WO2000025461A9 - Procede et dispositif de controle d'acceptation de connexion reglable pour un commutateur a base de paquets - Google Patents

Procede et dispositif de controle d'acceptation de connexion reglable pour un commutateur a base de paquets

Info

Publication number
WO2000025461A9
WO2000025461A9 PCT/US1999/024999 US9924999W WO0025461A9 WO 2000025461 A9 WO2000025461 A9 WO 2000025461A9 US 9924999 W US9924999 W US 9924999W WO 0025461 A9 WO0025461 A9 WO 0025461A9
Authority
WO
WIPO (PCT)
Prior art keywords
connections
new
variable speed
factor
admission control
Prior art date
Application number
PCT/US1999/024999
Other languages
English (en)
Other versions
WO2000025461A1 (fr
Inventor
Herbert Paul Holzworth
Satoshi Kakuma
William Lipp
Gary Deval
Original Assignee
Fujitsu Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Fujitsu Ltd filed Critical Fujitsu Ltd
Priority to AU13223/00A priority Critical patent/AU1322300A/en
Priority to JP2000578941A priority patent/JP2002529005A/ja
Publication of WO2000025461A1 publication Critical patent/WO2000025461A1/fr
Publication of WO2000025461A9 publication Critical patent/WO2000025461A9/fr

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q3/00—Selecting arrangements
    • H04Q3/0016—Arrangements providing connection between exchanges
    • H04Q3/0062—Provisions for network management
    • H04Q3/0091—Congestion or overload control
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J3/00—Time-division multiplex systems
    • H04J3/24—Time-division multiplex systems in which the allocation is indicated by an address the different channels being transmitted sequentially
    • H04J3/247—ATM or packet multiplexing
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q11/00—Selecting arrangements for multiplex systems
    • H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
    • H04Q11/0062—Network aspects
    • H04Q11/0066—Provisions for optical burst or packet networks
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q11/00—Selecting arrangements for multiplex systems
    • H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
    • H04Q11/0005—Switch and router aspects
    • H04Q2011/0037—Operation
    • H04Q2011/0039—Electrical control
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q11/00—Selecting arrangements for multiplex systems
    • H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
    • H04Q11/0005—Switch and router aspects
    • H04Q2011/0052—Interconnection of switches
    • H04Q2011/0058—Crossbar; Matrix
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q11/00—Selecting arrangements for multiplex systems
    • H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
    • H04Q11/0062—Network aspects
    • H04Q2011/0086—Network resource allocation, dimensioning or optimisation

Definitions

  • the present invention relates generally to controlling the admission of new connections to a packet-based switch. More specifically, the present invention relates to an adjustable connection admission control system for a packet-based switch.
  • Fig. 1 is a schematic view of a conventional packet-based switching system.
  • traffic flows from left to right.
  • the interfaces IFl through IF4 are represented on both the left and right side of a switching matrix.
  • the left interfaces show traffic entering the switching matrix, and the right interfaces show traffic exiting the switching matrix.
  • a user supplies traffic to an interface on the left and takes traffic from an interface (the same interface) on the right.
  • the user may contract for the type of connection needed. For example, the user may contract for a constant bit rate (“CBR") connection, a variable bit rate (“VBR”) connection or an unspecified bit rate (“UBR”) connection.
  • CBR constant bit rate
  • VBR variable bit rate
  • UBR unspecified bit rate
  • the user might provide traffic information such as a sustained cell rate, a peak cell rate, a maximum burst size, etc.
  • This traffic information provides the switch with information regarding the maximum bounds for the user's traffic.
  • the traffic rate is expected to be bursty and somewhat unpredictable, and the switch can accommodate all traffic that fits with the maximum bounds defined by the traffic information.
  • One way to address the resource allocation problem is for the switch to assign a nominal bit rate to each requested connection. The number of permissible connections is determined from the nominal bit rate using a connection admission control (also referred to as "CAC”) system. CAC must be done for each point of possible congestion.
  • CAC connection admission control
  • connection admission control is used.
  • CAC is done at each egress points. For example, if all users connected to interface 1 transmit at their maximum permissible rate, there may be congestion in the link carrying traffic from interface 1 to the switching matrix.
  • Conventional connection admission control is described in U.S. Patent Nos. 5,949,757; 5,936,958; 5,751,691; 5,696,764; 5,583,857; 5,555,265 and 5,341,366, which are hereby incorporated by reference.
  • Connection admission control is based on traffic descriptors such as peak cell rate, sustained cell rate, maximum burst size, cell delay variation tolerance, etc.
  • the CAC mechanism allocates the minimum switch resources necessary to meet the requirements of the requested connection.
  • CAC Connection admission control is done in different ways for different traffic classes (also referred to herein as different connection types). That is, constant bit rate, variable bit rate and unspecified bit rate connections are treated differently. For non- constant bit rate service, CAC provides statistical multiplexing. Bandwidth for variable bit rate connections is allocated by determining an equivalent bandwidth ("EBW") based on the peak cell rate sustained cell rate and maximum burst size. EBW is also determined based on the link between the switch components being considered. For the link, parameters such as link speed, buffer size, buffer read out rate, and buffer structure (shared or individual) are considered.
  • EBW equivalent bandwidth
  • connection admission control requires complex mathematical manipulation of data. To provide superior service, it is desirable to allocate resources conservatively. On the other hand, to accommodate more users, it is desirable to allocate resources aggressively. Different switch operators desire a more or less aggressive approach to resource allocation. However, connection admission control is determined in advance by the switch manufacturer. Because of the complexities associated with connection admission control, it cannot be altered by the individual switch operator.
  • an adjustable connection admission control method and device for packet-based switches that assigns equivalent bandwidths to variable speed connections.
  • Equivalent bandwidths are assigned to variable speed connections.
  • the equivalent bandwidths of the variable speed connections are increased or reduced by a scaling factor to achieve an assigned bandwidth.
  • the scaling factor can be adjusted to change the assigned bandwidths .
  • the method and device determine whether to accept or refuse new variable speed connections based on whether the sum of assigned bandwidths for existing variable speed connections and new variable speed connections exceeds the bandwidth available to variable speed connections.
  • the bandwidth available to variable speed connections is increased or reduced by a variable speed traffic factor.
  • the variable speed traffic factor can be adjusted.
  • the connection admission control method and device also determines whether to accept or refuse new constant speed connections. To do this the sum of bandwidths for existing and new constant speed connections is obtained.
  • the connection admission control method and device determines whether to accept or refuse new unspecified connections. At least a portion of the unspecified connections do not have a sustained cell rate. The sustained cell rate is determined by multiplying a peak cell rate by an SCR factor, which factor can be adjusted. Equivalent bandwidths are also assigned to unspecified connections. The equivalent bandwidths of the unspecified connections are increased or reduced by the scaling factor to achieve an assigned bandwidth. New unspecified connections are accepted or refused based on whether the sum of assigned bandwidths for existing and new unspecified connections exceeds a bandwidth available to unspecified connections. An original scaling factor is maintained for all existing variable speed connections.
  • a new scaling factor is used to allocate bandwidth for all new variable speed connections.
  • the amount of assigned bandwidth freed by the termination is determined based on the original scaling factor.
  • the freed up resources, however, are reallocated based on the new scaling factor.
  • Fig. 1 is a schematic view of a conventional packet-based switching system
  • Fig. 2 is a schematic view of an adjustable connection admission control device according to a preferred embodiment of the present invention.
  • Fig. 2 is a schematic view of an adjustable connection admission control device according to the present invention.
  • the device shown schematically in Fig. 2 would be used at each point of possible congestion, where connection admission control is to be performed. That is, the device shown schematically in Fig. 2 would be used in Fig. 1 at the egress points represented by circles.
  • Fig. 2 shows a plurality of connections being multiplexed onto a single link by multiplexer 8.
  • the terms "bandwidth" and "bit rate” are used synonymously, both possibly having units of bits per second.
  • bandwidth allocator 10 can reallocate the bandwidth available at the egress point. For example, if 1 Gbps of bandwidth is available at the egress point, 300 Mbps could be allocated to CBR connections, 300 Mbps could be allocated to UBR connections and 400 Mbps could be allocated to VBR connections.
  • the bandwidth allocator 10 could change the allocation so that 500 Mbps would be allocated to CBR connections and 200 Mbps would be allocated to VBR connections.
  • Allocation allows for CAC to be performed independently for each type of connection. Reallocation minimizes the number of connections that are refused.
  • Fig. 2 shows three constant bit rate connections CBR,-CBR 3 received at a first controller 12.
  • the bandwidth allocated for a constant bit rate connection must at least equal the nominal bandwidth (bit rate) of the CBR connection. If the number of CBR connections is fewer than a maximum number m, the first controller 12 signals CBR traffic controller 14A to operate at 100 % efficiency.
  • the value of m can be adjusted varied by the switch operator when the switch is online (without dropping connections) or offline. At 100 % efficiency, the entire bandwidth allocated to CBR connections can be used. That is, new CBR connections can be established if the following equation is satisfied:
  • ⁇ CBR is the sum of the nominal bit rates for all existing and new CBR connections.
  • TBW CBR is the bandwidth allocated to CBR connections by bandwidth allocator 10.
  • p CBR is a CBR traffic parameter, which is equal to " 1 " for 100 % efficiency.
  • first controller 12 communicates with CBR traffic controller 14A to reduce the effective bandwidth available to CBR connections.
  • p CBR may be set to 1 for maximum efficiency, but would be reduced to a number between 0 and 1 when the number of CBR connections exceeds the maximum number m.
  • the value of p CBR can be adjusted varied by the switch operator when the switch is online (without dropping connections) or offline.
  • CBR, to CBR are the nominal bit rates for n CBR connections and P CBR,I t0 P CBR .
  • ⁇ re the CBR traffic parameters for n CBR connections.
  • the above equation (2) takes into account that different connections may have been established using different values for p CBR .
  • the value of p CBR at peak efficiency (usually 1) will be different from the value of p CBR when the number of CBR connections exceeds the maximum number m.
  • the switch operator can manipulate the value of p CBR while the switch is online. Usually the switch operator would not change the peak efficiency value of p CBR from the default value, 1. However, it is highly possible that the switch operator would change the reduced efficiency value of p CBR (greater than m CBR connections) while the switch is online.
  • the user may or may not specify a sustained cell rate. If the user does not specify a sustained cell rate, the UBR connection is sent to a second controller 16.
  • UBR is sent to second controller 16.
  • a sustained cell rate is computed based on the peak cell rate.
  • the sustained cell rate is computed by multiplying the peak cell rate by an SCR parameter .
  • the SCR parameter ⁇ can be adjusted by the switch operator, and according to one implementation, the range for is 0 ⁇ 2 with granularity of 0.001. If the UBR connection has a sustained cell rate associated therewith, it is not necessary to supply the connection to the second controller 16. Referring to Fig. 2, UBR 2 has a specified sustained cell rate and is not sent through second controller 16.
  • Both UBR, and UBR 2 are eventually sent to EBW device 18 where equivalent bandwidths (EBWs) are determined in a manner similar to that described in connection with the related art. That is, the equivalent bandwidths are determined based on parameters such as sustained cell rate, peak cell rate, maximum burst size, buffer size, egress location, buffer read-out rate, etc.
  • EBWs equivalent bandwidths
  • the equivalent bandwidths are determined based on parameters such as sustained cell rate, peak cell rate, maximum burst size, buffer size, egress location, buffer read-out rate, etc.
  • ⁇ The scaling factor ⁇ can be adjusted by the switch operator when the switch is online (without dropping connections) or offline. New UBR connections are accepted if the following equation is satisfied:
  • VBR connections For VBR connections, an equivalent bandwidth is determined by EBW device 18, as described above for UBR connections. Then, the equivalent bandwidth is increased or reduced by the scaling factor ⁇ and third controller 20. Next, the VBR connections are sent to VBR traffic controller 14B. Here the amount of bandwidth available for VBR connections may be decreased from the amount allocated by bandwidth allocator 10. The amount of available bandwidth is reduced by the VBR traffic parameter p VBR in a manner similar to CBR connections. New VBR connections are accepted if the following equation is satisfied:
  • admission controller 22 establishes or refuses the new connection. For this purpose, admission controller 22 is connected to CBR traffic controller 14A for CBR connections, to third controller 20 for UBR connections and to VBR traffic controller 14B for VBR connections.
  • each of the parameters m, p CBR , ⁇ and p VBR can be varied independently by the switch operator. If the switch operator wishes to be more or less aggressive than the switch manufacturer, the switch operator can increase or decrease the parameters m, p CBR , ⁇ and p VBR . However, the effect of changing one or more of the parameters m, p CBR, ⁇ , ⁇ and p VBR on the switch may not be readily apparent to the switch operator. The switch operator may need a trial and error process to fully understand how to achieve his or her goals. However, the bandwidth of existing connections cannot be reallocated unless the existing connections are terminated. Because of quality of service and reliability issues, it is impermissible to terminate connections.
  • the present invention allows the switch operator to vary the parameters m, p CBR ⁇ , ⁇ and p VBR for new connections only, without disturbing existing connections.
  • bandwidth is reallocated based on the new parameters m, p CBR ⁇ , ⁇ and p VBR .
  • the admission controller 22 is connected to a memory 24.
  • the memory 24 stores the nominal bandwidth allocated for that connection.
  • the memory 24 is used to determine how much bandwidth has been freed up by the termination.
  • CAC bandwidth requirements for effected classes of service at each link (congestion point) within the switch. This process is done stepwise, link-by-link until the recalculation is complete. There is no need to reroute existing connections and there is no strong time dependency between the reallocation of the first and last congestion point. It is therefore be possible to continue processing connections even as the bandwidth is being reallocated.
  • changing one or more of the CAC parameters while the switch is in operation may cause the allocated bandwidth to increase. This results in a temporary over subscription of capacity. For example, assume that the scaling parameter ⁇ is increased from 1 to 2. If the bandwidth available for allocation (TBW «p) is 622 Mbps and 500 Mbps is already allocated for existing VBR connections, the allocated bandwidth for existing VBR connections effectively becomes 10000 Mbps. Although the bandwidth allocated is now greater than the capacity, the actual traffic has not changed. There is therefore no need to drop connections in order to make them fit within the 622 Mbps link. However, no new connections will be accepted through this link since there is no excess capacity available. Eventually, the existing connections will terminate, freeing up bandwidth. When the allocated bandwidth decreases below 622 Mbps, new connections will once again be accepted. This mechanism provides a graceful way for switch operators to tune their system while not disrupting service. This same method works whenever changing any of the CAC parameters m, p CBR ⁇ , ⁇ and p VBR -

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Computer Hardware Design (AREA)
  • Signal Processing (AREA)
  • Data Exchanges In Wide-Area Networks (AREA)
  • Communication Control (AREA)

Abstract

L'invention concerne un procédé et un dispositif (22) de contrôle d'acceptation de connexion pour des commutateurs à base de paquets affectant des largeurs de bande équivalentes à des connexions à vitesse variable. Les largeurs de bande (18) des connexions à vitesse variable sont augmentées ou réduites à l'aide d'un facteur d'échelle (20), afin d'obtenir une largeur de bande affectée. Le procédé et le dispositif déterminent s'il faut accepter ou refuser de nouvelles connexions à vitesse variable lorsque la somme des largeurs de bande équivalentes des connexions à vitesse variable existantes et des nouvelles connexions à vitesse variable dépasse la largeur de bande disponible pour des connexions à vitesse variable. Le procédé et le dispositif de commande d'admission de connexion déterminent également s'il faut accepter ou refuser de nouvelles connexions non spécifiées et à vitesse constante.
PCT/US1999/024999 1998-10-26 1999-10-26 Procede et dispositif de controle d'acceptation de connexion reglable pour un commutateur a base de paquets WO2000025461A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
AU13223/00A AU1322300A (en) 1998-10-26 1999-10-26 Adjustable connection admission control method and device for packet-based switch
JP2000578941A JP2002529005A (ja) 1998-10-26 1999-10-26 パケット方式交換機用の調節可能なコネクション承認制御方法及び装置

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US10583698P 1998-10-26 1998-10-26
US60/105,836 1998-10-26

Publications (2)

Publication Number Publication Date
WO2000025461A1 WO2000025461A1 (fr) 2000-05-04
WO2000025461A9 true WO2000025461A9 (fr) 2001-01-04

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Country Link
JP (1) JP2002529005A (fr)
AU (1) AU1322300A (fr)
WO (1) WO2000025461A1 (fr)

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH02220531A (ja) * 1989-02-22 1990-09-03 Toshiba Corp 呼接続制御方式および流量監視方式
JPH05227193A (ja) * 1992-02-17 1993-09-03 Kokusai Denshin Denwa Co Ltd <Kdd> Ａｔｍ呼受付制御方式
JP2928452B2 (ja) * 1994-03-17 1999-08-03 富士通株式会社 Ａｔｍ交換機及びａｔｍ交換機における呼受付け装置及び呼受付け方法
US5781531A (en) * 1995-12-27 1998-07-14 Digital Equipment Corporation Method and apparatus for hierarchical relative error scheduling
US5936940A (en) * 1996-08-22 1999-08-10 International Business Machines Corporation Adaptive rate-based congestion control in packet networks
US5909443A (en) * 1997-01-03 1999-06-01 International Business Machines Corporation ATM network congestion control system using explicit rate cell marking
US6014367A (en) * 1997-04-25 2000-01-11 Mmc Networks, Inc Method for weighted fair queuing for ATM cell scheduling

Also Published As

Publication number Publication date
AU1322300A (en) 2000-05-15
JP2002529005A (ja) 2002-09-03
WO2000025461A1 (fr) 2000-05-04

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