 list L 7
`Yes
`
`Update weight table to be used by WFQ in the next Ts
`
`

`
`W0 97/14240
`
`PCT/CA96/00681
`
`- 9 _
`
`7.
`
`A fair queue servicing arrangement in a multi-service class packet switched
`
`network, comprising a weighted fair queuing controller, and buffer means for receiving
`
`incoming packets in queues, characterized in that further comprises means for monitoring
`
`buffer usage for each queue. means for determining the bandwidth requirements of each
`
`class of service. and a service weights manager for dynamically modifying the weights of
`
`said weighted fair queuing controller means in response to said buffer usage and
`
`bandwidth requirements.
`
`8.
`
`A fair queue servicing arrangement as claimed in claim 7, characterized in that it
`
`further comprises a service class manager which stores the cell transfer delay cell loss
`
`ratio requirements for each class of service, and said service weights manager is also
`
`responsive to said class of service requirements stored in said service class manager to
`
`dynamically modifythe weights of said weighted fair queuing controller means.
`
`9.
`
`A fair queue servicing arrangement as claimed in claim 8, characterized in that
`
`.
`said means for monitoring buffer usage comprises a queue growth monitor which
`
`performs real—time estimation of the queue growth in said buffer means.
`
`10.
`
`A fair queue servicing arrangement as claimed in claim 8, characterized in that
`
`said queue growth monitor outputs to said service weights manager the queue growth rate
`
`of each output queue i during a sampling interval, the length of the output queue i at
`
`sampling time, and the arrival rate of cells A, during the sampling interval.
`
`1 l.
`
`A fair queue servicing arrangement as claimed in any of claims 8 to 10,
`
`characterized in that said network is an ATM network.
`
`

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`PCT/CA96/00681
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`1/3
`
`
`
`Connection
`Handnn
`(SVC & P C)
`
`10
`
`
`
`
` Service
`class
`
`
`manager
`Connection
`Admission
`
` Congestion
`Controller
`control
`
`mechanisms
`
`
`
`
`
`Timescale = ~ 100 cell units
`————-l>
`
`Timescale El~ milliseconds
`
`
`data
`
`
` Service
`Weights
`Manager
`
`1'
`12
`
`13
`
`1n
`
`FIG. 1
`
`Xi
`
`Qi
`KC’!
`
`L"
`
`AQi
`
`FIG. 2
`
`

`
`W0 97/14240
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`PCT/CA96/00681
`
`2/3
`
`,
`'
`Ts: Sampling interval
`Wi: service weight. Number of cells to be served in T's for output queue i.
`
`From CAC and the service class manager.
` min_ Wi: minimum service weight table
`
`
`TQSi: Target Queue Size table
`L: Queue Service Priority List (Sorted)
`
`
`
` From the Queue Growth monitor (every Ts):
`
`Qi: queue size at the end of Ts.
`Al: number of arrivals during previous Ts
`
`
`
`AQi: change of queue size during previous Ts
`
`
`
`
`
`
`
`SWM updates All Queue Weights after one Ts:
`(see Figure 4 for detailed algorithm
`(1) Queue growth rate AQi
`_
`arrival rate éi AW‘
`I
`.
`I
`I queue size
`I
`_
`(2) WI = min_ WI, guarantees minimum weight,
`provides protection for high priority queues
`
`order, specified by list L:
`Wi = wi+AWi, it Shared Weight Pool isn't empty.
`Wi = min_Wi, otherwise (Ws = 0).
`
`FIG. 3
`SUBSTITUTE SHEET (RULE 26)
`
`
`
`
`
`§e,%%Ve(3/V‘/iVe'ght
`'
`d W I mp '_
`Sh
`W5 = T3 ' )3 ml” - W‘
`
`priority
`Order
`
`
`
`(3) Further allocate the A Wi to Wi in the priority
`
`
`

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`3/3
`
`20
`
`23
`
`From the Queue Growth monitor:
`Oi: queue size at the end of Ts.
`Ai: number of arrivals during previous Ts
`
`
`Oi: change of queue size during previous Ts
`
`
`
`
`
`
`
`Weights Re- calculations per Ts
`
`YES
`
`22
`
`21
`
`
`Queue Growth Positive ?
`Alli > 0?
`
`
`
`
`Conservatively adjust service weight to
`bring queue size to TQSL
`Wi = max {( Al + Qi + Oi — TQSi, min_ Wi
`
`
`
`
`
`
`Adjust service to bring queue
`size to TQSi.
`Wi = max {( Al + Oi - TQSI, min_ Wi}
`
`
`
`
`
`
`
`AWi =Wi - min_ Wi
`
`24
`
`Weights Entorcements
`
`
`
`25
`
`YES
`
`
`NO
`
`26
`
`27
`
`
`
`Remained Weight
`YES
`
`Large Enough,
`
`Ws>, AWi ?
`
` W3 + O
`
`
`Ws = Ws-Awi
`
`28
`
`31
`
`HQ _ 4
`
`Update weight table to be used by WFO in the next Ts
`
`SUBSTITUTE SHEET (RULE 26)
`
`

`
`Inter
`
`anal Apphcatton No
`
`PCl/CA 96/00681
`
`UBJECI‘ MATTER
`A. CLASSIFICATION
`IPC 6
`Ho4L137§6
`H04Q11/04
`
`Accordmg to Intemauonal Patent Clasuficanon (IPC) or to both national clasnficauon and [PC
`8, FIELDS SEARCHED
`
`Mtmmum documentauon searched (classIFIcatIon system followed by classtlicauon symbols)
`IPC 6
`HO4L H040
`
`Document.-«mon searched other than mInImum documentauon to the extent that such documenLs are Included In the fields searched
`
`Eleclromc data base consulted dunng the Internauonal search (name of data base and, where practical, search terms used)
`
`C. DOCUMENTS CONSIDERED TO BE RELEVANT
`
`Relevant to clatm No.
`
`CItatIon of document, wuh Indtcauon. where appropnate, of the relevant passage
`
`US 5 432 790 A (HLUCHYJ MICHAEL G
`11 July 1995
`* Figures 4,5,6 *
`see column 1,
`line 56 - column 2,
`see column 3,
`line 3-25
`see column 3,
`line 50-68
`see column 4,
`line 41-54
`
`ET AL)
`
`line 3
`
`X
`
`A
`
`EP 0 592 027 A (NEDERLAND PTT)
`1994
`
`see page 2,
`
`line 3-11
`
`_
`
`'I'
`
`Patent famtly members are lIsted In annex.
`later document pubhshed after the International filmg date
`or pnonty date and not In confltct wtth the apphcauon but
`::lI|tVecdmt]oonunderstand the pnncIpIe or theory underlymg the
`.X.. document or pamculu mlcvance; me claimed mvmuon
`cannot be eonstdered novel or cannot be constdered to
`Involve an Invenuve step when the document Is taken alone
`-Y- documem of Pamcum. relevmoc; me claimed mvmuon
`ca.rInot be conndered to Involve an Invenuve step when the
`document Is combIned wnh one or more other such docu»
`ments, such combmauon bemg obvIous to a person slulled
`m m‘ "L
`'&" document member of the same patent famtly
`Date of maIlIng of the Intemauonal search report
`
`_
`
`Further documents are lmed In the conunuauon of box C.
`' Speqal categones of uted documents :
`.
`.
`3" wmch ‘5 “°‘
`A ddgugcng
`-5’ ea-lIer;!ocummt but pubhshed on or alter the International
`‘ ‘"5
`‘C
`'L' document whIch may throw doubts on pnonty cla.Im(s) or
`when Is ctted to estabhsh the publIcatIon date of another
`“anon °r (“her Spec”! R350“ (‘S "‘T"°“fi°d)
`'0' document relen-Ing to an oral dlsclosure, use, exhIhIuon or
`other means
`‘P’ document publtshed pnor to the Intemauonal fillng date but
`later than the pnonty date clatmed
`Date of the actual compleuon ot the Internauonal search
`
`20 January 1997
`Name and maIlIng address of the ISA
`European Patent Office, P.B. SKIS Patentlaan 2
`NL - 2180 HV Rl]SWl]k
`Tel. (+3!-70) 340-2040, Tx. 31 65l e
`n1,
`Hx(rMJm3wJm6
`Form PC'I‘,v’ISA.-'2|n (second sheet) (July 1992)
`
`pa
`
`34. 01. 97
`
`Authonzed officer
`
`Dhondt, E
`
`page 1 of 2
`
`

`
`Inter
`
`onal Appncanon No
`
`
`
`PC:/CA 96/00681
`
`
`
`INTERNATIONAL SEARCH REPORT
`
`C.(Conunuauon) DOCUMENTS CONSIDERED TO BE RELEVANT
`
`
`
`
`
`
`Category '
`
`Cnuuon of document, with mdncauon, where appropnatz, of the relevant passages
`
`Relevant to claim N0.
`
`
`
` PROCEEDINGS OF THE INTERNATIONAL
`CONFERENCE ON DISTRIBUTED COMPUTIN
`
`SYSTEMS, POZNAN, POLAND,
`JUNE 21 - 24,
`1994,
`INSTITUTE OF
`no. CDNF. 14, 21 June 1994,
`ELECTRICAL AND ELECTRONICS ENGINEERS,
`pages 268-275, XPOOO48909O
`GUHA A ET AL:
`“REAL-TIME SUPPORT OF
`CONTINUOUS AND VARIABLE BIT RATE TRAFFIC
`ON AN ATM NETWORK"
`
`
`
`
`
`
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`
`
`
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`
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`
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`
`
`
`
`
`
`* Figure 1 *
`see page 270, column 2, Tine 35-37
`see page 270, column 2, Tine 45 - page
`271, column 1,
`line 6
`see page 271, column 1, Tine 30-43
`
`
`
`Form PCT/ISA,«'2l0 (cnnunualgon of second sheet) (July 1992]
`
`page 2 of 2
`
`

`
`
`
`INTERNATIONAL SEARCH REPORT
`mfommuon on patznl famzly members
`
`
` [mm anal Apphcauon No
`
`
`
`PCT/CA 96/00681
`Publication
`date
`
`Patent family
`member[s)
`
`I Patynt document
`cited m seaxch report
`
`Publication
`date
`
`US-A-5432790
`
`ll-07-95
`
`
`
`
`
`AU-A-
`EP-A-
`
`7558294
`0680679
`9508230
`
`03-04-95
`08-11-95
`23-03-95
`
`
`
`
`9201668
`18-04-94
`6268660
`22-09-94
`
`
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`Fnnn PCTJISAIZID (palm! family annex) (July I992]