WO1997035443A2

WO1997035443A2 - System and method for providing services to subscriber stations connected to an access network

Info

Publication number: WO1997035443A2
Application number: PCT/EP1997/001359
Authority: WO
Inventors: Niels Hansen; Tony Jakobsen
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 1996-03-20
Filing date: 1997-03-18
Publication date: 1997-09-25
Also published as: AU2288697A; CN1214655C; CA2250327A1; BR9708125A; WO1997035443A3; AU726064B2; MY128978A; MY121654A; CN1219328A; JP2000508843A; EP0951787A2; DE19611001A1; KR20000064709A

Abstract

An access node, an access network and a telecommunication system is disclosed that allows an access network (AN) to be fully treated as black box. The subscriber stations (SS-1, SS-2, SS-4) as well as the service network (SN) are terminated on the termination boundary (TB) of the access network (AN), whilst the internal access nodes (AN1, AN2, AN3) contain special routing, broadcasting and switching capabilities, that allow all services arriving from the service network (SN) at the termination point (TP3) via a single connection line to be delivered to the individual subscriber stations (SS-1, SS-2, SS-4), without an identification being necessary as to which access node is connected to the very subscriber station that has requested services from the service network. The invention is particularly advantageous with V5-interfaces.

Description

SYSTEM AND METHOD FOR PROVIDING SERVICES TO SUBSCRIBER STATIONS CONNECTED TO AN ACCESS NETWORK

FIELD OF THE INVENTION

The invention relates to an access node for use in an access network, an access network for providing data communication between at least one subscriber station and at least one service network and a telecommunication system comprising a number of subscriber stations, a service network and an access network. Furthermore, the invention relates to a method for providing services from a service network to one or more subscriber stations connected to an access network.

BACKGROUND OF THE INVENTION

Access networks now play an important role in providing efficient data communication between a number of subscriber stations. Such an access network is generally configured as is shown in fig. 11. A number of subscriber stations SS-1, SS-2, SS-3, SS-4 are connected respectively to an access node AN1, AN2, AN3, AN4 via a respective data communication or traffic path TRP1, TRP2, TRP3, TRP . As is shown with the dotted line in fig. 11, it is also possible to connect two subscriber stations SS-1, SS-5 to one and the same access node AN1. The access nodes AN1 to AN4 are interconnected via traffic paths, in the simplest case only with one ad acent access node, as is indicated with the traffic path TRP12, thus forming the access network AN for the subscriber stations. As is indicated with dotted lines, of course each access node can be interconnected with several other access nodes. For example, in normal telephony, the traffic paths TRP1, TRP2, TRP3, TRP4 will each use a 64kbιt/s channel of digital data, resulting from a digital decoding of the respective analog speech signal. For setting up a connection between a subscriber station e.g. SS-1, and the respective access node, e.g. AN1, the concerned access node AN1 must be able to interpret the signalling protocol used by the respective subscriber station SS-1. Once the connection has been set up, the data communication can take place. In f g. 11, such a signalling protocol or signalling format is schematically indicated by SS-F. Further, whilst fig. 11 shows all subscriber stations SS-1, SS-2, SS-3, SS-4 to use the same signalling format SS-F, in principle, depending on the capabilities of the respective access nodes AN1, AN2, AN3, AN4, each subscriber station depending on its capability may have a different signalling format. Withm the access network AN, the data communication between two respective access nodes can use the same signalling format as is used by the subscriber stations, however, generally, data communication between the access nodes can also be different, i.e. the signalling format for the data communication can be freely selected according to need.

The structure of such an access network as shown in fig. 11 is very general and can be applied both to a private networks or public networks, as is e.g. in DE 42 30 561 Al . Such access networks are particularly advantageous, since the subscriber stations themselves must only know that they can hook up to an access node, whereas they do not have to take care of how the data communication with respect to a number of subscriber stations is physically maintained within the access network. Hence, the access network can be treated as an abstract entity, as is shown with the abstract boundary AB in fig. 11.

The European Telecommunication Standards Institute (ETSI) has now compiled general guidelines of how such access networks should be handled, e.g. regarding the use of protocols, the transmission systems and fault management. This is e.g. described in reference [1] DTR/TM-2222 "The Management of Access Network" published by ETSI TM2 Access Network SEG, Copenhagen, 12-16 September 1994.

Whilst in the past access networks were solely used to enable the subscriber stations to exchange data and/or talk to each other, more advanced telecommunication techniques allow to provide additional services to the subscriber stations. According to the definitions in the afore-said ETSI-reference [1], such service provisioning functions include all procedures which are necessary to establish a service to the subscriber. Such additional services may e.g. teletext, video communication, etc., which can e.g. be provided through an additional ISDN-link.

Starting with an access network according to fig. 11, fig. 12a shows how these services are provided to the access network and thus to the subscriber stations by a service network SN. The service network SN may be a single local exchange or a number of interconnected local exchanges. Hereinafter, the term "service network" will be used, should however be understood. as comprising all such possibilities. A similar architecturre is shown in the afore-mentioned DE 42 30 561 Al, wherein a private network can provide data communication between subscribers and also provide some services, e.g. a call protocol system, to subscribers which are connected within a public network.

However, as is shown in fig. 12a, rather than using the signalling format SS-F of the subscriber stations, the services network SN can use its own signalling protocol or signalling format SN-F on its interconnection traffic path TRP-SN. Therefore, initially the service network SN does not know to which access node AN1, AN2 it can be connected, i.e. whether it is the access node AN1 or the access node AN2, which will have a termination point (shown with the black dot in fig. 12a) supporting its signalling format. In addition, as is shown in fig. 12a, the used traffic path TRP-SN will have to be a line of larger bandwidth than the ones used by the subscriber stations for transmitting the services. Therefore, when in fig. 12b the subscriber station SS-1 requests services, the access node AN1 must first be identified and checked, whether it is adapted for setting-up a signalling format used by the service network SN. If so, the line is terminated at the access node AN1 by setting up the signalling format on the traffic path TRP-SN. With this fixed connection of the traffic path TRP-SN, services can be provided to the subscriber station SS-1, wherein the term "providing of services" of course includes the transmitting of data to the subscriber station SS-1 as well as the receiving of response data from the subscriber station SS-1. In this respect, it is also to be understood that "subscriber station" is used here as a generic term, that not only comprises a telephone, but also other devices like a computer, a screen, an answer phone etc. Considering fig. l2b, where the subscriber SS-1 has requested the services from the service network SN, the situation shown there corresponds to the physical spanning of an individual line between the service network SN and the subscriber station SS-1, namely through the access node AN1 capable of terminating or setting-up the line. Considering the fixed set-up of the line as in fig. 12b, of course this leads to a major disadvantage, when the subscriber station SS-2 also requests services from the service network SN. Assuming in fig. 12c, that AN2 cannot support the signalling format and it is only access node AN1, which can be used for a connection of the service network SN, then the provision of services to the subscriber station SS-2 can only be established through the access node AN1. This is shown with dotted lines in fig. 12c.

However, as long as the subscriber station SS-1 also requesting services occupies the traffic path TRP-SN- TRP1, this traffic path is not available to other subscribers. Then, the link through AN1 is established for the other subscriber SS-2. Since no direct connection can be established to AN2, this concept is called "virtual connection concept". Such a virtual connection concept is also used in DE 42 30 561 Al in order to provide additional services to a number of subscriber stations.

As is schematically shown in fig. 12d, of course the situation worsens, if there is a further subscriber SS-4 also simultaneously requesting services from the service network SN. In this case, two virtual connections VCτ_, VC2 must be established. Despite such virtual connection concept being generally known also in the field of ATM-switching systems (see e.g. WO 94/09576) they result in the major disadvantage, that not only the abstraction level of the access network as established in fig. 11 is destroyed, but more importantly, the network resources are not optimally used.

As explained before, the service network SN itself may be constituted by a number of different entities such as a local exchange or several interconnected local exchangess, as long as it is capable of providing the required services to the subscriber stations. Nowadays, very sophisticated new service networks are considered to be interfaced to an access network, e.g. via a service network interface such as V5.

The European Telecommunications Standards Institute (ETSI) has also compiled general guidelines and recommendations of how such a V5-interface should be configured within the framework of an access network. Generally and in particular for two versions of the V5-interface (namely the V5.1- interface and the V5.2-interface) ETSI has standardised the signalling protocols and switching procedures for a configuring of the V5-interface with respect to an access network. The following documents may be referred to for further information regarding the V5-interface: reference [2] ETSI: Final Draft prETS 300 376-1: 1994; Signalling Protocols and Switching (SPS) ; Q3 interface at the Access Network (AN) for configuration management of V5 interfaces and associated user ports; reference [3] ETSI: DE/SPS-3003.1; Signalling Protocols and Switching; V interfaces at the digital Local Exchange (LE) ; V5.1 interface for the support of Access Network (AN); reference [4] ETSI: DE/SPS-3003.2; Signalling Protocols and Switching; V interfaces at the digital Local Exchange (LE) ; V5.2 interface for the support of Access Network (AN); and reference [5] DIAX Telecommunications: 9402803D011; Operation's Guide; DIAmuX. Fig. 13, which is analogous to fig. 12, describes the procedure when setting up a V5-ιnterface between a local exchange LE, SN and an access network AN. Whilst again fig. 13a shows the abstract treatment of the access network, fig. 13b and fig. 13c demonstrate the problem, i.e. that it is necessary to determine, where to terminate the V5-ιnterface on the AN side, i.e. to identify the access node where the V5-protocol can be interpreted. As is shown in fig. 13b, subscribers SS-1, SS-2, SS-3, SS-4 are connected to their respective access node withm the access network AN, whilst access nodes AN1, AN2 are indirectly connected to the local exchange LE through access node AN3, which serves as an entry point to the access network. (Such a configuration may be found e.g. in reference [5]) .

Again, the problem, that arises is how to support the V5- subscriber services on the network management layer, i.e. how to set up the V5-ιnterface protocols on the access network (see fig. 13a) .

So far, not making any difference between the specific features of the V5.1-ιnterface and the V5.2-ιnterface, generally and as is shown m fig. 11, the access network topology can be rather complex and it is not always obvious how and where the V5-ιnterfaces are to be set up in order to provide services to the subscriber stations. Even if one refers to the latest literature in e.g. reference [2], the standards regarding the problem in fig. 13a are rather vague about the definition of the object class "access network", so that presently, there are no clear guidelines available per se as to how the V5-mterfaces are to be set up on access networks . δ

As is demonstrated in fig. 13c, 13d depending on the location of the subscriber requesting the V5-supported service, the access node ANl within the access network AN is identified to which the subscriber is connected. If V5-interfaces can be established on this access node, this node ANl is used directly to provide the subscriber service. In case of the V5-supported service, this connection will be a single 2Mbit/s line.

If the V5-interfaces have, however, not already been established on the access node AN2, the virtual 2Mbit/s connection from the local exchange to the access node ANl must be set up and configured for the special V5-interface signalling protocol. For example, in fig. 13e, the subscriber SS-2 has also requested a V5-supported service, however, no V5-interface has been set up on its respective access node AN2 in advance. Then, access nodes ANl, AN2 have both been designed to terminate 2Mbit/s connections from local exchanges, but in the case of access node ANl, the 2Mbit/s connection from the local exchange is not terminated in ANl itself, but rather cross-connected to enable the 2Mbit/s connection to be terminated in access node AN2 (2Mbit/s connections are used between ANl, AN2 (see also reference [2]) .

Therefore, using the access node ANl as a transport access node and AN2 as the final target access node, it is possible to string a virtual 2Mbit/s connection between the local exchange LE and the access node AN2, such that the V5- interface can be terminated at the access node AN2, thus allowing the subscriber station SS-2 to be provided with services supported by the V5-interface (e.g. basic rate ISDN- BA) . Of course, if there are more subscribers present as is shown in fig. 12d, the situation becomes even worse also for the V5-mterface connections, since individual virtual connections will have to be set up to each target access node. Thus, generally and in particular for the V5-mterface, the followmg disadvantages can be summarized:

1. the abstraction level of the access network AN must be broken, since it is not possible to avoid looking into the access network when setting up the service network interface (e.g. the V5-mterface) ;

2. the utilization of the access network resource is not optimal, since the service network interfaces (e.g. V5- mterfaces) will have to be terminated at all access nodes, which connect subscriber stations requiring services, thus requiring virtual connections.

For example, fig. 13e, when two subscriber stations SS-1 and SS-2 both have requested the V5-supported services, e.g. the basic rate ISDN, then invariably two separate 2Mbιt/s connections between the local exchange and the access node ANl will have to be set up in order to support two different V5-mterfaces, one terminated at access node ANl and the other terminated at access node AN2. However, for capacity and resource utilization reasons, it would of course be better to have only one 2Mbιt/s connection set up between the local exchange LE and one of the access nodes within the access network AN order to simultaneously provide services to both subscribers SS-1 and SS-2.

SUMMARY OF THE INVENTION

Therefore, it is the object of the present invention to provide an access node, an access network, a telecommunication system and a method for providing services to subscriber stations of an access network, that allow to make optimum use of the capacity and resources of the access network, without destroying the abstraction level of the access network.

According to the invention, this object is solved by an access node (claim 1) for use in an access network to which are connected, via a subscriber traffic path and a service network traffic path, respectively, at least one subscriber station and at least one service network, which provides services for said subscriber stations, comprising:

a) a front end translator for interpreting a signalling format used by said at least one service network and/or said at least one subscriber station for data communications, and

b) a transmission/reception means for transmitting/receiving said services to/from said front end translator and for transmitting/receiving said services to/from at least one other access node of said access network and/or to/from at least one connected subscriber station via a respective traffic path.

According to the invention, the above object is also solved by an access network (claim 14) for providing data communication between at least one subscriber station and at least one service network, which provides services for said subscriber stations, said at least one subscriber station and said at least one service network being adapted for performing data communications respectively using a specific signalling format, comprismg: Hi a) a termination boundary having termination points adapted for a connection of said at least one subscriber station and said at least one service network via a respective subscriber station traffic path or a service network traffic path;

b) said termination points being respectively connected to an internal access node inside said termination boundary via a respective traffic path;

c) said access nodes being interconnected to each other via a respective traffic path; and

d) wherein each access node is constituted as mentioned above.

According to the invention, the object is also solved by a telecommunication system (claim 31) comprising a number of subscriber stations and a service network connected, via respective subscriber station traffic paths and a service network traffic path, respectively, to a respective termination point of an access network as afore-mentioned.

According to the invention, the object is further solved by a method (claim 36) for providing services from a service network to one or more subscriber stations connected to an access network as afore mentioned, comprising the following steps :

a) connecting said service network to a termination point of said access network supporting said service network signalling format via a service network traffic path; b) setting-up said service network with its signalling format in the front end translator of said access node, wherein said access node becomes the entry access node for said service network into said access network;

c) sending one or a number of services for one or more subscriber stations requesting said services via said connected service traffic path from said service network to said entry access node; and

d) receiving said services at said entry access node;

e) wherein said entry access node and each of said interconnected other access nodes route and switch said received services respectively to other interconnected access nodes and to said subscriber stations having requested said services.

Since in the above method, the telecommunication system and the access network, the access nodes are provided with the front end translator and the transmission/reception means, service network interfaces can be terminated on the boundary of complex access network interfaces. This facilitates a flexible and uniform set-up of service network interfaces on access networks, no matter how complex their internal topology is. Therefore, the access network can be treated a real black box entity, without any need for looking inside the access network structure, when setting up the service network. It is only necessary to know the very termination point on the termination boundary, that will support the service network interface and only a single line has to be connected to this termination point, whereas still all subscribers connected to the access network can request services from the service network, also simultaneously, if desired. Since no virtual concept is used, access networks configured with such access nodes can be treated as real black boxes to be interconnected to other access networks having the same functionality. Another advantage is, that the same structure may be applied to the service network itself, such that access and service network topology can be mutually interconnected by just interconnecting the black boxes at their termination boundary.

Accordmg to an aspect (claim 2) of the invention, with respect to the access node, preferably said front end translator is adapted for interpreting said signalling format of said service network and said signalling format of said subscriber stations.

According to another aspect (claim 3) of the invention, with respect to the access node, preferably said front end translator is adapted for terminating a subscriber traffic path having a bandwidth of 2Mbit/s or 64kbit/s and/or a service network signalling path of 2Mbit/s, if a V5-network interface is used.

Accordmg to another aspect (claim 4) of the mvention, with respect to the access node, preferably said transmission/reception means is adapted for receiving simultaneously services from said service network traffic path as a respective number of separate circuits or channels each having a specific bandwidth.

According to another aspect (claim 5) of the invention, with respect to the access node, preferably said transmission/reception means receives said services on said circuits and dynamically allocates said services on respective circuits on said traffic paths connected to said other access nodes and/or subscribers stations.

According to another aspect (claim 6) of the invention, with respect to the access node, preferably said circuits transmitted/ received to/from said subscriber stations each occupy 64kbit/s.

According to another aspect (claim 7) of the invention, with respect to the access node, preferably said services provided by said service network for said subscriber stations each occupy one or more of said 64kbit/s circuits.

According to another aspect (claim 8) of the invention, with respect to the access node, preferably communication data of said services is carried on 64kbit/s channels on B-channels and signalling data of said services is carried on 16kbit/s D-channels, if said service is basic rate ISDN.

According to another aspect (claim 9) of the invention, with respect to the access node, preferably said front end translator receives a number of bearer channels for communication data and a number of communication channels for signalling data.

According to another aspect (claim 10) of the invention, with respect to the access node, preferably said transmission/reception means is adapted for switching and routing a respective subset of bearer channels and all of said communication channels to interconnected other access nodes or subscriber stations via said traffic paths.

According to another aspect (claim 11) of the invention, with respect to the access node, preferably said transmission/reception means examines said signalling data on said communication channels and broadcasts said communication channels to other interconnected access nodes.

According to another aspect (claim 12) of the invention, with respect to the access node, preferably said transmission/reception means examines said signalling data on said communication channels and routes said communication channels to other interconnected access nodes.

According to another aspect (claim 13) of the invention, with respect to the access node, preferably said transmission/reception means comprises a routing switch, which examines received signalling data on said communication channels, selects free channels on the traffic paths leading to interconnected other access nodes or subscriber stations and then connects said channels dynamically.

According to a further aspect (claim 15) of the invention, with respect to the access network, preferably each front end translator in said access nodes interprets all signalling formats used by said subscriber stations and said service networks, wherein each subscriber station and service network can be connected to an arbitrary one of said termination points .

According to a further aspect (claim 16) of the invention, with respect to the access network, preferably said termination points each carry a termination point port connection table indicating which signalling formats are handled by said respective termination points.

According to a further aspect (claim 17) of the invention, with respect to the access network, preferably said termination point, to which said service network is connected, supports a bandwidth of 2Mbιt/s and each termination point, to which said subscriber stations are connected, support a bandwidth of 64Mbιt/s or 2Mbιt/s.

According to a further aspect (claim 18) of the invention, with respect to the access network, preferably said service network is adapted for providing said services on said service network traffic path as a respective number of separate circuits each having a specific bandwidth.

According to a further aspect (claim 19) of the invention, with respect to the access network, preferably said transmission/reception means of said access nodes receives said services on said circuits and dynamically allocates said services on respective circuits on internal traffic paths between said access node and other access nodes or on respective circuits on a subscriber station traffic path connected to a subscribers station.

According to a further aspect (claim 20) of the invention, with respect to the access network, preferably said circuits transmitted/received to/from said subscriber stations each have a 64kbιt/s bandwidth.

According to a further aspect (claim 21) of the invention, with respect to the access network, preferably said services provided by said service network for said subscriber stations each occupy one or more of said 64kbιt/s channels.

According to a further aspect (claim 22) of the invention, with respect to the access network, preferably said service network provides communication data of said services on 64kbιt/s channels on B-channels and signalling data of said services is carried on 16kBit/s D-channels, if said service is basic rate ISDN.

According to a further aspect (claim 23) of the invention, with respect to the access network, preferably said service network is a local exchange connected to said access network via a V5-interface or a VB5 broadband interface.

According to a further aspect (claim 24) of the invention, with respect to the access network, preferably said V5- interface is a V5.1-interface or a V5.2-interface.

According to a further aspect (claim 25) of the invention, with respect to the access network, preferably one of said services is a V5- or VB5-supported service, e.g. ISDN (ISDN- BA) or POTS (plain old telephone service) or a leased line service.

According to a further aspect (claim 26) of the invention, with respect to the access network, preferably said service network allocates a number of bearer channels for communication data and a number of communication channels for signalling data.

According to a further aspect (claim 27) of the invention, with respect to the access network, preferably said V5- interface uses n x 31 time slots for transmission/reception, wherein n=l for a V5.1-interface.

According to a further aspect (claim 28) of the invention, with respect to the access network, preferably said basic rate ISDN uses 2 bearer channels for communication data and 1 to 3 communication channels for signalling data, when using a V5-interface. 4δ

According to a further aspect (claim 29) of the invention, with respect to the access network, preferably said V5.1 interface uses a static allocation of bearer channels and said V5.2 interface uses a dynamic allocation of bearer channels .

According to a further aspect (claim 30) of the invention, with respect to the access network, preferably said access nodes are adapted for switching and routing a respective subset of bearer channels and all of said communication channels to interconnected other access nodes or subscriber stations .

According to a still further aspect (claim 32) of the invention, with respect to the telecommunication system, preferably one or more other access networks are connected to said access network and/or said service network.

According to a still further aspect (claim 33) of the invention, with respect to the telecommunication system, preferably one or more other service networks are connected to said access network and/or said service network.

According to a still further aspect (claim 34) of the invention, with respect to the telecommunication system, preferably said one or more service networks and/or said one or more access networks are interconnected at their termination points on their termination boundaries.

According to a still further aspect (claim 35) of the invention, with respect to the telecommunication system, preferably two or more of said interconnected access networks are connected into a generalized access network having a termination boundary on which termination points of said access and/or service networks are terminated as generalized termination points.

According to another further aspect (claim 37) of the invention, with respect to the method, preferably said service network provides said services on said service network traffic path as a number of bearer channels and communication channels and said access nodes respectively examine received signalling data on communication channels, select free channels on the traffic paths leading to other access nodes and/or to subscriber stations and dynamically connect said channels.

According to another further aspect (claim 38) of the invention, with respect to the method, preferably said sending of channels from said service network to said access network and said transmission/reception of said channels between the access nodes is performed using a time division multiplexing-method.

Embodiments of the invention will hereinafter be described with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a diagram that shows the treatment of the access network as a black box having termination points TP on the termination boundary TB according to the invention;

Fig. 2a is a diagram that shows an access node, an access network and a telecommunication system according to a first embodiment of the invention;

Fig. 2b is a diagram that shows a front end translator

FET and a transmission/reception means TR-SR according to the first embodiment of the invention;

Fig. 3a is a diagram showing an access node, an access network and a telecommunication system according to a second embodiment of the invention;

Fig. 3b is a diagram showing a front end translator

FET and a transmission/reception means TR-SR according to the second embodiment of the invention;

Fig. 3c is a diagram showing how the subscriber stations SS-1, SS-2 and the service network SN can be connected to an arbitrary termination point according to the second embodiment of the invention;

Fig. 3d is a diagram showing a termination point port connection list according to the second embodiment of the invention;

Fig. 4 is a diagram showing the method of providing services to the subscriber stations SS-1, SS- 2, SS-4 using a switching and routing of channels in the respective access nodes ANl, AN2, AN3; Fig. 5 is a diagram showing a third embodiment of an access node, an access network and a telecommunication system when setting up a V5- interface on the termination boundary TB;

Fig. 6a is a diagram showing the broadcast of signalling information for a V5.1-interface set-up, when all subscriber stations SS-1, SS- 2, SS-3, SS-4, SS-5 have respectively requested basic rate ISDN-BA from the local exchange LE, SN;

Fig. 6b, 6c in combination constitute a flow chart that describes the switching and routing of bearer channels and communication channels according to an embodiment of the method for providing services to subscriber stations, when applied to the V5.1-interface set-up shown in fig. 6a;

Fig. 7 is a diagram showing the routing of signalling information when all subscriber stations SS request basic rate ISDN-BA from the V5.1- interface;

Fig. 8 is a diagram showing the switching of bearer channels BC and communication channels CC at access nodes for a V5.2-interface;

Fig. 9 is a diagram showing an extended network topology using black box networks AN-1, AN-2, SN-1 each being configured as is shown in fig. 1 according to a fourth embodiment of the invention; Fig. 10 is a diagram showing the regrouping of networks to form a generalized "black box" network having a new termination boundary TB^T according to a fourth embodiment of the invention;

Fig. 11 is a diagram showing a conventional access network;

Fig. 12a is a diagram that illustrates the problem with connecting a service network SN to an access network according to fig. 11;

Fig. 12b is a diagram that shows a fixed set-up connection of the service network to the access node ANl;

Fig. 12c is a diagram showing the virtual connection concept when both subscribers SS-1, SS-2 have requested services from the service network SN;

Fig. 12d is a diagram showing the problems of virtual connection when three subscriber stations have simultaneously requested services from the service network;

Fig. 13a is a diagram that shows the problem when conventionally setting up a V5-interface on an access network;

Fig. 13b is a diagram that shows the interconnection of the local exchange to the access network; Fig. 13c is a diagram showing the V5-interface termination at access node ANl;

Fig. 13d, 13e are diagrams, that respectively show the interconnection and cross-linking of the V5- interface when one or two subscribers SS-1, SS-2 have simultaneously requested a V5- supported service.

DESCRIPTION OF THE EMBODIMENTS

Hereinafter, the same reference symbols as in the above- described fig. 11 to 13 are used for denoting the same or similar parts.

The general concept of the invention is illustrated in fig. 1. As seen in fig. 1, by contrast e.g. to fig. 12b, the service network SN is now terminated on the boundary TB of the access network, no matter how complex the access network may be. The termination boundary comprises a number of termination points TPl, TP2, TP3, on which the respective traffic paths TRP1, TRP2, TRP3 are terminated. If such a concept is used, then the access network can be treated as a real black box. Of course, there must be a "visibility" of termination points on the termination boundary TB, i.e. in a simplest case, where all subscribers have the same signalling format SS-F and the service network SN uses a different signalling format SN-F, the termination points must carry a label or flag that indicates that the service network and the subscriber stations, respectively, can be terminated at the such identified termination point. However, the advantage with this approach is obviously, that no further knowledge about the internal structure the access network capabilities is necessary.

First embodiment

Fig. 2a, 2b generally show the internal functionalities, that will allow this access network to be treated as a real black box. As shown in fig. 2a, an access node AN3 has been identified as supporting the signalling format SN-F of the service network SN. The subscriber stations SS-1, SS-2, SS-4 are respectively terminated on the termination points TPl, TP2, TP4 with their respective traffic paths TRP1, TRP2, TRP . The termination points are respectively connected with the access nodes ANl, AN2, AN3, wherein it is possible to connect more than one termination point to one access node as is indicated with the dotted lines. For simplicity, the internal connection of the access network nodes is shown as interconnected only with the adjacent access node via a respective traffic path TRP31, TRP21. However, of course, if more access nodes are provided in the access network, the interconnection can be arbitrary, as shown in fig. 11. It should, however, be noted that despite the fact that all subscriber stations SS-1, SS-2, SS-4 can simultaneously request services from the service network SN, there is only one single individual line set up between the switching network SN and the access node AN3 via the termination point TP3.

Fig. 2b shows the internal structure of the access nodes according to the first embodiment of the invention. The access node AN3 contains a front end translator that is capable of interpreting the interface signalling protocol SN-F from the switching network SN (or if necessary, also from an interconnected subscriber station in a termination 5 point TP4) . The front -end translator FET interprets the signalling format SN-F and provides for the internal signalling format IN-F needed to establish communication with the other internal access nodes ANl, AN2. This internal signalling format IN-F can be adjusted according to need. The access node AN3 also comprises a transmission/reception means TR-SR, that receives and transmits the services from the other interconnected access node ANl (or other connected access nodes or termination points as is shown with the dotted lines) . Having configured the access nodes as shown in fig. 2a, 2b, such that they are respectively adapted to interpret the required signalling protocol SS-F, SN-F and comprise a respective transmission/reception means, services for all interconnected subscriber stations SS-1, SS-2, SS-4 can be simultaneously provided on the single traffic path TRP3, while the access nodes AN3, ANl, AN2 respectively perform a routing and switching of the services. That is, access node AN3 (having set up the service network signalling format on its front end translator FET) receives all services from the service network SN, takes out the required service for the subscriber station SS-4 and switches the rest of the services via traffic path TRP31 to the adjacent access node ANl (all performed by the transmission/reception means TR- SR) .

In turn, the access node ANl receives the remaining services and route services required by subscriber station SS-1 to subscriber station SS-1, whereas it switches the remaining services to the access node AN2, which in turn routes the services for the subscriber station SS-2 to said subscriber station SS-2. Relying upon such internal switching and routing functionalities, the access network can be treated as a black box and maintains its abstraction level, as long as the termination point carries a label or indication as to what signalling format can be interpreted at the respective connected access node.

Second embodiment

Fig. 3a, 3b show essentially a structure similar to the one shown in fig. 2a, 2b, however, the access nodes ANl, AN2, AN3 each have the capability of interpreting all signalling formats SS-F, SN-F. As shown in fig. 3b, the front end translator according to the second embodiment is now configured so as to interpret both signalling formats SN-F, SS-F and to convert it into an internal signalling format IN- F. The switching and routing capabilities of the transmission/reception means are equivalent to those in fig. 2a, 2b. In an access network having access nodes as is shown in fig. 3a, however, there is no need for the termination points to carry a specific indication as to what signalling format can be interpreted.

This means, as is shown in fig. 3c, there is a complete black box treatment of the access network, meaning that the subscriber stations SS-1, SS-2 and the service network SN, can be connected arbitrarily to any termination point TPl, TP2, TP3 on the termination boundary TB (schematically shown with the dotted line in fig. 3c) . Of course, in general each subscriber station SS-1, SS-2 can even use a different signalling format SS-F or can even be adapted to use one of a plurality of signalling formats SS-F. Likewise, the service network may be configured to use one or several ones of signalling formats. In accordance therewith, the front end translator is adapted to respectively include the signalling formats that are used by the service network and the subscriber stations. As is shown in fig. 3d, the termination point, i.e. the physical port of the (abstract) termination boundary TB can carry a termination point port connection list TPCL indicating which kind of protocols are available at this termination point. However, in any case, with the switching and routing functions of the individual access nodes ANl, AN2, AN3, it is not required to possess any knowledge about the internal structure of the access network.

Fig. 4 shows a method of switching and routing the individual services, something that is carried out by the transmission/reception means in each access node. In fig. 4, it is assumed (as in fig. 3a) that the access nodes only support the respective signalling format required by the connected subscriber station SS-1, SS-2 and the service network SN, respectively.

As already indicated in fig. 3a, there is one connection between the service network SN and the access node AN3, that will support a specific bandwidth of x Mbit/s. This bandwidth is capable of supporting a number of circuits (circuits in this connection is to be regarded as an individual interconnection between the service network and the subscriber having requested a service, e.g. the entire route from SN to SS-2 via AN3->AN1- AN2 in fig. 4) , e.g. consisting of channels of specific bandwidths nι_, n_j, n2, n_c as is indicated in fig. 4. Naturally, the termination point TP3 will be able to support this bandwidth. The services respectively to be provided to the subscriber stations will each be transmitted on one or more channels SS-1 CH, SS-4 CH, SS-2 CH. Also necessary are of course one or more channels C- CH for the communication data, i.e. the exchange of signalling information. In fig. 4, the subscriber station SS-1 has as an example requested a service that requires three channels, the subscriber station SS-2 has requested a service requiring two channels and the subscriber station SS-4 has requested a service requiring only one channel. In this case, the termination points TP4, TPl, TP2 will respectively be adapted to support at least the required bandwidth as is indicated in fig. 4. Since in fig. 4 two communication channels C-CH are used, two communication channels will be switched and routed up to the access node AN2 through the access node ANl. Therefore, the indicated traffic paths TRP31, TRP12 respectively have the minimum bandwidth indicated in fig. 4. Of course, they can provide a larger bandwidth.

Whilst generally, bearer channels SS-1 CH, SS-4 CH, SS-2 CH and C CH of deferring bandwidth can be used in a t me division multiplexing method, these channels are usually of an equal bandwidth. It is not necessary to provide a specific fixed time relationship between the input channels on the input traffic path to the access node AN3 and the respective internal traffic path TRP31 or the traffic path to the termination point TP4, as long as the access node AN3 performs the necessary switching and routing of the correct channels, that originate from the service network. This means, the access node AN3 dynamically selects and allocates the channels from its input to its output traffic path. Likewise, the access nodes ANl, AN2 will perform the dynamic allocation of channels, until all service channels are respectively routed to the subscriber station having requested services from the service network.

The advantage of using a transmission/reception means for switching and routing of the individual channels will thus ensure, that the abstraction level of the access network is not destroyed; namely, there is neither a need to identify the specific access node, which is connected to the very subscriber station, that requires services, nor is there any necessity to string up virtual connections. Therefore, one single connection line between the service network and the respective access node (capable of interpreting the service network interface protocol) is sufficient and nevertheless, all subscriber stations can be provided with services, provided the total bandwidth of required channels does not exceed the bandwidth of the traffic path between the switching network and the respective access node.

Third embodiment

Whilst the above-proposed solution is very general and is not related to the usage of any specific interface or protocol format, in the following it will be described, how the problems with setting up a V5-interface (see fig. 12, 13 discussed above) can be solved by using a concept as shown with fig. 1 to 4.

Again, in fig. 5, the V5-interface is terminated on the boundary of the access network AN, while the access nodes ANl to AN4 have the special functionalities as described with reference to fig. 1 to 4. The V5-interface is terminated on the termination point TP6 using a 2Mbit/s bandwidth. Of course, again all 2Mbit/s access node termination points interfacing towards the service network are visible on the termination boundary TB of the access network AN. Visibility again means (as was discussed with reference to fig. 1, 2) , that it is known, which access node or which front end translator is capable of interpreting the V5-interface protocol. Looking at fig. 5, this means, that all SN interfacing 2Mbit/s termination points of access node ANl D

(the entry access node into the access network) will be known outside the access network. Likewise, this comment applies to all other termination points TPl, TP2, TP3, TP4, TP5 (which may be regarded as the exit nodes for the access network with respect to the provision of services to the subscriber stations) and also such termination points that interface to other access networks (see fig. 9) . All descriptions made for the termination points TP1-TP6 interfacing to subscribers SS-1 to SS-5 and to the local exchange LE in fig. 5 therefore only apply in a similar range manner to such termination points, that interface to another access network AN-2 or a service network SN-1 in fig. 9.

As already discussed in fig. 4, the traffic paths between the individual subscriber stations SS-1, SS-2, SS-3, SS-4, SS-5 support the minimum bandwidth required for the respective service (n x 64kbit/s) . When leased lines from other companies are used, these traffic paths can of course also support 2Mbit/s, since leased lines are only charged for the time period, during which they are occupied by data. For illustration purpose, again the access nodes ANl to AN4 are only as an example interconnected to one adjacent access node, whilst the general interconnection configuration may be taken from fig. 11.

Using the service network interfacing 2Mbit/s termination points TP on the termination boundary TB, the service network may now be interfaced in a conventional way. In fig. 5, this means that the V5-interface is in fact terminated again at the access node ANl, however, this is transparent outside the access node.

In the following, the switching and routing of channels will be described for the V5.1 and V5.2-interfaces, however, the switching and routing- is similar in as much both enable the access networks to be treated as black boxes when the V5- interfaces are set up.

V5.1-solution

In fig. 6a, the V5.1-interface is terminated at a respective termination point TP6 on the boundary, which is in turn connected to the entry access node ANl. As an example, all subscriber stations are assumed to have requested basic rate ISDN-services at their premises. Each such service to be provided to the respective subscriber station will in this case require two bearer channels BC (carrying the payload data as the channels SS-1 CH, SS-4 CH, SS-2 CH in fig. 4) of e.g. 64kbit/s (e.g. on B-channels) and two communication channels CC (carrying the signalling information as the channels C-CH in fig. 4) e.g. each occupying 16kbit/s (e.g. D-channel) . The communication channels and the bearer channels are respectively denoted with CC, BC in fig. 6a.

If 5 subscriber stations simultaneously request the basic rate ISDN, then there will be needed 10 bearer channels and 2 communication channels wherein the communication channels are used for the exchange of signalling information and the bearer channels will carry the communication data for the service. In total, the required bandwidth in this case would be 10 x 64kbit/s + 2 x 64kbit/s = 768kbit/s, which can easily be supported on the termination point of 2Mbit/s where the V5.1-interface is terminated (in a V5-interface the communication channel bandwidth is 64kbit/s) .

In fact, the V5-interface uses n x 31 bearer channels of 64kbit/s amounting e.g. to a bandwidth of 1984 kbit/s (for a V.51-interface n=l), which can fully be supported on the said termination point. Whilst the number of bearer channels (e.g. 10 for 5 subscriber stations) is fixed and dependent on the chosen V5.1-ιnterface configuration, 1, 2 or 3 64kbιt/s communication channels for signalling can be used. In fig. 6a, two communication channels CC are used.

With reference to fig. 6b, 6c, which together show a flow chart relating to the switching and broadcasting of channels in fig. 6a, the method of providing services to each subscriber station in a V5.1-ιnterface configuration will be described. First, the service network (here one local exchange LE) is connected to the termination point TP6 via the network interface in step S2 after starting the procedure step SI. In the connection step S2, the front end translator FET of the access node ANl will set up a signalling format or protocol used by the V5.1-mterface . In step S3, all subscriber stations request the V5-supported service. Therefore, m step S4, the 10 64kbιt/s bearer channels CC and (m the illustrated case) two communication channels CC are allocated and subsequently transmitted to the access node ANl step S5.

In step S6, it is determined, whether or not the subscriber station SS-1 has requested a service and if so, the access node ANl will use this information to support, i.e. to switch and route the ISDN-service to subscriber SS-1; namely, access node ANl takes out two bearer channels BC m step S7, i.e. it allocates the incoming channels to channels on the traffic path between ANl and subscriber station SS-1. Now, in step S8, the subscriber station SS-1 can use the ISDN-service, wherein there will be a transmission/reception of data on the two bearer channels. When in step S9 it is -detected in node ANl, that also the subscriber station SS-5 has requested an ISDN-service, then in steps S10, Sll, S12 again two bearer channels for the subscriber stations SS-5 are taken out and the two communication channels are again used for signalling. AN4 in step 11 transmits the two bearer channels BC to subscriber station SS-5 after having received also the two communication channels. The remaining channels (in this case 6 bearer channels and 2 communication channels) are then transmitted to the access node AN2 in step S13.

Access node AN2 will in turn check whether subscriber station SS-2 has made an ISDN-request in step S14 and if so, again two bearer channels BC are taken out and the transmission/reception takes place in steps S15, S16. The remaining channels (now 4 bearer channels and 2 communication channels) are transmitted to access node AN3 in step S17, which in step S18, S21 performs an examination as to whether the subscriber stations SS-3, SS-4 have requested the ISDN- service. If this is so, again the taking-out of channels and the transmission/reception takes place in steps S19, S20 (for subscriber station SS-3) and in steps S22, S23 (for subscriber station SS-4), before the procedure comes to an end in step S24.

Thus, whilst all services are provided on the V5.1-interface, there is a selection and transmission of bearer channels in the internal structure of the access network until the last subscriber station having requested service has been provided with the requested service. By doing so, it is ensured that the bearer channels arrive at their proper destination.

The signalling information on the communication channels is required by the access nodes to support the subscriber services. In fig. 6a, . access node ANl is obviously aware of two communication channels on the V5.1-interface. These two communication channels contain the complete signalling information that is required by all subscriber services on the V5.1-interface. The access node ANl has therefore the choice of either examining the signalling information and "route" it to the concerned access nodes AN2, AN4 (see fig. 7) or to "broadcast" it to access nodes AN2, AN4 as was done in fig. 6a. In doing so, access node AN2 will in turn broadcast the signalling information to access node AN3. This way, all access nodes within the access network will receive the very same signalling information, although parts or all of this information may not apply to them. However, it is ensured that all access nodes will receive their required signalling information via the two communication channels CC used for this signalling information.

As indicated in fig. 6a, the broadcast of signalling information is indeed feasible for most practical applications, however, it can have the undesired effect of signalling information taking up too many time slot channels on the signalling paths between the individual access nodes. As seen in fig. 6a, the two communication channels CC are always broadcast to the adjacent access node, despite this access node might not need the complete signalling information. This increases the bandwidth requirements.

Fig. 7 uses the principle of having the access nodes examine the received signalling information on the communication channels CC and then only to route it to the concerned access nodes. That is, the access node ANl will examine, which signalling information is needed by access node AN4 and perform the routing of this channel only, whilst the remaining communication channel is routed to the other access node AN2. Therefore, in this case, the steps S6, S7; S9, S10; S14, S15; S18, S19; S21, S22 in fig. 6b, 6c are appropriately altered, so as to include the examination of the communication channel and only route to the respective access node such signalling information, that is required there.

V5.2-sol tion

Setting up a V5.2-interface on the access network is not intrinsically different from the V5.1-case. However, rather than using a fixed allocation of time slots on the bandwidth, the V5.2-interface uses a dynamic time slot allocation (see references [2] to [5]) and thus, in this case, the access nodes are expected to support more advanced transmission/reception capabilities in order to ensure that all bearer and signalling data arrive at their proper destinations in the access network, i.e. at the respective access nodes. Dynamic allocation of time slots in this connection means that the access nodes cannot rely upon the individual channels always having the same slot position in the bandwidth.

As in the V5.1-case, the V5.2-interface will be terminated at a termination point TP6, i.e. at access node ANl (see fig. 8) . Now, since the V5.2-interface uses a dynamic time slot allocation, access node ANl will have to examine its received signalling information on the communication channels CC in order to route the bearer and signalling data appropriately to the other access nodes AN2, AN4.

In this case and is schematically shown in fig. 8, the access node ANl (and also the access nodes AN2, AN3) will have to examine the signalling information for the communication channels CC in order to determine, which ones to route to access node AN4 and AN2 (in the case of access node ANl) . Thus, the access nodes incorporate a switch, that can examine the received signalling information on the communication channels, select free channels on the aggregate and tributary side for data transmission and then connect these channels dynamically. This way, bearer and signalling data will be routed to their proper destination the access network, much like in the V5.1-case as illustrated in fig. 6, 7. Whilst of course the examining of signalling information in this way is more complicated than the mere routing or broadcasting of signalling information (as in fig. 6, 7), the advantage of such a dynamic time slot channel allocation is also that there will be no fixed relationship described on each of the signalling paths between the individual access nodes ANl - AN2, AN2 - AN3, ANl - AN4.

Whilst in fig. 6, 7, 8, the routing and switching of channels has been described for an illustrative example with reference to the V5-interface, it should be noted that this concept is generally applicable to any service network interface, as long as it provides its services on a time slot channel basis, obtainable e.g. through a TDM-method or other channel multiplexing method.

Fourth embodiment

For each of the V5.1-interfaces and V5.2-interfaces, a solution has been presented above for treating the access network as a complete black box as was described with reference to fig. 1. As long aε the internal access nodes have the special switching, routing or broadcast capability in combination with the interpreting of the signalling format, this allows a flexible set-up of V5-interfaces on complex access network topologies. Thus, the abstract level of the access network is not broken, since the interfaces can be set up without looking into the access network. This will facilitate a higher abstraction level for network management. The utilization of the access network resources is optimal, i.e. bearer and signalling information will only take up channels on a minimum set of 2Mbit/s transmission resources.

The treatment of access networks comprising access nodes as described above, will allow telecommunication systems to be flexibly set up, as is shown in fig. 9. As long as the abstraction level of the respective networks are not broken, the access networks or service networks can be interconnected freely and flexibly, without looking into the internal structure of the access network itself. All that is required iε, that the termination point on the boundary will support the signalling format used by the respective interconnected other network.

This principle can even be extended further as is shown in fig. 10. Here, a number of general access networks AN-1¹, AN-2', AN-3' (each having an internal structure of access nodes as described above) are again interconnected, leading to a new generalized "black box" network with a new termination boundary TB' . Thus, the access networks AN-1', AN-2', AN-3' behave, as if they were access nodes within one single access network (e.g. the one denoted with AN-1') . Such a flexible set-up is possible, since the respective basic units of access nodes support the functionality as described above, i.e. such that the access networks can be treated as real black boxes with no breaking of the abstraction level. 3δ

Reference numerals in.the claims only serve illustration purposes and do not limit the scope of these claims.

Claims

CLA?IMS

An access node (AN3; ANl, AN2, Fig.l, 2a) for use in an access network (AN) to which are connected, via a subscriber traffic path (TRP1, TRP2) and a service network traffic path (TRP3), respectively, at least one subscriber station (SS-1, SS-2, SS-4) and at least one service network (SN) , which provides services for said subscriber stations, comprising:

a) a front end translator (FET; Fig. 2b) for interpreting a signalling format (SN-F; SS-F) used by said at least one service network and/or said at least one subscriber station for data communications, and

b) a transmission/reception means (TR-SR; Fig. 2b) for transmitting/receiving said services to/from said front end translator (FET) and for transmitting/receiving said services to/from at least one other access node (ANl) of said access network and/or to/from at least one connected subscriber station (SS-4) via a respective traffic path (TRP31; TRP2) .

An access node (AN3; ANl, AN2) according to claim 1, characterized in that said front end translator (FET; Fig. 3a, 3b) is adapted for interpreting said signalling format (SN-F) of said service network (SN) and said signalling format (SS-F) of said subscriber stations (SS1-F, SS2-F) . H

3. An access node (AN3; ANl, AN2) according to claim 1, characterized in that said front end translator (FET, Fig. 1, 2a) is adapted for terminating a subscriber traffic path (TRP1, TRP2) having a bandwidth of 2Mbit/s or 64kbit/s and/or a service network traffic path (TRP3) of 2Mbit/s, if a V5- network interface is used.

4. An access node (AN3, ANl, AN2) according to claim 1, characterized in that said transmission/reception means (TR-SR; Fig. 4) is adapted for receiving simultaneously services from said service network traffic path (TRP3) as a respective number of separate circuits (SS-1CH, SS2-CH, SS-4CH) each having a specific bandwidth (nl kbit/s, n2 kbit/s, n4 kbit/s, nc kbit/s) .

5. An access node (AN3, ANl, AN2) according to claim 4, characterized in that said transmission/reception means (TR-SR) receives said services on said circuits (SS-1CH, SS2-CH, SS-4CH) and dynamically allocates said services on respective circuits (SS-1CH, SS2-CH, SS-4CH) on said traffic paths (TRP31, TRP12; TRP4) connected to said other access nodes (ANl, AN2) and/or subscribers stations (SS-4) .

6. An access node (AN3, ANl, AN2) according to claim 4 and 5, characterized in that said circuits (SS-1CH, SS2-CH, SS-4CH) transmitted/ received to/from said subscriber stations (SS) each occupy 64kbit/s. 7. Access node (AN3-; ANl, ANl) according to claim 6, characterized in that said services provided by said service network (SN) for said subscriber stations (SS) each occupy one or more of said 64kbit/s circuits.

8. Access node (AN3; ANl, AN2) according to claim 1, characterized in that communication data (BC) of said services is carried on 64kbit/s channels on B-channels and signalling data (CC) of said services is carried on 16kBit/s D-channels, if said service is basic rate ISDN.

9. Access node (AN3; ANl, AN2) according to claim 1, characterized in that said front end translator (FET) receives a number of bearer channels (BC) for communication data and a number of communication channels (CC) for signalling data.

10. Access node (AN3; ANl, AN2) according to claim 9, characterized in that said transmission/reception means (TR-SR, Figs. 4, 6a, 7) is adapted for switching and routing a respective subset (n2, nl) of bearer channels (BC) and all (nc) of said communication channels (CC) to interconnected other access nodes or subscriber stations via said traffic paths (TRP31, TRP21) .

11. Access node (AN3; ANl, AN2) according to claim 9, characterized in that said transmission/reception means (TR-SR) examines said signalling data on said communication channels (CC) and broadcasts (Fig.- 6a) said communication channels (CC) to other interconnected access nodes.

12. Access node (AN3; ANl, AN2) according to claim 9, characterized in that said transmission/reception means (TR-SR) examines said signalling data on said communication channels (CC) and routes (Fig. 7) said communication channels (CC) to other interconnected access nodes.

13. Access node (AN3; ANl, AN2) according to claim 9, characterized in that said transmission/reception means (TR-SR) comprises a routing switch, which examines received signalling data on said communication channels (CC) , selects free channels on the traffic paths (TRP31, TRP4) leading to interconnected other access nodes or subscriber stations and then connects said channels dynamically.

14. An access network (AN; Fig. 2a) for providing data communication between at least one subscriber station (SS-1, SS-2, SS-4) and at least one service network (SN) , which provides services for said subscriber stations, said at least one subscriber station and said at least one service network being adapted for performing data communications respectively using a specific signalling format (SS-F, SN-F), comprising:

a) a termination boundary (TB) having termination points (TPl, TP2, TP3, TP4) adapted for a connection (TRP1, TRP2, TRP3, TRP4) of said at least one subscriber station and said at least one service network via a respective subscriber station traffic path (TRP1, TRP2, TRP4) or a service network traffic path (TRP3) ;

b) said termination points (TPl, TP2, TP3, TP4) being respectively connected to an internal access node

(ANl, AN2, AN3) inside said termination boundary via a respective traffic path (TRP1, TRP2, TRP3, TRP ) ; and

c) said access nodes (ANl, AN2, AN3) being interconnected to each other via a respective traffic path (TRP31, TRP21); and

d) wherein each access node (ANl, AN2, AN3) is constituted according to one or more of claims 1- 13.

15. An access network (AN) according to claim 14, characterized in that each front end translator (FET; Fig. 3a, 3b) in said access nodes interprets all signalling formats (SS-F, SN-F) used by said subscriber stations and said service networks, wherein each subscriber station (SS-1; SS-2) and service network (SN) can be connected (Fig. 3c) to an arbitrary one of said termination points (TPl, TP2, TP3, TP4) .

16. An access network (AN) according to claim 14, characterized in that said termination points (TPl, TP2, TP3, TP4) each carry a termination point port connnection table (TPCL; Fig. 3d) indicating which signalling formats are handled by said respective termination points (TP) . 17. An access network (AN) according to claim 14, characterized in that said termination point (TP3, Fig. 3a), to which said service network (SN) is connected, supports a bandwidth of 2Mbit/s and each termination point (TPl, TP2, TP4) , to which said subscriber stations (SS) are connected, support a bandwidth of 64Mbit/s or 2Mbit/s.

18. An access network (AN) according to claim 14, characterized in that said service network (SN) is adapted for providing said services on said service network traffic path (TRP3) as a respective number of separate circuits (SS-1CH, SS2- CH, SS-4CH) each having a specific bandwidth (nl kbit/s, n2 kbit/s, n4 kbit/s, nc kbit/s) .

19. An access network (AN) according to claim 18, characterized in that said transmission/reception means (TR-SR) of said access nodes receives said services on said circuits (SS-1CH, SS2-CH, SS-4CH) and dynamically allocates said services on respective circuits (SS-1CH, SS2-CH, SS-4CH) on internal traffic paths (TRP31, TRP12) between said access node (AN3) and other access nodes (ANl, AN2) or on respective circuits on a subscriber station traffic path (TRP4) connected to a subscribers station (SS-4) .

20. Access network (AN) according to claim 18, characterized in that said circuits (SS-1CH, SS2-CH, SS-4CH) transmitted/received to/from said subscriber stations (SS) each have a 64kbit/s bandwidth. ^5

21. Access network (AN) according to claim 20, characterized in that said services provided by said service network (SN) for said subscriber stations (SS) each occupy one or more of said 64kbit/s circuits.

22. Access network (AN) according to claim 14, characterized in that said service network (SN) provides communication data (BC) of said services on 64kbit/s channels on B-channels and signalling data (CC) of said services is carried on 16kBit/s D-channels, if said service is basic rate ISDN.

23. Access network (AN) according to claim 14, characterized in that said service network (SN) is a local exchange (LE) connected to said access network (AN) via a V5-interface or a VB5 broadband interface.

24. Access network (AN) according to claim 23, characterized in that said V5-interface is a V5.1-interface or a V5.2- interface.

25. Access network (AN) according to claim 23, characterized in that one of said services is a V5 or VB5 supported service, e.g. ISDN (ISDN-BA), or POTS (plain old telephone service) or a leased line service. 26. Access network (AN) according to claim 14, characterized in that said service network (SN) allocates a number of bearer channels (BC) for communication data and a number of communication channels (CC) for signalling data.

27. Access network (AN) according to claim 25 and 26, characterized in that said V5-interface uses n x 31 time slots for transmission/reception.

28. Access network (AN) according to claim 25 und 26, characterized in that said basic rate ISDN (ISDN-BA) uses 2 bearer channels for communciation data and 1 to 3 communication channels (CC) for signalling data, when using a V5-interface.

29. Access network (AN) according to claim 19 and 24, characterized in that said V5.1 interface uses a static allocation of bearer channels and said V5.2 interface uses a dynamic allocation of bearer channels.

30. Access network (AN) according to claim 26, characterized in that said access nodes (AN1-AN4) are adapted for switching and routing a respective subset (n2, nl) of bearer channels (BC) and all (nc) of said communication channels (CC) to interconnected other access nodes or subscriber stations. 31. A telecommunication system (Fig. 1) comprising a number of subscriber stations (SS-1, SS-2) and a service network (SN) connected, via respective subscriber station traffic paths (TRPl, TRP2) and a service network traffic path (TRP3) , to a respective termination point

(TPl, TP2; TP3) of an access network (AN) according to one or more of claims 14-30.

32. A telecommunication system (Fig. 9) according to claim 31, characterized in that one or more other access networks (AN-2) are connected to said access network (AN-1) and/or said service network (SN-1) .

33. A telecommunication system (Fig. 9) according to claim 31, characterized in that one or more other service networks (SN-1) are connected to said access network (AN-1) and/or said service network (SN) .

34. A telecommunication system (Fig. 9) according to claim

33, characterized in that said one or more service networks (SN-1) and/or said one or more access networks (AN-1, AN-2) are interconnected at their termination points on their termination boundaries.

35. A telecommunication system (Fig.10) according to claim

34, characterized in that two or more of said interconnected access networks (AN-1', AN-2', AN-3') are connected into a generalized access network having a termination boundary (TB') on which termination points (TP') of said access and/or 4δ service networks -are terminated as generalized termination points (TP¹) .

36. A method (Fig. 4, Fig. 6b, c) for providing services (ISDN-BA) from a service network (SN) to one or more subscriber stations (SS-1, SS-2) connected to an access network (AN) according to claims 14-30, comprising the following steps:

a) connecting said service network (SN) to a termination point (TP3) of said access network (AN) supporting said service network signalling format (SN-F) via a service network traffic path (TRP3) ;

b) setting-up said service network (SN) with its signalling format (SN-F) in the front end translator (FET) of said access node (AN3) , wherein said access node (AN) becomes the entry access node (EAN) for said service network (SN) into said access network (AN) ;

c) sending one or a number of services (ISDN-BA, BC, CC, SS-1CH, SS2-CH, SS-4CH) ) for one or more subscriber stations requesting said services via said connected service traffic path (TRP3) from said service network (SN) to said entry access node

(EAN) ; and

d) receiving (TR-SR) said services (ISDN-BA, BC, CC, SS-1CH, SS2-CH, SS-4CH) ) at said entry access node (EAN) ;

e) wherein said entry access node (EAN) and each of said interconnected other access nodes (AN1-AN4) route and switch said received services respectively to other interconnected access nodes (AN1-AN4) and to said subscriber stations having requested said services.

37. A method (Fig. 6, 7, 8) according to claim 36, characterized in that said service network (SN) provides said services on said service network traffic path (TRP3, V5.1, V5.2) as a number of bearer channels (BC) and communication channels (CC) and said access nodes respectively examine received signalling data on communication channels (CC) , select free channels on the traffic paths leading to other access nodes and/or to subscriber stations and dynamically connect said channels.

38. A method (Fig. 4) according to claim 36, characterized in that said sending of channels from said service network (SN) to said access network (AN) and said transmission/reception of said channels between the access nodes is performed using a time division multiplexing method.