WO2001047199A1 - Procede et appareil de transmission transparente entre un reseau amrt et un reseau de paquets ou de cellules - Google Patents

Procede et appareil de transmission transparente entre un reseau amrt et un reseau de paquets ou de cellules Download PDF

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Publication number
WO2001047199A1
WO2001047199A1 PCT/SE2000/002515 SE0002515W WO0147199A1 WO 2001047199 A1 WO2001047199 A1 WO 2001047199A1 SE 0002515 W SE0002515 W SE 0002515W WO 0147199 A1 WO0147199 A1 WO 0147199A1
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WO
WIPO (PCT)
Prior art keywords
packet
buffer
cell
network
ofthe
Prior art date
Application number
PCT/SE2000/002515
Other languages
English (en)
Inventor
Lars-Olof Haster
Mark Anthony Hannon
Olof EKSTRÖM
Ibrahim Qazzaz
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 AU24163/01A priority Critical patent/AU2416301A/en
Publication of WO2001047199A1 publication Critical patent/WO2001047199A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00—Data switching networks
    • H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
    • H04L12/40—Bus networks
    • H04L12/40052—High-speed IEEE 1394 serial bus
    • H04L12/40091—Bus bridging
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00—Data switching networks
    • H04L12/66—Arrangements for connecting between networks having differing types of switching systems, e.g. gateways
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00—Data switching networks
    • H04L12/64—Hybrid switching systems
    • H04L12/6418—Hybrid transport

Definitions

  • the present invention relates to communications systems, and in particular to the communication between circuit switched and packet or cell based communications systems.
  • a first apparatus for communication between a Time Division Multiplex (TDM) network and a packet or cell based network comprising buffer means for receiving and storing bytes, or words, originating from one connection in the TDM network, comparing means for comparing the content of at least one ofthe bytes, or words, in the buffer to a predetermined bit sequence when the buffer is full; cell or packet transmission means for transmitting or discarding the content ofthe buffer in dependence ofthe result ofthe comparison.
  • TDM Time Division Multiplex
  • a second apparatus for communication between a TDM network and a packet or cell based network comprising clock means for determining when a packet or cell related to one particular connection in the TDM network should be expected from the packet or cell based network, frame generation means for generating a frame comprising bytes, or words, of a predetermined pattern if an expected packet or cell was not received; TDM transmission means for transmitting the generated frame.
  • the object is also achieved according to the invention by a method of compressing information transmitted from a TDM network through a packet or cell based network to the same or another TDM network, characterized in that it comprises the following steps performed in a unit intercon- necting the TDM network and the packet or cell based network:
  • the method also comprises the following steps:
  • the first and second apparatus in such a way that the first apparatus removes idle cells where the traffic enters the packet or cell based network and the second apparatus reinserts the cells where the traffic again enters the TDM network.
  • the comparing means of the first apparatus is arranged to compare the content of every byte, or word, in the buffer to the predetermined buffer and that the transmission means is arranged to discard the content ofthe buffer only if every byte in the buffer matches the predetermined bit sequence.
  • the frame generation means of the second apparatus is arranged to generate a frame of bytes of one particular bit sequence when an expected packet or cell is not received.
  • the transmission means is arranged to discard the content of the buffer only if even' byte, or word, in the buffer matches the last byte of the previous cell, and the frame generation means is arranged to generate a frame of bytes similar to one ofthe bytes ofthe last packet or cell received related to the connection.
  • bit sequences of more than one type may be removed, still without the need for tables.
  • Figure 2 shows the connection between an access network, or a local exchange, and a cell or packet based transport network according to the invention.
  • Figure 1 illustrates a type of network commonly used in telecommunications today. Subscribers (not shown) are connected to an access network or an access node 1. The access network is connected, through a transport network 3, to a local exchange 5. The local exchange 5 is connected to other units in the network, such as other ex- changes and/or other transport networks, in ways well known in the art. More access networks and/or exchanges may be connected to the transport network; however, for clarity only the units needed for the discussion are shown.
  • the transport network is assumed to be an Asynchronous Transfer Mode (ATM) network, capable of transmitting with the ATM IP
  • Constant Bit Rate (CBR) or Variable Bit Rate in real time (VBR-rt) service type In order for the transport network 3 to be transparent, the bit stream at a point A between the access network 1 and the transport network 3 and at a point B between the transport network 3 and the local exchange 5 has to be exactly the same.
  • the access network 1 performs, among other things, a concentration function. It also multiplexes traffic coming from a number of subscribers onto one cable. The method most commonly used for this is called Pulse Code Modulation (PCM). With PCM, 32 connections of 64kbit/s each are multiplexed to one bit stream of 2Mbit/s. In the United States, 24 connections are instead multiplexed to one bit stream of 1.5Mbit/s. The actual number of channels, or bit rate, is of no importance to the method according to the invention.
  • PCM Pulse Code Modulation
  • a 2 Mbit/s PCM frame comprises 32 time slots numbered from 0 to 31, each of which is able to carry an octet.
  • the time slots having the same number in a sequence of PCM frames constitute a channel corresponding to one 64 kbit/s connection.
  • the traffic is circuit switched and therefore arrives at the packet or cell based transport network 3 at a fixed rate.
  • the traffic is handled according to the ATM protocol.
  • the buffer unit 11 has one buffer for each channel. Each buffer stores the number of bytes that goes into one cell, so that the whole buffer will be filled with bytes, or octets, received on the relevant channel. When the buffer is full, it is packed as a cell and transmitted through the transport network and the procedure starts over.
  • the second converting unit 9 therefore receives cells corresponding to a particular PCM channel in the transport network 1 at regular intervals, with a predefined maximum deviation.
  • the first converting unit 7 comprises logic for examining each buffer, or each cell that is to be transmitted, and determining if it contains useful information. If every octet in the buffer, or cell, comprises the "no information" bit sequence, the whole cell is discarded, i.e. not transmitted. The bandwidth that would have been taken up by this cell can then be used for other information. If, on the other hand, one or more octets comprise a bit sequence different from the "no information" sequence, the whole cell is transmitted.
  • the second con- verting unit 9 determines that the cell probably was not transmitted from the first converting unit 7, because it only comprised "no information" bit sequences.
  • the second converting unit 7 therefore adds to the bit stream either an ATM cell in which the payload comprises only such bit sequences, or a sequence of as many such bit sequences as goes into a cell or packet, depending on the point in the net- work in which the information is added.
  • the opposite direction information may be handled in the same way, stored in the second buffer unit 13 transmitted through the access network and received by the first converting unit 7, which adds information in the same way as described above if a cell is not received.
  • the transport network may of course also be located, and perform the same function, between two local exchanges or between two access networks.
  • the invention has been discussed in the above using 2Mbit/s connections as an example. As already stated the skilled person could easily apply the teachings to " 1.5Mbit/s connections.
  • the method according to the invention can also be applied to higher-order connections, i.e. multiples of 2Mbit s or 1.5Mbit/s used in telecommunications connections. In any case the PCM frame received is demultiplexed into individual 64 kbit/s channels before being handled according to the invention.
  • sequences of any bit sequence could be removed.
  • the first cell or packet comprising only a particular bit sequence would have to be transmitted, but then previous cells or packets comprising only this particular bit se- quence could be withheld. Only when there is a change will there be a need to transmit a cell. In this way, the receiving converting unit would always know that if no cell or packet is received, a cell or packet similar to the last one received should be generated. Alternatively, only the last byte of a cell or packet would have to be examined, and there would be no need to transmit a cell that only consisted of one ofthe predefined bit sequences.
  • Figure 2 shows in more detail the interface between the TDM network and the packet or cell based network according to the invention.
  • the interface is formed by a converting unit like the one shown in Figure 1, which is in Figure 2 denoted 107.
  • the converting unit 107 For transmission from the TDM network to the cell or packet based network the converting unit 107 has at least one input port 109 for receiving incoming TDM frames from the TDM network.
  • the frames have already been demultiplexed into single channels, each usually carrying a 64kit/s connection.
  • the converting unit also comprises a buffer 111, 111 ', 111" for each channel that may be received from the TDM network.
  • the bytes received on the appropriate channel are stored until the buffer is full.
  • Comparing means 113 are present to compare the bytes in a buffer to a predetermined pattern, once the buffer is full.
  • the predetermined pattern is stored in a memory unit 115 in or in connection to the comparing means. If all bytes in the buffer correspond to the predetermined pattern, the entire content ofthe buffer is discarded, if not, the content ofthe cell is pack- etized and transmitted on an appropriate output port 117 in the way common in the art.
  • the predetermined pattern may be one specific pattern, or one of a number of pre- determined patterns, as described in connection with Figure 1. If more than one predetermined pattern is to be used, the memory unit 115 must be able to store the last byte transmitted for each channel, and, if applicable, the predetermined bit sequences that may be discarded.
  • the converting unit 107 also comprises means, i.e. one or more input ports 119 for receiving packets or cells from the cell or packet based network and clock means 121 for determining when a cell or packet should be received for a particular connection.
  • the clock means co-operates with frame generation means 123 in such a way that if the clock means 121 determines that a cell that should have been received has not been received within a predeter- mined maximum delay period, it orders the frame generation means 123 to generate a frame, which is transmitted via an output port 125. Afterwards, of course, the frames may be multiplexed to the appropriate level in the way generally used in TDM systems.
  • the content ofthe generated frame depends on the embodiment. In the simplest embodiment, where only bytes of one particular bit sequence may be discarded, the content is always the same. Alternatively, if more than one bit sequence may be discarded, the frame generation means 123 comprises or is connected to memory means 127 for storing the last byte transmitted for each connection.
  • the converting means 107 may of course be implemented as two different units, one for each transmission direction.

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  • 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 de transmission transparente entre un réseau AMRT et un réseau de paquets ou de cellules. Le procédé consiste à réaliser dans une unité interconnectant le réseau AMRT au réseau de paquets ou de cellules : - la mémorisation dans un tampon de chaque octet reçu sur le canal et à la comparaison du contenu du tampon à une séquence de bits prédéterminée. Si chaque octet du tampon correspond à la séquence de bits, le contenu du tampon est supprimé; sinon le contenu du tampon est empaqueté dans un paquet ou une cellule et transmis par le réseau de paquets ou de cellules. Il est déterminé dans une unité correspondante interconnectant le réseau de paquets ou de cellules et le réseau AMRT si un paquet ou une cellule afférent(e) à un canal particulier doit être attendu(e). En l'absence de réception d'un paquet ou d'une cellule attendu(e), une trame est générée et transmise au réseau AMRT.
PCT/SE2000/002515 1999-12-21 2000-12-13 Procede et appareil de transmission transparente entre un reseau amrt et un reseau de paquets ou de cellules WO2001047199A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU24163/01A AU2416301A (en) 1999-12-21 2000-12-13 Method and apparatus for transparent transmission between a tdm network and a packet or cell based network

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE9904695-5 1999-12-21
SE9904695A SE520080C2 (sv) 1999-12-21 1999-12-21 Förfarande och anordning för kommunikation mellan ett TDM-nät och ett datapaket- eller cellbaserat- nät

Publications (1)

Publication Number Publication Date
WO2001047199A1 true WO2001047199A1 (fr) 2001-06-28

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/SE2000/002515 WO2001047199A1 (fr) 1999-12-21 2000-12-13 Procede et appareil de transmission transparente entre un reseau amrt et un reseau de paquets ou de cellules

Country Status (5)

Country Link
CN (1) CN1166136C (fr)
AU (1) AU2416301A (fr)
ES (1) ES2204342A1 (fr)
SE (1) SE520080C2 (fr)
WO (1) WO2001047199A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004110000A1 (fr) * 2003-06-05 2004-12-16 Telefonaktiebolaget Lm Ericsson (Publ) Reduction de la largeur de bande dans des reseaux commutes par paquet en n'envoyant pas d'intervalles de temps au repos
US7228265B2 (en) * 2003-05-02 2007-06-05 Egenera, Inc. System and method for emulating serial port communication

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1848715B (zh) * 2005-04-05 2010-06-16 中兴通讯股份有限公司 实现同步串行数据在tdm网透传的方法、系统及处理装置

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1997008838A2 (fr) * 1995-08-14 1997-03-06 Ericsson Inc. Procede et equipement permettant de modifier un en-tete normalise de couche de protocole inter-reseaux
WO1998051113A2 (fr) * 1997-05-02 1998-11-12 Northern Telecom Limited Suppression et regeneration de donnees

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1997008838A2 (fr) * 1995-08-14 1997-03-06 Ericsson Inc. Procede et equipement permettant de modifier un en-tete normalise de couche de protocole inter-reseaux
WO1998051113A2 (fr) * 1997-05-02 1998-11-12 Northern Telecom Limited Suppression et regeneration de donnees

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7228265B2 (en) * 2003-05-02 2007-06-05 Egenera, Inc. System and method for emulating serial port communication
US7809546B2 (en) 2003-05-02 2010-10-05 Egenera, Inc. System and method for emulating serial port communication
WO2004110000A1 (fr) * 2003-06-05 2004-12-16 Telefonaktiebolaget Lm Ericsson (Publ) Reduction de la largeur de bande dans des reseaux commutes par paquet en n'envoyant pas d'intervalles de temps au repos
US7292546B2 (en) 2003-06-05 2007-11-06 Telefonaktiebolaget Lm Ericsson (Publ) Bandwidth reduction within packet switched networks by not sending idle timeslots

Also Published As

Publication number Publication date
SE520080C2 (sv) 2003-05-20
AU2416301A (en) 2001-07-03
SE9904695L (sv) 2001-06-22
CN1413402A (zh) 2003-04-23
ES2204342A1 (es) 2004-04-16
CN1166136C (zh) 2004-09-08
SE9904695D0 (sv) 1999-12-21

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