CA2157877A1 - Label handling in packet networks - Google Patents
Label handling in packet networksInfo
- Publication number
- CA2157877A1 CA2157877A1 CA002157877A CA2157877A CA2157877A1 CA 2157877 A1 CA2157877 A1 CA 2157877A1 CA 002157877 A CA002157877 A CA 002157877A CA 2157877 A CA2157877 A CA 2157877A CA 2157877 A1 CA2157877 A1 CA 2157877A1
- Authority
- CA
- Canada
- Prior art keywords
- label
- data packet
- sublist
- table look
- switch unit
- Prior art date
- Legal status (The legal status 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 status listed.)
- Abandoned
Links
Classifications
-
- 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
- H04L49/309—Header conversion, routing tables or routing tags
-
- 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
- H04L49/3009—Header conversion, routing tables or routing tags
-
- 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
- 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
- H04L49/25—Routing or path finding in a switch fabric
- H04L49/253—Routing or path finding in a switch fabric using establishment or release of connections between ports
Abstract
In a packet network for electronic transfer of data packets from an end station to another end station there are, in the conventional way, a number of switch units. Each end station is connected to a switch unit and the switch units perform the transfer of data packets along an established connection. The switch units are provided with switch ports on all of its connections. In these switch ports a substitution is performed of labels of the data packets, both for data packets arriving to a switch unit and for data packets forwarded from a switch unit. It is performed in order to avoid that data packets belonging to different connections will have the same label and also for offering distributed services in the data network. The data packet labels are constructed of a VPI field and a VCI field and for data packets, which arrive directly from or are sent directly to an end station, also a GFC-field. In the substitution of the label of a data packet arriving to a switch unit, in the associated switch port first a table look-up is performed by means of the contents of the VPI field of the data packet.
The result of the table look-up gives a direct information if the data packet belongs to a connection having a label comprising only a VPI field (VP connection) and then its contents are replaced by a record obtained in the table look-up. If the data packet has both a VPI and a VCI field (VP
connection), its VPI and VCI fields are replaced by new label portions obtained from a second table look-up.
The result of the table look-up gives a direct information if the data packet belongs to a connection having a label comprising only a VPI field (VP connection) and then its contents are replaced by a record obtained in the table look-up. If the data packet has both a VPI and a VCI field (VP
connection), its VPI and VCI fields are replaced by new label portions obtained from a second table look-up.
Description
U'O 94t21069 215 7 8 7 7 PCTtSE94tO0196 I.ABEL ~NI~-TNG IN PACXET NETWORRS
FIELD OF THE lNV~;~.LlON
The present invention is related to networks and switches for the transmission or transfer of data packets or data cells and in particular a proce~sing performed at the incr~;ng and outgoing side6 of a switch involving a translation of the labels, which data packets carry for identifying that they belong to a particular logical connection established through the network and the switch.
BACKGROUND OF THE lNV~;N-LlON AND PRIOR ART
In a data packet network it is required, in the transfer of data packets from sending units to receiving units through various nodes in the network, that each data packet can be uniquely as6igned a connection, which has been established earlier in the setup of the logical connection through the network. It is achieved by providing the data packets with labels, i.e. a special field comprising identification information. In the transfer in the network through many nodes, where the data packet is switched from an incoming connection line to an outgoing connection line, it may occur that data packets have been provided with the same label what will cause difficulties or even errors in the transmission.
Data packets belonging to different types of established connections may in addition have label fields of different formats, e.g. such that data packets belonging to some connections have a shorter label field while data packets belonging to other connections also have such a short label field but also in addition thereto a longer label field. In the second case the first short label field may then indicate a group of connections, of which the connection is a part. Such different parts may be present when for instance some established connections are assigned more permanent paths in the network than other connections. These different formats result in further problems in the processing of the labels of the individual data packets.
The data packets considered here are in the common way transmitted through the network from one end station to another WO94~1~9 PCT/SE94/00196 ~lS787~
end ~tation. The end station6 are then provided with a 6ingle connection interface, both for sending and for receiving, coupled through a connection line to an as60ciated connection node in the network. Special format restrictions may then be valid for the labels depen~ing if a data packet i6 tran6mitted directly from such an end station or is received by an end 6tation or if a data packet is in the proces~ of being forwarded between two 6witching nodes in the ~ystem.
Prior art for the handling of in particular addre6ses in data packets is disclosed e.g. in the documents US-A 4,894,822, US-A f 4,218,756, US-A 3,979,733, US-A 4,494,230, EP-A2 0 282 197, EP-A2 0 206 403, SU-A 478 445.
In the European patent application EP-A2 0 406 842 a packet switch network is disclosed comprising label proces6ing at incoming and outgoing links of a switch. Therein the numbers in data packets identifying the logical connection - VP or VC
number - are substituted by new numbers found in lists stored in memories at the incoming and outgoing sides of the 6witch. When many logical connections are to be 6imultaneously active, the lists will be correspondingly long and memory space therefor must be provided in the construction of the switch.
Label proces6ing is also disclosed in EP-A2 0 481 447, US-A
4,947,388, US-A 5,099,475, US-A 4,995,032, US-A 5,166,926. (~
DESCRIPTION OF THE lNv~.LlON
It is an object of the invention to provide a network and a packet ~witch allowing an efficient use of the memory space available for storing label conversion lists at the incnming and outgoing sides of a switch.
It is another object of the invention to provide a network and a switch allowing a correct h~n~l i ng of particular fields identifying the type of link, on which a data packet has arrived to a ~witch and on which it is to be transmitted from the switch.
W~94~1~9 ~1~ 7 8 7 7 PCT/SE94/00196 The objects mentioned above are achieved by a network and a switch according to the invention, by means of which al60 the difficulties mentioned above are avoided. The characteri6tics of the network and switch of the invention are set out in the appended claims.
The network for the tran6fer of data packets thus in the common way compri6es a number of end station6. from which the data packets are issued and which receive the data packets. The end 6tations comprise a connection or terminal point having a connection line extending to an as60ciated switch unit. The switch units are nodes in the network and have a number of co~nection points of which some can extend to end stations and other to other switch units. Connection lines connect the different connection or coupling points of the switch unit6.
Each connection point is bi-directed such that it comprises an output side and an input side. When information is to be forwarded from an end station to another one, in some way a connection is established in the network between these two end stations. This connection thus is a contemplated path through the network along which the various data packets in which the information to be transferred i6 carried, are guided through the network.
All switch units are on the connection points thereof provided with ports and in these a 6ubstitution is performed of a label in each data packet pas6ing through the connection line of the port. These labels are establi6hed in the establishment of the connection and indicate the connection to which a data packet belongs. The sub6titution of the label is performed to prevent that several connections have data packets with the same label and to simplify the handling of labels in the network, 6uch that each switch unit not neces6arily must be provided with information in regard of exactly all labels used in the network.
The sub6titution of the label of a data packet in the connection point, where the data packet arrives to a ~witch unit, can be supplemented by a substitution also in the port associated with the connection point, from which the data packet is forwarded from the switch unit.
wo g4J21069 2 1 S 7 8 7 ~ ~/SE94/OOlg6 As has already been mentioned, the substitution of the labels is performed to avoid that for-instance data packets-belonging to different connections, in their travel through a switch unit, will be provided with the same label. The label could in addition be used by each switch unit to send the data packet to the correct output connection point of the switch unit, but practically therefor a particular internal address is used being coded to control, in the simplest possible way, the various circuits from which the switching circuit6 or the switch core of the 6witch unit is constructed. The substitution of the label also on an output connection point is preferable, since hereby ~-distributed services can be offered in a simple way in the network. ThUs for instance a data packet which arrives to a switch unit, can be forwarded from the switch unit on several different connection lines and on these connection lines be ~-provided with, when it is necessary, different labels in order that a confusion with labels of already existent connections will not occur.
In the ~ubstitution of the label of a data packet which is performed in the ports of the switch unit, in some way a list is established ContA i n ing records with information relating to the method of sub6titution of the label of a data packet and also the new internal label~. For data packets arriving to a port all the internal labels and the corresponding arriving labels may thus be stored in this list, where the internal labels thus are (-the labels which a data packet will carry in its travel through the ~witch unit. This list can then for instance only contain all internal labels in a suitable sequence such that an internal address in the list has a position corresponding to the arriving label thereof, that is generally such that the list is addressed by means of the contents of the label field of the data packet or generally such that a table record is accessed in some way by means of the label of the data packet. A corresponding list may of cour~e be arranged for the substitution of the internal labels in a port, from which the data packets are forwarded, where thus all the internal labels and the corresponding forwarding labels are collected in a list.
w~s4m ~9 21 S ~ 8 7 7 PCT/SE94/00196 The labels of the data packets comprise two different parts, a first part and a second part, where only the first part is u6ed for some connections, say for connections of a first kind, and both the first and the second part is used for other connections, say for connections of a second kind. A table look-up by means of the whole label field and for the sub6titution of the whole label could be performed if a sufficiently large and rapid memory was arranged for the list used in the table look-up. In order to reduce the requirement of memory a table look-up is performed, there is performed a first table look-up with the first part of the label of an arriving data packet as an entry or addres6 in a first subli6t. Hereby information can also be obtained in regard of the kind of connection to which the data packet belongs, i.e. if it belongs to a connection which has only a first label part, or if it belongs to the kind of connection which has both a first and a second label part.
Further, in the first table look-up the new label part can be obtained which is to replace the first label part. In the case where the data packet belongs to a connection of the second kind, it could, however, also be considered that this sub6titution of the first part also is performed, but preferably the whole label comprising the first and second part is replaced by a new or a second table look-up in a second subli6t. As an entry or address to this second list a pointer can be used based on both information obtained in the first table look-up and the second label part of the data packet. Further in some way information is also inserted in the data packet in regard of the kind of connection to which the data packet belongs or generally if the data packet uses only the first label field or the two parts. This information is only retained internally in the switch unit and is removed on the output port, from which the data packet is forwarded from the switch unit.
The table look-up can be performed in the same way in an output port, where the internal label is substituted by a forwarding label.
Further data packets which arrive directly from an end station or are forwarded directly to an end station, can have a first ~094/~1~9 2 1 ~ 7 ~ ~ 7 ~ PCT/SE94/00196 label format, for instance in the shape of a short field, and the data packets being forwarded between ~witch unit6 have a second label format, for instance in the shape of a longer field, such that the short field is a part of the longer field.
In the e~tablishment of a connection then the various label formats are established which are valid for data packets belonging to this ro~nection, by the fact that in~icAtor elements, for instance specific data bits in ~ome register or memory, are transferred to various signal positions valid for the connection, i.e. if data bits are used, that they are set or reset. When a data packet then arrives to a switch unit and to a port thereof, it is decided in this arriving port by means of a the appropriate indicator element, if the packet from the switch unit is to be forwarded directly to an end station and, if it i5 the case, the label of the data packet is substituted by an internal label having the first format, and otherwise the label of the data packet is substituted by an internal label having the second format. In the case where the fir~t label format is a short field being a part of a longer field, which constitutes the second label format, when necessary for some transfers, a longer field may be filled with data bits in the form of zeroes, such as in a transfer from shorter to longer field~ for the label.
The lists, in which the table look-up according to the above is performed, can also be organized such that the possible contents of a data packet arrived to or received by a port, this data packet arriving from the outside or from the switch unit itself, are stored in a sequential order. Then the new contents of the label field are obtained from the position or the sequential number of the contents of the data packet in this list. This organization of a list is chosen, when an ordinary list would require too much memory space.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described with reference to an embodiment, which is given in an explaining but not limiting purpose and which is illustrated in the aCcnmrAnying drawings, in which w~ 94nl069 2 ~ 5 7 ~ ~ ~ PCTISE94l~6 - Fig. 1 is a schematic picture generally showing a network, - Figs. 2 and 3 show two different formats for the label portions of packets in the network, where the translation thereof at the arrival to a switching node is ~chematic~lly illustrated in the lower portion of the figures, - Fig. 4 shows the structure of a table for a part of the label which is associated with connections established more permanently than other c~nnections, - Fig. 5 6hows a table for the processing of a ~econd part of the label, - Fig. 6 shows an alternative ~tructure of a table for the processing of the whole label of an arriving data packet, - Fig. 7 schematically illustrates the hAn~ling of a label of a data packet in an incoming side of an interface unit of a node in the network, - Fig~. 8 and 9 show the two different formats of the label parts of packets in the network, where the translation thereof at the forwarding from a switching node is schematically illustrated in the lower portion of the figures, - Fig. 10 schematically illustrates the handling of the label of a data packet on an output side of an interface unit of a node in the network.
PREFERRED EMBODIMENT
In Fig. 1 a network is schematically illustrated intended for the transfer of data packets, ~uch as between end stations or terminals 1. The end stations 1 are thus both receivers and senders of the data packets, i.e. the origins or sources and the destinations of data packets considered here. The network in addition comprises a multitude of intermediate switching points or switches 3. Each end station 1 has basically only one connection point (not shown) which is bidirected and thus is arranged both for receiving and sending data packets. This connection point or unit i8 through appropriate lines coupled to ;a connection point 4 of a switching unit 3. The switch units 3 ---have several such connection points 4, which are also bidirected. The switching units 3 are, through some of their connection points, connected to other similar switching or ~ch~nge units 3.
21 j7g77 U094~1~9 ~ PCT/SE94100196 When an end 6tation l requests to 6tart sending data packet6 in the network to another end station l, a logical signal path is e6tabli6hed through the network. Such a path can be established by the ~Yc~Ange of various message6 or control information between the 6witch units 3.-When a connection path i6 e6tsbli6hed, a me6~age can be transmitted to the end 6tation l, which ha6 reque6ted the connection, that the connection now i6 e6tablished and is ready to be used for the transfer of data packets from the end station.
For each ~witch unit 3 its connection points 4 are provided by f 6witching ports 5, one switching port arranged for each connection point. Every ~witching port 5 is divided into an input, incoming or arriving side 5a and an output, outgoing or forwarding ~ide 5b, 6uch that each data packet outgoing from a switch unit 3 will pass through the output side 5b of a switching port 5 and a data packet arriving to a switch unit 3 will pass through the input side 5a of a switching port 5. The phy~ical links or connections between a end station l and its as60ciated switch unit 3, this type of links in the figures being indicated as UNI, can be constructed differently and have other requirements on the connection and on the structure of the data packets than links or connections between two switch units, which in the figures are indicated as being type NNI.
In the transport through the network the data packets are provided with a field for identification of the packet and also contAining other information relating to the hAn~ling of the content~ of the data packet, and further the real or proper information field of the packet contAining the user information which is to be transported from the source end station to the destination station. The identification field comprises a label field, the general configuration of which is illustrated at the top in Figs. 2 and 3. The number or generally the information in this field i~entifies the estAhli~hed connection, to which the ; -data packet belongs.
A data packet forwarded on link from and to an end station has a label field with the configuration as indicated at the top of
FIELD OF THE lNV~;~.LlON
The present invention is related to networks and switches for the transmission or transfer of data packets or data cells and in particular a proce~sing performed at the incr~;ng and outgoing side6 of a switch involving a translation of the labels, which data packets carry for identifying that they belong to a particular logical connection established through the network and the switch.
BACKGROUND OF THE lNV~;N-LlON AND PRIOR ART
In a data packet network it is required, in the transfer of data packets from sending units to receiving units through various nodes in the network, that each data packet can be uniquely as6igned a connection, which has been established earlier in the setup of the logical connection through the network. It is achieved by providing the data packets with labels, i.e. a special field comprising identification information. In the transfer in the network through many nodes, where the data packet is switched from an incoming connection line to an outgoing connection line, it may occur that data packets have been provided with the same label what will cause difficulties or even errors in the transmission.
Data packets belonging to different types of established connections may in addition have label fields of different formats, e.g. such that data packets belonging to some connections have a shorter label field while data packets belonging to other connections also have such a short label field but also in addition thereto a longer label field. In the second case the first short label field may then indicate a group of connections, of which the connection is a part. Such different parts may be present when for instance some established connections are assigned more permanent paths in the network than other connections. These different formats result in further problems in the processing of the labels of the individual data packets.
The data packets considered here are in the common way transmitted through the network from one end station to another WO94~1~9 PCT/SE94/00196 ~lS787~
end ~tation. The end station6 are then provided with a 6ingle connection interface, both for sending and for receiving, coupled through a connection line to an as60ciated connection node in the network. Special format restrictions may then be valid for the labels depen~ing if a data packet i6 tran6mitted directly from such an end station or is received by an end 6tation or if a data packet is in the proces~ of being forwarded between two 6witching nodes in the ~ystem.
Prior art for the handling of in particular addre6ses in data packets is disclosed e.g. in the documents US-A 4,894,822, US-A f 4,218,756, US-A 3,979,733, US-A 4,494,230, EP-A2 0 282 197, EP-A2 0 206 403, SU-A 478 445.
In the European patent application EP-A2 0 406 842 a packet switch network is disclosed comprising label proces6ing at incoming and outgoing links of a switch. Therein the numbers in data packets identifying the logical connection - VP or VC
number - are substituted by new numbers found in lists stored in memories at the incoming and outgoing sides of the 6witch. When many logical connections are to be 6imultaneously active, the lists will be correspondingly long and memory space therefor must be provided in the construction of the switch.
Label proces6ing is also disclosed in EP-A2 0 481 447, US-A
4,947,388, US-A 5,099,475, US-A 4,995,032, US-A 5,166,926. (~
DESCRIPTION OF THE lNv~.LlON
It is an object of the invention to provide a network and a packet ~witch allowing an efficient use of the memory space available for storing label conversion lists at the incnming and outgoing sides of a switch.
It is another object of the invention to provide a network and a switch allowing a correct h~n~l i ng of particular fields identifying the type of link, on which a data packet has arrived to a ~witch and on which it is to be transmitted from the switch.
W~94~1~9 ~1~ 7 8 7 7 PCT/SE94/00196 The objects mentioned above are achieved by a network and a switch according to the invention, by means of which al60 the difficulties mentioned above are avoided. The characteri6tics of the network and switch of the invention are set out in the appended claims.
The network for the tran6fer of data packets thus in the common way compri6es a number of end station6. from which the data packets are issued and which receive the data packets. The end 6tations comprise a connection or terminal point having a connection line extending to an as60ciated switch unit. The switch units are nodes in the network and have a number of co~nection points of which some can extend to end stations and other to other switch units. Connection lines connect the different connection or coupling points of the switch unit6.
Each connection point is bi-directed such that it comprises an output side and an input side. When information is to be forwarded from an end station to another one, in some way a connection is established in the network between these two end stations. This connection thus is a contemplated path through the network along which the various data packets in which the information to be transferred i6 carried, are guided through the network.
All switch units are on the connection points thereof provided with ports and in these a 6ubstitution is performed of a label in each data packet pas6ing through the connection line of the port. These labels are establi6hed in the establishment of the connection and indicate the connection to which a data packet belongs. The sub6titution of the label is performed to prevent that several connections have data packets with the same label and to simplify the handling of labels in the network, 6uch that each switch unit not neces6arily must be provided with information in regard of exactly all labels used in the network.
The sub6titution of the label of a data packet in the connection point, where the data packet arrives to a ~witch unit, can be supplemented by a substitution also in the port associated with the connection point, from which the data packet is forwarded from the switch unit.
wo g4J21069 2 1 S 7 8 7 ~ ~/SE94/OOlg6 As has already been mentioned, the substitution of the labels is performed to avoid that for-instance data packets-belonging to different connections, in their travel through a switch unit, will be provided with the same label. The label could in addition be used by each switch unit to send the data packet to the correct output connection point of the switch unit, but practically therefor a particular internal address is used being coded to control, in the simplest possible way, the various circuits from which the switching circuit6 or the switch core of the 6witch unit is constructed. The substitution of the label also on an output connection point is preferable, since hereby ~-distributed services can be offered in a simple way in the network. ThUs for instance a data packet which arrives to a switch unit, can be forwarded from the switch unit on several different connection lines and on these connection lines be ~-provided with, when it is necessary, different labels in order that a confusion with labels of already existent connections will not occur.
In the ~ubstitution of the label of a data packet which is performed in the ports of the switch unit, in some way a list is established ContA i n ing records with information relating to the method of sub6titution of the label of a data packet and also the new internal label~. For data packets arriving to a port all the internal labels and the corresponding arriving labels may thus be stored in this list, where the internal labels thus are (-the labels which a data packet will carry in its travel through the ~witch unit. This list can then for instance only contain all internal labels in a suitable sequence such that an internal address in the list has a position corresponding to the arriving label thereof, that is generally such that the list is addressed by means of the contents of the label field of the data packet or generally such that a table record is accessed in some way by means of the label of the data packet. A corresponding list may of cour~e be arranged for the substitution of the internal labels in a port, from which the data packets are forwarded, where thus all the internal labels and the corresponding forwarding labels are collected in a list.
w~s4m ~9 21 S ~ 8 7 7 PCT/SE94/00196 The labels of the data packets comprise two different parts, a first part and a second part, where only the first part is u6ed for some connections, say for connections of a first kind, and both the first and the second part is used for other connections, say for connections of a second kind. A table look-up by means of the whole label field and for the sub6titution of the whole label could be performed if a sufficiently large and rapid memory was arranged for the list used in the table look-up. In order to reduce the requirement of memory a table look-up is performed, there is performed a first table look-up with the first part of the label of an arriving data packet as an entry or addres6 in a first subli6t. Hereby information can also be obtained in regard of the kind of connection to which the data packet belongs, i.e. if it belongs to a connection which has only a first label part, or if it belongs to the kind of connection which has both a first and a second label part.
Further, in the first table look-up the new label part can be obtained which is to replace the first label part. In the case where the data packet belongs to a connection of the second kind, it could, however, also be considered that this sub6titution of the first part also is performed, but preferably the whole label comprising the first and second part is replaced by a new or a second table look-up in a second subli6t. As an entry or address to this second list a pointer can be used based on both information obtained in the first table look-up and the second label part of the data packet. Further in some way information is also inserted in the data packet in regard of the kind of connection to which the data packet belongs or generally if the data packet uses only the first label field or the two parts. This information is only retained internally in the switch unit and is removed on the output port, from which the data packet is forwarded from the switch unit.
The table look-up can be performed in the same way in an output port, where the internal label is substituted by a forwarding label.
Further data packets which arrive directly from an end station or are forwarded directly to an end station, can have a first ~094/~1~9 2 1 ~ 7 ~ ~ 7 ~ PCT/SE94/00196 label format, for instance in the shape of a short field, and the data packets being forwarded between ~witch unit6 have a second label format, for instance in the shape of a longer field, such that the short field is a part of the longer field.
In the e~tablishment of a connection then the various label formats are established which are valid for data packets belonging to this ro~nection, by the fact that in~icAtor elements, for instance specific data bits in ~ome register or memory, are transferred to various signal positions valid for the connection, i.e. if data bits are used, that they are set or reset. When a data packet then arrives to a switch unit and to a port thereof, it is decided in this arriving port by means of a the appropriate indicator element, if the packet from the switch unit is to be forwarded directly to an end station and, if it i5 the case, the label of the data packet is substituted by an internal label having the first format, and otherwise the label of the data packet is substituted by an internal label having the second format. In the case where the fir~t label format is a short field being a part of a longer field, which constitutes the second label format, when necessary for some transfers, a longer field may be filled with data bits in the form of zeroes, such as in a transfer from shorter to longer field~ for the label.
The lists, in which the table look-up according to the above is performed, can also be organized such that the possible contents of a data packet arrived to or received by a port, this data packet arriving from the outside or from the switch unit itself, are stored in a sequential order. Then the new contents of the label field are obtained from the position or the sequential number of the contents of the data packet in this list. This organization of a list is chosen, when an ordinary list would require too much memory space.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described with reference to an embodiment, which is given in an explaining but not limiting purpose and which is illustrated in the aCcnmrAnying drawings, in which w~ 94nl069 2 ~ 5 7 ~ ~ ~ PCTISE94l~6 - Fig. 1 is a schematic picture generally showing a network, - Figs. 2 and 3 show two different formats for the label portions of packets in the network, where the translation thereof at the arrival to a switching node is ~chematic~lly illustrated in the lower portion of the figures, - Fig. 4 shows the structure of a table for a part of the label which is associated with connections established more permanently than other c~nnections, - Fig. 5 6hows a table for the processing of a ~econd part of the label, - Fig. 6 shows an alternative ~tructure of a table for the processing of the whole label of an arriving data packet, - Fig. 7 schematically illustrates the hAn~ling of a label of a data packet in an incoming side of an interface unit of a node in the network, - Fig~. 8 and 9 show the two different formats of the label parts of packets in the network, where the translation thereof at the forwarding from a switching node is schematically illustrated in the lower portion of the figures, - Fig. 10 schematically illustrates the handling of the label of a data packet on an output side of an interface unit of a node in the network.
PREFERRED EMBODIMENT
In Fig. 1 a network is schematically illustrated intended for the transfer of data packets, ~uch as between end stations or terminals 1. The end stations 1 are thus both receivers and senders of the data packets, i.e. the origins or sources and the destinations of data packets considered here. The network in addition comprises a multitude of intermediate switching points or switches 3. Each end station 1 has basically only one connection point (not shown) which is bidirected and thus is arranged both for receiving and sending data packets. This connection point or unit i8 through appropriate lines coupled to ;a connection point 4 of a switching unit 3. The switch units 3 ---have several such connection points 4, which are also bidirected. The switching units 3 are, through some of their connection points, connected to other similar switching or ~ch~nge units 3.
21 j7g77 U094~1~9 ~ PCT/SE94100196 When an end 6tation l requests to 6tart sending data packet6 in the network to another end station l, a logical signal path is e6tabli6hed through the network. Such a path can be established by the ~Yc~Ange of various message6 or control information between the 6witch units 3.-When a connection path i6 e6tsbli6hed, a me6~age can be transmitted to the end 6tation l, which ha6 reque6ted the connection, that the connection now i6 e6tablished and is ready to be used for the transfer of data packets from the end station.
For each ~witch unit 3 its connection points 4 are provided by f 6witching ports 5, one switching port arranged for each connection point. Every ~witching port 5 is divided into an input, incoming or arriving side 5a and an output, outgoing or forwarding ~ide 5b, 6uch that each data packet outgoing from a switch unit 3 will pass through the output side 5b of a switching port 5 and a data packet arriving to a switch unit 3 will pass through the input side 5a of a switching port 5. The phy~ical links or connections between a end station l and its as60ciated switch unit 3, this type of links in the figures being indicated as UNI, can be constructed differently and have other requirements on the connection and on the structure of the data packets than links or connections between two switch units, which in the figures are indicated as being type NNI.
In the transport through the network the data packets are provided with a field for identification of the packet and also contAining other information relating to the hAn~ling of the content~ of the data packet, and further the real or proper information field of the packet contAining the user information which is to be transported from the source end station to the destination station. The identification field comprises a label field, the general configuration of which is illustrated at the top in Figs. 2 and 3. The number or generally the information in this field i~entifies the estAhli~hed connection, to which the ; -data packet belongs.
A data packet forwarded on link from and to an end station has a label field with the configuration as indicated at the top of
2~7~77 W~94/21~9 - PCT/SE94/00196 Fig. 2. The label field comprises three subfields, a field of four bit6, in the figure indicated as GFC, a field of eight bits, in the figure in~icAted a~ VPI, and a field of sixteen bits, in the figure indicated as VCI. When a packet comprising a label field having this configuration is forwarded from an end 6tation l to the as60ciated 6witch unit, in the 6witching port 5 of the switch unit, to which the data packet will first arrive in the travel through the network, the information in the VPI
field and pos6ibly also the information in the VCI field are replaced or translated. If the data packet from this most adjacent switch unit 3 is to be sent back immediately to an end station l without any transport through other 6witch units, the field GFC of the data packet is not affected. Otherwise, when the data packet is to be transmitted further in the network and travel through another or several 6witch units 3, the GFC field is removed and the data packet is given the configuration illustrated at the top of Fig. 3.
The actual labels are comprised or written in the fields called VPI and VCI respectively. Some connections, called VP
connections, have only information in the VPI field, while other connections, called VC connections, have information both in the field VPI and the field VCI. When a data packet arrives to a switch unit 3, it may happen, that its label as specified in the fields VPI and/or VCI coincides with the label of another connection and that data packets of this other connection arrive to the same switch unit 3 on another input port. To avoid a confu6ion of such labels the label fields are translated to or ~ubstituted by an internal label in the 6witching port or interface unit 5, on which the data packet arrives to the switch unit 3. In the case where data packets arrive directly from an end station, their label field thus has the configuration as illustrated at the top in Fig. 2. The label field is acces6ed in the switching port 5, i.e. in the input side Sa thereof, in order to be processed.
At the bottom in Fig. 2 the procedure is illustrated, in-thi6 case with data packets arriving directly from an end station, for changing the label field in the switching port S. From the W~94n1~9 215 7 8 7 7 PCT/SE94tO0196 label field first the information carried in the VPI field i6 acces6ed. By means of thi6 information a table look-up in a database or register is performed. From this table look-up information is first obtained, whether the data packet belongs to a VP connection or a VC connection. Further also information i~ obtained, whether the data packet is to be forwarded to an end station connection of the same kind, which here as above is called a UNI link, or if the packet is to be conveyed further in the network, the latter case a6 above also being called that the packet is to be forwarded next through an NNI link.
For the case when a packet arrives on a UNI link, the packet belongs to a VP connection and is to be forwarded directly to another end ~tation connected to the same ~witch unit, that is to a UNI link, only the contents of the VPI field in the original data packet are substituted by a new VPI number, which is obtained directly from the table look-up, without any change of the length of the VPI field. If the data packet belongs to a VP connection but instead is to be forwarded to an NNI link, the VPI field is enlarged to comprise also the GFC field, such that the information in the GFC field and the VPI field is replaced by a new longer VPI number obtained in the table look-up. In the latter ca6e, the GFC field is thus removed and in both cases the information in the VCI field is not affected.
If the data packet in the table look-up instead is decided to belong to a VC connection, in the table look-up new information is obtained which is used for an additional table look-up. At the same time other information is also obtained, in particular as above information whether the data packet is to be sent to a UNI link or to an NNI link. If the data packet is to be sent to a UNI link, the information in the VPI and VCI fields is substituted by the information obtained in this later table look-up, thus the VPI and VCI fields of the packet being merged to one field. In the correspon~ing way the GFC, VPI-and VCI
field~ are merged to one field and then thus the contents of these GFC, VPI and VCI fields are replaced by a new unified VPI
and VCI number, when the packet is to be forwarded to an NNI
link. In the latter case, thus also the information in the GFC
W~94~1~9 2 1 S 7 8 7 7 PCT/SE94lOOV6 field is overwritten.
Further, both for VP and VC connections an additi~nAl information unit is inserted in the data packet in its identification part but out6ide the label field, in the shape of an addressing mode bit AM, in~icAting if the data packet belongs to a VP connection or to a VC connection.
A data packet arriving to a switch unit 3 on a connection line, which is not directly connected to an end station l, has the configuration illustrated at the top in Fig. 3. Here there is a VPI field comprising 12 bits and a VCI field compri6ing 16 bits.
In the substitution or replacement of the information in the VPI
and VCI label fields inside the identification field of the arriving data packet a procedure is performed analogous to the one described above, with the exception that here there is no GFC field and, that when the packet is to be sent to a UNI link, a zeroed or reset GFC field is inserted, c~rAre the lower part of Fig. 3.
Thus first a table look-up is performed by means of the contents of the VPI field. From the table look-up information is first obtained if the data packet belongs to a VP or a VC connection.
In the former case also information is obtained if the packet is to be sent to a UNI or NNI connection. If the packet is decided to belong to a VP connection and is to be sent to a UNI link, in the beginning of the VPI field a reset GFC field comprising four zero bits is inserted, such that the VPI field i~ shortened, and further in this new shorter VPI field information is inserted which has been obtained in the table look-up. If the packet instead i~ to be next transferred through an NNI link, the information in the VPI field of the data packet is substituted by information obtained in the table look-up. In these two cases the information in the VCI field is unaffected. When it in the table look-up instead has been decided that-the data-packet-belongs to a VC connection, an additionAl table look-up is performed based both on the-information which has been obtained in the first table look-up and by means of the information present in the VCI field of the data packet. In this second ~1~787~
Wo94~1~s PCT1SE94/~196 table look-up, a6 above, information is obtained, whether the data packet i6 to be forwarded on a UNI or an NNI link. In the UNI ca6e, in the beginning of the label, a6 above a re6et GFC
field i6 in~erted, which thu6 will be a part of the original VPI
field. Further a new label i6 obtained, which for tran6mi~6ion through a UNI link ha6 a corre6pondingly 6horter length and in the shape of a unified VPI and VCI number it i6 in6erted in both the re6t of the VPI field and the whole VCI field in the original data packet. In the tr~nEmi66ion through an NNI link the new unified VPI and VCI number ha6 a whole length and replaces the all Gf the original VPI and VCI field6. Further, the addres6ing mode bit AM i6 inserted in the data packet in the ~ame way a6 de6cribed above.
In Fig6. 4 and 5 it is 6chematically illu6trated a po66ible organization of the tables, in which table look-up6 are performed in the translations or substitution6, de6cribed above with reference to Figures 2 and 3, of the label6 on an incoming link.
A6 i6 illu6trated in Fig. 4, for each VPI number, that i6 for each contents of the VPI field, of an incoming data packet there i6 a record of three field6. The content6 of the field illu6trated rightmo6t in the figure indicate if the connection i6 a VP connection or a VC connection. Thi6 field i8 a 6imple flag field comprising one bit and storing the value l or 0.
There i8 another 6irilAr flag field compri6ing one bit, which i6 ~hown to the left of the mentioned field. Thi6 middle field contain6 a flag, indicating if the connection will next continue-to a link of type UNI or type NNI. Further there i6 in each record in the table a longer part compri6ing 12 bit6, in which, for VP connectiGn6, the new internal label i6 located or stored.
In the ca~e where the connection will next continue to a UNI
link, however, the four fir6t bit6 in thi6 field are not used.
In the case where the connect~on i6- a VC connection, there i~
instead of a new internal label a ba6e addre66 located in the mentioned field. Thi6 base addres6 is used in the ~econd table look-up.
- 2~78~F7 W094/21069 PCT/SE94/~lg6 In Fig. 5 the structure of the second table is gchematically illustrated, which is used only for VC connections. The table contain~ a number of records, which are addres6ed by means of both the base addres6 which has been taken from the table of Fig. 4, and the VCI number of the data packet, that is the contents of the VCI field of the packet, for instance by an addition of the base addres6 and the VCI number of the data packet. In the same way as in the table of Fig. 4, there is in each record a flagfield of one bit length storing a flag indicating if the connection next continues to a UNI or NNI
connectiQn respectively. In a longer field the information is located which i6 to replace the contents of the VPI and VCI
fields of the data packet. In a practical case with a number of simultaneou61y establi6hed connections which is not too great, this new field can for instance comprise 16 bits and contain the new internal label, which in this case then will replace the information only in the VCI field of the data packet, while in the information in the VPI field is reset. If desired, the record can of course contain a still longer field at most comprising 28 bits, if the number of connections simultaneou61y established is very large.
An alternative structure of a table used for the label translation of an arriving data packet is illustrated in Fig. 6.
Here for an incoming link of NNI type, all possible contents of the whole label field considered as one field, i.e. the joined VPI and VCI fields of an arriving data packet, are listed or stored in a sequential order. For an incoming link of UNI type the unified contents of the VPI and VCI fields of the incoming data packets, in the same way considered as one field, are inserted and stored in a sequential order (this case is not shown). The whole internal label of a data packet belonging to some connection is in this case obtained from the position of the label of the data packet in the list of contents, or from the address of the position in a memory, where exactly these ;--contents are stored. For every possible contents there is like above a sLmple bit position having-a flag indicating if the dat-a packet i5 to be forwarded next to an output of the switch unit connected to a link of UNI or NNI type.
~ 2 ~ 7 7 ~Os4nl~s ~ PCT1SE94/00196 In Fig. 7 a block diagram i~ shown illustrating the label processing in the input side of an interface unit, where a table structure according to Figures 4 and 5 is used, the interface unit being connected to a switch unit 3. The data packets first arrive to a buffer 601 snd here, from a received packet, its label field is accecsed or extracted in a block 603 and it i8 stored in a register or memory field 604. Then only the VPI
field is taken out of the whole label field stored in 604 in a block 605, where the length of the VPI field is determined by means of a flag, which i6 ~tored in a memory cell 607 and has been set earlier in the configuration or ~etup of the switching ~~
port, to provide an indication if the input link is of UNI or NNI type. By means of the contents of the VPI field a table look-up is performed in a block 609 in a write and read memory 611 and a table record 610 i~ obtained temporarily stored in a memory field 610. By means of the result of the table look-up it is decided in a block 612, if the data packet belongs to a VP
connection or a VP connection. In the former case the table look-up directly gives a new VPI field 614, which is formed in a block 613, and also a flag "UNI/NNI out" indicating, if the output link, to which the data packet will be forwarded next, is of UNI or NNI type. Both the new VPI field and the obtained flag of output link are fed to logic circuits 617 for the insertion of a new VPI field, the length thereof being determined by the flag "UNI/NNI out', and for a possible reset of a now formed GFC
field, determined by the two flags "UNI/NNI in" and "UNI/NNI utn t in combination. Therefor the logic circuits 617 also need information whether the input link is of UNI or NNI type, which is obtained from the flag "UNI/NNI in" stored in the memory -field 607. The logic circuits 617 for the insertion then place the new label information and the addressing mode bit AM in the data packet when it for instance travels through a buffer 619.
The buffers 601 and 619 may be the same physical buffer.
When in the block 612 for the decision based on the result of - - - -the table look-up in the block 609, it is instead decided, that the arrived data packet belongs to a VC connection, a new address is formed in a block 621 by means of the contents of the VCI field of the data packet and also by means of the table WO 94~1~g 2 1 ~ 7 8 7 7 PCT/SE94/~196 record stored in the cell 610 contAining the result of the table look-up already performed in the block 609. An alternative hereto is to directly use, instead of the result of this former table look-up, the contents of the VPI field used in the block 605. Then another table look-up is performed in a block 623 in the write and read memory 611. Here as above a table record stored in a memory field 624 is obtained contAining among other things a flag "UNI/NNI out" indicating, if the link, to which the data packet will be next transferred, is of UNI or NNI type respectively. Further, in a block 627 a new unified VPI and VCI
field is obtained and temporaxily stored in a memory field 628.
The unified field stored in the field 628 obtained in this later table look-up i~ as above tran~ferred to a logic block 620, to insert in the data packet in the buffer 609 the new label in the VCI field, in the corresponding case a reset of the part of the VPI field which will form a new GFC field, and pos6ibly a further reset of the rest of the unified VCI and VPI field and insertion of the addressing mode bit AM which in this case indicates that the data packet belongs to a VC connection.
Therefore, like the block 617, also this block 629 need~
information from the memory cell 607, whether the link on which the data packet arrived is of UNI or NNI type respectively.
From the second buffer 619 the data packet is then transferred to the as60ciated switch unit 3.
Inside the switching units 3 the data packets are transferred from an input connection point given in the establishment of the logical connection, to an output connection point by means of specific addresses, which are inserted in a particular, added internal header field, at the arrival of the data packet to a switch unit. These internal addresses are given in such a form that they easily can be decoded, for instance dPCoA~ directly by hardware, in the circuits inside the switch unit, without requiring any table look-up therefor. Data packets belonging to different connections can thus have the same internal address but they will always have different internal labels. At the arrival to an output connection point the internal header fields are removed and thus the internal address and then also a wo s4nl~s 21~ 7 8 7 ~ PCT/SE94l~lg6 sub6titution or replacement is performed of the information in the label of the data packet. It will be described more closely with reference to Figs. 8 and 9.
In Fig. 8, at the top thereof, thus the addressing mode bit AM
and the label part are shown in the two different formats for a data packet which is to be transferred to an output connection point, which, through its associated switching port, is connected directly to an end station, i.e. a UNI link. As is further apparent from Fig~ 8, it i8 decided by means of contents of the addressing mode bit, if the data packet belong~ to a VP
connection or a VC connection. The GFC field will in this case not be involved in the translation of the label part. It can contain information from earlier stages, if the data packet directly has arrived from a link of UNI type, or the field may contain only zeroes, if the packet has arrived to the switch unit on a link of NNI type. When the data packet, as is indicated by the AM bit, belongs to a VP connection, a table look-up is performed by means of the contents of the VPI field, and if the data packet belongs to a VC connection, all of the contents in the two fields VPI and VCI are used, where in many cases the VPI field will actually only contain zeroes and pocsibly the VCI field also in its most significant positions will have only zeroes. It is decided by the number of simultaneous connections which is to be handled by a switch unit and its switching ports. For a VP connection a new VPI number is ~--obtained and it is inserted in the VPI field, the VCI field in thi~ case being left unaffected. For a VC connection, from the table look-up a new VCI number is obtained, which is inserted in the VPI field of the data packet, and also a new VCI number which i6 inserted in the VCI field of the data packet. The addressing mode bit AM can be removed together with other information, which possibly has been added to the data packet in its travel through the switch unit, or be used for other purposes or simply be left.
Fig. 9 is drawn in the same way as Pig. 8 and illustrates the ca~e of substitution of the label fields for a data packet which i8 to be sent to a link of NNI type. In the data packet there is w~ 94mo6g 2 l 5 7 8 ~ 7 PCT/SE94/~lg6 then no GFC field and the VPI field or the unified VPI and VCI
field is then correspondingly longer. In the same way as in Fig.
8, in addition a table look-up i~ performed for the two cases of a VP connection and a VC connection. The sole difference is that the VPI field i6 longer.
In Fig. 10 a block diagram is drawn illustrating the proce~l~re of the substitution of labels is performed in a switching port of the output side of a 6witch unit. The data packets arrive from a switch unit 3 to a buffer 901, from which in a block 903, the label field of the data packet and the AM bit thereof are accessed and stored in a register or memory field 905. By means of the contents of the AM bit it is decided in a block 907, if the data packet belong~ to a vP connection or a Vc connection.
In the former case, in a block 909 a suitable address is formed by means of the address in the VPI field in regard of its length which is obtained by means of a flag "UNI/NNI out", which is obtained from a memory cell 911, contAining information if the output connection point is of UNI or NNI type. The table look-up for this case with a VP connection is performed in a block 913 by means of the address formed in the block 909. The table look-up is performed in a write and read memory 915. If it instead is decided in the block 907, that the data packet belongs to a VC
connection, in a block 917 an addre~s is formed by means of the contents of the VCI field of the data packet, in the general case the contents of both the VPI and VCI fields, but in a preferred practical case the VPI field in the label of the data packet is reset in its transfer through the switch unit 3. A
table look-up is then performed in a block 919 by means of the address formed in the block 917. From the write and read memory 915 information is obtained, which in a block 923 is used to form the conten~s of new VPI and VCI fields temporarily stored in a memory field 921. By means of the flag stored in the register 911 indicating, if the output link is of UNI or NNI
type and~hereby the length of the VPI field, the new label is inserted in the data packet in a block 925 comprising appropriate logic circuits. The data packet can be considered as being stored in a buffer 927, which actually can be identical to the earlier mentioned buffer 901, to which the cell stream 2157~77 Wo94~106s - PCT/SE94/00196 arrives directly from the 6witch. From the buffer 907 the data packet pa~se~ in the outgoing data packet 6tream through a connection line to an end station.
In a block 929 new content6, temporarily stored in a memory field 931, are formed in the case of a VP connection, by mean~
of the result of the table look-up in the block 913. The~e contents in the memory 931 are to be in6erted in the VPI field, and in the same way as for a VC connection there are logic circuits in a block 933 to insert these contents in the data packet which i~ ~upposed to be ~tored or hold in the buffer 927. f
field and pos6ibly also the information in the VCI field are replaced or translated. If the data packet from this most adjacent switch unit 3 is to be sent back immediately to an end station l without any transport through other 6witch units, the field GFC of the data packet is not affected. Otherwise, when the data packet is to be transmitted further in the network and travel through another or several 6witch units 3, the GFC field is removed and the data packet is given the configuration illustrated at the top of Fig. 3.
The actual labels are comprised or written in the fields called VPI and VCI respectively. Some connections, called VP
connections, have only information in the VPI field, while other connections, called VC connections, have information both in the field VPI and the field VCI. When a data packet arrives to a switch unit 3, it may happen, that its label as specified in the fields VPI and/or VCI coincides with the label of another connection and that data packets of this other connection arrive to the same switch unit 3 on another input port. To avoid a confu6ion of such labels the label fields are translated to or ~ubstituted by an internal label in the 6witching port or interface unit 5, on which the data packet arrives to the switch unit 3. In the case where data packets arrive directly from an end station, their label field thus has the configuration as illustrated at the top in Fig. 2. The label field is acces6ed in the switching port 5, i.e. in the input side Sa thereof, in order to be processed.
At the bottom in Fig. 2 the procedure is illustrated, in-thi6 case with data packets arriving directly from an end station, for changing the label field in the switching port S. From the W~94n1~9 215 7 8 7 7 PCT/SE94tO0196 label field first the information carried in the VPI field i6 acces6ed. By means of thi6 information a table look-up in a database or register is performed. From this table look-up information is first obtained, whether the data packet belongs to a VP connection or a VC connection. Further also information i~ obtained, whether the data packet is to be forwarded to an end station connection of the same kind, which here as above is called a UNI link, or if the packet is to be conveyed further in the network, the latter case a6 above also being called that the packet is to be forwarded next through an NNI link.
For the case when a packet arrives on a UNI link, the packet belongs to a VP connection and is to be forwarded directly to another end ~tation connected to the same ~witch unit, that is to a UNI link, only the contents of the VPI field in the original data packet are substituted by a new VPI number, which is obtained directly from the table look-up, without any change of the length of the VPI field. If the data packet belongs to a VP connection but instead is to be forwarded to an NNI link, the VPI field is enlarged to comprise also the GFC field, such that the information in the GFC field and the VPI field is replaced by a new longer VPI number obtained in the table look-up. In the latter ca6e, the GFC field is thus removed and in both cases the information in the VCI field is not affected.
If the data packet in the table look-up instead is decided to belong to a VC connection, in the table look-up new information is obtained which is used for an additional table look-up. At the same time other information is also obtained, in particular as above information whether the data packet is to be sent to a UNI link or to an NNI link. If the data packet is to be sent to a UNI link, the information in the VPI and VCI fields is substituted by the information obtained in this later table look-up, thus the VPI and VCI fields of the packet being merged to one field. In the correspon~ing way the GFC, VPI-and VCI
field~ are merged to one field and then thus the contents of these GFC, VPI and VCI fields are replaced by a new unified VPI
and VCI number, when the packet is to be forwarded to an NNI
link. In the latter case, thus also the information in the GFC
W~94~1~9 2 1 S 7 8 7 7 PCT/SE94lOOV6 field is overwritten.
Further, both for VP and VC connections an additi~nAl information unit is inserted in the data packet in its identification part but out6ide the label field, in the shape of an addressing mode bit AM, in~icAting if the data packet belongs to a VP connection or to a VC connection.
A data packet arriving to a switch unit 3 on a connection line, which is not directly connected to an end station l, has the configuration illustrated at the top in Fig. 3. Here there is a VPI field comprising 12 bits and a VCI field compri6ing 16 bits.
In the substitution or replacement of the information in the VPI
and VCI label fields inside the identification field of the arriving data packet a procedure is performed analogous to the one described above, with the exception that here there is no GFC field and, that when the packet is to be sent to a UNI link, a zeroed or reset GFC field is inserted, c~rAre the lower part of Fig. 3.
Thus first a table look-up is performed by means of the contents of the VPI field. From the table look-up information is first obtained if the data packet belongs to a VP or a VC connection.
In the former case also information is obtained if the packet is to be sent to a UNI or NNI connection. If the packet is decided to belong to a VP connection and is to be sent to a UNI link, in the beginning of the VPI field a reset GFC field comprising four zero bits is inserted, such that the VPI field i~ shortened, and further in this new shorter VPI field information is inserted which has been obtained in the table look-up. If the packet instead i~ to be next transferred through an NNI link, the information in the VPI field of the data packet is substituted by information obtained in the table look-up. In these two cases the information in the VCI field is unaffected. When it in the table look-up instead has been decided that-the data-packet-belongs to a VC connection, an additionAl table look-up is performed based both on the-information which has been obtained in the first table look-up and by means of the information present in the VCI field of the data packet. In this second ~1~787~
Wo94~1~s PCT1SE94/~196 table look-up, a6 above, information is obtained, whether the data packet i6 to be forwarded on a UNI or an NNI link. In the UNI ca6e, in the beginning of the label, a6 above a re6et GFC
field i6 in~erted, which thu6 will be a part of the original VPI
field. Further a new label i6 obtained, which for tran6mi~6ion through a UNI link ha6 a corre6pondingly 6horter length and in the shape of a unified VPI and VCI number it i6 in6erted in both the re6t of the VPI field and the whole VCI field in the original data packet. In the tr~nEmi66ion through an NNI link the new unified VPI and VCI number ha6 a whole length and replaces the all Gf the original VPI and VCI field6. Further, the addres6ing mode bit AM i6 inserted in the data packet in the ~ame way a6 de6cribed above.
In Fig6. 4 and 5 it is 6chematically illu6trated a po66ible organization of the tables, in which table look-up6 are performed in the translations or substitution6, de6cribed above with reference to Figures 2 and 3, of the label6 on an incoming link.
A6 i6 illu6trated in Fig. 4, for each VPI number, that i6 for each contents of the VPI field, of an incoming data packet there i6 a record of three field6. The content6 of the field illu6trated rightmo6t in the figure indicate if the connection i6 a VP connection or a VC connection. Thi6 field i8 a 6imple flag field comprising one bit and storing the value l or 0.
There i8 another 6irilAr flag field compri6ing one bit, which i6 ~hown to the left of the mentioned field. Thi6 middle field contain6 a flag, indicating if the connection will next continue-to a link of type UNI or type NNI. Further there i6 in each record in the table a longer part compri6ing 12 bit6, in which, for VP connectiGn6, the new internal label i6 located or stored.
In the ca~e where the connection will next continue to a UNI
link, however, the four fir6t bit6 in thi6 field are not used.
In the case where the connect~on i6- a VC connection, there i~
instead of a new internal label a ba6e addre66 located in the mentioned field. Thi6 base addres6 is used in the ~econd table look-up.
- 2~78~F7 W094/21069 PCT/SE94/~lg6 In Fig. 5 the structure of the second table is gchematically illustrated, which is used only for VC connections. The table contain~ a number of records, which are addres6ed by means of both the base addres6 which has been taken from the table of Fig. 4, and the VCI number of the data packet, that is the contents of the VCI field of the packet, for instance by an addition of the base addres6 and the VCI number of the data packet. In the same way as in the table of Fig. 4, there is in each record a flagfield of one bit length storing a flag indicating if the connection next continues to a UNI or NNI
connectiQn respectively. In a longer field the information is located which i6 to replace the contents of the VPI and VCI
fields of the data packet. In a practical case with a number of simultaneou61y establi6hed connections which is not too great, this new field can for instance comprise 16 bits and contain the new internal label, which in this case then will replace the information only in the VCI field of the data packet, while in the information in the VPI field is reset. If desired, the record can of course contain a still longer field at most comprising 28 bits, if the number of connections simultaneou61y established is very large.
An alternative structure of a table used for the label translation of an arriving data packet is illustrated in Fig. 6.
Here for an incoming link of NNI type, all possible contents of the whole label field considered as one field, i.e. the joined VPI and VCI fields of an arriving data packet, are listed or stored in a sequential order. For an incoming link of UNI type the unified contents of the VPI and VCI fields of the incoming data packets, in the same way considered as one field, are inserted and stored in a sequential order (this case is not shown). The whole internal label of a data packet belonging to some connection is in this case obtained from the position of the label of the data packet in the list of contents, or from the address of the position in a memory, where exactly these ;--contents are stored. For every possible contents there is like above a sLmple bit position having-a flag indicating if the dat-a packet i5 to be forwarded next to an output of the switch unit connected to a link of UNI or NNI type.
~ 2 ~ 7 7 ~Os4nl~s ~ PCT1SE94/00196 In Fig. 7 a block diagram i~ shown illustrating the label processing in the input side of an interface unit, where a table structure according to Figures 4 and 5 is used, the interface unit being connected to a switch unit 3. The data packets first arrive to a buffer 601 snd here, from a received packet, its label field is accecsed or extracted in a block 603 and it i8 stored in a register or memory field 604. Then only the VPI
field is taken out of the whole label field stored in 604 in a block 605, where the length of the VPI field is determined by means of a flag, which i6 ~tored in a memory cell 607 and has been set earlier in the configuration or ~etup of the switching ~~
port, to provide an indication if the input link is of UNI or NNI type. By means of the contents of the VPI field a table look-up is performed in a block 609 in a write and read memory 611 and a table record 610 i~ obtained temporarily stored in a memory field 610. By means of the result of the table look-up it is decided in a block 612, if the data packet belongs to a VP
connection or a VP connection. In the former case the table look-up directly gives a new VPI field 614, which is formed in a block 613, and also a flag "UNI/NNI out" indicating, if the output link, to which the data packet will be forwarded next, is of UNI or NNI type. Both the new VPI field and the obtained flag of output link are fed to logic circuits 617 for the insertion of a new VPI field, the length thereof being determined by the flag "UNI/NNI out', and for a possible reset of a now formed GFC
field, determined by the two flags "UNI/NNI in" and "UNI/NNI utn t in combination. Therefor the logic circuits 617 also need information whether the input link is of UNI or NNI type, which is obtained from the flag "UNI/NNI in" stored in the memory -field 607. The logic circuits 617 for the insertion then place the new label information and the addressing mode bit AM in the data packet when it for instance travels through a buffer 619.
The buffers 601 and 619 may be the same physical buffer.
When in the block 612 for the decision based on the result of - - - -the table look-up in the block 609, it is instead decided, that the arrived data packet belongs to a VC connection, a new address is formed in a block 621 by means of the contents of the VCI field of the data packet and also by means of the table WO 94~1~g 2 1 ~ 7 8 7 7 PCT/SE94/~196 record stored in the cell 610 contAining the result of the table look-up already performed in the block 609. An alternative hereto is to directly use, instead of the result of this former table look-up, the contents of the VPI field used in the block 605. Then another table look-up is performed in a block 623 in the write and read memory 611. Here as above a table record stored in a memory field 624 is obtained contAining among other things a flag "UNI/NNI out" indicating, if the link, to which the data packet will be next transferred, is of UNI or NNI type respectively. Further, in a block 627 a new unified VPI and VCI
field is obtained and temporaxily stored in a memory field 628.
The unified field stored in the field 628 obtained in this later table look-up i~ as above tran~ferred to a logic block 620, to insert in the data packet in the buffer 609 the new label in the VCI field, in the corresponding case a reset of the part of the VPI field which will form a new GFC field, and pos6ibly a further reset of the rest of the unified VCI and VPI field and insertion of the addressing mode bit AM which in this case indicates that the data packet belongs to a VC connection.
Therefore, like the block 617, also this block 629 need~
information from the memory cell 607, whether the link on which the data packet arrived is of UNI or NNI type respectively.
From the second buffer 619 the data packet is then transferred to the as60ciated switch unit 3.
Inside the switching units 3 the data packets are transferred from an input connection point given in the establishment of the logical connection, to an output connection point by means of specific addresses, which are inserted in a particular, added internal header field, at the arrival of the data packet to a switch unit. These internal addresses are given in such a form that they easily can be decoded, for instance dPCoA~ directly by hardware, in the circuits inside the switch unit, without requiring any table look-up therefor. Data packets belonging to different connections can thus have the same internal address but they will always have different internal labels. At the arrival to an output connection point the internal header fields are removed and thus the internal address and then also a wo s4nl~s 21~ 7 8 7 ~ PCT/SE94l~lg6 sub6titution or replacement is performed of the information in the label of the data packet. It will be described more closely with reference to Figs. 8 and 9.
In Fig. 8, at the top thereof, thus the addressing mode bit AM
and the label part are shown in the two different formats for a data packet which is to be transferred to an output connection point, which, through its associated switching port, is connected directly to an end station, i.e. a UNI link. As is further apparent from Fig~ 8, it i8 decided by means of contents of the addressing mode bit, if the data packet belong~ to a VP
connection or a VC connection. The GFC field will in this case not be involved in the translation of the label part. It can contain information from earlier stages, if the data packet directly has arrived from a link of UNI type, or the field may contain only zeroes, if the packet has arrived to the switch unit on a link of NNI type. When the data packet, as is indicated by the AM bit, belongs to a VP connection, a table look-up is performed by means of the contents of the VPI field, and if the data packet belongs to a VC connection, all of the contents in the two fields VPI and VCI are used, where in many cases the VPI field will actually only contain zeroes and pocsibly the VCI field also in its most significant positions will have only zeroes. It is decided by the number of simultaneous connections which is to be handled by a switch unit and its switching ports. For a VP connection a new VPI number is ~--obtained and it is inserted in the VPI field, the VCI field in thi~ case being left unaffected. For a VC connection, from the table look-up a new VCI number is obtained, which is inserted in the VPI field of the data packet, and also a new VCI number which i6 inserted in the VCI field of the data packet. The addressing mode bit AM can be removed together with other information, which possibly has been added to the data packet in its travel through the switch unit, or be used for other purposes or simply be left.
Fig. 9 is drawn in the same way as Pig. 8 and illustrates the ca~e of substitution of the label fields for a data packet which i8 to be sent to a link of NNI type. In the data packet there is w~ 94mo6g 2 l 5 7 8 ~ 7 PCT/SE94/~lg6 then no GFC field and the VPI field or the unified VPI and VCI
field is then correspondingly longer. In the same way as in Fig.
8, in addition a table look-up i~ performed for the two cases of a VP connection and a VC connection. The sole difference is that the VPI field i6 longer.
In Fig. 10 a block diagram is drawn illustrating the proce~l~re of the substitution of labels is performed in a switching port of the output side of a 6witch unit. The data packets arrive from a switch unit 3 to a buffer 901, from which in a block 903, the label field of the data packet and the AM bit thereof are accessed and stored in a register or memory field 905. By means of the contents of the AM bit it is decided in a block 907, if the data packet belong~ to a vP connection or a Vc connection.
In the former case, in a block 909 a suitable address is formed by means of the address in the VPI field in regard of its length which is obtained by means of a flag "UNI/NNI out", which is obtained from a memory cell 911, contAining information if the output connection point is of UNI or NNI type. The table look-up for this case with a VP connection is performed in a block 913 by means of the address formed in the block 909. The table look-up is performed in a write and read memory 915. If it instead is decided in the block 907, that the data packet belongs to a VC
connection, in a block 917 an addre~s is formed by means of the contents of the VCI field of the data packet, in the general case the contents of both the VPI and VCI fields, but in a preferred practical case the VPI field in the label of the data packet is reset in its transfer through the switch unit 3. A
table look-up is then performed in a block 919 by means of the address formed in the block 917. From the write and read memory 915 information is obtained, which in a block 923 is used to form the conten~s of new VPI and VCI fields temporarily stored in a memory field 921. By means of the flag stored in the register 911 indicating, if the output link is of UNI or NNI
type and~hereby the length of the VPI field, the new label is inserted in the data packet in a block 925 comprising appropriate logic circuits. The data packet can be considered as being stored in a buffer 927, which actually can be identical to the earlier mentioned buffer 901, to which the cell stream 2157~77 Wo94~106s - PCT/SE94/00196 arrives directly from the 6witch. From the buffer 907 the data packet pa~se~ in the outgoing data packet 6tream through a connection line to an end station.
In a block 929 new content6, temporarily stored in a memory field 931, are formed in the case of a VP connection, by mean~
of the result of the table look-up in the block 913. The~e contents in the memory 931 are to be in6erted in the VPI field, and in the same way as for a VC connection there are logic circuits in a block 933 to insert these contents in the data packet which i~ ~upposed to be ~tored or hold in the buffer 927. f
Claims (27)
1. A switch for the transfer of data packets comprising - input and output ports, - a switch core, which is arranged to transfer data packets, arrived to an input port to a selected output port, where - each data packet comprises a label including a first part and a second part, and - each input port of a switch unit is arranged to substitute the label of a data packet arrived to the input port, by an internal label, characterized in - that each input port of a switch unit comprises a list of records including a first and a second sublist, - that each input port of a switch unit is arranged to perform, for a data packet arrived to the port:
- - a first table look-up in the first sublist based on the first part of the label of the data packet, whereby information is obtained relating to:
- - - if a second table look-up also will be performed, and - - - further, if a second table look-up will not be performed, an internal label, - - in the case where the information indicates that a second table look-up will not be performed, a substitution of the first part of the label of the data packet by the internal label obtained in the first table look-up, - - in the case where the information indicates that a second table look-up will be performed, - - - a second table look-up based on the second part of the label of the packet, in the second sublist of the list of internal labels, whereby an internal label is obtained, and --- - a substitution of the label of the data packet by the internal label obtained in the second table look-up.
- - a first table look-up in the first sublist based on the first part of the label of the data packet, whereby information is obtained relating to:
- - - if a second table look-up also will be performed, and - - - further, if a second table look-up will not be performed, an internal label, - - in the case where the information indicates that a second table look-up will not be performed, a substitution of the first part of the label of the data packet by the internal label obtained in the first table look-up, - - in the case where the information indicates that a second table look-up will be performed, - - - a second table look-up based on the second part of the label of the packet, in the second sublist of the list of internal labels, whereby an internal label is obtained, and --- - a substitution of the label of the data packet by the internal label obtained in the second table look-up.
2. A switch according to claim 1, characterized in that an input port is arranged, in performing the second table look-up in the first sublist, to take the first part of the label of the data packet as an index or an address.
3. A switch according to one of claims 1 - 2, characterized in that an input port is arranged to perform the table look-up in the first sublist by:
- taking the first part of the label of the data packet as a number, - adding a first base address or a first base number to this number to obtain a sum, - using the sum as an address or a sequential number of a record in the first sublist, - accessing this record.
- taking the first part of the label of the data packet as a number, - adding a first base address or a first base number to this number to obtain a sum, - using the sum as an address or a sequential number of a record in the first sublist, - accessing this record.
4. A switch according to one of claims 1 - 3, characterized in that an input port is arranged to perform the table look-up in the second sublist by:
- obtaining from the result of the table look-up in the first sublist further information, - using this further information together with the second part of the label of the data packet to obtain a pointer, - using the pointer to access a record in the second sublist.
- obtaining from the result of the table look-up in the first sublist further information, - using this further information together with the second part of the label of the data packet to obtain a pointer, - using the pointer to access a record in the second sublist.
5. A switch according to one of claims 1 - 4, characterized in that an input port is arranged to perform the table look-up in the second sublist by:
- taking the second part of the label of the data packet as a number, - obtaining from the result of the table look-up in the first sublist a second base address or a second base number, - adding this second base address or second based number to the number given by the second part of the label to obtain a sum, - using the sum as an address or a sequential number of a record in the second sublist, -- accessing this record.
- taking the second part of the label of the data packet as a number, - obtaining from the result of the table look-up in the first sublist a second base address or a second base number, - adding this second base address or second based number to the number given by the second part of the label to obtain a sum, - using the sum as an address or a sequential number of a record in the second sublist, -- accessing this record.
-6. A switch according to one-of claims 1 - 5, characterized in that each output port of a switch unit is arranged to substitute the label of a data packet received by the output port, by a forwarding label.
7. A switch according to claim 6, characterized in - a list comprised in each output port of a switch unit, - the list comprising the forwarding labels used for data packets forwarded from this output port and - the list including a first sublist and a second sublist, - the output port being arranged to perform, in the determination of the forwarding label of a data packet, - - in a first case, where only the first of part of the label of the data packet has been substituted by an internal label, - - - a first table look-up in the first sublist of the list of forwarding labels, based on the first part of the internal label of the data packet, to obtain a forwarding label, and - - - a substitution of the first part of the label of the data packet by the forwarding label obtained in the first table look-up,- - in another, second case where the label of the data packet has been substituted by an internal label, - - - a second table look-up in the second sublist based on the internal label of the packet, to obtain a forwarding label, and - - - a substitution of the internal label of the data packet by the forwarding label obtained in the second table look-up.
8. A switch according to claim 7, characterized in that an output port is arranged to perform the table look-up in the first sublist by:
- taking the first part of the internal label of the data packet as a number, - adding a first base address or a first base number to this number to obtain a sum, - using the sum as an address or a sequential number of a record in the first sublist, - accessing this record.
- taking the first part of the internal label of the data packet as a number, - adding a first base address or a first base number to this number to obtain a sum, - using the sum as an address or a sequential number of a record in the first sublist, - accessing this record.
9. A switch according to one of claims 7 - 8, characterized in that an output port is arranged to perform-the table look-up in the second sublist by:
- obtaining from the result of the table look-up in the first sublist further information, - using this further information together with the second part of the internal label to obtain a pointer, - using the pointer to access a record in the second sublist.
- obtaining from the result of the table look-up in the first sublist further information, - using this further information together with the second part of the internal label to obtain a pointer, - using the pointer to access a record in the second sublist.
-10. A switch accordinq to one of claims 7 - 8, characterized ln that an output port is arranged to perform the table look-up in the second sublist by:
- taking the second part of the internal label of the data packet as a number, - obtaining from the result of the table look-up in the first sublist a second base address or a second base number, - adding this second base address or second based number to the number given by the second part of the internal label to obtain a sum, - using the sum as an address or a sequential number of a record in the second sublist, - accessing this record.
- taking the second part of the internal label of the data packet as a number, - obtaining from the result of the table look-up in the first sublist a second base address or a second base number, - adding this second base address or second based number to the number given by the second part of the internal label to obtain a sum, - using the sum as an address or a sequential number of a record in the second sublist, - accessing this record.
11. A switch according to claim 7, characterized in that an output port is arranged to perform the table look-up in the second sublist by:
- taking the whole internal label of the data packet as a number, - adding a second base address or a second base number to this number, - using the sum an address or a sequential number of a record in the second sublist, - accessing this record.
- taking the whole internal label of the data packet as a number, - adding a second base address or a second base number to this number, - using the sum an address or a sequential number of a record in the second sublist, - accessing this record.
12. A network for the transfer of data packets belonging either to a first or a second type of logical connections, comprising - end stations, which are start and end points for the data packets, - switch units having a number of input and output ports between which a data packet can be transferred inside each unit, - a connections line from each end station to an input and output-port of a switch unit, this switch unit being associated with this end station, and connection lines mutually between the input and output ports of the switch units, which are not connected to an end station, - each switch unit being arranged, when a signal arrives from an end station, to which the switch unit is associated, to establish a logical connection of the first or second type to another end station, to establish this logical connection through the switch unit and in the network in cooperation with other switch units to the other end station, and to establish an internal label, including a first part and a second part, for this connection, - each data packet comprising a label including a first part and a second part and identifying the connection, to which the data packet belongs, - each input port of a switch unit being arranged to substitute the label of a data packet, arriving to the input port on a connection line, by the internal label, which is established for the logical connection, to which the data packet belongs, characterized in - that each input port of a switch unit comprises a list of records including a first and a second sublist, - that each input port of a switch unit is arranged to perform, for a data packet arrived to the port:
- - in the case, where the data packet belongs to the first type of logical connection, - - - a first table look-up in the first sublist based on the first part of the label of the data packet, to obtain an internal label, and - - - a substitution of only the first part of the label of the data packet by the internal label obtained in the first table look-up, - - in the case where the data packet belongs to the second type of logical connection, - - - a second table look-up in the second sublist based on the second part of the label of the packet, to obtain an internal label, and - - - a substitution of the label of the data packet by the internal label obtained in the second table look-up.
- - in the case, where the data packet belongs to the first type of logical connection, - - - a first table look-up in the first sublist based on the first part of the label of the data packet, to obtain an internal label, and - - - a substitution of only the first part of the label of the data packet by the internal label obtained in the first table look-up, - - in the case where the data packet belongs to the second type of logical connection, - - - a second table look-up in the second sublist based on the second part of the label of the packet, to obtain an internal label, and - - - a substitution of the label of the data packet by the internal label obtained in the second table look-up.
13. A network according to claim 12, characterized in - that the first sublist in an input port of a switch unit comprises information relating to the type of logical connection and - that the input port is arranged to perform, for all data packets arrived to the input port, the first table look-up in the first sublist, based on the first part of the label of a data packet arrived to the input port, to obtain the type of logical connection, to which the data packet belongs.
14. A network according to one of claims 12 - 13, characterized in that an input port of a switch unit is arranged to insert information in regard of type of logical connection in a data packet arrived to the input port.
15. A network according to claim 14, characterized in that an output port in a switch unit is arranged to remove from a data packet to be forwarded from the switch unit the information in regard of type of logical connection.
16. A network according to one of claims 12 - 15, characterized in that an input port in a switch unit is arranged to perform the table look-up in the first sublist by:
- taking the first part of the label of the data packet as a number, - adding a first base address or a first base number to this number to obtain a sum, - using the sum as an address or a sequential number of a record in the first sublist, - accessing this record.
- taking the first part of the label of the data packet as a number, - adding a first base address or a first base number to this number to obtain a sum, - using the sum as an address or a sequential number of a record in the first sublist, - accessing this record.
17. A network according to one of claims 13 or 16, characterized in that in the case where a data packet belongs to a logical connection of the second type, an input port of a switch unit is arranged to perform the table look-up in the second sublist by:
- obtaining from the result of the table look-up in the first sublist further information, - using this further information together with the second part of the label of the data packet to obtain a pointer, - using the pointer to access a record in the second sublist.
- obtaining from the result of the table look-up in the first sublist further information, - using this further information together with the second part of the label of the data packet to obtain a pointer, - using the pointer to access a record in the second sublist.
18. A network according to one of claims 13 or 16, characterized in that in the case where a data packet belongs to a logical connection of the second type, an input port of a switch unit is arranged to perform the table look-up in the second sublist by:-- taking the second part of the label of the data packet as a number, - obtAining from the result of the table look-up in the first sublist a second base address or a second base number, - adding this second base address or second based number to the number given by the second part of the label to obtain a sum, - using the sum as an address or a sequential number of a record in the second sublist, - accessing this record.
19. A network according to one of claims 12 - 18, characterlzed in - that each switch unit, in the establishment of a logical connection, is arranged to also determine a forwarding label of this connection, and - that an output port of a switch unit, from which port a data packet is forwarded, is arranged to substitute the internal label of the packet by the forwarding label, which is determined for the logical connection, to which the data packet belongs.
20. A network according to claim 19, characterized ln - a list comprised in each output port of a switch unit, - the list comprising the forwarding labels used for data packets forwarded from this output port and - the list including a first sublist and a second sublist, - the output port being arranged to perform, in the determination of the forwarding label of a data packet, - - in the case, where the data packet belongs to the first type of logical connection, - - - a first table look-up in the first sublist of the list of forwarding-labels, based on the-first part of the internal-label of the data packet, to obtain a forwarding label, and - - - a substitution of the first part of the label of the data packet by the forwarding label obtained in the first table look-up, - - in the case where the data packet belongs to the second type of logical connection, - - - a second table look-up in the second sublist based on the internal label of the packet, to obtain a forwarding label, and - - - a substitution of the internal label of the data packet by the forwarding label obtained in the second table look-up.
21. A network according to claim 20, characterized in that the output port is arranged to perform the table look-up in the first sublist by:
- taking the first part of the internal label of the data packet as a number, - adding a first base address or a first base number to this number to obtain a sum, - using the sum as an address or a sequential number of a record in the first sublist, - accessing this record.
- taking the first part of the internal label of the data packet as a number, - adding a first base address or a first base number to this number to obtain a sum, - using the sum as an address or a sequential number of a record in the first sublist, - accessing this record.
22. A network according to one of claims 20 - 21, characterized in that the output port is arranged to perform the table look-up in the second sublist by:
- obtaining from the result of the table look-up in the first sublist further information, - using this further information together with the second part of the internal label to obtain a pointer, - using the pointer to access a record in the second sublist.
- obtaining from the result of the table look-up in the first sublist further information, - using this further information together with the second part of the internal label to obtain a pointer, - using the pointer to access a record in the second sublist.
23. A network according to one of claims 20 - 21, characterized in that the output port is arranged to perform the table look-up in the second sublist by:
- taking the second part of the internal label of the data packet as a number, - obtaining from the result of the table look-up in the first sublist a second base address or a second base number, - adding this second base-address or second based number to the number given by the second part of the internal label to obtain a sum, - using the sum as an address or a sequential number of a record in the second sublist, - accessing this record.
- taking the second part of the internal label of the data packet as a number, - obtaining from the result of the table look-up in the first sublist a second base address or a second base number, - adding this second base-address or second based number to the number given by the second part of the internal label to obtain a sum, - using the sum as an address or a sequential number of a record in the second sublist, - accessing this record.
24. A network according to claim 20, characterized in that the output port is arranged to perform the table look-up in the second sublist by:
- taking the whole internal label of the data packet as a number, - adding a second base address or a second base number to this number, - using the sum an address or a sequential number of a record in the second sublist, - accessing this record.
- taking the whole internal label of the data packet as a number, - adding a second base address or a second base number to this number, - using the sum an address or a sequential number of a record in the second sublist, - accessing this record.
25. A network according to one of claims 12 - 24, wherein data packets, which arrive directly from an end station or are forwarded directly to an end station, have a first label format and data packets which are forwarded between switch units, have a second label format, characterized in - an indicator element in each input port of a switch unit and for each logical connection having data packets passing through the input put, indicating whether a data packet, arriving to the port, after the transfer through the switch unit, is to be forwarded from the switch unit directly to an end station or not, - each input port of the switch unit being arranged to perform, when a data packet arrives to the input port, - - a decision based on the indicator element for the logical connection, to which the data packet belongs, whether the packet i to be forwarded directly from the switch unit to an end station or not, and - - in the case, where the packet is to be forwarded directly from the switch unit to an end station, the label of the data packet is substituted by an internal label, which has the first format, - - in the case, where the packet is not to be forwarded directly from the switch unit to an end station, the label of the data packet is substituted by an internal label having the second format.
26. A network according to one of claims 1 - 25, characterized in - that at least one list in a port of a switch unit is arranged to contain sequentially all the possible contents of label fields which a data packet can have, which is received by the port, and - that the port is arranged to obtain the label which is to replace the label of a data packet received by the port, from the position or the sequential number of this label in the list.
27. A network according to one of claims 1 - 26, characterized in - that an input port of a switch unit is arranged, at the arrival of a data packet to the input port, to add to the data an extra field, in which an internal address of the data packet is inserted, indicating how the data packet is to be transferred inside the switch unit, and - that each output port of the switch unit is arranged to remove this extra field, when a data packet is forwarded from the switch unit.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| SE9300793A SE515422C2 (en) | 1993-03-10 | 1993-03-10 | Label management in parcel networks |
| SE9300793-8 | 1993-03-10 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2157877A1 true CA2157877A1 (en) | 1994-09-15 |
Family
ID=20389178
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002157877A Abandoned CA2157877A1 (en) | 1993-03-10 | 1994-03-08 | Label handling in packet networks |
Country Status (13)
| Country | Link |
|---|---|
| US (1) | US5546387A (en) |
| EP (1) | EP0688484B1 (en) |
| JP (1) | JPH08510102A (en) |
| KR (1) | KR100237336B1 (en) |
| CN (1) | CN1119059A (en) |
| AU (1) | AU696446B2 (en) |
| BR (1) | BR9406380A (en) |
| CA (1) | CA2157877A1 (en) |
| DE (1) | DE69433812T2 (en) |
| FI (1) | FI954217A (en) |
| NO (1) | NO953538L (en) |
| SE (1) | SE515422C2 (en) |
| WO (1) | WO1994021069A1 (en) |
Families Citing this family (30)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2726669B1 (en) * | 1994-11-04 | 1996-11-29 | Thomson Csf | METHOD AND DEVICE FOR TRANSLATING A CELL HEADER APPLIED TO THE ENTRY OF A NODE OF AN ASYNCHRONOUS PACKET DATA NETWORK |
| JP3035868B2 (en) * | 1995-01-26 | 2000-04-24 | インターナシヨナル・ビジネス・マシーンズ・コーポレーシヨン | Method and apparatus for ATM exchange |
| US5623492A (en) * | 1995-03-24 | 1997-04-22 | U S West Technologies, Inc. | Methods and systems for managing bandwidth resources in a fast packet switching network |
| US6044076A (en) * | 1995-06-09 | 2000-03-28 | Canon Kabushiki Kaisha | Network system for transmitting a plurality of channels, and node device, packet transmission method, terminal equipment connection table generation method, and connection information registration method used in the system |
| JP3202160B2 (en) * | 1996-01-25 | 2001-08-27 | 富士通株式会社 | Identifier conversion device |
| DE19629765A1 (en) * | 1996-07-23 | 1998-01-29 | Siemens Ag | Address reduction method in ATM switching systems |
| FR2764757B1 (en) | 1997-06-13 | 1999-08-27 | Thomson Csf | TRANSLATION METHOD OF A CELL HEADER FOR ATM SWITCH |
| US6081522A (en) * | 1997-06-30 | 2000-06-27 | Sun Microsystems, Inc. | System and method for a multi-layer network element |
| US6097726A (en) | 1997-09-18 | 2000-08-01 | Ascend Communications, Inc. | Virtual path merging in a multipoint-to-point network tunneling protocol |
| US6262985B1 (en) * | 1998-03-30 | 2001-07-17 | Nortel Networks Limited | Method and apparatus for full range translation of large external identifier to small internal identifier |
| US6094685A (en) * | 1998-04-14 | 2000-07-25 | Ascend Communications, Inc. | Use of control blocks to map multiple unidirectional connections |
| DE19825541A1 (en) * | 1998-06-08 | 1999-12-09 | Bosch Gmbh Robert | Device and method for mapping object addresses |
| FR2787267B1 (en) * | 1998-12-14 | 2001-02-16 | France Telecom | DEVICE AND METHOD FOR PROCESSING A SEQUENCE OF INFORMATION PACKETS |
| US6331978B1 (en) * | 1999-03-09 | 2001-12-18 | Nokia Telecommunications, Oy | Generic label encapsulation protocol for carrying label switched packets over serial links |
| US6633565B1 (en) * | 1999-06-29 | 2003-10-14 | 3Com Corporation | Apparatus for and method of flow switching in a data communications network |
| US6700897B1 (en) | 1999-10-29 | 2004-03-02 | Advanced Micro Devices, Inc. | Apparatus and method for identifying data packet types in real time on a network switch port |
| US6567406B1 (en) | 1999-12-10 | 2003-05-20 | Tropic Networks Inc. | Method of labeling data units with a domain field |
| US6865183B1 (en) * | 1999-12-17 | 2005-03-08 | Pmc-Sierra, Inc. | F5-to-F4 OAM alarm notification and cell generation in multiple connection ATM switches |
| CA2296213C (en) * | 2000-01-07 | 2009-04-14 | Sedona Networks Corporation | Distributed subscriber management |
| JP2001251351A (en) | 2000-03-02 | 2001-09-14 | Nec Corp | Input packet processing system for packet switch |
| EP1168720B1 (en) * | 2000-06-28 | 2007-01-10 | Alcatel | Telecommunication carrier processor subsystem with in-band control and addressing via cell header fields |
| US6963565B1 (en) | 2000-08-14 | 2005-11-08 | Advanced Micro Devices, Inc. | Apparatus and method for identifying data packet at wire rate on a network switch port |
| US20020116669A1 (en) * | 2001-02-12 | 2002-08-22 | Maple Optical Systems, Inc. | System and method for fault notification in a data communication network |
| JP4460195B2 (en) * | 2001-08-06 | 2010-05-12 | 株式会社日立製作所 | Packet transfer device and routing control device |
| US8014395B1 (en) | 2002-01-10 | 2011-09-06 | Ericsson Ab | Method and apparatus for processing labels |
| US7082128B1 (en) | 2002-01-10 | 2006-07-25 | Redback Networks Inc. | Method and apparatus for non-stop forwarding with labels |
| US7139272B1 (en) * | 2002-01-10 | 2006-11-21 | Redback Networks Inc. | Method and apparatus for a label forwarding information base |
| KR100424614B1 (en) * | 2002-04-27 | 2004-03-27 | 삼성전자주식회사 | Internet protocol based communication system and host address setting and source address selection method thereof |
| JP4608936B2 (en) * | 2004-04-28 | 2011-01-12 | パナソニック株式会社 | Communication method and communication apparatus |
| US8280631B2 (en) * | 2008-10-02 | 2012-10-02 | Certusview Technologies, Llc | Methods and apparatus for generating an electronic record of a marking operation based on marking device actuations |
Family Cites Families (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SU478445A1 (en) * | 1972-12-18 | 1975-07-25 | Военная Инженерная Краснознаменная Академия Им.А.Ф.Можайского | Device for the selection of asynchronous information flows |
| US3979733A (en) * | 1975-05-09 | 1976-09-07 | Bell Telephone Laboratories, Incorporated | Digital data communications system packet switch |
| US4218756A (en) * | 1978-06-19 | 1980-08-19 | Bell Telephone Laboratories, Incorporated | Control circuit for modifying contents of packet switch random access memory |
| US4494230A (en) * | 1982-06-25 | 1985-01-15 | At&T Bell Laboratories | Fast packet switching system |
| US4641302A (en) * | 1985-06-24 | 1987-02-03 | Racal Data Communications Inc. | High speed packet switching arrangement |
| CA1264845A (en) * | 1987-03-13 | 1990-01-23 | Ernst August Munter | Digital telephone switching system having a message switch with address translation |
| US4894822A (en) * | 1987-11-24 | 1990-01-16 | AT&T Information Systems American Telephone and Telegraph Company | Fast packetized data delivery for digital networks |
| JP2667868B2 (en) * | 1988-04-06 | 1997-10-27 | 株式会社日立製作所 | Cell switching system |
| IT1224493B (en) * | 1988-10-17 | 1990-10-04 | Cselt Centro Studi Lab Telecom | LABEL CONTROL AND SWITCHING INTERFACE FOR FAST SWITCHING OF ASYNCHRONOUS PACKAGE |
| JP2892689B2 (en) * | 1989-07-05 | 1999-05-17 | 株式会社日立製作所 | Packet communication network and packet switch |
| JP2907886B2 (en) * | 1989-09-14 | 1999-06-21 | 株式会社日立製作所 | Switching system |
| JPH04151933A (en) * | 1990-10-16 | 1992-05-25 | Toshiba Corp | Communication network control system |
| US5166926A (en) * | 1990-12-18 | 1992-11-24 | Bell Communications Research, Inc. | Packet address look-ahead technique for use in implementing a high speed packet switch |
| JPH04248729A (en) * | 1991-02-05 | 1992-09-04 | Fujitsu Ltd | Atm exchange |
| FR2681164A1 (en) * | 1991-09-06 | 1993-03-12 | Thomson Csf | Process for routing a data packet within a digital transmission network |
-
1993
- 1993-03-10 SE SE9300793A patent/SE515422C2/en not_active IP Right Cessation
-
1994
- 1994-03-08 WO PCT/SE1994/000196 patent/WO1994021069A1/en active IP Right Grant
- 1994-03-08 DE DE69433812T patent/DE69433812T2/en not_active Expired - Lifetime
- 1994-03-08 CN CN94191409A patent/CN1119059A/en active Pending
- 1994-03-08 KR KR1019950703786A patent/KR100237336B1/en not_active IP Right Cessation
- 1994-03-08 JP JP6519895A patent/JPH08510102A/en active Pending
- 1994-03-08 AU AU62660/94A patent/AU696446B2/en not_active Ceased
- 1994-03-08 EP EP94910081A patent/EP0688484B1/en not_active Expired - Lifetime
- 1994-03-08 CA CA002157877A patent/CA2157877A1/en not_active Abandoned
- 1994-03-08 BR BR9406380A patent/BR9406380A/en not_active Application Discontinuation
- 1994-03-10 US US08/208,386 patent/US5546387A/en not_active Expired - Lifetime
-
1995
- 1995-09-08 NO NO953538A patent/NO953538L/en not_active Application Discontinuation
- 1995-09-08 FI FI954217A patent/FI954217A/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| DE69433812T2 (en) | 2005-06-09 |
| EP0688484B1 (en) | 2004-05-26 |
| BR9406380A (en) | 1996-01-16 |
| KR960701543A (en) | 1996-02-24 |
| DE69433812D1 (en) | 2004-07-01 |
| AU6266094A (en) | 1994-09-26 |
| FI954217A0 (en) | 1995-09-08 |
| WO1994021069A1 (en) | 1994-09-15 |
| SE9300793D0 (en) | 1993-03-10 |
| FI954217A (en) | 1995-09-08 |
| EP0688484A1 (en) | 1995-12-27 |
| AU696446B2 (en) | 1998-09-10 |
| SE9300793L (en) | 1994-09-11 |
| SE515422C2 (en) | 2001-07-30 |
| CN1119059A (en) | 1996-03-20 |
| JPH08510102A (en) | 1996-10-22 |
| NO953538D0 (en) | 1995-09-08 |
| NO953538L (en) | 1995-11-09 |
| KR100237336B1 (en) | 2000-01-15 |
| US5546387A (en) | 1996-08-13 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP0688484B1 (en) | Label handling in packet networks | |
| US5119369A (en) | Packet switch communication network using packet having virtual channel identifier | |
| US5485453A (en) | Method for handling redundant switching planes in packet switches and a packet switch for carrying out the method | |
| US5214639A (en) | Communication switching element and method for transmitting variable length cells | |
| JP3445802B2 (en) | Method and apparatus for multipoint-to-point communication in ATM networks | |
| JP3064650B2 (en) | Broadcast communication device | |
| AU685606B2 (en) | Shared buffer memory switch for an ATM switching system and its broadcasting control method | |
| AU604444B2 (en) | Frame relay type data switching apparatus | |
| EP0683949B1 (en) | A method for handling redundant switching planes in packet switches and a switch for carrying out the method | |
| JP3109829B2 (en) | Method and apparatus for specifying destination and source addresses in a packet network | |
| US6747954B1 (en) | Asynchronous transfer mode switch providing pollstate status information | |
| JP3370025B2 (en) | Switch device | |
| US6483831B1 (en) | Asynchronous transfer mode switch | |
| JPH05268241A (en) | Conversion system for header in atm exchange | |
| JP2962916B2 (en) | ATM switch | |
| KR0164833B1 (en) | Atm cell splitting apparatus | |
| JPH1056465A (en) | Multiple address fixed length cell disassembling device | |
| JP2000183908A (en) | Multicast device | |
| JPH05114915A (en) | Changeover switch device | |
| JPH10224371A (en) | Data communication equipment | |
| CA2313683A1 (en) | Data switching system and data switching method | |
| JPH05260077A (en) | Message processing system for connectionless communication | |
| JPH036152A (en) | Data switching device |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Discontinued |