CA2139197C - Connection-oriented network using distributed network resources and predetermined vpis for fast vc establishment - Google Patents

Abstract

In a connection-oriented network, a normal signaling packet is sent from a source user to the network. A first virtual path identifier (VPI) is determined at a first node of the network according to a destination address in the packet, and the first VPI is inserted into the packet, and forwarded to the second node, where it determines a second VPI
according to the packet's destination address, adds the second VPI to the first VPI in the packet to produce a source route, and forwards the normal signalling packet to a destination user. The destination user returns an acknowledgment (ACK) packet to the source user, containing the source route. In response ko the ACK, the source user stores the source route contained in the packet into a source route table, and selects an initial VPI
and an initial virtual channel identifier (VCI) from a copy of network resource, and sends a fast signaling packet, captaining the source route, the initial VPI and VCI. At the first node, a first VCI is selected according to the first VPI in the source route of the fast signaling packet, the initial VPI/VCI in the packet are mapped to the first VPI/VCI, and the initial VCI in the packet is overwritten with the first VCI, and the packet is forwarded to the second network node, where a second VCI is selected according to the second VPI in the source route of the packet, and the first VPI/VCI in the packet are mapped to the second VPI/VCI, and the first VCI in the packet is overwritten with the second VCI, and the packet is forwarded to the destination user.

Description

94 12i2T 23:58 '~'81 3 3545 418T ~IOR1SAKI ~i~ SIITiCA f~ 002 qs TITLE OF TINE INVENTION

2 "Connection-Oriented Network Using Distributed Network Resources and 3 Predetermined VPIs for Fast VC Establishment"
BACKGROUND OF THE INVENTION
Field of the Invention 6 The present invention relates generally to connection-oriented 7 communications networks, and more specifically to a signaling technique 8 for establishing a virtual connection in a network such as asynchronous 9 transfer mode (ATM network.
1 0 Description of the Related Art i i Studies on signaling protocols for ATM networks were 12 undertaken by international bodies such as Working party XI/6 of CCITT
13 Study Group XI and ATM Forum, and proposals were made In the form 14 of draft standards such as Draft Text for Q. 93B, pages 1 to 14 and t 5 Signaling Specification Draft, pages l4 to 20, respectively.
1 6 VI~'hile the proposals secure availability for many types of 1 '7 variable length signaling message and provide such flexibility that signal >. 8 units can be inserted into any location of a message, a substantial amount 19 of time will be taken to establish a virtual connection due to increased 2 0 processing time and increased propagation delays. Specifically, each 21 network node is required to examine the called party address contained 2 2 in the signaling message to determine the link to the next hop. When the 2 3 route extends to the desired called party address, the signaling is made 2 a an the basis of the called party subaddress contained in the message. As 25 a result, the processing time taken by each node of the network 2 6 increases, and the connection establishment time will be increased 2 7 significantly with an increase in the number of network nodes.

2 9 It is therefore an object of the present invention to provide a 3 o signaling technique for a connection-oriented communications network capable of fast connection establishment.
According to a first aspect of the present invention, there is provided a connection-oriented communications network comprising: a user terminal including a source route table storing a plurality of routing information of virtual connections established in previous message transfers from the user terminal to a plurality of destination terminals, each of said routing information including a series of node-by-node route records each containing a respective virtual path identifier (VPI), and means for transmitting to the network a signaling packet containing one of the route records of said table; and a plurality of interlinked network nodes, each of the nodes including a translation table and means for receiving the signaling packet, reading a VPI from the received signaling packet and mapping incoming and outgoing routing information in said translation table in accordance with the read VPI.
According to a second aspect, the present invention provides a connection-oriented communications network comprising a user terminal including a source route table for storing therein a series of reference numbers corresponding to a destination user terminal, means for transmitting a signaling packet containing the series of reference numbers to the network, each of the reference numbers representing routing information containing a virtual path identifier (VPI), and a plurality of interlinked network nodes, each of the nodes including a translation table, and means for -2a-receiving the signaling packet, translating a corresponding one of the reference numbers in the received packet to a VPI, and mapping incoming and outgoing routing information in the translation table in accordance with the translated VPI.
According to a third aspect, the present invention provides a connection-oriented communications network comprising a user terminal including means for transmitting a signaling packet to the network, and a plurality of interlinked network nodes, each of the nodes including means for receiving the packet, a translation table, a source route table for '94 12/27 2J:57 'x'81 S 35.15 4187 yORISAKI -i11 SMT/CA

_3_ 1 storing therein, in correspondence to the destination address in the 2 received packet, a source route containing a series of route records each 3 containing a virtual path identifier (VPI), each of the network nodes 4 reading a VPI from a corresponding one of the route records of the signaling packet and mapping incoming and outgoing routing 6 information in the translation table in accordance with the read VPI.
7 According to a fourth aspect, the present invention provides a $ COnnectfon-Orienfed communications network comprising a user terminal 9 including a first source route table for storing therein a reference number corresponding to a destination address and means for transmitting a 1 i signaling packet to the network, the signaling packet containing the ~ 2 destination address and the reference number, and a plurality of 3 interlinked network nodes, each of the nodes including means for I 4 receiving the packet, a translation table, a second source route table for 1 S storing therein, in correspondence to the destination address in the 16 received packet, a source route containing a series of route records each t 7 containing a virtual path identifier (VPf), each of the network nodes 18 translating the reference number in the received packet to the source 1 9 route In the second source route table, reading a VPI from a corresponding one of the route records of the source route, and 21 mapping incoming and outgoing routing information in the translation z 2 table in accordance with the read VPI, 2 3 According to a fifth aspect, the present invention provides a 24 method for a connection-oriEnted communications network including first 2 5 and second user terminals and first and second interlinked network nodes.
2 6 The method comprises the steps of:
2 7 a) pending a normal signaling packet from the first user 2 8 terminal to the network, the normal signaling packet containing a 2 9 destination address of the second user terminal;
3 D b) receiving the normal signaling packet at the first network a ' 9.I 12/27 23: S8 '~81 3 3545 4187 mORISARI 1-~-. SMT: C~ BOOS

i node, determining a first virtual path identifier (VPI) according to the 2 destination address in the packet, inserting the first VPI into the received 3 signaling packet, and forwarding the packet to the second network node;
c) receiving the normal signaling packet at the second network node, determining a second Vp1 according to the destination address in 6 the packet, adding the second VPI to the first VPI in the packet to produce 7 a source route, and forwarding the packet to the second user terminal;
8 d) responsive to the normal signaling packet from the second 9 network node, sending an acknowledgment packet from the second user terminal back to the first user terminal via the second and first network 1 1 nodes, the acknowledgment packet containing the source route;
12 e) receiving the acknowledgment packet at the first user r 3 terminal and storing the source route Contained therein into a source 1 ~. route table;
1 5 f) selecting, at the first user terminal, an initial VPl and an initial 16 virtual channel identifier (VCI) from a copy of network wesource, sending a 17 fast signaling packet from the first user terminal, the fast signaling packet 1 8 containing the stored source route, and the initial VPI and the initial VCI;
19 g) receiving the fast signaling packet at the first network node, 2 0 selecting a first VCI according to the first VPI in the source route of the 21 packet, mapping the initial VPI and the initial VCI in the packet to the first 2 2 VPI and the selected first VCI, rewriting the initial VCI in the packet with the 2 3 first VII, and forwarding the packet to the second network node as a new 24 fast signaling packet; and 2 5 h) receiving the new fast signaling packet at the second 2 6 network node, selecting a second VC1 according to the second VPl in the 2 7 source route of the packet, mapping the first VPI and the first VCI in the 2 8 packet to the second VPI and the second VCI, rewriting the first VCI in the 29 packet with the second VCI, and forwarding the packet to the second 3 0 user terminal.

_2139197 '94 12/27 23:59 $'91 3 x545 4187 1IORISAKI ~~-. SMTiCA 0008 _$_ i According to a sixth aspect, the present invention provides a 2 method for a connection-oriented communications network including first 3 and second user terminals and first and second interlinked network nodes, 4 The method comprises the steps of:
a) sending a normal signaling packet from the first user 6 terminal to the network, the normal signaling packet containing a 7 destination address of the second user terminal;
8 b) receiving the normal signaling packet at the first network 9 node, determining a first virtual path identifier (VPI) according to the 1 0 destination address in the packet, assigning a first reference number to 1 1 the first VPI, inserting the first reference number into the received signaling 12 packet, and torwarding the packet to the second network node;
13 c) receiving the normal signaling packet at the second network 14 node, determining a second VPi according to the destination address in 15 the packet, assigning a second reference number to the second VPI, 1 6 adding the second reference number to the first reference number in the packet to produce a source route, and forwarding the packet to the second user terminal;
19 d) responsive to the normal signaling packet from the second 2 0 network node, sending an acknowledgment packet frorm the second user 2 i terminal back to the first user terminal via the second and first network 2 2 nodes, the acknowledgment packet containing the source route;
2 3 e) receiving the acknowledgment packet at the first user terminal and storing the source route contained therein into a source 2 5 route table;
2 6 f) selecting, at the first user terminal, an initial VPI and an initial 2 ~ virtual channel identifier (VCI) from a copy of network resource, sending a 28 fast signaling packet from the first user terminal, the fast signaling packet 29 containing the stored source route, and the initial VPI and the initial VCI;
3 4 g) receiving the fast signaling packet at the first network node, ~J

_ zt3sis7 fl4 12!27 25:59 $81 ~ 5545 4187 DIORISAKI ~-~-~ SDIT%CA 1~0o7 _g_ 1 translating the first reference number in the source route of the packet to z the first VPI, selecting a first VCI according to the translated first VPI, 3 mapping the initial VPI and the initial VCI in the packet to the translated .4 VPI and the selected first VCI, rewriting the initial VPI and the initial VCi in the packet with the first VPI and the first VCI, respectively, and forwarding 6 the packet to the second network node as a new fast signaling packet;
'7 and 8 h) receiving the new fast signaling packet at the second 9 network node, translating the second reference number in the source route of the packet to the second VPI, selecting a second VCI according to ~ 1 the translated second VPI, mapping the first VPI and the first VCI in the 1 2 packet to the translated second VPI and the second VCI, rewriting the first 13 VPI and the first VCI in the packet with the second VP1 and the second VCI, 1 a ~ espectively, and forwarding the packet to the second user terminal.
According to a seventh aspect, the present invention provides a t 6 method for a connection-oriented communications network including first 17 and second user terminals arid first and second interlinked network nodes.
1 s The method comi~rises the steps of:
x 9 a) selecting, at the first user terminal, an initial VPI and an initial ? D virtual channel identifier (VCI) from a copy of network resource, sending a z t fast signaling packet from the first user terminal, the fast signaling packet 2 2 containing a destination address of the second user terminal and the initial 2 3 VPI and the initial VCI;
2 a b) receiving the fast siqnaliryg packet at the first network node, 2 5 returning a negative acknowledgment packet to the first user terminal if a 26 source route corresponding to the destination address in the packet is Trot 2'7 present in a source route table;
2 8 c) responsive to the negative acknowledgment packet, 29 sending a normal signaling packet from the first user terminal to the 3 0 network, the normal Signaling packet containing the destination address;

. 2139197 94 12/28 00:00 '~81 ~ 3S4S 4187 MORISARI ~~-. SMT~CA X008 NE-s3z 1 d) receiving the normal signaling packet at the first network 2 node, determining a first virtual path identifier (VPI) according to the 3 destination address in the packet, inserting the first VPI into the received 4 signaling packet, and forwarding the packet to the second network node;
e) receiving the normal signaling packet at the second network 6 node, determining a second VPI according to the destination address in the packet, adding the second VPI to the first VPI in the packet to produce 8 a source route, and forwarding the packet to the second user terminal;
9 f) responsive to the affirmative acknowledgment packet, 1 0 sending a normal signaling packet from the first user terminal to the 11 network" sending a connection indicating packet from the second user 1 ? terminal back to the first network node, the connection indicating packet 13 containing the source route;
14 g) receiving the connection indicating packet at the first network node and storing the source route contained therein into the 1 6 source route table, and returning the connection indicating packet to the 17 first user terminal;
1 8 h) if the source route is present in the source route table, 1 9 selecting, at the first network node, a first VCI according to the first VPl in 2 0 the source route of the fast signaling packet from the first user terminal, 21 mapping the initial VPI and the initial VCI in the packet to the first VPI
and 2 2 the Selected first VCI, rewriting the initial VCI in the packet with the first 23 VCI, and forwarding the packet to the second network node as a new fast 2 4 signaling packet; and 2 5 j) receiving the new fast signaling packet at the second z 6 network node, selecting a second VCI according to the second VPf in the 2~ source route of the packet., mapping the first VPI and the first VCI in the 2 8 packet to the second VP1 and the second VCI, rewriting the first VCI in the 2 9 packet with the second VCI, and forwarding the packet to the second 3 0 user terminal.

'94 12/28 00:00 $'91 3 3545 4187 '~ORISAKI -~i~ SMT'CA ~ 009 _g_ 1 According to an eighth aspect, the present invention provides a 2 method for a connection-oriented communications network including first 3 and second user terminals and first and second interlinked network nodes, 4 The method comprises the steps of:
a) determining whether a reference number corresponding to b a destination address of the second user terminal are present in a first 7 50UrCe route table;
8 b) if the reference number is not present, sending a normal 9 signaling packet from the first user terminal to the network, the normal signaling packet containing a destination address of the second user 11 terminal;
t z c) if reference numbers is present, selecting an initial VPI and 13 an initial virtual channel identifier (VCI) from a copy of netvdork resource, 14 sending a fast signaling packet from the first user terminal, the fast 1 5 signaling packet containing the stored reference number, the initial VNI
16 and the initial VCf;
1 7 d) receiving the normal signaling packet at the first network 1 8 node, determining a first virtual path identifier (VPl) according to the 19 destination address in the packet, inserting the first VPI into the received signaling packet, and forwarding the packet to the second network node;
21 e) receiving the normal signaling packet at the second network 2 2 node, determining a second VPI according to the destination address in z 3 the packet, adding the second VPI to the first VPI in the packet to produce 2 4 a source route, and forwarding the packet to the second user terminal;
2 5 f) responsive to the normal signaling packet from the second Z E network node, sending an acknowledgment packet frorn the second user 2 7 terminal back to the first network node via the second and first network, 2 8 the acknowledgment packet containing the source route;
2 9 g) receiving the acknowledgment packet at the first network 3 o node and storing the source route contained therein into a second source '94 12:28 00:01 '~81 3 3545 4187 3IORISAKI ~-~-. SMTiCA f~010 _g_ 1 route table and assigning the reference number to the source route;
z h) receiving, at the first network node, the fast signaling packet 3 from the first user terminal, translating the reference number in the received packet to the source route, selecting a first VCI according to the first VPI in the translated source route, mapping the initial VPI aid the 6 initial VC! in the packet to the first VPI and the selected first VCI, rewriting 7 the initial VPI and the initial VCI in the packet with the first VPI and the first 8 VCI, respectively, inserting tJ~e source route in the packet, and forwarding 9 the packet to the second network node as a new fast signaling packet;
and 11 i) receiving the new fast signaling packet at the second 12 network node, selecting a second VCI according to the second VPI in the 13 source route of the packet, mapping the first VPI and the first VCI in the packet to the second VPI and the second VCI, rewriting the first VPI and 1 5 the first VCI in the packet with the second VPI and the second VCI, 1 6 respectivEly, and forwarding the packet to the second user terminal.
1 ~ To reduce the time between transmission of a signaling packet I B and transmission of a data message, any of the methods according to 1 9 the frfth to the eighth aspects further comprises the step of sending a data 24 message immediately following the sending of a fast signaling packet 21 from the first user terminal.
22 ~~IIEF DE~RIPT(ON OF THE ~AWIN
2 3 The present invention will be described in further detail with 24 reference to the accompanying drawings, in which:
2 5 Fig. 1 is a block diagram of an ATM network according to a first 2 6 embodiment of the present invention;
27 Fig. 2 is a flowchart of the operation of a user terminal of the first 2 8 embodiment;
2 9 Fig. 3 is a flowchart ~f the operations of a network node of the 3 0 first embodiment;

L

'84 12/28 00:01 $81 9 35.15 4187 ~ORISAKI ~-.~ SMT~CA ~JO11 N ~-63 2 1 Flgs. 4A, 4B and ~C are diagrams useful for describing the 2 operations of the first embodiment;
3 Fig. 5 is an illustration of the contents of fast signating packets 4 used in the present invention;
Fig. 6 is a block diagram of an AT'M network according to a 6 second embodiment of the present invention;
7 Fig. 7 is a flowchart of the operation of a network node of Fig. 6;
8 Fig. 8 is a block diagram of an ATM network according to a third 9 embodiment of the present invention;
1 o Fig. 9 is a flowchart of the operation of a user terminal of the 11 third embodiment;
Fig. 10 is a flowchart of the operations of a network node of the i 3 third embodiment;
14 Fig. 11 is a diagram useful for describing the operation of the third embodiment;
16 Fig. 12 is a block diagram of an ATM network according to a 17 fourth embodiment of the present invention;
18 Fig. 13 is a flowchart of the operation of a user terminal of the fourth embodiment; and ? U Fig. 14 is a flowchart of the operations of a network node of the 21 fourth embodiment of this invention.
2 z I~ETAiLFD DFSCRlPTION
2 3 Referring now to Fig. 1, there is shown an ATM (asynchronous 24 transfer mode) network according to a first embodiment of the present 2 5 invention. The network includes a plurality of nodes, ar ATM switches 26 110, 111, 112 and 113 interconnected by transmission lines. The nodes z ~ 111 and 113 are connected by virtual cross-connect paths via node 112.
2 8 each nude includes a header translation table 130 having incoming 29 entries for storing input port numbers IP, incoming VPIs and incoming 3 0 VCIs, and outgoing entries for storing output port numbers pP, outgoing VPIs and outgoing VCIs. User terminals 100 and 101 are connected respectively to the endpoint nodes 110 and 113, respectively. Note that nodes 111 and 113 are interconnected by a virtual path (VP) cross-connect system located at node 112. VCI (virtual channel identifier) establishment is not performed by the intermediate node 112. It is assumed that user terminals 100 and 101 are source and destination terminals, respectively. The source user terminal 100 is provided with a source route table 120 which is a cache memory for mapping destination addresses with corresponding "source routes". A timer 121 is provided for measuring the time lapse from the instant a source route of a given destination is stored into the table 120 and erases it when the measured time of the source route exceeds a predetermined time-out period.
This source route is created by having each node on the route add an output port number and a VPI to the packet as it propagates through the network. The source route of a signaling packet is therefore a series of concatenated route records of the nodes through which the packet has traveled.
As will be described, a source route is completed at the destination endpoint node, which transmits the source route data to the destination user where it is inserted into an acknowledgment packet transmitted back to the source user.
According to the present invention, the VPI/VCI
resource of the network is distributed among user terminals and network nodes so that each user terminal and each network node has a copy of the network resource. Therefore, each user terminal has the ability to quickly select a VPI/VCI from its own network resource. Each network node has its own pool of VPIs/VCIs which are reserved for each input port and each output port of the node. When the node receives a signaling packet, the network node makes a search through the pool of reserved VPIs/VCIs on a hardware basis.
According to the first embodiment of the present invention, the source user terminal and each network node provide VCC (virtual channel connection) establishment according to the flowcharts of Figs. 2 and 3, respectively.
In Fig. 2, the operation of source user terminal 100 begins with decision step 200 which determines whether or not a virtual connection (VC) has been established. If no virtual connection has been established, control proceeds to step 201 to make a search through the source route table 120 for a source route corresponding to the destination address U2 and proceeds to step 202 to determine if there is one. If the source route is not present, control branches at step 202 to step 203 to send a normal SETUP packet to the network, containing the destination address DA using the protocols set by the CCITT Q.93B Recommendation. Exit then is to step 204 to check to see if a normal CONNECT packet is received from the network within a specified period following the trans-mission of the signaling packet. If not, control returns to step 203 to resend the normal SETUP packet. If the normal CONNECT packet is received from the network, the source user terminal reads the source route data from the received packet n..

_13_ 2139197 and stores it into the source route table 120 (step 205). At step 206, the source user now transmits a data message to the network over the established virtual connection.
If a virtual connection is established already when the source user has a message to transmit, control branches at step 200 to step 206 to send a data packet to the destination over the established connection.
If the source route is stored in the source route table 120, the decision at step 202 is affirmative, and the source user selects VPI and VCI all by itself from its own network resource (step 207) and sends a FAST SETUP packet to the network, containing the selected VPI/VCI in the allocated VPI/VCI field of the packet for message transmission, the source route data stored in the source route table 120 corresponding to the destination address and a header containing the selected VPI and a VCI which is preassigned for signaling purposes (step 208).
Exit then is to step 209 to determine whether or not the source user terminal is in a high speed mode. If the source user is not in the high speed mode, control branches at step 209 to step 210 to check to see if a FAST CONNECT packet is received from the network. If the answer is negative at step 210, control returns to step 208 to resend the FAST SETUP
packet, and if the answer is affirmative, control proceeds to step 206 to send a data packet, and control terminates the routine.

-13a-If the source user terminal is in a high speed mode, control branches at step 209 to step 211 to send a data message over the established connection and waits for the reception of a FAST CONNECT packet from the destination (step 212). If it fails to receive the FAST CONNECT packet within a specified period following the transmission of the fast signaling packet, control returns to step 208 for retransmission. If a FAST CONNECT packet is received at step 212, the source user terminal terminates its operation until the next data packet is sent.
In Fig. 3, the operation of a network node that receives a signaling packet begins with decision step 300 to determine whether the received packet is a normal SETUP packet or a FAST SETUP packet. If the received packet is a normal SETUP packet, control exits to step 301 to select an output port number OP and a VPI from the header translation table of the node according to the destination address contained in the packet. Exit then is to step 302 to check to see if the packet is received direct from a user terminal or from an upstream node by examining the type of interfaces being used.
If the packet is received via a user-network interface (UNI), control branches at step 302 to step 303 to select an incoming port number, an incoming VPI and an incoming VCI from a list of resource data reserved for the node and set the selected incoming VPI and VCI into an incoming entry of the header translation table. The node further proceeds to select an output port number OP, an outgoing VPI and an outgoing VCI

-13b- 2 1 3 9 1 9 7 according to the destination address and set the selected OP
and outgoing VCI and VPI into an outgoing entry of the header translation table corresponding to the incoming entry. The node then ~.

' 84 12/28 00:04 x'81 5 3545 418'T hlORISARI 1-.-. SMT% CA ~I015 1 rewrites the VP1 value of the packet's header with the selected outgoing 2 VPI and sets the selected outgoing VCI into the allocated-VCI field of the 3 packet.
4 If the packet is received from an upstream node, control exits to s step 304 to set the VPi of the packet's header and the VCI of the allocated 6 VCI field of the packet into an incoming entry of the header translation 7 table, select an output part number, outgoing VPI and outgoing VCI
8 according to the destination address, set them into an outgoing entry of 9 the header translation table corresponding to the incoming entry, and rewrite the VPi value of the header of the packet with the selected 1 1 outgoing VPI.
12 Following step 303 or 304, control exits to step 305 to add the 1 3 output port number OP and the outgoing VPI to the source route field of the packet and sends the packet downstream. The node then receives a 1 5 normal CONNECT packet containing a source route from the destination 1 6 user or a downstream node (step 306) and it sends the packet upstream, containing the Vpl/VCI to be used by the source user (step 307).
i 8 If the packet is determined to be a FAST SETUP packet at step 19 300, control proceeds to step 308 to set the VPI of the packet's header 2o and the message transmission VCI into the incoming entry of the header 2 1 translation table. At step 309, control reads an output part number OP
z z and a VPI from the source route of the packet which are specified by the 2 3 hop count value and selects an outgoing VCI according to the read VPI
24 and sets the selected VCI and the source-route's OP and VPI into the 2 5 outgoing entry of the header translation table and rewrites the VPi of the z 6 header and the VCI of the allocated VCI field of the packet with the 27 source-route VPI and the selected VCI, respectively.
z 8 At step 310, the hop taunt of the packet is incremented by one 2 9 and the packet is sent downstream. The node then receives a FAST
3 0 CONNECT packet from the destination user or a downstream node (step .:

94 12-28 UU:04 $81 9 3545 4187 MORISAKI ~~1 SMT.'CA f~',018 1 311 ) and it sends the packet upstream (step 312).
2 tf the user terminal 140 wishes to send a message to the user 3 terminal 101 using a normal SETUP packet. Initially, the decision at step 202 is negative, and source user 100 sends a normal SETUP packet to tire network, which is received by each successive node along the route.
6 Each node examines the destination address in the packet and selects an 7 output port number (7P, a VPI, and an appropriate VCI for message 8 transmission, and sets the OP and VPt values into the packet as the route 9 records of the nodes, and sets the VPI into the packet's header and the VCI into the allocated VCI field of the packet and forwards the packet to a 1 I downstream node where a new route record is added to the previous i 2 record routes. As illustrated in Fig. ~A, OP and Vpl values (OPI, VP1}, 13 (OP3, VP2), (QP2, VP3) are successively set up in the header transtatian 14 tables of nodes 110, 111 and 113 and added to the packet a~ their route records, producing a source route (OPI, VP1), (OP3, VP2), (OP2, VP3). At 16 the intermediate node 1 12, the VPI value in the packet's header is 17 rewritten according to a value preassigned to the cross-connect path. At 1 8 the destination terminal 101, the source route data is inserted into a x g normal CONNECT packet, and the packet is sent back from the 2 0 destination user to the source user terminal 100, signaling successful 21 receipt of the SETUP packet. In response to the normal CONNECT
2? packet, the source user terminal saves the aource route data into the 2 3 source route table 120 (step 205) and sends a data message over the 2 4 established virtual connection (step 206}.
2 5 After transmission of data packets, the virtual connection will be 2 5 cleared off. However, if the time-out period of timer 121 is not expired, 27 the source route for the destination user terminal 101 remains in the ? 8 source route table 120 at the source user. When the user terminal 100 2 9 attempts to establish a virtual connection to the user terminal 101 again, 3 D the decision at step 202 is affirmative, and the source user selects a v ~1391;~~
94 1228 00:05 '~'81 3 3545 4187 310RISAHI ~1~ SMT.'C~ ~J017 NE-fi32 1 VPI/VCI from the its own VPI/VCI resource (step Z07} and sets the stored 2 source route into a packet and sends it as a FAST SETUP packet to the 3 network (step 208), If the source terminal is in a low speed mode, it waits 4 for the return of a FAST CONNECT packet acknowledging receipt of the S FAST SETUP packet (step 210) before it sends a data message over the 6 established connection (step 206).
7 In response to the FAST SETUP packet, each node examines the 8 source route of the packet, selects an outgoing VCI according to the OP
9 and VPI in the source route, sets the output port number OP and the VPI in the source route into the outgoing entry of the header translation table, sets the selected VCl into the allocated VCI field of the packet and the 12 source-route VPI into the header, and forwards the packet to the next 1 3 node. As illustrated in Fig. 4B, VPI/VCI establishment is performed at 1 ~ nodes 110, 111 and 113 using the source route data (OP1, VP1 ), (OP3, VP2), (OP2, VP3). Because of the use of the established OP/VPl routing 16 information, the processing time of each node is reduced significantly and t 7 the amount of time the source user is required to wait for 18 acknowledgment is reduced.
19 More specifically, when the source user 100 sends a FASO' SETUP
2 0 packet 500, it selects a message-transmission VCI=VCO and a VPI=VPO
z 1 according to the destination address from its own network resource, 22 inserts the source route data of the destination into the source route field 23 of the packet, as shown In Fig. S, sets the hop count to 1, sets the seler_ted 2 ~ VCO into the allocated field of the packet, and sets the selected VPO and a z 5 preassigned signaling VCIm(S) into the header.
2 6 In response to the packet 500, the node 110 sets the VP1 and 27 VC1 of the packet into the incoming entry of translation table 130 (see z 8 Fig. 1 ), reads OP1 and VP1 from the source route which are located in a 29 route record position specified by hop count 1, selects VC1 as an 30 outgoing VC! according to OP1 and VP1 and sets Opl, VC1 and VP1 into the outgoing entry of the translation table 130 and sets the VC1 into the allocated VCI field of the packet and the VP1 into the packet's header (step 309), and increments the hop count to 2 and sends the modified packet as a FAST SETUP
packet 501.
In response to the packet 501, the node 111 sets the VP1 and VC1 of the packet into the incoming entry of transla-tion table 131 (Fig. 1), reads OP3 and VP2 from a route record of the source route of the packet specified by hop count 2, selects VC2 as an outgoing VCI according to OP3 and VP2, and sets OP3, VP2 and VC2 into the outgoing entry of the translation table 131 and rewrites the header with VP2 and the allocated VCI field of the packet with VC2, increments the hop count to 3 and sends the modified packet as a FAST SETUP
packet 502.
The intermediate node 112 located in the virtual cross-connect path rewrites the VPI of the header with a preassigned VPI=C value and forwards the packet 502 over the cross-connect path to node 113 as a packet 503.
On receiving the packet 503, node 113 sets VP2 and VC2 of the packet into the incoming entry of translation table 133 (Fig. 1), reads OP2 and VP3 specified by hop count 3, selects VC3 according to OP2/VP3, and sets OP2, VP3 and VC3 into the outgoing entry of the translation table 133, rewrites the packet's header with VP3 and the allocated VCI field with VC3, increments the hop count to 4, and sends the modified packet as a FAST SETUP packet 504 to the destination 101.
x;

Since the source user has its own VPI/VCI resource and the ability to select a VPI/VCI (step 207) and each network node has its own pool of VPIs/VCIs which is searched on a hardware basis in response to a signaling packet, a virtual connection can be established with a high probability of success. Therefore, the source user is not necessary to wait for acknowledgment to send a data message. Furthermore, if the source user terminal is operating in a high speed mode, the decision at step 209 (Fig. 2) is affirmative, and the user 110 sends a data message to the network without waiting for an acknowledgment packet from the destination as illustrated in Fig. 4C. If the VC establishment should fail (step 212), the FAST SETUP packet will be retransmitted, followed by the retransmission of data message (steps 208, 209, 211).
Additionally, the source route carried by the FAST
SETUP signaling packet allows each successive node to use the output port number and a VPI to select an appropriate VCI.
Since the virtual path identifier (VPI) is an identifier given to a bundle of multiplexed virtual channels (VC), the selection of a VCI using a VPI is the process of selecting one of VCI's belonging to that VPI. Therefore, the present invention significantly reduces the processing time of each network node, and hence there is a reduction in the overall propagation time of the signaling packet.
To facilitate multivendor applications, it is advantageous that the source route data for each destination be represented by a reference number in each network node.
i Therefore, the source user receives and sends a source route in the form of a series of such reference numbers, instead of the OP/VPI combination. This feature is provided by a second embodiment of this invention illustrated in Fig. 6. In this embodiment, the user terminal 100 is provided with a source route table 600 for mapping destination addresses with corresponding sequences of reference numbers and a timer 601 that provides a time-out action for each entry of the table 600. Network nodes 110, 111 and 113 are provided with header translation tables 610, 611 and 613, respectively, for mapping the OP/VPI combination for each destination entry with a locally unique reference number. In the illustrated example, the OP1/VPl combination at node 110 for the outgoing port OP1 is represented by reference number "1" and mapped in the header translation table 610, and the OP3/VP2 combination at node 111 for the outgoing port OP3 is represented by reference number "3" and mapped in the header translation table 611.
Likewise, the OP2/VP3 combination at node 113 for the outgoing port OP2 is represented by reference number "2" and mapped in the header translation table 613.
According to the second embodiment, the operation of the source user terminal 100 proceeds in accordance with the flowchart of Fig. 2 as in the case of the first embodiment, and the operation of each network node proceeds according to a flowchart shown in Fig. 7 which differs from the flowchart of Fig. 3 in that it includes step 700 in addition to step 304 of Fig. 3 and step 701 instead of step 309 of Fig. 3. At step ~~2139197 700, a reference number is assigned to the combination of OP/VPI that is set in the outgoing entry of the header translation table of each node. The assigned reference number is mapped with the OP/VPI in the header translation table and the reference number is set into the source record field of the normal SETUP packet, which is subsequently sent downstream. Thus, the source route field of the signaling packet contains a series of reference numbers concatenated at each successive node. This series of reference numbers is contained in the normal CONNECT packet at the destination user and transmitted back to the source user, which saves the concatenated reference numbers into the appropriate destination entry of source route table 120. At step 701 that follows step 308 of Fig. 3, the reference number contained in the FAST SETUP packet is translated to OP/VPI, and an outgoing VCI is selected according to the translated VPI, and the selected VCI and the OP/VPI are set in the outgoing entry of the header translation table, and the VPI in the packet's header is overwritten with the translated VPI and the VCI in the allocated VCI field of the packet is overwritten with the selected VCI. Step 701 is then followed by step 310 of Fig. 3 for incrementing the hop count by one and the packet is forwarded downstream.
According to a third embodiment of the present invention, the source table is created at the entry point node of the network interfacing the source user terminal as illustrated in Fig. 8. In the illustrated embodiment, node -21- 2 1 3 9 1 9 ?
110 is the entry point node, where a source route table 800 is created by mapping destination addresses and corresponding source routes. As in the previous embodiment, the contents of each entry are erased by a timer 801 following the expiration of time-out period. As shown in Fig. 9, the operation of the source user terminal begins with step 900. If no virtual connection is established, control exits to step 901 to select a VPI/VCI and send a FAST SETUP packet to the network, containing a destination address and the selected VPI/VCI. At step 902, the source user determines whether an affirmative acknowledgment (ACK) packet is returned from the network, indicating that the network (entry point node) has a source route data for the destination or whether a negative acknowledgment (NACK) packet is returned indicating that the network has no source route for the destination. If a NACK
packet is received, control branches at step 902 to step 903 to send a normal SETUP packet to the network and awaits the return of a normal CONNECT packet from the destination (step 904). If an ACK packet is received, control exits to step 906. If the source user terminal is not in a high speed mode, it simply waits for a FAST CONNECT packet from the destination (step 907) before sending a data message (step 905). If the source user is in a high speed mode, a data message is sent immediately in response to the ACK packet (step 908) to confirm reception of a FAST CONNECT packet (step 909). If it fails to receive a confirmation (steps 907 and 908), control returns to step 901 to repeat the process.

-21a-The network begins operating at step 1000 which determines the type of signaling packet is received. If the received packet is a FAST SETUP packet, control branches at step 1000 to step 1001 to check to see if the packet is received directly from a user or an upstream node. If the packet is from a user terminal, control exits to decision step 1002 to search through the source route table 800 and determines whether a source route is available for the destination address contained in the packet. If the answer is affirmative, an ACK packet is sent to the user (step 1003) and the destination address of the packet is converted to the source route (step 1004). Step 1004 is followed by subroutine 1005 comprising steps 308 to 312 of Fig. 3. By executing subroutine 1005, the destination-converted source route in the received signaling packet is carried by each subsequent node to the destination.
If the decision at step 1002 is negative, a NACK
packet is sent to the requesting user (step 1006). If the FAST SETUP packet is from a node, control branches at step 1001 to subroutine 1005, skipping steps 1002 to 1004.
When a normal SETUP packet is received, control branches at step 1000 to subroutine 1007 which comprises steps 301 to 306 of Fig. 3 to send a normal SETUP packet and receive a normal CONNECT packet. Exit then is to step 1008 to check to see if the normal signaling packet that was received at step 1000 is one directly received from user or node. If the signaling packet was from a node control proceeds to step 1009 -21b-to send a normal CONNECT packet upstream, containing VPI/VCI.
If the normal signaling packet of step 1000 was from a user, the source route contained in the received CONNECT packet is stored into the source route table 800 at step 1010 and control exits to step 1009.
Therefore, the source user is allowed to send a data message at the instant it received an ACK packet during the high speed mode (step 908). As shown in Fig. 11, the source user terminal 100 will receive an ACK packet 1100 from node 110 immediately following the transmission of a FAST SETUP
packet, data message transmission can be started very quickly.
By the provision of a source route table at an entry point node of the network, the source route table can be advantageously shared by a 94 12/28 00:08 '181 3 3545 4187 MORISAKI ~-~-~ SMT/CA X1023 1 group of-users that are serviced by the node. In addition, if an alteration 2 is made in the source route of a destination address, the entry point node 3 can quickly respond to it by making changes in the Corresponding entry 4 of the source route table.
A fourth embodiment of the present invention is shown in Figs.
6 12, 13 and 14, which is a modification of the third embodiment. In this modification, source route tables are created both at source user terminal 8 and entry point node, and the source route data of each destination is 9 assigned a locally unique reference number. As shown in Fig. 12, the 1 0 source user terminal 100 and the entry point node 110 have the ability to 1 1 create source route tables 1200 and 1201. The time lapse of each entry 12 of the source route table 1201 is monitored by timer 1202 in the same 13 manner as in the previous embodiments. The source route table 1200 14 defines a map between destination addresses and corresponding ~ 5 reference numbers, and the source route table 1207 defines a map 1 6 between reference numbers and source routes comprising a series of 17 output port numbers and VPIs.
18 In Fig. 13, the user terminal begins operation at step 13UU to 1 9 check to see if a virtual connection is established. If not, control exits to 20 step 1301 to search through its source route table for a reference number 21 corresponding to the desired destination. If the answer is negative, 22 control branches at step 1301 to step 1302 to send a norr»al SETUP
2 3 packet to the network. If a normal CONNECT packet is not received (step 24 1303), the normal SETUP packet will be retransmitted (step 1302). If it is 2 5 received, control exits to step 1304 to store the reference number Carried z 6 by the received normal CONNECT packet into the source route table z'l 1200 and sends a data message (step 1305).
8 If the decision at step 1301 is affirmative, VPI/VCI is selected and a 2 9 FAST SETUP packet is sent to the network, containing the reference 3 4 number detected in the source route table and the selected VPIIVCI (step ..

1306). At step 1307, the mode of operation is checked. If the source user terminal is in a low speed mode, a check is made at step 1308 to see if a FAST CONNECT packet is received.
If not, steps 1306 and 1307 are repeated, and if not, a data message is sent (step 1305). If the user terminal is in a high speed mode, the data message is sent (step 1309) immediately following the transmission of the FAST SETUP
packet to the network, and subsequently a check is made for confirming that a FAST CONNECT packet is received or not.
In Fig. 14, each of the network nodes begins operating at step 1400 which determines whether a received packet is a normal or FAST SETUP packet. If the signaling packet is of the normal type, control executes subroutine 1401 comprising steps 301 to 306 of Fig.3 to send a normal SETUP
packet and receive a normal CONNECT packet. At subsequent step 1402, control checks to see if the normal signaling packet received at step 1400 is one directly received from user or node. If the signal packet was from a node, control advances to step 1403 to send a normal CONNECT packet upstream. If the normal signaling packet of step 1400 was from a user, the source route contained in the received CONNECT packet is stored into the source route table 1201 and a reference number is assigned to the stored source route (step 1404) and control exits to step 1405 to send a normal CONNECT packet upstream, containing the reference number.
If the signaling packet received at step 1400 is a FAST SETUP packet, control checks to see if this packet is -23a- 2 1 3 9 1 9 7 from user or node at step 1406. If it is from user, the source route table 1201 is searched for the reference number contained in the received signaling packet and this reference number is converted to the corresponding source route data (step 1407). Control then executes subroutine 1408 comprising steps 308 to 312 of Fig. 3 to send the FAST SETUP packet downstream to receive a FAST CONNECT packet. If the signaling packet is from a node, control branches at step 1406 to subroutine 1408, skipping step 1407.

Claims (11)

1. A connection-oriented communications network comprising:
a user terminal including a source route table storing a plurality of routing information of virtual connections established in previous message transfers from the user terminal to a plurality of destination terminals, each of said routing information including a series of node-by-node route records each containing a respective virtual path identifier (VPI), and means for transmitting to the network a signaling packet containing one of the route records of said table; and a plurality of interlinked network nodes, each of the nodes including a translation table and means for receiving the signaling packet, reading a VPI from the received signaling packet and mapping incoming and outgoing routing information in said translation table in accordance with the read VPI.

2. A connection-oriented communications network as claimed in claim 1, wherein each of said route records stored in said source route table is represented by a reference number, and wherein each of said network nodes of a route is arranged to translate the reference number of a corresponding route record to routing data necessary for mapping said incoming and outgoing routing information in said translation table.

3. A connection-oriented communications network as claimed in claim 1, wherein said series of route records stored in said source route table is represented by a reference number and wherein one of said network nodes of a route is arranged to translate the reference number to a plurality of routing information necessary for each of the network nodes of the route for mapping said incoming and outgoing routing information in said translation table.

4. In a connection-oriented communications network including first and second user terminals and first and second interlinked network nodes, a method comprising the steps of:
a) sending a normal signaling packet from the first user terminal to the network, said normal signaling packet containing a destination address of the second user terminal;
b) receiving the normal signaling packet at the first network node, determining a first virtual path identifier (VPI) according to the destination address in the packet, inserting the first VPI into the received signaling packet, and forwarding the packet to the second network node;
c) receiving the normal signaling packet at the second network node, determining a second VPI according to the destination address in the packet, adding the second VPI to the first VPI in the packet to produce a source route, and forwarding the packet to the second user terminal;
d) responsive to the normal signaling packet from the second network node, sending an acknowledgment packet from the second user terminal back to the first user terminal via said second and first network nodes, the acknowledgment packet containing said source route;
e) receiving the acknowledgment packet at said first user terminal and storing the source route contained therein into a source route table;
f) selecting, at the first user terminal, an initial VPI and an initial virtual channel identifier (VCI) from a copy of network resource, sending a fast signaling packet from the first user terminal, the fast signaling packet containing the stored source route, and the initial VPI and the initial VCI;
g) receiving the fast signaling packet at the first network node, selecting a first VCI according to the first VPI
in the source route of the packet, mapping the initial VPI and the initial VCI in the packet to the first VPI and the selected first VCI, rewriting the initial VCI in the packet with the first VCI, and forwarding the packet to the second network node as a new fast signaling packet; and h) receiving the new fast signaling packet at the second network node, selecting a second VCI according to the second VPI in the source route of the packet, mapping the first VPI and the first VCI in the packet to the second VPI

and the second VCI, rewriting the first VCI in the packet with the second VCI, and forwarding the packet to the second user terminal.

5. A method as claimed in claim 4, wherein the step (f) further comprises the step of sending a data message immediately following the sending of said fast signaling packet from the first user terminal.

6. In a connection-oriented communications network including first and second user terminals and first and second interlinked network nodes, a method comprising the steps of:
a) sending a normal signaling packet from the first user terminal to the network, said normal signaling packet containing a destination address of the second user terminal;
b) receiving the normal signaling packet at the first network node, determining a first virtual path identifier (VPI) according to the destination address in the packet, assigning a first reference number to the first VPI, inserting the first reference number into the received signaling packet, and forwarding the packet to the second network node;
c) receiving the normal signaling packet at the second network node, determining a second VPI according to the destination address in the packet, assigning a second reference number to the second VPI, adding the second reference number to the first reference number in the packet to produce a source route, and forwarding the packet to the second user terminal;
d) responsive to the normal signaling packet from the second network node, sending an acknowledgment packet from the second user terminal back to the first user terminal via said second and first network nodes, the acknowledgment packet containing said source route;
e) receiving the acknowledgment packet at said first user terminal and storing the source route contained therein into a source route table;
f) selecting, at the first user terminal, an initial VPI and an initial virtual channel identifier (VCI) from a copy of network resource, sending a fast signaling packet from the first user terminal, the fast signaling packet containing the stored source route, and the initial VPI and the initial VCI;
g) receiving the fast signaling packet at the first network node, translating the first reference number in the source route of the packet to said first VPI, selecting a first VCI according to the translated first VPI, mapping the initial VPI and the initial VCI in the packet to the translated VPI and the selected first VCI, rewriting the initial VPI and the initial VCI in the packet with the first VPI and the first VCI, respectively, and forwarding the packet to the second network node as a new fast signaling packet; and h) receiving the new fast signaling packet at the second network node, translating the second reference number in the source route of the packet to said second VPI, selecting a second VCI according to the translated second VPI, mapping the first VPI and the first VCI in the packet to the translated second VPI and the second VCI, rewriting the first VPI and the first VCI in the packet with the second VPI and the second VCI, respectively, and forwarding the packet to the second user terminal.

7. A method as claimed in claim 6, wherein the step (f) further comprises the step of sending a data message immediately following the sending of said fast signaling packet from the first user terminal.

8. In a connection-oriented communications network including first and second user terminals and first and second interlinked network nodes, a method comprising the steps of:
a) selecting, at the first user terminal, an initial VPI and an initial virtual channel identifier (VCI) from a copy of network resource, sending a fast signaling packet from the first user terminal, the fast signaling packet containing a destination address of the second user terminal and the initial VPI and the initial VCI;
b) receiving the fast signaling packet at the first network node, returning a negative acknowledgment packet to the first user terminal if a source route corresponding to the destination address in the packet is not present in a source route table;

c) responsive to said negative acknowledgment packet, sending a normal signaling packet from the first user terminal to the network, the normal signaling packet containing said destination address;
d) receiving the normal signaling packet at the first network node, determining a first virtual path identifier (VPI) according to the destination address in the packet, inserting the first VPI into the received signaling packet, and forwarding the packet to the second network node;
e) receiving the normal signaling packet at the second network node, determining a second VPI according to the destination address in the packet, adding the second VPI to the first VPI in the packet to produce a source route, and forwarding the packet to the second user terminal;
f) responsive to said affirmative acknowledgment packet, sending a normal signaling packet from the first user terminal to the network, sending a connection indicating packet from the second user terminal back to the first network node, the connection indicating packet containing said source route;
g) receiving the connection indicating packet at said first network node and storing the source route contained therein into said source route table, and returning the connection indicating packet to said first user terminal;
h) if said source route is present in said source route table, selecting, at said first network node, a first VCI
according to the first VPI in the source route of the fast signaling packet from the first user terminal, mapping the initial VPI and the initial VCI in the packet to the first VPI
and the selected first VCI, rewriting the initial VCI in the packet with the first VCI, and forwarding the packet to the second network node as a new fast signaling packet; and i) receiving the new fast signaling packet at the second network node, selecting a second VCI according to the second VPI in the source route of the packet, mapping the first VPI and the first VCI in the packet to the second VPI
and the second VCI, rewriting the first VCI in the packet with the second VCI, and forwarding the packet to the second user terminal.

9. A method as claimed in claim 8, further comprising the steps of returning an affirmative acknowledgment packet from said first network node to the first user terminal if said source route is present in said source route table, and sending a data message from the first user terminal to the network.

10. In a connection-oriented communications network including first and second user terminals and first and second interlinked network nodes, a method comprising the steps of:
a) determining whether a reference number corresponding to a destination address of the second user terminal is present in a first source route table;

b) if said reference number is not present, sending a normal signaling packet from the first user terminal to the network, said normal signaling packet containing a destination address of the second user terminal;
c) if reference numbers are present, selecting an initial VPI and an initial virtual channel identifier (VCI) from a copy of network resource, sending a fast signaling packet from the first user terminal, the fast signaling packet containing the stored reference number, the initial VPI and the initial VCI;
d) receiving the normal signaling packet at the first network node, determining a first virtual path identifier (VPI) according to the destination address in the packet, inserting the first VPI into the received signaling packet, and forwarding the packet to the second network node;
e) receiving the normal signaling packet at the second network node, determining a second VPI according to the destination address in the packet, adding the second VPI to the first VPI in the packet to produce a source route, and forwarding the packet to the second user terminal;
f) responsive to the normal signaling packet from the second network node, sending an acknowledgment packet from the second user terminal back to the first network node via said second and first network, the acknowledgment packet containing said source route;
g) receiving the acknowledgment packet at said first network node and storing the source route contained therein into a second source route table and assigning said reference number to the source route;
h) receiving, at the first network node, the fast signaling packet from the first user terminal, translating the reference number in the received packet to said source route, selecting a first VCI according to the first VPI in the translated source route, mapping the initial VPI and the initial VCI in the packet to the first VPI and the selected first VCI, rewriting the initial VPI and the initial VCI in the packet with the first VPI and the first VCI, respectively, inserting said source route in the packet, and forwarding the packet to the second network node as a new fast signaling packet; and i) receiving the new fast signaling packet at the second network node, selecting a second VCI according to the second VPI in the source route of the packet, mapping the first VPI and the first VCI in the packet to the second VPI
and the second VCI, rewriting the first VPI and the first VCI
in the packet with the second VPI and the second VCI, respectively, and forwarding the packet to the second user terminal.

11. A method as claimed in claim 10, further comprising the step of sending a data message from the first user terminal immediately following the transmission of said fast signaling packet therefrom.