EP0787411A1 - Dispositif de gestion de trafic de telecommunications - Google Patents

Dispositif de gestion de trafic de telecommunications

Info

Publication number
EP0787411A1
EP0787411A1 EP95933525A EP95933525A EP0787411A1 EP 0787411 A1 EP0787411 A1 EP 0787411A1 EP 95933525 A EP95933525 A EP 95933525A EP 95933525 A EP95933525 A EP 95933525A EP 0787411 A1 EP0787411 A1 EP 0787411A1
Authority
EP
European Patent Office
Prior art keywords
network
virtual
traffic
service
capacity
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.)
Withdrawn
Application number
EP95933525A
Other languages
German (de)
English (en)
Inventor
Gillian Holmes
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
British Telecommunications PLC
Original Assignee
British Telecommunications PLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by British Telecommunications PLC filed Critical British Telecommunications PLC
Priority to EP95933525A priority Critical patent/EP0787411A1/fr
Publication of EP0787411A1 publication Critical patent/EP0787411A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q3/00—Selecting arrangements
    • H04Q3/0016—Arrangements providing connection between exchanges
    • H04Q3/0029—Provisions for intelligent networking
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q3/00—Selecting arrangements
    • H04Q3/0016—Arrangements providing connection between exchanges
    • H04Q3/0062—Provisions for network management
    • H04Q3/0091—Congestion or overload control
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q3/00—Selecting arrangements
    • H04Q3/64—Distributing or queueing
    • H04Q3/66—Traffic distributors
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q2213/00—Indexing scheme relating to selecting arrangements in general and for multiplex systems
    • H04Q2213/13522—Indexing scheme relating to selecting arrangements in general and for multiplex systems traffic management
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q2213/00—Indexing scheme relating to selecting arrangements in general and for multiplex systems
    • H04Q2213/13531—Indexing scheme relating to selecting arrangements in general and for multiplex systems virtual networks - inc. PVN
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q2213/00—Indexing scheme relating to selecting arrangements in general and for multiplex systems
    • H04Q2213/13561—Indexing scheme relating to selecting arrangements in general and for multiplex systems congestion - inc. overflow

Definitions

  • the present invention relates to traffic management arrangements in communications, and finds particular application in virtual private networks.
  • a customer is allocated communications capacity from a larger communications network, under the control of software. That is, part of a large communications network is allocated to the customer simply by a question of network and service management. There are no physically dedicated communication lines permanently associated with that customer.
  • the capacity allocated to the customer may be allocated in accordance with a service level agreement or other contractual relationship.
  • a particular advantage of virtual networks is that, if the customer uses up their allocated capacity, it is possible to offer them additional capacity from the larger network to carry overflow traffic. Relevant conditions for this facility, which may for instance be limited to particular users of a customer, can be set out in the service level agreement.
  • a virtual communications network comprising allocated traffic-carrying capacity together with service switching and control means, for providing one or more services, selected from an available set of services, to a customer, the available set of services including an overflow service which operates to route traffic by means of traffic-carrying capacity not allocated to the virtual network in the event that capacity is not available in the virtual network, wherein the overflow service is triggered by a response to an attempt to route traffic via the virtual network.
  • the response might be for instance a congestion message, or "busy" indication.
  • the relevant equipment can be provided in a relatively simple manner by means of technology now in use for communications networks, particularly where a network has an "Intelligent Network" (IN) type of architecture.
  • IN Intelligent Network
  • PSTNs public switched telephone networks
  • the transmission switches in a network have been able to recognise a call destination for an incoming call, route it appropriately, and can usually perform some traffic management such as providing secondary routeing to the destination if a primary route to that destination is not available.
  • PSTNs public switched telephone networks
  • PSTNs public switched telephone networks
  • the transmission switches in a network have been able to recognise a call destination for an incoming call, route it appropriately, and can usually perform some traffic management such as providing secondary routeing to the destination if a primary route to that destination is not available.
  • PSTNs public switched telephone networks
  • an IN type of architecture considerably more sophisticated call processing can be provided, the best known type probably being that based on number translation in which an originally called number is substituted by another number determined for instance by a service profile associated with a customer
  • trigger tables are used in association with the transmission switches to determine whether the dialled destination number of an incoming call needs traditional or IN call processing. If it is a call of the old PSTN type, the switch applies traditional routeing to set up a connection across the transmission network to the called destination. If however the call is of an IN type, requiring more sophisticated call processing, then it will be recognised by means of the trigger tables and the more sophisticated call processing is brought into play.
  • This type of technology is described in a special report published in Telephone Engineer & Management, entitled “The Promise of Intelligent Networks", by Warren G Bender, dated 1 February 1 989. A more recent description was published in the IEE Review in March 1 994, called "Putting Thought Into Networks", by Simon Glynn.
  • IN architectures provide intelligence, i.e. decision-making software, elsewhere than embedded in the transmission switches of a network and can be particularly flexible in terms of the provision and management of services.
  • an overflow service according to an embodiment of the present invention might be provided. It may further be the case that overflow traffic is charged at a higher rate to the customer, in accordance with the service level agreement. It may also be the case, in embodiments of the present invention, that the amount of overflow capacity available to a virtual network is limited to a predetermined maximum. From these points of view, therefore, it may be preferable to put in place maximum overflow capacity. This can be implemented by counting the instances of overflow traffic in progress at any one time. If an additional attempt at a traffic instance arises, above the maximum overflow capacity, the service switching and control means might then simply connect an announcement (or other form of message) and clear the attempted traffic instance.
  • PBXs private branch exchanges
  • a first user connected by means of a first PBX
  • PBXs private branch exchanges
  • the response to the attempt to route traffic may be a congestion indicator of some sort, generated according to a normal design feature of the network.
  • a particularly advantageous embodiment of the present invention arises if a "hunt" group is provided at the PBX. This, in combination with the feature "reroute on busy", provides a particularly simple means for triggering overflow without having to count each traffic instance arising in the VPN.
  • Hunt groups are known. They are groups of communication lines, for instance trunk (known in the US more commonly as long distance) connections, which have a single allocated number so that the group looks like a single number to the user. Each group may in practice though comprise multiple lines, for instance thirty, which the network hunts through until it reaches a free line on which to make a connection.
  • the SSP associated with the first user will be caused to reroute because the hunt group at the second user's PBX has hunted through all the lines of its group and reached the last without finding an available line.
  • a method of routing communications traffic by means of traffic-carrying capacity comprising the steps of: i) receiving a request for a traffic instance to be carried by the virtual network; ii) attempting to route the traffic instance by means of the virtual network; iii) generating a congestion indicator, or the like, in the event that there is no available capacity in the virtual network to carry the traffic instance; and iv) responding to the congestion indicator by routing the traffic instance by means of capacity which is not allocated to the virtual network.
  • the congestion indicator or the busy message which causes the overflow routing is preferably generated as a direct response to lack of further capacity in the VPN for the traffic instance requested, at the time when the capacity of the VPN cannot meet the new request for a traffic instance, and not in response to an ongoing monitoring exercise such as counting all traffic instances in the VPN. That is, the overflow is in response to a message returned for instance from a called number PBX, or from the SSP associated with the called number PBX, and not in response to a reference to a data store, for instance in a service control point being used to keep a direct measure of usage in the VPN by counting.
  • FIG. 1 shows, in block schematic format, elements of a virtual communications network together with overflow capacity provided by a public switched network
  • Figures 2 and 3 show, in two parts, a flow diagram of a process for providing overflow capacity to a virtual communications network customer. It should be noted that the network described below is a switched voice network but networks carrying non-voice traffic are included in the scope, of the present invention.
  • a virtual private communications network will provide communications links between private branch exchanges 1 ,2 of a customer's network. Users of that customer will have terminal equipment connected directly to those private branch exchanges 1 ,2. Calls from a first private branch exchange 1 , coming onto the virtual network, will be switched at a Service Switching Point (SSP) 3, under the control of a Service Control Point (SCP) 4.
  • SSP 3,5 comprises a Customer Access Point (CAP) 6, Call Control (CC) 7 and Service Switching Control Function (SSCF) 8.
  • CAP Customer Access Point
  • CC Call Control
  • SSCF Service Switching Control Function
  • Calls incoming from a customer PBX 1 are received at the SSP 3 via the CAP 6.
  • the SSCF 8 provides a database for call information, updatable in real time, and Call Control 7 provides management functions affecting call set up and routing.
  • the SSP 3 triggers the SCP 4 which translates the dialled number and returns a destination address in the virtual network.
  • the SSP 3 routes the incoming call
  • An overflow situation occurs when a call attempting to terminate on a dedicated access line in the virtual private communications network (VPN) meets congestion at the link between the CAP 6 and the terminating customer's equipment, or between a terminating SSP 5 and a remote Customer Access Point if no other routing is available in the VPN.
  • the overflow service then allows a re ⁇ route to try and ensure that the call is connected. This is "Direct Termination Overflow” (DTO).
  • DTO Direct Termination Overflow
  • DTO comes into operation as follows. In order to establish the service for a particular customer site, at "Day 1 ", a "DTO status" is set, in the SCP 4, against each dialled number that terminates on that particular customer site. If DTO status has been allocated in this way, then for a call incoming to a relevant dedicated access line, the SCP 4 will include a "DTO trigger arming flag" in the calling set up message sent to the SSP 3 with an initial destination address. It will also return the received information of calling party for storage within the SSP 3. On receipt of this, the SSCF 8 within the SSP 3 stores the received information and tells Call Control 7 to monitor for a congestion message. The SSP 3 then tries to route the call.
  • Call Control detects it and, instead of simply connecting an announcement as it would where DTO is not a service provided, it informs the SSCF 8.
  • the SSCF 8 now packages together its stored information and re-presents the dialled number to the SCP 4, at the same time setting a re- trigger flag to indicate that this is a re-trigger.
  • the SCP 4 performs a second translation and returns a new destination and "DTO trigger arming flag" and increments a counter.
  • the feature will cease at this point as once the call has been handed over to an external carrier there can be no further DTO.
  • the maximum number of re-tries has been exceeded. This is detected by the value of the counter which has been incremented for each re- triggering to the SCP 4. In this case the SCP 4 will instruct the SSP 3 to connect an announcement and clear the call.
  • the originating SSP 3 receives a congestion message. This may be generated by known means, perhaps using switch technology designed for network management. However, a particularly advantageous arrangement is the use of a hunt group in the PBX, which causes a busy message when all the lines in the group are found to be busy. The VPN then responds in the manner of "reroute on busy". This offers a particularly simple technical solution to providing direct termination overflow for a VPN without having to monitor all the traffic instances in progress on the VPN.
  • the process in operation is as follows.
  • the process goes to start, STEP 201 , in the event of an incoming call.
  • An incoming trunk to the SSP 3 is seized by the PBX 1 , STEP 202, and the SSP 3 receives the destination number, STEP 203, for example 1 1 2233.
  • the SSP 3 will trigger the SCP 4, STEP 204, sending it the received destination number and details of the originating PBX 1 .
  • the SCP 4 carries out a privilege check, STEP 205, checking the privileges allowed for the calling user. If the calling user is entitled to the privileges it has requested, the SCP 4 translates the destination number, STEP 206, using any
  • the SSP 3 will now route the call based on the information received from the SCP 4, STEP 210. That is, it routes the call to a second SSP 5 in the virtual private network.
  • the SSP 3 will also do a check for the mid-call trigger arm for the overflow feature, STEP 212. If the trigger arm is present, the SSP 3 will store all the information originally sent to SCP 4, in the SSCF 8, STEP 213.
  • the SCP 3 will also tell Call Control 7 to monitor for a congestion signal, STEP 214. If there is not a mid-call trigger arm present in the information returned from the SCP 4 to SSP 3, the DTO process goes no further, STEP 219.
  • the terminating Customer Access Point, or SSP 5 will now look for a trunk to the destination. If a trunk is available, the terminating Customer Access Point, or SSP 5, will return "Called User Answer” and the DTO process comes to a stop STEP 219. If, however, all trunks to the destination are busy, for instance because the last line of a hunt group has been tried and found busy, it will return a congestion message to the SSP 3 which monitors for receipt, STEP 21 5. If a congestion message is received at STEP 21 5, then the SSP 3 goes into the overflow process, (DTO Process Part II) STEP 217.
  • the overflow process starts, STEP 301 , with the SSP 3 re-triggering the SCP 4, STEP 302. That is, Call Control detects the congestion signal at the SSP 3 and informs the SSCF 8.
  • the SSCF 8 assembles the stored information and re- sends it to the SCP 4 along with an indication that this is a re-trigger because of overflow.
  • the SCP 4 firsts checks, STEP 306, the number of re-trigger attempts already made, indicated by the counter.
  • the SCP 4 simply instructs the SSP 3 to send an appropriate message to the calling user, and to clear the call, STEP 307. If however, the number of re-trigger attempts already made is less than the total allocated, the SCP 4 does a re-translation based on the overflow condition, STEP 303, and returns a new destination to the SSP 3, for example public number 456789 8000. At the same time, it increments the counter, STEP 308. In this case, the SSP 3 will now route the call via the Public Switched
  • STEP 304 forwarding the public number.
  • the carrier for the Public Switched Network 9 connects the call to the destination PBX 2, forwarding the extension digits 8000, and "Called User Answer" is returned across the virtual private network, STEP 305.
  • the overflow process then terminates, STEP 21 9.
  • SSCF Service Swithing Control Function
  • SCP service control point
  • a virtual communications network comprising allocated traffic-carrying capacity together with service switching and control means, for providing one or more services, selected from an available set of services, to a customer, the service or services provided including an overflow service which operates to route traffic by means of capacity not allocated to the virtual network in the event of congestion in the virtual network, wherein the overflow service is triggered by a congestion indicator response to an attempt to route traffic via the virtual network.
  • congestion indicator response comprises a message generated by a unit comprising switching equipment of the network and returned across the network in response to said attempt.
  • a virtual communications network according to either one of paragraphs 1 or 2 wherein the congestion indicator response comprises a message generated by a service switching point of the network and returned across the network in response to said attempt.
  • a virtual communications network according to either one of paragraphs 1 or 2 wherein the congestion indicator response comprises a message generated by a private branch exchange of the network and returned across the network in response to said attempt.
  • the congestion indicator response comprises a message generated by a private branch exchange of the network and returned across the network in response to said attempt.
  • a virtual communications network according to any one of the preceding paragraphs, further comprising monitoring means for monitoring the extent to which traffic has been routed by means of the capacity not allocated to the virtual network.
  • a virtual communications network which further comprises means for setting a maximum overflow capacity such that traffic instances arising when the maximum overflow capacity is already in use will not be routed.
  • the monitoring means comprises a counter in the service switching and control means.
  • a virtual communications network according to any one of the preceding paragraphs wherein said congestion indicator comprises a congestion message returned to the service switching and control means.
  • a virtual communications network according to any one of the preceding paragraphs wherein the service switching and control means includes two or more service switching points and at least one service control point.
  • Communications routing equipment for providing access for a user to a virtual communications network, the equipment comprising a private branch exchange connected directly or indirectly to a service switching point of the network, wherein the service switching point is provided with means for receiving a request from the network to establish a communications connection to said user via the private branch exchange, the private branch exchange is provided with a hunt group of lines for establishing a communications connection to said user by means of the network, and the private branch exchange has means for returning a message to the service switching point when the following conditions are met: i) the private branch exchange has received a request from the service switching point to establish a communications connection to said user; ii) the private branch exchange has found the last line in the hunt group to be busy.
  • a method of routing communications traffic by means of traffic-carrying capacity, some of which is allocated to a virtual network comprising the steps of: i) receiving a request for a traffic instance to be carried by the virtual network; ii) attempting to route the traffic instance by means of the virtual network; iii) generating in the virtual network, in response to said attempt, a congestion indicator in the event that capacity of the virtual network is not available to carry the traffic instance; and iv) responding to a congestion indicator by routing the traffic instance by means of capacity which is not allocated to the virtual network.
  • a method according to paragraph 1 2 wherein said attempt to route the traffic instance comprises an attempt by a private branch exchange of the network to route said traffic instance by means of a hunt group to a user's terminal, and said congestion indicator is generated when the last line of the hunt group is found to be busy.

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Sub-Exchange Stations And Push- Button Telephones (AREA)
  • Monitoring And Testing Of Exchanges (AREA)
  • Telephonic Communication Services (AREA)

Abstract

L'invention concerne un service d'encombrement dans un réseau privé virtuel (VPN). Les appels entre des centraux de raccordements privés (1, 2) sont commutés au niveau d'un Point de Commutation de Services (3) sous la commande d'un Point de Commande de Services (4). Si la capacité du VPN est déjà utilisée en totalité, toute autre tentative d'appel va déclencher un message d'encombrement. Le Point de Commutation de Services répond au message d'encombrement par acheminement des autres tentatives d'appel vers une capacité d'encombrement qui n'est pas normalement attribuée au VPN. On peut régler une capacité maximum d'encombrement, en fonction d'un accord de niveaux de services entre l'opérateur du réseau et les clients de VPN, par exemple, au moyen d'un comptage du nombre de tentatives de réacheminement. Dans un mode de réalisation avantageux, un central de raccordement privé avec un groupe de recherche de lignes permet à l'utilisateur d'accéder au réseau. Ceci permet de déterminer simplement quels sont les moments où la capacité du VPN n'est pas disponible pour établir la communication demandée par l'utilisateur.
EP95933525A 1994-10-10 1995-10-10 Dispositif de gestion de trafic de telecommunications Withdrawn EP0787411A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP95933525A EP0787411A1 (fr) 1994-10-10 1995-10-10 Dispositif de gestion de trafic de telecommunications

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
EP94307414 1994-10-10
EP94307414 1994-10-10
PCT/GB1995/002399 WO1996011551A1 (fr) 1994-10-10 1995-10-10 Dispositif de gestion de trafic de telecommunications
EP95933525A EP0787411A1 (fr) 1994-10-10 1995-10-10 Dispositif de gestion de trafic de telecommunications

Publications (1)

Publication Number Publication Date
EP0787411A1 true EP0787411A1 (fr) 1997-08-06

Family

ID=8217874

Family Applications (1)

Application Number Title Priority Date Filing Date
EP95933525A Withdrawn EP0787411A1 (fr) 1994-10-10 1995-10-10 Dispositif de gestion de trafic de telecommunications

Country Status (6)

Country Link
EP (1) EP0787411A1 (fr)
AU (1) AU3615095A (fr)
CA (1) CA2202282A1 (fr)
GB (1) GB2308274A (fr)
NZ (1) NZ293663A (fr)
WO (1) WO1996011551A1 (fr)

Families Citing this family (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2315635B (en) 1996-07-19 2000-10-11 Ericsson Telefon Ab L M Dynamic load limiting
GB9622629D0 (en) * 1996-10-30 1997-01-08 British Telecomm Communications network
CN1169380C (zh) * 1996-12-04 2004-09-29 西门子公司 路由选择方法和路由选择系统
US5951633A (en) * 1996-12-16 1999-09-14 Intervoice Limited Partnership System and method for overflow resource allocation
AU5402698A (en) * 1996-12-20 1998-07-17 British Telecommunications Public Limited Company Telecommunications network
US6115460A (en) * 1997-06-30 2000-09-05 Lucent Technologies Inc. Call redirection system
US6421434B1 (en) 1998-11-25 2002-07-16 Telefonaktiebolaget L M Ericsson (Publ) System for the marketing of telecommunications traffic capacity
US6539483B1 (en) * 2000-01-12 2003-03-25 International Business Machines Corporation System and method for generation VPN network policies
FI119139B (fi) * 2004-03-18 2008-07-31 Teliasonera Finland Oyj Menetelmä matkapuhelinvaihteessa
US8509222B2 (en) 2010-02-12 2013-08-13 Ibasis, Inc. Common routing

Family Cites Families (2)

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Publication number Priority date Publication date Assignee Title
US4747130A (en) * 1985-12-17 1988-05-24 American Telephone And Telegraph Company, At&T Bell Laboratories Resource allocation in distributed control systems
US5042064A (en) * 1990-05-03 1991-08-20 At&T Bell Laboratories Call control strategy for high capacity telecommunication services

Non-Patent Citations (1)

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Title
See references of WO9611551A1 *

Also Published As

Publication number Publication date
WO1996011551A1 (fr) 1996-04-18
GB9707049D0 (en) 1997-05-28
GB2308274A (en) 1997-06-18
NZ293663A (en) 1998-11-25
AU3615095A (en) 1996-05-02
CA2202282A1 (fr) 1996-04-18

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