Abstract:
A network management system, and a method of, centrally provisioning a full transport LSP mesh and a full targeted LDP signaling session mesh in support of VPN services provisioning are provided. A network management system repository tracks Provider Edge nodes (PE) having label switch router functionality, transport LSP meshes and targeted LDP session meshes. The method includes selecting PE nodes for inclusion in a node group, identifying PE node pairs, and issuing commands to paired PE nodes to commission managed transport LSPs and targeted LDP signaling sessions. The advantages are derived from the full mesh LSP content transport provisioning and targeted LDP signaling session provisioning effected in a centralized network management context enabling service providers to: assure network resiliency, assure service quality, and provide accounting, in respect of Layer-2 and Layer-3 VPN services irrespective of client side deployed infrastructure while leveraging installed infrastructure in the service provider communications network core. Additional advantages are derived from increased operations management personnel productivity while reducing the probability of human error compared to manual provisioning thereof enabling wide availability of VPN services.

Description:
FIELD OF THE INVENTION  
       [0001]     The invention relates to network commissioning in a network management context. In particular to methods of provisioning full mesh Label Switched Path (LSP) connectivity between Provider Edge (PE) routers in support of Layer-2 Virtual Private Network (L2VPN) services such as Virtual Private Wire Services (VPWS) and Virtual Private LAN Service (VPLS).  
       BACKGROUND OF THE INVENTION  
       [0002]     In the field of communications, service provider networks are undergoing consolidation due to market pressure to reduce telecommunication service provisioning overheads associated with maintaining multiple networks. In particular, there is a need to address cost/complexity issues related to provisioning Frame Relay (FR) services. Also, there is a need to address high bandwidth overheads incurred during content transport over Asynchronous Transfer Mode (ATM) infrastructure.  
         [0003]     Internet Protocol (IP)/MultiProtocol Label Switching (MPLS)-based network provisioning enjoys an extensive deployment largely due to the availability of economic, high speed equipment suited for service-provider-side infrastructure deployment. IP/MPLS networks can support a variety of Layer-2 (L2) technologies; including Ethernet, ATM and FR.  
         [0004]     Large organizations (customers) have multitudes of geographically displaced sites, which typically utilize Ethernet Local Area Network (LAN) infrastructure at each site. Traditionally, to provide L2VPN connectivity between these geographically displaced sites, FR services were used for inter-site connectivity between site-specific Customer Edge (CE) nodes because, FR technologies provide traffic differentiation and deterministic content transport. With the advent of IP/MPLS technologies, service providers can provide similar or better levels of Quality-of-Service (QoS) to the customer.  
         [0005]     Service providers seek solutions for connecting their IP/MPLS networks with the customers&#39; Ethernet infrastructure to provide low cost, efficient service offerings to customers, at a throughput comparable to traditional FR Virtual Leased Line (VLL) services and ATM services. However, unlike ATM and FR, plain vanilla Ethernet/IP content transport is performed in accordance with a broadcast/best-effort discipline in accordance with which packets propagate between source and destination nodes non-deterministically, and without guarantees, without necessitating infrastructure redundancy in conveying packets around failed infrastructure.  
         [0006]     L2VPN services such as Virtual Private Wire Service (VPWS) and Virtual Private LAN Service (VPLS) can be provisioned over IP/MPLS networks.  
         [0007]     VPWS coined by the Internet Engineering Task Force (IETF), generically refers to a L2VPN service that provides an Open Systems Interconnect (OSI) Layer-2 (link layer) point-to-point service (link emulation) connecting two CE nodes, associated with two corresponding customer sites, across a service provider&#39;s communications network. VPWS is also known as an Ethernet Virtual Private Line (EVPL) service if the source and destination network nodes are Ethernet based.  
         [0008]     To provide content transport in an IP/MPLS network  10 , unidirectional Label Switched Paths (LSPs)  12  are created between multiple Label Switching Routers (LSRs)  14  as shown in  FIG. 1 . In order to provide deterministic content transport and quality-of-service support, source routed LSPs  12  must be established in accordance with a traffic engineering MPLS protocol such as Resource Reservation Protocol-Traffic Engineering (RSVP-TE).  
         [0009]     The introduction of MPLS technology not only provides support for deterministic traffic content transport but also provides a migration path for service providers in support of convergence leveraging currently deployed infrastructure. A multitude of transport layer/link layer/physical layer protocols and infrastructure are compatible with MPLS in conveying content. As such, MPLS may be provisioned over IP links  16  themselves provisioned over: an IP/Ethernet infrastructure (GigE), a Packet Over Synchronous Optical NETwork (SONET) (POS) infrastructure, an Asynchronous Transfer Mode (ATM) infrastructure, etc. No physical layer details of the infrastructure of the communications network  10  are shown in  FIG. 1  nor relevant as an abstraction thereof is made in employing MPLS technologies.  
         [0010]     In accordance with customer content traffic differentiation techniques, CEs  22  associated with customer sites  20  connect to corresponding PEs  24  via respective Attachment Circuits (ACs)  26 . Each AC  26  may be either a physical or a logical circuit provisioned in accordance with the installed communications network edge infrastructure in the aggregation/distribution portion of the communications network  10 . PEs  24  multiplex customer traffic ( 30 ) onto corresponding L2VPN connection(s)  40  (a pseudo wire L2VPN connection is show).  
         [0011]     A Pseudo Wire (PW)  40  refers to an emulated bi-directional point-to-point connection over a packet-switched communications network  10  providing connectivity between two remote network nodes  22  employing any OSI layer-2 technology allowing content traffic arriving an interface  28  of a PE switch  24  to be directed across the core of communications network  10  to a corresponding interface  28  on the corresponding peer PE  24 . PW technology gets its importance from what it brings to customers by extending customer services across long distances. PW mechanisms provide emulation of the essential attributes of a selected service through a core communications network  10  of a different infrastructure (and transport technology). From a customer&#39;s point of view, a PW  40  acts as an unshared link or circuit of a particular service—each content frame conveyed by one CE  22  over the PW  40  is received by, and only by, the remote peer CE  22 . Content frame forwarding via a PW  40  is not affected by the content frames themselves, rather defined by the end-to-end PW virtual circuit  40  to which the content frame is submitted for transmission.  
         [0012]     In order to support PW  40  connectivity in an MPLS domain, a targeted LDP session must be established between corresponding PEs  24  enabling the exchange of MPLS labels. Each targeted LDP session includes an LDP signaling link configured with knowledge of remote-peer loopback address information at each end. Only a single targeted LDP session is allowed between any pair of PEs  24 . Further information regarding PW and VPLS support is provided in draft-ietf-pwe3-requirements-08.txt, published by the Internet Engineering Task Force (IETF), specification which is incorporated herein by reference.  
         [0013]     Therefore, to support any arbitrary PW  40  in a service provider&#39;s communications network  10 , a full mesh of bi-directional LSP tunnels  12  and targeted LDP sessions need to be established between participating PE nodes  24 . The targeted LDP sessions enable setting up PWs  40  over the full mesh of LSP tunnels  12  which carry the PW content traffic.  
         [0014]     Currently, PW-using-LSP connectivity is provisioned manually. The problem is that tens, or even hundreds, of PE nodes  24  are typically employed in a particular service provider network  10  to provide customer services and therefore the number of fully meshed bi-directional LSP tunnels and targeted LDP sessions between N PE  24  nodes is in the order of N(N−1). Therefore manual setup provisioning is lengthy and error-prone. Also, once the full mesh is provisioned, manually adding or removing a PE node  24  is also time consuming and error-prone.  
         [0015]     A prior art U.S. application publication No. 2003/0177221 A1 entitled “Resource Allocation Using an Auto-Discovery Mechanism for Provider-Provisioned Layer-2 and Layer-3 Virtual Private Networks” which was published on Sep. 18, 2003, describes a method in accordance with which, rather than manually configuring VPN tunnels at each PE router, the VPN Capability Discovery Information (VCDI) is “piggy-backed” onto auto-discovery information as an extension to a conventional information distribution protocol, such as Border Gateway Protocol (BGP), Domain Name Service (DNS), and RADIUS. In order to implement the proposed method, auto-discovery protocols have to be extended to include the transmission of the VCDI information. After receiving such information, a tunnel is established by, and between, the appropriate PE nodes based on the information. While the solution has merit, it requires that each PE implement the modified auto-discovery protocol. The requirement suffers from complex implications related to the fact that multi-vendor heterogeneous PE equipment is typically employed in a typical communication network infrastructure and therefore the proposed solution need be adopted by multiple vendors. While the multiple vendors may adopt such a solution eventually, there is no telling how fast the solution may be deployed as all PE equipment will need upgrading. Further, vendors may see no incentive in upgrading older PE equipment rendering it obsolete and thus preventing service providers from leveraging their existing infrastructure investment.  
         [0016]     Therefore there is a need to solve the above mentioned issues in provisioning VPN services over a managed communications network.  
       SUMMARY OF THE INVENTION  
       [0017]     In accordance with an aspect of the invention, a method of provisioning support for Virtual Private Network (VPN) services, centrally, in a network management context is provided. The method includes establishing a full transport mesh of bi-directional Label Switched Paths (LSPs) between a multitude of managed Provider Edge (PE) communications network nodes in a managed communications network, and establishing a full signaling mesh of targeted Label Distribution Protocol (LDP) signaling sessions between the multitude of PE communications network nodes.  
         [0018]     In accordance with another aspect of the invention, in establishing the full transport mesh, the method further includes further steps. A group of PE communications network nodes participating in the managed communications network is selected. Each selected PE communications network node has a Label Switched Router (LSR). A multitude of PE communications network node pairs is derived from the selected group of PE communications network nodes. And, transport LSP commissioning commands are issued to each PE communications network node in the group to establish an LSP in respect of each corresponding PE communications network node pair.  
         [0019]     In accordance with a further aspect of the invention, prior to issuing LSP commissioning commands, the method includes further steps. A determination is made as to whether a managed LSPs already exist between pairs of PE communications network nodes in the group. A further determination is made regarding whether provisioning parameters associated with the discovered LSPs comply with corresponding transport mesh provisioning parameters. And, the discovered LSPs are conditionally included in the transport mesh if compliance exists.  
         [0020]     In accordance with a further aspect of the invention, the method further includes steps of commissioning an additional LSP. A pair of PE communications network nodes is selected, and LSP commissioning commands are issued to each PE communications network node in the pair to establish an additional LSP therebetween.  
         [0021]     In accordance with a further aspect of the invention, the method further includes steps of decommissioning a selected LSP. The two PE communications network nodes corresponding to the ends of the selected LSP are identified. A determination is made regarding whether content is being conveyed via the selected LSP in respect of an actively provisioned VPN service. And, LSP decommissioning commands are selectively issued to the two PE communications network end nodes if no content is being conveyed via the selected LSP.  
         [0022]     In accordance with a further aspect of the invention, the method further includes steps adding a PE communications network node to the group. A multitude of PE communications network node pairs is derived, each pair including the additional PE communications network node and one of the PE communications network nodes in the group. LSP commissioning commands are issued to the additional PE communications network node and each PE communications network node in the group, to establish an LSP corresponding to each PE communications network node pair determined.  
         [0023]     In accordance with a further aspect of the invention, the method further includes steps removing a PE communications network node from the group. Provisioned LSPs terminating at the PE communications network node to be removed are identified. PE communications network nodes corresponding to the ends of the identified LSPs are also identified. A determination is made regarding whether content is being conveyed via the identified LSPs in respect of at least one actively provisioned VPN service. LSP decommissioning commands are selectively issued to corresponding PE communications network end nodes for each identified LSP if no content is being conveyed therethrough. And, the PE communications network node is excluded from the group if all identified LSPs have been decommissioned.  
         [0024]     In accordance with a further aspect of the invention, the method includes further steps in establishing the full signaling mesh. A group of PE communications network nodes participating in the managed communications network is selected. A multitude of PE communications network node pairs is derived in respect of the selected PE communications network nodes in the group. And, targeted LDP session commissioning commands are issued to each PE communications network node in the group to establish a targeted LDP session in respect of each corresponding PE communications network node pair.  
         [0025]     In accordance with a further aspect of the invention, prior to issuing targeted LDP commissioning commands, the method includes further steps. A determination is made as to whether managed targeted LDP sessions already exist between a pairs of PE communications network nodes in the group. And, discovered targeted LDP sessions are included in the signaling mesh.  
         [0026]     In accordance with a further aspect of the invention, the method includes further steps in commissioning an additional targeted LDP session. A pair of PE communications network nodes is selected. A corresponding pair of interfaces may further be selected, each interface being associated with a respective PE communication network node in the pair. And, targeted LDP session commissioning commands are issued to each PE communications network node in the pair to establish the additional targeted LDP session therebetween.  
         [0027]     In accordance with a further aspect of the invention, the method includes further steps in decommissioning a selected targeted LDP session. The two PE communications network nodes corresponding to the ends of the selected targeted LDP session are determined. A further determination is made as to whether signaling information is being conveyed via the selected targeted LDP session in respect of at least one actively provisioned VPN service. And, targeted LDP session decommissioning commands are selectively issued to the two PE communications network end nodes if no signaling information is being conveyed via the selected targeted LDP session.  
         [0028]     In accordance with a further aspect of the invention, the method includes further steps adding a PE communications network node to the group. A multitude of PE communications network node pairs are determined, each pair including the additional PE communications network node and one of the PE communications network nodes in the group. Targeted LDP session commissioning commands are issued to the additional PE communications network node and each PE communications network node in the group, to establish a targeted LDP session corresponding to each PE communications network node pair determined.  
         [0029]     In accordance with a further aspect of the invention, the method includes further steps in removing a PE communications network node from the group. Provisioned targeted LDP session terminating at the PE communications network node to be removed are identified. PE communications network nodes corresponding to the ends of the identified targeted LDP sessions are selected. A determination is made whether signaling information is being conveyed via identified targeted LDP sessions in respect of at least one actively provisioned VPN service. Targeted LDP session decommissioning commands are issued to the selected PE communications network end nodes of no signaling information is being conveyed via the identified targeted LDP sessions. And, the PE communications network node is excluded from the group if all identified targeted LDP sessions have been decommissioned.  
         [0030]     In accordance with a further aspect of the invention, the method further includes a step of ascribing an identifier to one of: a transport mesh of LSPs, and a signaling mesh of targeted LDP sessions.  
         [0031]     In accordance with a further aspect of the invention, the method further includes a step of: tracking one of: a transport mesh and a signaling mesh in a network management system repository.  
         [0032]     In accordance with a further aspect of the invention, a network management system centrally provisioning full mesh MultiProtocol Label Switching (MPLS) connectivity in a managed communications network in support of Virtual Private Network (VPN) service provisioning is provided. The network management system includes a network management system repository tracking managed Provider Edge (PE) communications network nodes in the managed communications network, a full content transport Label Switched Path (LSP) mesh configuration and provisioning means for managing a multitude of content transport LSPs between a selected group of managed PE communications network nodes; and a full targeted Label Distribution Protocol (LDP) signaling session mesh configuration and provisioning means for managing a multitude of targeted LDP signaling sessions between the selected group of PE communications network nodes.  
         [0033]     In accordance with a further aspect of the invention, the full content transport LSP mesh configuration and provisioning means includes a human-machine-interface.  
         [0034]     In accordance with a further aspect of the invention, the full targeted LDP signaling session mesh configuration and provisioning means includes a human-machine interface.  
         [0035]     In accordance with a further aspect of the invention, the network management system further includes one of: managed PE communications network node filtering means, and managed PE communications network node pair selection means.  
         [0036]     In accordance with yet another aspect of the invention, the network management system further includes one of: LSP discovery means, targeted LDP session discovery means, and LSP parameter comparison means.  
         [0037]     Advantages are derived from the full mesh LSP content transport provisioning and targeted LDP session provisioning effected in a centralized network management context enabling service providers to: assure network resiliency, assure service quality, and provide accounting, in respect of Layer 2 and Layer 3 VPN including, but not limited to, PW and VPLS services irrespective of client side deployed infrastructure while leveraging installed infrastructure in the service provider communications network core. Additional advantages are derived from increased operations management personnel productivity while reducing the probability of human error compared to manual provisioning thereof enabling wide availability of L2 and L3 VPN services. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0038]     The features and advantages of the invention will become more apparent from the following detailed description of the exemplary embodiment(s) with reference to the attached diagrams wherein:  
         [0039]      FIG. 1  is a schematic diagram showing an exemplary bi-directional pseudo-wire provisioned manually over a pair of label switched paths across a communications network;  
         [0040]      FIG. 2  is a schematic diagram showing, in accordance with an exemplary embodiment of the invention, a plurality of exemplary content transport full meshes of bi-directional label switched paths and an exemplary full mesh of targeted label distribution protocol signaling sessions;  
         [0041]      FIG. 3  is a schematic diagram of showing, in accordance with an exemplary implementation of the exemplary embodiment of the invention, a content transport label switched path mesh configuration module;  
         [0042]      FIG. 4  is a schematic diagram showing, in accordance with the exemplary implementation of the exemplary embodiment of the invention, a state transition diagram corresponding to a content transport label switched path commissioning process;  
         [0043]      FIG. 5  is a schematic diagram showing, in accordance with another exemplary implementation of the exemplary embodiment of the invention, exemplary details of a content transport label switched path commissioning process;  
         [0044]      FIG. 6  is a schematic diagram of showing, in accordance with and exemplary implementation of the exemplary embodiment of the invention, a signaling label distribution protocol session mesh configuration module; and  
         [0045]      FIG. 7  is a schematic diagram showing, in accordance with the exemplary implementation of the exemplary embodiment of the invention, a state transition diagram corresponding to a signaling label distribution protocol session commissioning process;  
         [0046]      FIG. 8  is a schematic diagram showing, in accordance with another exemplary implementation of the exemplary embodiment of the invention, exemplary details of a signaling label distribution protocol session commissioning process;  
         [0047]      FIG. 9  is a schematic diagram showing Ethernet-based virtual private LAN service interworking over MPLS; and  
         [0048]      FIG. 10  is a schematic diagram showing hybrid ATM/Ethernet virtual private LAN service interworking over MPLS. 
     
    
       [0049]     It will be noted that in the attached diagrams like features bear similar labels.  
       DETAILED DESCRIPTION OF THE EMBODIMENTS  
       [0050]     In accordance with an exemplary embodiment of the invention, full mesh Label Switched Path (LSP) provisioning and full mesh targeted Label Distribution Protocol (LDP) session provisioning in a centralized network management context is provided.  
         [0051]     In a network management context shown in  FIG. 2 , at least one Network Management System (NMS)  100  is employed to manage network entities, such as, but not limited to: communications network nodes  102  in a managed communications network  104 . Communications network management is important particularly in view of complexities associated with typical service provider communications networks, regarding which the following relevant complexities are only exemplary:  
         [0052]     Multi-vendor equipment is employed in a typical communications network  104 . Multi-vendor equipment also includes multiple equipment types as well multiple versions of the vendor equipment running multiple versions of software/firmware.  
         [0053]     Communications network nodes  102  may be typically classified by function and the manner in which the communications network nodes  102  are employed as part of the (installed) infrastructure of the communications network  104 . It is important to keep in mind that each communications network node  102  may perform a variety of communications network functions. Typically communications network nodes  102  employed in a typical managed service provider network  104 , are configurable multi-shelf devices which implement physical transport technologies and content transport protocols on interface cards  106 , although monolithic network node devices  102  may also be employed.  
         [0054]     Communications network nodes  102  connected to Customer Edge (CE) equipment  108  via physical access links  110  are referred to as Provider Edge (PE) communications network nodes. Communications network nodes  102  not connected directly to CE equipment  108  are known as core Provider (P) communications network nodes  102 . It is understood that the flat communications network  104  representation shown in  FIG. 2  is exemplary only, in practice communications network nodes  102 , may act simultaneously as PE nodes  102  for some services and as core P nodes  102  for other services without any interference existing between the supported services.  
         [0055]     It is important to keep in mind that typical communications network nodes  102  employed in service provider networks  104  simultaneously support a variety of physical transport technologies and content transport protocols. Some such communications network nodes  102 , may also support MPLS content transport by implementing the MPLS protocol over the physical transport equipment installed therein (interface cards  106 , switching back-planes, etc.) while other communications network nodes  102 , are not aware of the MPLS content transport and are configured to simply switch content conveyed therethrough in accordance with the underlying content transport protocols supported which enable MPLS content transport on neighboring network node  102 .  
         [0056]     Each Label Switching Router (LSR)  112  is MPLS enabled and may be implemented either as a hardware device or implemented in software as a virtual LSR router instance. Either implementation of the LSR  112  represents a managed entity in the communications network  104 .  
         [0057]     The above mentioned complexities are addressed via communications network management. The above mentioned NMS  100  has an associated NMS repository  120  tracking managed entity information for the managed infrastructure of the service provider&#39;s communications network  104 . As shown, the NMS repository  120  may include for example an NMS database without limiting the invention thereto.  
         [0058]     In accordance with the exemplary embodiment of the invention, the functionality provided by the NMS  100  is augmented with centralized Layer-2 and Layer-3 VPN provisioning support.  
         [0059]     Aside from cable and link setup, depending on the particular implementation, communications network nodes  102  managed in the network management context may have to be assigned Provider Edge (PE)/Provider (P) communications network node roles. Further, quality-of-service policies may have to be uploaded and activated on participating PE and P communications network nodes  102 .  
         [0060]     In accordance with the exemplary embodiment of the invention, the functionality of the NMS  100  is augmented with centralized full mesh LSP tunnel establishment means. In accordance with an exemplary full mesh LSP tunnel establishment method, operations management personnel selects a group of PE network nodes  102  to provision PW services therebetween for customer sites connected thereto, LSP tunnel commissioning commands are issued from the NMS  100  to each PE  102  in the group to effect the LSP tunnel establishment therebetween.  
         [0061]     In selecting the group  312  of PE network nodes  102 , operations management personnel, interacting with a Transport LSP Mesh Configuration Module  300  having an exemplary interface schematically shown in  FIG. 3 , may be provided with a stylized map of the managed communications network  104  by interacting with a Show Network Map button  302 . The network map shows iconical representations managed network entities, from which PE network nodes  102  may be selected. In providing operations management personnel with the stylized map, the NMS  100  queries the NMS repository  120  for communications network nodes  102  (and logical positions thereof in the network).  
         [0062]     The NMS  100  may further query the NMS repository  120  for a list  304  of communications network nodes  102 , by interacting with a Get Node List button  306 , to aid operations management personnel in selecting PE communications network nodes  102 .  
         [0063]     Alternatively, in selecting the group  312  of PE communications network nodes  102 , having retrieved a list of communications network nodes  102 , operations management personnel may be provided with filtering means  308  to identify PE communications network nodes  102  for inclusion  310  into the group  312  of PE network nodes  102 .  
         [0064]     In order for the transport LSP tunnels to be established between the PEs in the group, each PE communications network node  102  must also have LSR functionality. Having LSR functionality may be one of the selection criteria used in filtering as mentioned above (see “Is LSR” filter  308 ).  
         [0065]     In ensuring quality-of-service in support of Service Level Agreements (SLA) in accordance with which VPN services are to be offered, LSP content transport tunnels may be commissioned to convey content therein in accordance with quality-of-service parameters  314  including, but not limited to: Committed Information Rate (CIR), Peak Information Rate (PIR), burst size, signaling protocol, tunnel bandwidth, etc. Quality of service parameters  314  may be specified and accepted by interacting with an Update Mesh Parameters button  316 .  
         [0066]     The details of centralized transport LSP tunnel commissioning are described elsewhere, suffice it to mention that, by interacting with a Commission Transport Mesh button  318 , each LSR on a corresponding pair of PE network nodes  102  is instructed by the NMS  100  to establish LSP tunnels therebetween relieving operations management personnel of doing so manually. N*(N−1) unidirectional LSP tunnels are therefore commissioned in respect of each full content transport mesh in providing bi-directional content transport between N PE communications network nodes  102 .  
         [0067]     It is possible for a content transport LSP tunnel to already be commissioned between a particular pair of PE network nodes  102  prior to full mesh LSP tunnel commissioning, the LSP tunnel already conveying content in accordance with the required transport LSP parameters  314 . In accordance with an exemplary implementation of the exemplary embodiment of the invention, a process  500  of commissioning  318  an LSP transport mesh shown in  FIG. 5 , may include determining  506  whether LSP transport tunnels, themselves managed entities in the network management context, already exist between PE communications network node pairs  502  and, subject  508  to compliant LSP transport tunnel parameters, including  510  the existing LSP transport tunnels in the transport mesh being commissioned. An exemplary iterative ( 504 ,  512 ) process  500  is shown. Accordingly, the NMS full transport mesh commissioning means  300 , further includes functionality for discovering  506  actively commissioned LSP content transport tunnels, and for determining  508  discovered LSP content transport tunnel adherence to a given set of LSP tunnel operational parameters.  
         [0068]     In the following, LSP tunnel establishment between PE network node pairs is assumed, although in practice, depending on the signaling protocol employed, the path taken by content conveyed in respect of an LSP tunnel may vary in accordance with communications network conditions experienced thus providing resilience therein.  
         [0069]     In accordance with the exemplary embodiment of the invention, the transport mesh of established LSP tunnels between a group  312  of PE communications network nodes represents a managed entity in the network management context. A transport mesh identifier  322  is associated with the transport mesh managed entity for further selection and reference, and a descriptive string  324  may be further associated with the managed transport mesh entity. A status  326  may be ascribed to the managed transport mesh entity and updated based on a multitude of related events. A Get Transport Mesh List button  328  is provided to query the NMS database  120  for transport mesh managed entities.  
         [0070]     The Transport LSP Mesh Configuration and Provisioning module  300  may be employed to create different types of LSPs using LDP or RSVP for signaling providing a choice in creating E-LSPs conveying content traffic for multiple Classes-of-Service (CoS) or creating CoS specific L-LSPs.  
         [0071]     Alternatively, depending on the implementation and/or details of a particular deployment in support of specific VPN services, multiple transport LSP tunnel full meshes may be commissioned between the same group  312  of PE network nodes  102 . Multiple transport LSP tunnel full meshes may exemplary be commissioned to support different levels of service in accordance with a corresponding multitude of SLA agreements. Typically service providers provide three levels of service such as “gold”, “silver”, and “bronze”, each level of service specifying different sets of full mesh transport configuration parameters  314  (burst size, bandwidth, etc.)  
         [0072]     Individual PE communications network nodes  102  may be added  310  to or removed  311  from a PE group  312 , as well additional LSP tunnels may be commissioned  330  between the PE network nodes  102  in the group  312 , or decommissioned  331 .  
         [0073]     With each PE network node  102  addition  310  to an existing group of N PE network nodes  312 , 2*N unidirectional LSP tunnels are commissioned between N pairs of PE network nodes: between the newly added PE network node  102  and the existing N PE network nodes  102  in the group  312 . With each PE network node  102  removal  311  from an existing group of N PE network nodes  312 , 2*(N−1) unidirectional LSP tunnels are decommissioned between N−1 pairs of PE network nodes: between the PE network node to be removed and the remaining N−1 PE network nodes  102  in the group  312 .  
         [0074]     The removal  311  of a PE network node  102  from the PE group may be conditional on the non-existence of any VPN services actively commissioned therethrough. The restriction condition may be further limited to VPN services terminating on the PE network node  102  to be removed  311 , as the removed PE  102  may still convey content in respect of managed VPN services as an intermediary MPLS communications network node  102 .  
         [0075]     LSP transport tunnels also represent managed entities in the NMS management contest and are tracked in the NMS repository  120 . Each LSP transport tunnel has an associated identifier  332 , a description  334 , and an status  336 . The NMS repository  120  may be queried, dependent on the active network management context, by interacting with a Get Transport LSP List button  338 . If the get transport LSP list button  338  is employed while a transport mesh is selected, then only the LSP transport tunnels of the selected transport mesh are displayed, otherwise all LSP transport tunnels are displayed. LSP tunnels commissioned in accordance with the exemplary embodiment of the invention are also ascribed identifiers and correspond to managed entities in the network management context. Naming conventions may be used in generating LSP tunnel identifiers  332 . Selecting an LSP transport tunnel, the corresponding pair  340  of PE communications network nodes  102 , and the LSP transport parameters  342  are displayed.  
         [0076]     Within each provisioned VPN service, and therefore in respect of each full mesh of LSP tunnels, actual traffic patterns may be inhomogeneous between the PE communications network node pairs; additional LSP tunnels being necessary between particular pair of PE network nodes to convey all the traffic, as shown in  FIG. 2 .  
         [0077]     The decommissioning  331  of an LSP transport tunnel may be made conditional on the non-existence of any VPN services actively commissioned therethrough. Updating  344  LSP transport tunnel parameters  342  may also be conditional on the non-existence of any VPN services actively commissioned through the corresponding LSP transport tunnel.  
         [0078]     A selected transport LSP full mesh may be decommissioned by interacting with button  346 . Decommissioning an transport LSP full mesh may be conditional on the non-existence of any VPN services actively commissioned therethrough.  
         [0079]      FIG. 4  shows a state transition diagram corresponding to the full mesh transport LSP configuration and provisioning process described above.  
         [0080]     Therefore the full mesh transport LSP configuration means described, hides the physical layer complexities of the communications network  104  and provides a content transport provisioning framework for a multitude of L2 and L3 VPN services.  
         [0081]     In support of Pseudo-Wire (PW) and VPLS (L2VPN) service provisioning, signaling means must be provided between the group of PE network nodes  102  associated with a full transport LSP mesh to establish VPN connections therebetween. The signaling means includes targeted LDP sessions.  
         [0082]     In accordance with the exemplary embodiment of the invention, the functionality of the NMS  100  is further augmented with centralized full mesh targeted LDP signaling session establishment means. Provisioned transport LSP meshes and targeted LDP signaling session meshes are provisioned independently and are used together to enable PW and VPLS service provisioning.  
         [0083]     In accordance with an exemplary full mesh targeted LDP signaling session establishment method, operations management personnel selects a group of PE network nodes  102  to provision PW services therebetween for customer sites connected thereto, targeted LDP signaling session commissioning commands are issued from the NMS  100  to each PE  102  in the group to effect the targeted LDP signaling session establishment therebetween.  
         [0084]     In selecting the group  612  of PE network nodes  102 , operations management personnel, interacting with a Targeted LDP Signaling Session Mesh Configuration Module  600 , having an exemplary interface schematically shown in  FIG. 6 , may be provided with a stylized map of the managed communications network  104  by interacting with a Show Network Map button  302  as describe above.  
         [0085]     The NMS  100  may further query the NMS repository  120  for a list  304  of communications network nodes  102 , by interacting with a Get Node List button  306  as described above.  
         [0086]     Alternatively, in selecting the group  312  of PE communications network nodes  102 , having retrieved a list of communications network nodes  102 , operations management personnel may be provided with filtering means  308  to identify PE communications network nodes  102  for inclusion  610  into the group  612  of PE network nodes  102 .  
         [0087]     In order for the targeted LDP signaling sessions to be established between the PEs in the group, each PE communications network node  102  must also have LSR functionality. Having LSR functionality may be one of the selection criteria used in filtering as mentioned above (see “Is LSR” filter  308 ).  
         [0088]     Targeted LDP signaling sessions may be commissioned to convey signaling information therein in accordance with signaling parameters  614  including, but not limited to: Hello hold-time, Keep hold-time, Path Vector Limit (Pvl), etc. Signaling mesh parameters  614  may be specified and accepted by interacting with an Update Mesh Parameters button  616 .  
         [0089]     By interacting with a Commission Signaling Mesh button  618 , each LSR on a corresponding pair of PE network nodes  102  is instructed by the NMS  100  to establish targeted LDP signaling sessions therebetween relieving operations management personnel of doing so manually. (N*(N−1))/2 bi-directional targeted LDP signaling sessions are therefore commissioned in respect of each full signaling mesh in providing signaling information exchange between N PE communications network nodes  102 .  
         [0090]     It is possible for a targeted LDP signaling session to already be commissioned between a particular pair of PE network nodes  102  prior to full targeted LDP signaling session mesh commissioning, the targeted LDP signaling session already conveying signaling information. In accordance with an exemplary implementation of the exemplary embodiment of the invention, a process  800  of commissioning  618  a targeted LDP signaling session mesh shown in  FIG. 8 , may include determining  806  whether targeted LDP signaling sessions, themselves managed entities in the network management context, already exist between PE communications network node pairs  802  and including  810  the existing targeted LDP signaling sessions in the signaling mesh being commissioned. An exemplary iterative ( 804 ,  812 ) process  800  is shown. Accordingly, the NMS full signaling mesh commissioning means  600 , further includes functionality for discovering  806  actively commissioned targeted LDP signaling sessions.  
         [0091]     In the following, targeted LDP signaling session establishment between PE network node pairs is assumed, although in practice, the path taken by signaling information conveyed in respect of a targeted LDP signaling session may vary in accordance with communications network conditions experienced thus providing resilience therein.  
         [0092]     In accordance with the exemplary embodiment of the invention, the full mesh of established targeted LDP signaling session between a group of PE communications network nodes  612  represents a managed entity in the network management context. A signaling mesh identifier  622  is associated with the full signaling mesh managed entity for further selection and reference, and a descriptive string  624  may be further associated with the managed signaling mesh entity. A status  626  may be ascribed to the managed signaling mesh entity and updated based on a multitude of related events. A Get Signaling Mesh List button  628  is provided to query the NMS database  120  for managed signaling mesh entities.  
         [0093]     Depending on the implementation and/or details of a particular deployment in support of specific VPN services, multiple targeted LDP signaling sessions terminating on interfaces on PE communications network nodes may be commissioned between particular PE network node pairs.  
         [0094]     Individual PE communications network nodes  102  may be added  610  to or removed  611  from a PE group  612 , as well additional targeted LDP signaling sessions may be commissioned  630  between interfaces on PE network nodes  102  in the group  312 , or decommissioned  631 .  
         [0095]     With each PE network node  102  addition  610  to an existing group of N PE network nodes  612 , N bi-directional targeted LDP signaling sessions are commissioned between N pairs of PE network nodes: between the newly added PE network node  102  and the existing N PE network nodes  102  in the group  612 . With each PE network node  102  removal  611  from an existing group of N PE network nodes  612 , N−1bidirectional targeted LDP signaling sessions are decommissioned between N−1 pairs of PE network nodes: between the PE network node to be removed and the remaining N−1 PE network nodes  102  in the group  612 .  
         [0096]     The removal  611  of a PE network node  102  from the PE group may be conditional on the non-existence of any VPN services actively conveying signaling information therethrough. The restriction condition may be further limited to VPN services terminating on the PE network node  102  to be removed  611 , as the removed PE  102  may still convey signaling information in respect of managed VPN services as an intermediary MPLS communications network node  102 .  
         [0097]     Targeted LDP signaling sessions also represent managed entities in the NMS management contest and are tracked in the NMS repository  120 . Each targeted LDP signaling session has an associated identifier  632 , a description  634 , and an status  636 . The NMS repository  120  may be queried, dependent on the active network management context, by interacting with a Get Signaling Session List button  638 . If the get signaling session list button  638  is employed while a signaling mesh is selected, then only the targeted LDP signaling sessions of the selected signaling mesh are displayed, otherwise all targeted LDP signaling sessions are displayed. Targeted LDP signaling sessions commissioned in accordance with the exemplary embodiment of the invention are also ascribed identifiers and correspond to managed entities in the network management context. Naming conventions may be used in generating targeted LDP signaling session identifiers  632 . Selecting a targeted LDP signaling session, the corresponding pair  640  of PE communications network nodes  102 , corresponding pair of interfaces  641 , and the targeted LDP signaling session parameters  642  are displayed.  
         [0098]     The decommissioning  631  of a targeted LDP signaling session may be made conditional on the non-existence of any VPN services actively conveying signaling information therethrough. Updating  644  targeted LDP signaling session parameters  642  may also be conditional on the non-existence of any VPN services actively conveying signaling information through the corresponding targeted LDP signaling session.  
         [0099]     A selected full mesh of targeted LDP signaling sessions may be decommissioned by interacting with button  646 . Decommissioning a full mesh of targeted LDP signaling sessions may be conditional on the non-existence of any VPN services actively conveying signaling information therethrough.  
         [0100]      FIG. 7  shows a state transition diagram corresponding to the full targeted LDP signaling session mesh configuration and provisioning process described above.  
         [0101]     Therefore the full targeted LDP signaling session mesh configuration means described, hides the physical layer complexities of the communications network  104  and provides a signaling information transport provisioning framework for a multitude of Layer-2 and Layer-3 VPN services.  
         [0102]     In accordance with the exemplary embodiment of the invention, the full mesh LSP content transport provisioning and full mesh targeted LDP signaling session provisioning effected in a centralized network management context enables service providers to: assure network resiliency, assure service quality, and provide accounting in respect of Layer-2 and Layer-3 VPN services irrespective of client-side deployed infrastructure while leveraging installed infrastructure in the service provider communications network core.  
         [0103]     Further Layer-2 and Layer-3 VPN service provisioning details are provided herein below in respect of particular infrastructure employed.  
         [0104]     In accordance with a VPWS services provisioning, Ethernet network interworking over MPLS is described.  
         [0105]     In accordance with the exemplary embodiment of the invention, Layer-2 Ethernet packets are enabled to traverse an MPLS service provider communications network  104  connecting two serviced customer Ethernet LAN segments  20  together. Packets received on an exemplary ingress 1 Gb Ethernet (GigE) interface of a PE network node  102  and are transmitted out of the originating PE network node  102  via an MPLS capable interface, such as, but not limited to Packet over SONET (PoS), GigE, or ATM. Making reference to  FIG. 9  two-deep MPLS label stack is employed as defined in IETF draft-martini-ethernet-encap-mpls-01.txt (draft-martini), which is incorporated herein by reference, where the inner label corresponds to the Layer-2 Ethernet connection and the outer label is used to forward MPLS encapsulated packets through the service provider communications network  104  onto the appropriate transport LSP/mesh. Label Distribution Protocol Downstream-Unsolicited (LDP-DU) signaled LSPs (S-LSPs) may be employed in provisioning the inner (label) LSP. RVSP-TE signaling is used to provision the outer (label) LSP. Labeled packets travel through the MPLS service provider communications network  104  to an MPLS capable interface (PoS, GigE, or ATM) to the egress PE network node  102 . The packets then exit the egress PE network node  102  via a GigE interface and are conveyed to the destination customer Ethernet LAN segment  20 .  
         [0106]     As described in draft-martini, a GigE port or VLAN interface is configured for network interworking, remote router, and Martini parameters. This initiates the signaling of the inner label through an LDP advertisement of the reachability of an Ethernet interface through an allocated MPLS label. When a match, of configured, Martini parameters is found between a configured interface and an advertised interface, the Layer-2 VPN connection may be configured and content traffic may be conveyed. All packets received on the ingress GigE interface are transported to the remote egress GigE interface.  
         [0107]     In order for Ethernet VPWS connections to be made, a signaled MPLS tunnel must exist between the PE communications network nodes  102  that attach to the customer equipment  22 . To establish a VPWS connection (pseudo-wire) over a signaled tunnel LSP, specific pseudo-wire configurations must be performed on both PE LSP routers  102 .  
         [0108]     When VPWS connections terminate at CE&#39;s  20  attached by dissimilar layer 2 technologies (e.g. ATM and GigE), the service offering requires conversion of packets from one Layer-2 technology to another, known as service interworking. This packet conversion or service interworking is performed at the PE network nodes  102  in the service provider&#39;s communications network  104 .  
         [0109]     As technology advances and the cost of higher bandwidth Ethernet equipment become more economical compared to OC-3 and OC-12 ATM equipment. Existing point-to-point networking using ATM point-to-point services may be migrated to use 100baseT and GigE interfaces at access point PE network nodes  12 . As such, service interworking may offer a way to upgrade existing ATM point-to-point network support using VPWS, as shown in  FIG. 10 , creating a point-to-point pseudo-wires between ATM and GigE interfaces. Layer-2 Ethernet packets are enabled to traverse an MPLS service provider communications network  104  and connect to a Layer-2 PE switch  102  or CE router  22  supporting ATM. In order for Ethernet/ATM service interworking VPWS connections to be made, a signaled MPLS tunnel must exist. Also, the ATM Virtual Path Identifier/Virtual Connection Identifier (VPI/VCI) must be encapsulated using ATM Adaptation Layer-5 (AAL5).  
         [0110]     Although, in the above extensive reference was made to PW services and L2VPN services in general, the invention is not limited thereto, implementations of the exemplary embodiment of the invention may also include provisioning support for Virtual Private Wire Services (VPWS) and Virtual Private LAN Service (VPLS), as well as Layer-3 VPN services.  
         [0111]     Further the invention is not limited to any transport LSP type. A variety of transport LSPs may be employed including, but not limited to: Label Distribution Protocol LSPs, Resource Reservation Protocol-Traffic Engineering (RSVP-TE) LSPs, Labeled LSP, etc.  
         [0112]     The embodiments presented are exemplary only and persons skilled in the art would appreciate that variations to the above described embodiments may be made without departing from the spirit of the invention. The scope of the invention is solely defined by the appended claims.