WO1999065187A2

WO1999065187A2 - Network management

Info

Publication number: WO1999065187A2
Application number: PCT/SE1999/000815
Authority: WO
Inventors: Niels Qvistgaard Hansen; Tony Thisted Jakobsen
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 1998-06-12
Filing date: 1999-05-14
Publication date: 1999-12-16
Also published as: SE9802110L; EP1088424A2; SE514589C2; SE9802110D0; AU4809199A; CA2334959A1; CN1312992A; WO1999065187A3

Abstract

The invention describes how telecommunication services can be handled in Access Networks (AN). A management concept is proposed that will enhance management by using a 'loose coupling' between the defined telecommunication services and the transport network on which they are based. A 'loose coupling' means here that Managed Objects in the service layer and in the transport layer are not that tightly coupled due to a separation of service, protocol and transport resources. This means that the service definitions will not be directly or indirectly logically contained in a physical port. Two embodiments of the invention are shown to demonstrate its use and advantages.

Description

NETWORK MANAGEMENT TECHNICAL FIELD OF THE INVENTION

The invention relates to how telecommunication services can be handled in Access Networks (AN) . A management concept is proposed that will enhance management between the defined telecommunication services and the transport network on which they are based. The concept will allow reconfiguration of the transport network without affecting the setup of the telecommunication services in use.

DESCRIPTION OF RELATED ART

When setting up a telecommunication service (e.g. PSTN, ISDN basic and primary rate, B-ISDN or Leased Line services) in an AN, it is important that this can be done in an easy and flexible way. This means that:

When the service information is entered it should be evaluated and any obstacles for configuring the service in the network should be discovered.

- It shall be possible to reconfigure the network with minimal interruption of the active services.

In ETSI (European Telecommunication Standards Institute) some standardization work is going on in order to define common TMN based (Telecommunication Management Network) AN management interfaces. However, the solutions proposed until now are not as flexible as they could be which will be shown later on.

ETSI has defined two standards for the interface between a Local Exchange station (LE) and an AN. The common name for these standards are V5.

V5.1 and V5.2 which are interfaces that cover services with bandwidth up to 2048 kbit/s are already standardized. VB5.1 and

VB5.2 are interfaces which will also allow broadband services to be set up. The standardization work for these is ongoing. Until now only an ETSI recommendation (ETR 257 1996-03 DTR/SPS- 03040) and a preliminary ETSI standard (DE/SPS-03046-1) exist. New standards do however emerge continuously.

Other ETSI standards define management interfaces for configuring services in an Access Network (AN) . Also in this area V5.1 and V5.2 are standardized while the VB5.1 and VB5.2 standardization work is ongoing. However, neither of these standards nor any of the standards they refer to address how the service definitions are tied to the transport resources in the Network Element (NE) . The NE is here used as a common term covering both the AN and the LE . The management interface for these transport resources is pretty well defined in an interim ETSI standard (I-ETS 300 653) .

Due to the lack of standardization of the broadband interfaces (VB5.1 and VB5.2) we will in this application only use V5.1 and V5.2 examples. However, the principles provided should be valid for VB5 too.

SUMMARY

The setting up of telecommunication services is today done in a not so very easy and flexible way. There are existing solutions which do not provide neither possibilities for evaluating entered service information, nor measures for discovering obstacles for configuring services in the network. This means that even small alterations in the service affects other parts of the service which in turn then could affect even more parts and so on. This makes the system inflexible and complicated.

The part of the service configuration that will be described in this application concerns a method for managing services in TMN- based Access Networks comprising service configuration and mapping of Managed Objects and a method for configuring the Local Exchange- and Access Network side of a Service Node Interface (i.e. e.g. the V5 interface itself) in a telecommunicaton system and the mapping of the related Managed Objects (MOs) to the MOs representing the transport network. MOs are here defined as logical representations of physical or logical resources.

The solutions proposed until now by ETSI are not as flexible as they could be. The entity relationships between the MOs in their latest proposal will work but has some major drawbacks. This will be described later but in short it implies that most of the V5 MOs containing the service definitions are too tightly coupled to the transport network by being directly or indirectly logically contained in a physical port. Containment is here unfortunate since the service cannot be moved from one port to another without deleting the service resources and create it again. This kind of change is very useful to be able to make if e.g. a board in the NE (Network Element) fails or the connection to the LE is broken, because recreating the MOs is no simple task. When a MO is deleted its associations with other MOs are removed. Reestablishing these associations often require operations on the MOs to which the MO in question is related.

Furthermore, the solution only reflects the immediate state of an Access Network (AN), i.e. it is not obvious how a service might be preprovisioned. The need for a service is normally known some days before it has to be activated, i.e. there will typically be some days from a subscriber orders a new service until it shall be deployed. If a service cannot be set up e.g. due to lack of internal bandwidth in the AN this will not be discovered until the management system tries to activate the service. At that point in time it may be costly or impossible to correct the error without affecting the service promised to the customer.

Also, some of the non-V5 specific parts of the Information model are usable for Passive Optical Networks (PONs) only. The invention proposes a management concept that will enhance management by using a "loose" coupling between the defined telecommunication services and the transport network on which they are based. A "loose coupling" means here that V5 MOs are not that tightly coupled anymore due to a separation of transport, protocol and service resources, i.e. the V5 MOs containing the service definitions will not be too tightly coupled to the transport network by not being directly or indirectly logically contained in a physical port. Instead, the associations between MOs belonging to the service resources and the MOs belonging to the transport resources are implemented using pointers which, contrary to containment relationships, can be changed during the lifetime of the MOs involved. Basing management on this concept will allow reconfiguration of the transport network without affecting the setup of the telecommunication services in use. On this concept may systems with the following properties be built:

- Separate containment hierarchies for MOs from the Transport Network, Service and Protocol fragments with only a loose coupling between MOs that are not part of the same fragment.

- Independence of the technology used in the AN (e.g. copper, fibre or radio) .

- Allows detection of service activation problems already when the service request is entered into the management system (before the service is due for activation) . This allows for proactiveness in service provisioning.

Can be realized using objects already defined in the standards .

In order to accomplish all abovementioned features at the same time, the solution according to the invention calls, as said, for a separation of the transport, protocol and service resources so that the LE protocol fragment and the AN Protocol fragment may be the only connection between the Service fragment and the Transport fragment.

A "fragment" in this context can be defined as a grouping of a limited number of object class definitions. Each fragment deals with a particular subject. The new idea is here the identification of these four fragments and the way which is chosen to tie these together. Hence, we have taken a number of independent standards and found a new method of combining them in a flexible way to obtain abovementioned and following advantages.

The implementation principle allows e.g. a change of protocol between the LE and the AN in an easy manner where the LE and AN protocol fragments can be replaced with other MOs representing the new protocol. The only influence on the MOs in the service and transmission fragments is that pointers to the protocol fragment MOs may have to be changed. That means that the often time consuming process of inventorying the line cards in the Network Elements do not have to be repeated. Inventorying is an activity performed by the user of the management system. It is done by specifying which hardware (e.g. cables and line cards) is or will be installed in the NE .

When a line card or a connection fails the service using that resource often have to be moved to non-alarmed resources . The loose coupling is beneficial independently of whether the failure affects the aggregate side (the LE-AN interface) or the tributary side (the line to a single subscriber) . The advantage is largest at the aggregate side.

BRIEF DESCRIPTION OF THE DRAWINGS

The features of the invention believed to be novel are set forth with particularity in the appended claims. The invention itself however, both as to organization and method of operation, together with further objects and advantages thereof, may be best understood by reference to the following description taken in conjunction with the accompanying drawings, in the several Figures in which:

FIG. 1 shows a sample Access Network according to prior art;

- FIG. 2 shows a V5 interface on Access Network according to prior art;

FIG. 3 shows a block diagram illustrating an entity- relationship diagram for V5 management according to an ETSI- solution;

- FIG. 4 shows a block diagram illustarting a proposed solution for a fragment relation in an Information Model;

FIG. 5 illustrates a possible layering of the Information Model;

FIG. 6 shows a block diagram illustrating a proposed entity- relationship diagram for V5 management in Access Networks;

FIG. 7 shows an Information Model for a proposed embodiment of the invention depicting a model of a PSTN service using V5.1 ;

FIG. 8 shows an Information Model for a proposed embodiment of the invention depicting a model of a PSTN service using V5.2.

DETAILED DESCRIPTION OF EMBODIMENTS

Two embodiments of the invention will be shown in detail to illustrate it's use and advantages.

- Figure 1 shows that an AN can either be a single Access

Network Node (ANN) or it can be a subnetwork consisting of a number of internally connected ANNs as shown in the figure. The internal structure of the AN does not concern the invention, therefore it will treat the AN as a "black box". Using this principle the AN depicted in fig 1 will look as in figure 2.

Figure 3 shows prior art according to an ETSI-solution (ETSI TM2/WG4, 1996-08: "Draft of DE/TM 2209.3: Transmission (Element) Fragment") where an Entity-relationship diagram for V5 management in optical networks is depicted. In the figure the diamonds are used for representing the tight logical containments and the absence of a diamond indicates a pointer from one entity to the other, i.e. a more "loose" containment/coupling. The dots indicates multiplicity e.g. an accessNetworkElement can contain several v5Interface instances, but a pPITtp can only contain one v5Ttp (no dot used) . For a better understanding of the figure it is appropriate to define the most important abbreviations: pPI - Plesiochronous Physical Interface, Ttp - Trail Termination Point, onu - Optical Network Unit, olt - Optical Line Terminal. For a more extensive list of abbreviations see last paragraph in this chapter.

In this approach most of the V5 MOs (managed objects) are very tightly coupled to the transport network by being directly or indirectly contained in a pPITtp representing a physical port. An important drawback is therefore that a service cannot be moved from one port to another without deleting the service definition and create it again.

Figure 4 depicts in a general manner and according to the solution of the invention, the relation between the different fragments of an Information Model. The transport, protocol and service resources are according to the idea of the invention here separated and the lines between the fragments symbolize associations between MOs contained in these. It is worth noting that the protocol fragment on each side may be the only connection between the service fragment and the transport fragment. The linking between the Service Management Layer MOs and the Network Management Layer MOs are somewhat different depending on whether concentration is used on the interface between the AN and the LE . Therefore the invention will be shown in two embodiments which will illustrate the fact that the advantages and properties mentioned in the summary can be realized in the same solution.

Common to the two solutions are that they are divided into three main layers: Service layer, Path layer and Transmission media layer. The path and transmission media layers can be subdivided if appropriate. The two solutions that will be described are based on 2048 kbit/s PDH and use four layers. The path layer is split into two as shown in figure 5. The invention is not to be understood as restricted to 2048 kbit/s and PDH, rather there is a possibility for system with other bitrates and hierarchies. Moreover also further subdivision of layers will naturally belong to the concept of the invention.

The service fragment in figure 4 contains MOs belonging to the service layer shown in figure 5, while the transport fragment contains MOs belonging to the path layer and transmission media layer. The MOs in the LE and AN protocol fragments belong to the service layer or the path layer.

Figure 6 shows according to the invention, with an entity- relationship diagram, that it is possible to construct a containment hierarchy without the tight hardware binding of the objects in the protocol fragment as can be seen in the ETSI proposal in figure 3 and yet to be able to accomplish conformance with the MOs defined in the standards. In the embodiments of the invention it will be shown that four instances of layerNetorkDomain (one for each layer in figure 5) are used for the Information Model representing the system. Using this principle with four layers in fig 6, the coupling between the v5Ttp (contained in the El layerNetworkDomain) and the physical nTTP (contained in the physical layerNetworkDomain) will be loose as is illustrated with the absence of diamonds between them. This means that the linking between them is solely with pointers and that there is no tight logical containment relationship.

The physical nTTP in fig 6 corresponds functionally to the ETSI pPITtp in fig 3 which has a tight containment based relation to its v5Ttp as is illustrated with the diamond between them. Note that fig 3 and fig 6 do not show all relations as the purpose is just to illustrate the containment hierarchy.

A layerNetworkDomain (LND) is used as a convenient way to separate the network according to transmission layers. As shown in figure 5 we use four layers in the example. There will be one LND for each of these layers.

Figure 7 and 8 will show two Information Models illustrating two different embodiments of the invention to make clear that the idea is feasible. The first (fig. 7) depicts a simplified version of a possible solution for a model of a PSTN service using V5.1, implementing "loose coupling" in a system with Fixed Time Slot Allocation .

ANs with fixed time slot allocation for services is the most commonly used today. This principle is easy to implement in the NE (Network Element) , but takes up more bandwidth on the communication links than necessary (considering that the average subscriber uses his phone/connection only a few minutes a day) . V5.1 supports only this fixed time slot allocation scheme.

The way associations are drawn in the instance diagrams (fig.7 and fig.8) deserves an explanation. The arrows show which way the associations can be traced through the model. When a full line is used, the association can be read from an attribute within the MO. A dotted line is used to show informative associations/relationships which are not directly visible through attributes in the model. The containment is not shown in figures 7 and 8 because it would clutter the diagrams without adding much information to the reader. Figure 7 clearly shows the different fragments and the separation of the transport, protocol and service resources into four blocks. We also see with the horizontal dotted lines how the different layers ( Service-, E0-, E1-, and the Physical layer) are divided.

The example used here is a scenario for defining a PSTN (POTS) service. It requires four steps to get to the instance diagram shown in figure 7.

1. Define/inventory the Transport Network resources.

2. Attach a protocol to one or more trails in the network.

3. Define the service by creating two Service NTTPs, a Service Trail, a Tandem Connection and set up an (inactive) Subnetwork Connection .

4. Activate the service by creating the relevant ports and channels in the protocol fragment and setting up their associations with the rest of the model.

Step 4 may be executed immediately after step 3. In many cases however, step 4 will be scheduled for execution some days after step 3. If the service for some reason cannot be set up, this will in most cases be discovered already in step 3 giving the operator extra time to fix the problem before step 4 i scheduled for execution.

Figure 8 shows in the same way as figure 7 a possible Information Model (IM) where the separation between the fragments is visible. Here in an embodiment with an IM solution of a PSTN service using V5.2 with Dynamic Time Slot Alloca tion (concentration) . When the time slot allocation is changed from static to dynamic the number of subscribers which can be served by a certain bandwidth between the LE and AN can be increased considerably. A concentration factor of 10 is not uncommon, meaning that one connection with dynamic time slot allocation can serve the same number of subscribers as 10 connections with the same bandwidth using static allocation.

Handling dynamic time slot allocation puts some extra requirements to the AN. In practice this means that the AN must be able to handle simple switching functionality. Dynamic time slot allocation is not supported by V5.1, i.e. V5.2 is required.

Furthermore this figure also indicates that the only connection between the service fragment and the transport fragment is via the protocol fragment on each side, which means that e.g. in a case when changing the protocol (e.g. from a vendor propriety protocol like e.g. CAS/ESM to standardized like V5.1 or V5.2) the MOs in the LE and AN protocol fragments can be replaced with other MOs representing the new protocol. The only influence on the MOs in the service fragment and transmission fragment is that pointers to the protocol fragment MOs may have to be changed.

The scenario for defining a PSTN service is repeated with some modifications. It requires three steps to get to the instance diagram shown in figure 8.

1. Define/Inventory the transport network (TN) resources

2. Attach a protocol to one or more trails in the network

3. Define and activate the service by creating two Service NTTPs and a Service Trail.

The difference between this example and the previous are not visible until the service is defined in step 3. Some of the associations valid when the time slot allocation is static cannot be used here. An important notice is that the figures only depicts a possible solution including numerous MOs, the solution thus illustrating the fact that the abovementioned advantageous properties can be realized in the same solution.

While the invention has been described in the context of a preferred embodiment, it will be apparent to those skilled in the art that the present invention may be modified in numerous ways and may assume many embodiments other than that specifically set out and described above, for example; while the examples shown in the document focus on V5 as this is one of the few protocols with a de jure standard TMN interface, the principles described can also be used in other environments where protocol dependent telecommunication services are set up in a network such as in a "video on demand" service in an ATM or ADSL network.

Hence, it is accordingly intended by the appended claims to cover all modifications of the invention which fall within the true spirit and scope of the invention.

Since the terminology in this technique is frequented with numerous abbreviations, following list is appended:

ADSL Asynchronous Digital Subscriber Line

AN Access Network

ANN Access Network Node

ATM Asynchronous Transfer Mode

CTP Connection Termination Point

E0 64 kbit/s

El 2048 kbit/s

ETSI European Telecommunications Standards Institute IM Information Model

ISDN-BA Integrated Digital Services Network-Basic Access

LC Link Connection

LE Local Exchange

MO Managed Object

NCTP Network Connection Termination Point

NE Network Element

NML Network Management Layer

NTTP Network Trail Termination Point

OLT Optical Line Terminal

ONU Optical Network Unit

PON Passive Optical Network

POTS Plain Ordinary Telephone Service

PPI Plesynchronous Physical Interface

PSTN Public Switched Telephone Network

SML Service Management Layer

SNC SubNetwork Connection

SNI Service Node Interface

TMN Telecommunications Management Network

TN Transport Network

TP Termination point

TS Time Slot (64kbit/s^' _; TTP Trail Termination Point

UNI User Network Interface

UPBC User Port Bearer Channel

VA Virtual Access

Claims

1. Method for managing services in TMN-based Access Networks comprising service configuration and mapping of Managed Objects (MOs) , c h a r a c t e r i z e d in a separation of service, transport and protocol resources by implementing said resources in a Service layer, a Path layer and a Transmission media layer identifying service-, transport- and protocol fragments, said service fragment comprising MOs belonging to the Service layer, said transport fragment comprising MOs belonging to the Path layer and Transmission media layer, said protocol fragment comprising MOs belonging to the Service layer and Path layer, - employing separate containment hierarchies for the MOs within each fragment respectively, - associate MOs in the service fragment with MOs in the transport fragments by using a loose coupling between the defined telecommunication services and the transport network on which they are based.

2. Method for managing services in TMN-based Access Networks according to claim 1, c h a r a c t e r i z e d in that associations via MOs in protocol fragments are the only connection between MOs from the Service fragment and the MOs from the Transport fragment.

3. Method for managing services in TMN-based Access Networks according to claim 1 or 2, c h a r a c t e r i z e d in that said service configuration concerns configuration of a V5 or a VB5 interface and that said mapping of MOs relates to the mapping of V5 or VB5 related MOs to the MOs representing the transport network.

4. Method for configuring the Local Exchange (LE) and Access Network (AN) side of a Service Node Interface in a telecommunication system employing service-, transport- and protocol resources, said resources being represented by Managed Objects (MOs) , c h a r a c t e r i z e d in that the configuring of said part of the Service Node Interface implies, an identification of a service-, a transport-, an LE protocol- and an AN protocol fragment, a separation of said resources into said fragments, an association of MOs in the service fragment with MOs in the transport fragment by using a loose coupling between defined telecommunication services and the transport network on which they are based, said loose coupling logically employed only via said LE protocol fragment and via said AN protocol fragment.

5. An Information model representing the Local Exchange (LE and the Access Network (AN) side of a Service Node Interface in a telecommunication system employing service-, transport- and protocol resources, said Information model comprising Managed Objects (MOs) and associations between said MOs, c h a r a c t e r i z e d in that said Information model further comprises; an identification of a service-, a transport-, an LE protocol- and an AN protocol fragment, a separation of said resources into said fragments.

6. An Information model representing the Local Exchange (LE and the Access Network (AN) side of a Service Node Interface in a telecommunication system according to claim 5, c h a r a c t e r i z e d in that said Information model further comprises; an association of MOs in the service fragment with MOs in the transport fragment by using a loose coupling between defined telecommunication services and the transport network on which they are based, said loose coupling logically employed via said LE protocol fragment and via said AN protocol fragment.