CN1132489C

CN1132489C - Method of transmitting ATM cell over ATM network

Info

Publication number: CN1132489C
Application number: CN97193411A
Authority: CN
Inventors: 特伦斯·杰弗里·霍奇金森; 艾伦·威廉·奥尼尔
Original assignee: British Telecommunications PLC
Current assignee: British Telecommunications PLC
Priority date: 1996-03-28
Filing date: 1997-03-21
Publication date: 2003-12-24
Anticipated expiration: 2017-03-21
Also published as: CN1214846A; EP0890290A1; NO984468L; NO984468D0; AU2037997A; JP2000510665A; WO1997036453A1; NZ331325A; KR19990087607A; AU725361B2

Abstract

An ATM network includes a set of interconnected switches and gateways. The ATM network is capable of providing both a conventional connection-oriented service or a connectionless service. Where a connectionless service is required, at the input interface, source and destination addresses are inserted into the header and fields in the header are set to values which indicate that a connectionless service is required and whether or not additional processing is also required. At each node between the input interface and the output interface, where a connectionless service is required, each ATM cell is routed in accordance with its source address and destination address and/or a routing table which is set up by routing protocol or network management.

Description

The method of transmission ATM cell on atm network

Technical field

The present invention relates between ATM input interface and ATM output interface, transmit the method for ATM(Asynchronous Transfer Mode) cell by atm network.

Background technology

In the atm network of routine, when a cell arrives the ATM input interface, in virtual route identifier (VPI) during initial value is inserted into to the end and virtual channel identifier (VCI) field.Vpi field provides the Route Selection of thick level for ATM cell, and VCI provides the Route Selection of thin level.Read VPI and/or vci field and utilize the routing table that is included in intranodal according to one in these fields or both value selection output ports at each switching node place between ATM input interface and ATM output interface.Before cell being forwarded on the selecteed output port, in these fields one or both values are updated.

In each switching node, the updating value of routing table and VPI and/or vci field part is set up by network management, and part is set up by signaling in call establishment.So conventional atm network provides connection-oriented service.In connection-oriented service, call out when calling out beginning and to set up by signaling and to be eliminated during at end of calling.Perhaps, routing table can be established with updating value provides one forever to be connected.

For example, must before being transmitted, data set up calling if wish at switch type atm network transmitting data from the data of the computer that is provided with atm card.If data are transmitted continuously more or less in calling procedure, the connection-oriented service that then conventional atm network provides can meet the demands.Yet often data are transmitted in hope off and on, and before next cell group was transmitted, following was a delay for a long time a cell group after.Yet, all set up and remove calling for each cell group and can bring the burden expense.Like this, Chang Gui switch type atm network is not optimized for intermittent transfer of data.

For no Connection Service is provided, proposed to add a server to provide no Connection Service as stack to atm network on atm network.Yet this solution has the defective that still has call establishment stage between input interface and server.

EP-A-O 552 385 has described a kind of atm network that no Connection Service can be provided.

Summary of the invention

According to an aspect of the present invention, a kind of method from source node to destination node that transmit the ATM(Asynchronous Transfer Mode) cell between ATM input interface and ATM output interface by atm network with a kind of connectionless-mode from is provided, each all has a network address described source node and destination node, described ATM cell comprises a stature and a User Part, described network comprises the network of interconnecting nodes (at least some are switching node), said method comprising the steps of:

At the ATM input interface, a field in the ATM cell head is set to the value of an indication nothing connection transmission and with in source address and the destination address insertion to the end, source address is the network address of source node, and destination address is the network address of destination node; And

Each switching node between ATM input interface and ATM output interface, determine that by the described field in the read head this cell will be forwarded with connectionless-mode, destination address in the read head is selected output port according to destination address at least, and this cell is forwarded on the selecteed output port.

The invention provides such advantage, promptly do not need to set up routing table by signaling for specific each ATM cell transmission that continues between node and the specific objective node.So when cell transmits in groups, each cell is not set up upright burden expense of calling out.

According to a further aspect in the invention, provide a kind of operation A TM network with between source node and destination node by atm network selectively with the method for connectionless-mode or connection-oriented mode transmit cell, each all has a network address described source node and destination node, each ATM cell comprises a stature and a User Part, and described atm network comprises the network of interconnecting nodes (at least some are switching node).

With connectionless-mode between ATM input interface and the ATM output interface by under the situation of Network Transmission ATM cell, said method comprising the steps of:

At the ATM input interface, a field of ATM cell head be set to an indication do not have to connect the value of transmission and insert a destination address and a source address to the end in, this source address is the network address of source node, this destination address is the network address of destination node; And

Each switching node between ATM input interface and ATM output interface, determine that by the described field in the read head this cell will be forwarded with connectionless-mode, destination address in the read head is selected output port according to destination address at least, and this cell is forwarded on the selecteed output port;

Passing through under the situation of Network Transmission ATM cell between ATM input interface and the ATM output interface in connection-oriented mode, described method comprises step:

At the ATM input interface, virtual route identifier (VPI) and virtual channel identifier (VCI) field in the head are set; And

Each switching node between ATM input interface and ATM output interface, VPI in the read head and/or vci field are selected an output port according to the value of VPI and/or VCI, upgrade VPI and/or vci field, and transmit this cell to the output port of selecting.

According to another aspect of the present invention, provide a kind of and transmitted the ATM(Asynchronous Transfer Mode) cell at least one destination node from a source node, between ATM input interface and ATM output interface, to provide the multicast service method with connectionless-mode by atm network, described ATM cell comprises a stature and a User Part, above-mentioned network comprises the network of interconnecting nodes (at least some are switching node), and said method comprises step:

At the ATM input interface, a field in the head be set to an indication do not have to connect the value of transmission and insert a source address and a destination address to the end in, this source address is the network address of source node, this destination address is the network address of multicast service; And

Each switching node between ATM input interface and ATM output interface, determine that by the described field in the read head this cell will be forwarded with connectionless-mode, destination address in the read head, at least select at least one output port according to destination address, and this cell is forwarded at least one selecteed output port.

Description of drawings

By example, the present invention will be described now in more detail with reference to the accompanying drawings:

Fig. 1 is the block diagram of the ATM(Asynchronous Transfer Mode) network of routine;

Fig. 2 shows the structure of basic ATM cell;

Fig. 3 shows the header fields that uses between the transmission period between user and the atm network interface in basic ATM cell;

Fig. 4 shows the field of using between transmission period between the node in atm network in the head of basic ATM cell;

Fig. 5 is the block diagram that embodies atm network of the present invention;

Fig. 6 is the flow chart of the operation on the input interface of the network in Fig. 5 ATM cell carried out;

Fig. 7 is the flow chart that is illustrated in the operation of the network switching node place among Fig. 5 being carried out by ATM cell;

Fig. 8 is the sequence of operation flow chart that is used for forming at IP (IP) the gateway place of the network of Fig. 5 ATM cell;

Fig. 9 shows the header fields that uses in the ATM cell of network in Fig. 5 when no Connection Service is provided.

Embodiment

With reference now to Fig. 1,, shows the block diagram of the atm network of a routine.Atm network comprises the network of the switching node of switch 10 to 18 forms that part interconnects.In the network of Fig. 1, switch 10,11,12,13,15,16,17 and 18 also work the switch that continues.Each switch that continues is connected to one group and switch is connected to other networks or is directly connected on the line attachment on the customer equipment.By diagram, Fig. 1 shows switch 17 and is connected on the computer 22 and by another line attachment by a line attachment and is connected on the multiplexer 24.Computer 22 is provided an atm card so that it can transmit and receive data with the form of ATM cell.Multiplexer 24 can receiver, video, and data and voice signal also convert them to ATM cell in multiplexed mode.Be similar to this, it can receive ATM cell and convert them to video, data and voice signal from switch 17.Typically, multiplexer 24 is positioned under user's prerequisite of atm network.

Known to the practician in this area, when transmission one ATM cell between ATM input interface and ATM output interface, the virtual route identifier (VPI) during initial value is inserted into to the end and empty like in Channel Identifier (VCI) field.The ATM input or output interface can be positioned at the intranodal that continues, or outside atm network, for example in computer 22 or multiplexer 24.Next, at each switching node place, the value of VPI and/or vci field is read out, and a value or this two values and routing table are used to select an output port together.Before ATM cell was left switch, VPI and vci field one or both values were updated according to the data that are contained in the routing table.Vpi field provides the Route Selection of a thick level and vci field provides the Route Selection of a thin level.The Route Selection matrix section is set up by network management, and part is established in call setup.Mainly, but be not that all the virtual route routing table is set up by network management, the pseudo channel routing table is set up by signaling in call setup.

A structure and a field of basic ATM cell will be described now.

Comprise that with reference to 2, one basic ATM cell of figure the user of 40 and 1 eight bit bytes of one 5 eight bit bytes pays load part 42.Header 40 is used so that to be the cell pathfinding between the switch of network pay load part 42 by, user and comprises user's data and it by delivery and sent to far-end without change in network pellucidly.

With reference now to Fig. 3 and 4,, show basic conventional ATM cell the head in field.Fig. 3 shows the field that is used to pass User Network Interface transmission ATM cell, and Fig. 4 shows the field that is used for running through the Network-Node Interface transmit cell in atm network.Except an exception below will describing, the field under two kinds of situations is the same.Explanation in the meaning table 1 below of these fields.

Table 1

The general flow control of GFC

The VPI virtual route identifier

The VCI virtual channel identifier

PT pays load type

The CLP Cell Loss Priority

HEC believes an error code correction

General flow control (GFC) field only occurs at User Network Interface.This field is used to arbitration use between a plurality of terminals of sharing the same switch that continues.This field be 4 long.

Virtual route identifier (VPI) field provides the Route Selection of thick level for ATM cell.The value of VPI is changed when cell is exchanged at the switch place that the virtual route exchange is provided at every turn.At the User Network Interface place, vpi field only has eight.It is increased to 12 between the node of network, because do not need general flow control position when cell is transmitted via network.

Virtual channel identifier (VCI) field provides the Route Selection of thin level for ATM cell.VCI value in the head is changed when cell is exchanged at the switch place that the pseudo channel Route Selection is provided at every turn.Vci field be 16 long.

Payment load type (PT) field is used to the universal class of data in the indication information element.The typical usage of this field is an identifying operation, OAM cell, last cell in congestion condition and resource management or the many cells message.This field be three long.

In atm network, exist a little danger of cell loss concealment.Cell Loss Priority (CLP) field be one long.When this position when being set, it is told that this cell of network is not really important and abandons it in the time of must taking place and adopt another cell when losing.

A letter Error detection (HEC) field provide header verification and.It can be checked the bit-errors in the header and can be used to revise them sometimes.This field be eight long.

Conventional switch type atm network, network as shown in Figure 1, the intermittent or paroxysmal data of uncomfortable incompatible transmission.If conventional switch type atm network is used to transmit such data, be established in the call setup of routing table before being required to transmit data and this is connected in the time that needs transfer of data and is kept.This shortcoming of bringing is will keep connection during data transmission sus-pension, and this wastes very much.This COS that is provided by conventional atm network is the data that connection-oriented service and this COS generally are not suitable for transmitting burst.In general the transmission of bursty data is more suitable in connectionless service.In no Connection Service, do not have call establishment, and routing table is routed and selects agreement or network management process to set up and not at call establishment stage.

Several agreements of no Connection Service are being provided, and for example in the Internet Protocol (IP), head comprises the field of an indication required service type.Estimate that each possible COS all has a corresponding value in this field.The example of COS postpones for hanging down, and the request switch keeps between buffer empty for returning to call out, and multicast, and wherein a calling is sought and being routed to more than a destination.In the ATM cell head, there is not corresponding field.COS is set up in call setup or by network management.Thereby,, can not provide another network desired COS based on each cell if an atm network receives data from another according to the network that no Connection Service sends data by suitable gateway.

With reference to figure 5, show the embodiment of an atm network of the present invention.It is very clear to become from the following description, and atm network can be with connection-oriented mode or connectionless-mode transmission ATM cell.It also can provide various COS such as above mentioned service and additional treatments.

Similar among Fig. 5 shown in the general layout of network and Fig. 1.Like this, the network among Fig. 5 comprises the network of the switching node of ATM switch 110 to 118 forms that part interconnects.Switch 110,111,113,115,117 and 118 are the switch that continues, and receive the data that come from other networks or directly come from the subscriber equipment on the I/O circuit 120.By diagram, illustrate switch 117 be connected to Fig. 1 in computer 22 roughly similarly on the computer 122, and also be connected to Fig. 1 in multiplexer 24 roughly similarly on the multiplexer 124.

Switch 116 is transfused to/and outlet line is connected on the IP gateway 131 and switch 112 is connected on the IP gateway 133 by circuit 132.Each

IP gateway

131 and 133 can be to/IP network reception/transmission data from the I/O circuit 134.

In operation, the data that receive from IP network when an

IP gateway

131 or 133 pairs play input and continue time spent of doing of node, and it resolves into ATM cell with this IP bag.When one in these gateways was continued node as output, it was reassembled into the IP bag with ATM cell.

When network shown in Figure 5 was used between ATM input interface and ATM output interface to transmit ATM cell in connection-oriented mode, ATM cell was transmitted by network with the usual manner of describing with reference to figure 1, and the field of head as shown in Figure 3.Yet, now on the ATM of routine, provide additional treatments, whether carry out to determine this transmission in connection-oriented mode.When the network shown in Fig. 5 is used between ATM input interface and ATM output interface to transmit ATM cell in connectionless mode, the field in transmission means and the head the two with conventional atm network in the transmission means used and in field different.This difference will be described now.

With reference now to Fig. 9,, shows a field that when providing no Connection Service, is used to the ATM cell in Fig. 5 network.Explanation in the meaning table 2 below of these fields.

Table 2

The SA source address

The OF option field

The DA destination address

PT pays load type

The CLP Cell Loss Priority

HEC believes an Error detection

The network address of source address (sa) field indication source node.This source node just often will be in the input interface of the atm network shown in Fig. 5.For example, source node may be switch 113 or computer 122 or multiplexer 124 or IP gateway 131.

Option field (OF) can be changed to the value that an indication needs special services or needs additional treatments.The Service Instance that may be supported is that the request switch keeps cushion space for returning to call out, and request is low to be postponed or multicast.Each possible COS is invested a unique value in option field.The requirement of carrying out additional operations is also invested a unique value in option field.The example of additional treatments is the intelligent network operation, network management operation or Route Selection operation.

When the cell that requires additional treatments was received at the switch place, this cell is sent to the high-rise of switch and its payment load part is examined need to determine which kind of additional treatments.For example, intelligent network operation if desired, this switch can be visited a remote data base and be determined new destination address with the destination address from cell.This destination address is next by corresponding change.

According to another example, some positions of payment load part can indicate and require network management operation in the cell.When such cell was sent to switch high-rise, this switch was carried out necessary operations.

Destination address (DA) field is used to the network address of indicating target node.This destination address just often will be at the output interface place.When multicast service was provided, this destination address was the network address of multicast service.

Source address, destination address and option field ordering and structure are the network domains characteristics, and territory is the set of node of sharing the same form of these fields herein.

The present invention is not limited in the atm network that uses the conventional header shown in Fig. 3 and 4 and payment load configuration and size.Here, as this example, these conventional headers and payment load configuration are used, and 28 are assigned to SA altogether, DA and OF field.Reason be this by the GFC of routine, the employed figure place of VPI and vci field.Distribute to SA, these positions of DA and OF field can be selected arbitrarily, but they must be specific in specific fields.

In this example, SA and da field each be 12 long and OF fields be 4 long.Thereby the network domains shown in Fig. 5 can be supported 4096 source addresses, 4096 destination addresses and 16 options.

Can be in the payment load part of source and target address first cell in each transmission that network is outer by supplemental instruction.

Payment load type (PT) field is identical with the field of using in conventional ATM cell head except that predefined value, and this predefined value is ＂ 111 ＂ in this example, is used to indicate this service for connectionless.

CLP and HEC field are identical with these fields in the conventional ATM cell head.

When the user of the network shown in Fig. 5 wishes to use no Connection Service transmission ATM cell on network, its in the switch that continues one, for example switch 117 is indicated and is required a no Connection Service and destination address is provided.If specific service or additional treatments are required, its also operation indication.Operation shown in each ATM cell execution graph 6 that next switch that continues receives from the user it.These operations will be described now.Perhaps, if on the node of input interface outside network, operate on that node and be performed.

In 200 steps, the PT field value of being set to ＂ 111 ＂ are with the no Connection Service of indication.Then, in 201 steps, insert destination address and insert source address in 202 steps.At last, in 203 steps, if specific COS or additional treatments are required that the OF field is configured to corresponding value.

Fig. 7 shows the operation that each the switch place between input interface and output interface carries out ATM cell.These operations will be described now.

In 220 steps, this cell enters switch.Then, in 221 steps, switch reads the PT field and is required to determine whether a no Connection Service.If failed call does not have Connection Service, it carries out the operation that conventional ATM switch is carried out.Like this, in 222 steps, it reads VPI and/or vci field.Some ATM switch only are virtual path switches, and some only are that pseudo channel switch and other be virtual path switch also are the pseudo channel switches.Like this, these fields that are read and are used will rely on switch type.Then, in 223 steps, the value of routing table and VPI and/or vci field is used to select an output port together.Then, in 224 steps, VPI and/or vci field are updated according to the data in the routing table.At last, in 225 steps, cell will leave switch on selecteed output port.

If find that in 221 steps a no Connection Service is required that following operation is performed.

In 230 steps, the source and target address in its read head (SA and da field).In 231 steps, it reads the OF field to determine COS.In 232 steps, its carry out may appointment in option field operation, for example keep between buffer empty or carry out additional treatments.

Then, in 233 steps, it utilizes the value of destination address or both values of source and target address and routing table to select output port.Therefore, the back is being followed the route of not having the connection ATM cell and may depended on source address and destination address when being transmitted on network.

At last, cell leaves switch in 225 steps.

With reference now to Fig. 8,, the IP that shows a reception from

IP gateway

131 and 133 wraps the sequence of operation of execution to form each ATM cell.

At first, in 250 steps, an ATM cell is formed by decomposing the IP bag.As the result who decomposes the IP bag, source and target address, desired COS and any request of additional treatments is read.

Then, in 251 steps, the PT field is configured to indication and requires a no Connection Service.Next, in 252 steps and 253 steps, during destination address and source address are inserted into to the end.At last, in 254 steps, if suitable, option field is configured to indicate desired COS or indication to require additional treatments.

Network shown in Fig. 5 can be that a public wide field network (WAN) maybe can be a private network, for example office's field network (LAN).

The network address of source and target node is set up by network management.It is permanent that these addresses are established on this meaning indefinitely at them.The cell that makes that is used for switching node is set up by network management rather than by signaling according to the routing table of no Connection Service transmission.Thereby even in source node first position by the specific destination node of Network Transmission ATM cell to, cell also is transmitted under the situation of not carrying out signaling manipulation.

Claims

One kind between ATM input interface and ATM output interface by atm network with connectionless-mode from the method for source node to destination node transmission ATM(Asynchronous Transfer Mode) cell, each has a network address described source node and destination node, described ATM cell comprises a stature and a User Part, described network comprises that one of them is the network of the interconnecting nodes of switching node a bit, and described method comprises step:

At ATM input interface place, with a field in the ATM cell head be arranged to an indication do not have to connect the value of transmission and insert a source address and a destination address to the end in, this source address is the network address of source node, destination address is the network address of destination node; With

Each switching node between ATM input interface and ATM output interface, determine that by the described field in the read head this cell will be forwarded with connectionless-mode, destination address in the read head is selected output port according to destination address at least, and this cell is forwarded on the selecteed output port.
2. the method in the claim 1 comprises following additional step:

Each switching node between ATM input interface and ATM output interface reads source address; And wherein

Each switching node between ATM input interface and ATM output interface, in selecting the described step of output port, the two selects an output port according to destination address and source address.
3. the method in claim 1 or the claim 2 also comprises the following steps:

At the ATM input interface, insertion requires in the indication to the end of particular type of service; With

On each switching node between ATM input interface and the ATM output interface, check the indication that requires particular type of service in the head, and, carry out once-through operation at least so that desired COS to be provided in suitable place.
4. claim 1 or 2 method comprise following additional step:

At the ATM input interface, at least one node that is inserted between ATM input interface and the ATM output interface requires in the indication to the end of additional treatments;

Each switching node between ATM input interface and ATM output interface is checked the indication that requires additional treatments in the head; With

In suitable place, at least one node between ATM input interface and the ATM output interface is carried out desired additional treatments.
5. the method for claim 3 comprises following additional step:

At the ATM input interface, at least one node that is inserted between ATM input interface and the ATM output interface requires in the indication to the end of additional treatments;

Each switching node between ATM input interface and ATM output interface is checked the indication that requires additional treatments in the head; With

In suitable place, at least one node between ATM input interface and the ATM output interface is carried out desired additional treatments.
6. claim 1 or 2 method, cell of data or wrap in ATM input interface place and be received wherein according to agreement rather than ATM, described method comprises following other steps:

At the ATM input interface, decompose the cell of data receive or wrap in the ATM cell; With

At the ATM output interface, according to cell of data or wrap in the received agreement in node place that continues re-assembly ATM cell to cell of data or the bag in.
7. the method for claim 3, cell of data or wrap in ATM input interface place and be received wherein according to agreement rather than ATM, described method comprises following other steps:

At the ATM input interface, decompose the cell of data receive or wrap in the ATM cell; With

At the ATM output interface, according to cell of data or wrap in the received agreement in node place that continues re-assembly ATM cell to cell of data or the bag in.
8. the method for claim 4, cell of data or wrap in ATM input interface place and be received wherein according to agreement rather than ATM, described method comprises following other steps:

At the ATM input interface, decompose the cell of data receive or wrap in the ATM cell; With

At the ATM output interface, according to cell of data or wrap in the received agreement in node place that continues re-assembly ATM cell to cell of data or the bag in.
9. the method for claim 5, cell of data or wrap in ATM input interface place and be received wherein according to agreement rather than ATM, described method comprises following other steps:

At the ATM input interface, decompose the cell of data receive or wrap in the ATM cell; With

At the ATM output interface, according to cell of data or wrap in the received agreement in node place that continues re-assembly ATM cell to cell of data or the bag in.
An operation A TM network with between source node and destination node by atm network selectively with the method for connectionless-mode or connection-oriented mode transmit cell, each has a network address described source node and destination node, each ATM cell comprises a stature and a User Part, and described atm network comprises that one of them is the network of the interconnecting nodes of switching node a bit;

Passing through under the situation of Network Transmission ATM cell between ATM input interface and the ATM output interface with connectionless-mode, described method comprises step:

At the ATM input interface, a field in the ATM cell head be set to an indication do not have to connect the value of transmission and insert a destination address and a source address to the end in, this source address is the network address of source node, destination address is the network address of destination node; With

Each switching node between ATM input interface and ATM output interface, determine that by the described field in the read head this cell will be forwarded with connectionless-mode, destination address in the read head is selected output port according to destination address at least, and this cell is forwarded on the selecteed output port.

Passing through under the situation of Network Transmission ATM cell between ATM input interface and the ATM output interface in connection-oriented mode, described method comprises step:

At the ATM input interface, identifier of the virtual route (VPI) and virtual channel identifier (VCI) field in the head are set; And

Each switching node between ATM input interface and ATM output interface, the VPI of read head and/or vci field are selected output port according to VPI and/or VCI value, upgrade VPI and/or vci field, and transmit this cell to selecteed output port.
11. one kind is used for from a source node at least one destination node transmission ATM(Asynchronous Transfer Mode) cell, between ATM input interface and ATM output interface, to provide the multicast service method with connectionless-mode by atm network, described ATM cell comprises a stature and a User Part, described network comprises that one of them is the network of the interconnecting nodes of switching node a bit, and described method comprises step:

At the ATM input interface, a field in the head be set to an indication do not have to connect the value of transmission and insert a source address and a destination address to the end in, this source address is the network address of source node, this destination address is the network address of multicast service; And

Each switching node between ATM input interface and ATM output interface, determine that by the described field in the read head this cell will be forwarded with connectionless-mode, destination address in the read head, at least select at least one output port according to destination address, and this cell is forwarded at least one selecteed output port.