WO1998027689A1 - Radiodiffusion dans un reseau mta - Google Patents

Radiodiffusion dans un reseau mta Download PDF

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Publication number
WO1998027689A1
WO1998027689A1 PCT/SE1997/002018 SE9702018W WO9827689A1 WO 1998027689 A1 WO1998027689 A1 WO 1998027689A1 SE 9702018 W SE9702018 W SE 9702018W WO 9827689 A1 WO9827689 A1 WO 9827689A1
Authority
WO
WIPO (PCT)
Prior art keywords
cell
atm
cells
tcb
broadcasting
Prior art date
Application number
PCT/SE1997/002018
Other languages
English (en)
Inventor
Pål HELLUM
Kristin Aksnes
Original Assignee
Telefonaktiebolaget Lm Ericsson (Publ)
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 Telefonaktiebolaget Lm Ericsson (Publ) filed Critical Telefonaktiebolaget Lm Ericsson (Publ)
Priority to AU54215/98A priority Critical patent/AU5421598A/en
Publication of WO1998027689A1 publication Critical patent/WO1998027689A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q11/00—Selecting arrangements for multiplex systems
    • H04Q11/04—Selecting arrangements for multiplex systems for time-division multiplexing
    • H04Q11/0428—Integrated services digital network, i.e. systems for transmission of different types of digitised signals, e.g. speech, data, telecentral, television signals
    • H04Q11/0478—Provisions for broadband connections
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L49/00—Packet switching elements
    • H04L49/30—Peripheral units, e.g. input or output ports
    • H04L49/3081—ATM peripheral units, e.g. policing, insertion or extraction
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00—Data switching networks
    • H04L12/54—Store-and-forward switching systems 
    • H04L12/56—Packet switching systems
    • H04L12/5601—Transfer mode dependent, e.g. ATM
    • H04L2012/5638—Services, e.g. multimedia, GOS, QOS
    • H04L2012/5646—Cell characteristics, e.g. loss, delay, jitter, sequence integrity
    • H04L2012/5651—Priority, marking, classes
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00—Data switching networks
    • H04L12/54—Store-and-forward switching systems 
    • H04L12/56—Packet switching systems
    • H04L12/5601—Transfer mode dependent, e.g. ATM
    • H04L2012/5678—Traffic aspects, e.g. arbitration, load balancing, smoothing, buffer management
    • H04L2012/5681—Buffer or queue management

Definitions

  • the present invention relates to the efficient and fast broadcasting of cells between an Asynchronous Transfer Mode (ATM) node and a number of physical interfaces, in which the traffic may consist of different types of traffic with different demands on the transfer performance.
  • ATM Asynchronous Transfer Mode
  • An ATM network transfers data that is divided and packed in cells of a fixed size instead of packets of variable size as in traditional packet switching. Cells are transferred at high speeds over optical fibres and undergo immediate and fast hardware switching.
  • An ATM network is flexible and can offer services requiring different transfer speeds and the network also efficiently utilizes the selection of different transfer paths.
  • Cells consist of units of equal length comprising both payload and a header comprising, among other things, a Virtual Path Identifier/Virtual Channel Identifier (VPI/NCI) which, by looking in routing tables identifies the virtual interface in which the cell was originally generated.
  • VPI/NCI Virtual Path Identifier/Virtual Channel Identifier
  • Each ATM node uses the VPI and/or VCI as an addition to the information about the physical interface from which the cell came to identify the cell and determine what physical interface or interfaces the cell is to be transmitted to. Information about the originating physical interface is important, as two cells from different interfaces may have the same VPI/NCI.
  • the data in the cells is multiplexed over ATM connections with very high capacity to switch matrices having switch elements which, when activated, are to route the cells to the respective intended output channel and then on to the right destination.
  • a conventional switch can therefore handle point-to-point communication by switching a cell from an input only to one of a number of possible outputs. Therefore it is a problem to achieve multicasting/broadcasting since it is not possible to achieve point-to-multipoint communication, that is from a source node to a number of receiver nodes, by transmitting the same cell from a certain input channel on the switch through a number of output channels.
  • the cells may be duplicated in a number of copies corresponding to the number of physical interfaces they are to be transmitted to. This information may be retrieved through the header information in a routing table. By stopping the incoming flow of cells and duplicating them one at a time, they may be forwarded to the desired physical interface.
  • This operation takes time, since the cells that are to be copied must be stored in a buffer and transmitted to the different interfaces. This introduces a Cell Delay Variation (CDV) and a Cell Transfer Delay (CTD). This is not acceptable in certain types of traffic requiring a constant bit rate.
  • CDV Cell Delay Variation
  • CTD Cell Transfer Delay
  • UTOPIA Universal Test and Operations PHY Interface for ATM
  • EP 0 448 046 discloses a system for broadcasting in ATM, in which a label is added to the header in the ATM cell coming in to the switch. The cell is then copied to the switch elements leading to the switch outputs to which the cell is destined, according to information in the label. The switch element then transmits the cell on the desired output channels simultaneously, thus achieving a broadcast of the cell.
  • the label length is here proportional to the number of switch elements connected to the respective input channel.
  • the document does not describe the handling of different types of traffic, such as Continuous Bit Rate (CBR), Variable Bit Rate (VBR), Available Bit Rate (ABR) or Unspecified Bit Rate (UBR).
  • the invention shows a device and a method of solving the problem of time delay in broadcast traffic and also of providing the service required by different traffic types, by identifying the traffic class of the cell and add to this a prefix, or a label, showing the physical interfaces to be addressed by the cell in question and also the priority that should be assigned to the cell.
  • the purpose of the invention is achieved, said purpose being to arrange, in a safe and fast way, a possibility for cells having different transfer requirements, to be broadcast from an ATM layer to an arbitrary number of physical interfaces.
  • the addressing to the different physical interfaces takes place over the data pins defined by SINGLE-PHY-UTOPIA and the need for an extra address pin is eliminated by adding a minimal prefix to the cell format standardized by SINGLE PHY UTOPIA.
  • the prefix is to serve as an address and will in the following be referred to as the address field.
  • the address field which it is feasible to add to the cell header, can address several physical interfaces as well as different buffers in each physical interface.
  • the buffers may be used for sorting different types of traffic, for example having high or low priority.
  • the address field is added to the cell and used in the direction towards the physical interfaces for the indication of the destination of the cell transmitted from an ATM node in the ATM layer.
  • This direction will in the following be referred to as the egress direction.
  • the address field is used for identification of the physical interface that transmitted the cell. This direction is called the ingress direction.
  • An ATM node is normally equivalent to an ATM switch.
  • the address field is of such a kind that each physical interface corresponds to a special reserved bit indicating whether or not the interface in question is to receive just this cell, so called bit mapping.
  • bit mapping indicates, through a bitmap, the physical interfaces to be addressed.
  • One great advantage is then achieved in the possibility to transmit the same cell to several physical interfaces during only one cell interval, eliminating the problem of having to step the incoming cell flow to the switch to copy the cells, since all cells are transmitted to all physical interfaces, which then receive or discard depending on the bitmap.
  • the address field may also comprise an identification of the traffic class, such as CBR, VBR, ABR or UBR, to which the cell belongs, and in each physical interface. Thus, a buffer may be implemented for each traffic class.
  • the inventive idea has more advantages than the ones mentioned above. No additional pins are needed compared to point-to-point connections, and no additional links are needed to handle different traffic classes. Further, the invention offers the possibility of broadcasting cells to an unlimited number of physical interfaces and the length of the address field is not dependent on the number of switch elements in the switch. If the physical interfaces are provided with the capacity of address recognition they need less decoding logic.
  • Figure 1 is a block diagram of an ATM node connected to a number of physical interfaces by means of a bus, each interface comprising a plurality of buffers;
  • Figure 2 is a schematic representation of broadcasting in ATM and in particular the principle of the bitmapping function;
  • Figure 3 shows an address field according to a preferred embodiment and also the same address field added to a standard ATM cell;
  • Figure 4 shows a second embodiment of the invention illustrated by a block diagram with an ATM node connected to a plurality of physical interfaces by means of a bus, each interface comprising only one buffer.
  • Figure 1 shows an ATM switch connected to a plurality of physical interfaces PI 1 - PI m.
  • an incoming cell 1 to the switch In broadcasting an incoming cell 1 to the switch is to be transmitted from the switch through a bus 5 to all the physical interfaces PI 1 - PI m and in multicasting the cell is transmitted to a number of selected interfaces in the egress direction.
  • all cells are transmitted as usual (without being copied) through the switch and then pass, according to a preferred embodiment, an identification module 2 determining what cells are to be broadcast to what physical interfaces, using information in the header of each cell. The information is retrieved from routing tables by determining the VPI/NCI of the header and the physical interface from which the cell originates.
  • the identification module 2 later adds an address field to the cell header based on said information in the routing table.
  • Figure 3 shows an ATM cell having a header and payload as usual.
  • the additional address field may be seen as an addition to the cell header.
  • the address field is added to the header in the identification module 2 and is used for addressing the physical interfaces PI 1 - PI m that are to receive the cell in question, by means of bitmapping. Therefore, only one bit is needed for each physical interface to indicate whether or not a particular interface is to receive the cell.
  • Figure 2 is an example of such bitmapping in an ATM switch that is to broadcast a cell 4 to two out of four connected interfaces.
  • the bitmap 3 shows that the interface to the far left and the one to the far right are to receive the cell 4.
  • the cell is thus transmitted to all the interfaces, but the ones having a zero in the bitmap (in this example) will discard the cell.
  • each physical interface may use different buffers TCB 1 - TCB n for each traffic class, so called traffic class buffers (TCB).
  • TCB traffic class buffers
  • some cells may be given a higher priority than others.
  • CBR cells with high throughput requirements may be offered the service they need while other types of traffic, having a lower priority, such as ABR or UBR must accept a longer wait in their respective buffers.
  • These buffers may also be implemented as one big buffer for each interface, in which each traffic class of cells is instead sorted into different address areas in the same buffer (TCB), as illustrated in Figure 4, in which each physical interface only has one buffer.
  • the different TCBs can be addressed by means of binary numbers. If there are n different traffic classes it suffices to add log2n bits in the address field to be able to identify the TCB in which the cell is to be put, since every cell may be assumed to be in the same buffer in all physical interfaces to which it is destined. For example, it will not occur that the same cell is put in the CBR buffer in one interface and the ABR buffer in another interface. Just like the identification of the physical interfaces PI 1 - PI m to which the cell is destined, the identification of the traffic class to which the cell belongs takes place in the identification module 2. Information about this is also retrieved in the routing tables through the cell header.
  • the extra address field added to the header in the identification module 2 thus comprises information both about the physical interfaces to receive the cell and the traffic class to which the cell belongs, and thus the buffer in each interface to which the cell is going.
  • the different traffic classes, and thus the different TCBs represent different traffic classes (CBR, VBR etc.).
  • the invention should, however, not be seen as limited to sorting the cells according to traffic classes but can of course also be arranged to sort the cells into buffers according to other criteria and conditions. To achieve a more general term for "traffic classes" it is appropriate to use the word "priority classes".
  • Figure 3 also shows how an address field may look according to a preferred embodiment of the invention.
  • the address field is here divided into two parts.
  • One part (PI A) addresses the different physical interfaces (PI 1 - PI m) whereas the other (TCB A) addresses the different TCBs (TCB 1 - TCB n).
  • PI A addresses the different physical interfaces
  • TCB A addresses the different TCBs
  • log2n bits are needed.
  • the ad- dress field preferably added to the cell header, thus only has to consist of m+log2n bits.
  • the address field may consist of only PI A, if only one traffic class is used so that only one buffer for each physical interface is needed.
  • the address field may consist of only TCB A, if more than one traffic class is used, but only one interface. In this case, however, broadcasting does not occur. The mutual location of the two address field parts, PI A and TCB A will not affect the functionality of the invention.
  • the address field part PI A is used to identify the physical interface PI 1 - PI M from which the cell originates.
  • the HEC field which has already been defined, in the ATM cell header as an address field. This would, however, impose a limitation of the address field to 8 or 16 bits.
  • the HEC field may be used provided it is regenerated in the physical interface after the cell has been output from the switch. It is often common that the interfaces packing ATM cells, for example, in
  • HEC HEC being used in the connection but not internally in the ATM switch. Internally, parity checks are often used instead.

Landscapes

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

Abstract

L'invention concerne un procédé et un dispositif de radiodiffusion/multidiffusion de cellules MTA d'un noeud MTA vers MTA vers un certain nombre d'interfaces physiques (PI 1-PI m), tenant compte de la classe de priorité ou classe de trafic à laquelle la cellule appartient. Un tampon (TCB1-TCBn) par classe de priorité est aménagé dans chaque interface pour trier les cellules. Un champ d'adresse avec phototrame (PI A) est ajouté à la cellule pour déterminer les interfaces physiques destinées à la recevoir. Le champ d'adresse comporte également une indication (TCB A) relative à la classe de priorité à laquelle la cellule appartient.
PCT/SE1997/002018 1996-12-06 1997-12-02 Radiodiffusion dans un reseau mta WO1998027689A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU54215/98A AU5421598A (en) 1996-12-06 1997-12-02 Broadcasting in an atm-network

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE9604513A SE511957C2 (sv) 1996-12-06 1996-12-06 Broadcasting över ATM
SE9604513-3 1996-12-06

Publications (1)

Publication Number Publication Date
WO1998027689A1 true WO1998027689A1 (fr) 1998-06-25

Family

ID=20404897

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/SE1997/002018 WO1998027689A1 (fr) 1996-12-06 1997-12-02 Radiodiffusion dans un reseau mta

Country Status (3)

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AU (1) AU5421598A (fr)
SE (1) SE511957C2 (fr)
WO (1) WO1998027689A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1111839A2 (fr) * 1999-10-21 2001-06-27 Nortel Networks Limited Méthode et système pour le traitement et la transmission de paquets multidestinataires
US9896655B2 (en) 2008-12-03 2018-02-20 The Scripps Research Institute Methods of enhancing cell survival of stem cells
CN109284234A (zh) * 2018-09-05 2019-01-29 珠海昇生微电子有限责任公司 一种存储地址分配方法及系统

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5202885A (en) * 1990-03-14 1993-04-13 Alcatel N.V. Atm exchange with copying capability
US5436893A (en) * 1992-12-05 1995-07-25 Netcom Limited ATM cell switch suitable for multicast switching
EP0719008A2 (fr) * 1990-03-19 1996-06-26 Fujitsu Limited Système de diffusion de cellules ATM

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5202885A (en) * 1990-03-14 1993-04-13 Alcatel N.V. Atm exchange with copying capability
EP0719008A2 (fr) * 1990-03-19 1996-06-26 Fujitsu Limited Système de diffusion de cellules ATM
US5436893A (en) * 1992-12-05 1995-07-25 Netcom Limited ATM cell switch suitable for multicast switching

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1111839A2 (fr) * 1999-10-21 2001-06-27 Nortel Networks Limited Méthode et système pour le traitement et la transmission de paquets multidestinataires
EP1111839A3 (fr) * 1999-10-21 2005-01-05 Nortel Networks Limited Méthode et système pour le traitement et la transmission de paquets multidestinataires
US9896655B2 (en) 2008-12-03 2018-02-20 The Scripps Research Institute Methods of enhancing cell survival of stem cells
CN109284234A (zh) * 2018-09-05 2019-01-29 珠海昇生微电子有限责任公司 一种存储地址分配方法及系统
CN109284234B (zh) * 2018-09-05 2020-12-04 珠海昇生微电子有限责任公司 一种存储地址分配方法及系统

Also Published As

Publication number Publication date
SE9604513L (sv) 1998-06-07
AU5421598A (en) 1998-07-15
SE9604513D0 (sv) 1996-12-06
SE511957C2 (sv) 1999-12-20

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