Scalable abstraction of topology across domain boundaries

Methods and systems are disclosed for scalable advertising of an abstracted form of an arbitrary network of nodes and links to external nodes or networks. One or more phantom hub nodes can be used that are connected to at least one node, forming one or more virtual network topology representing the internal connectivity of the network.

FIELD OF THE INVENTION

The present invention generally relates to telecommunication networks more particularly the invention relates to abstraction and advertising network topologies.

BACKGROUND OF THE INVENTION

In telecommunication networks, various independent networks (domains) communicate amongst themselves. Each domain can have various internal routing protocols. Passing communications from one domain to another, across domain boundaries (through border nodes), requires the advertising of a link and node topology so that a node, originating data, can determine the appropriate path (between nodes) through which the data should be passed. The links and nodes can be advertised as a network topology, which can represent a real-time view of the status and availability of intra and inter domain connections amongst nodes using various types of advertise information, such as routing information (e.g. destination address, priority level, least-cost route, minimum route delay, minimum route distance, route congestion level, bandwidth, color, metric, and the like). Data originating nodes can use the advertised information (called routing considerations) to determine the appropriate path amongst various potential paths.

Routing protocols allow networks to dynamically adjust to changing conditions. There are several conventional routing protocols, e.g. Open Shortest Path First (OSPF), Intermediate System to Intermediate System (IS—IS) and Private Network Node Interface (PNNI) routing protocols. Conventional art systems attempt to extend these for multi-domain environments within the ITU-T (ITU-T is the telecom standardization organization of the International Telecommunication Union (ITU)).

Conventional systems use a method of abstraction for illustrating the actual internal domain topology between intra-domain border nodes and may advertise all border nodes (BN) with abstract links interconnecting them. In such a system, as the number of border nodes increases, a full mesh of abstract links is advertised. When a border node is added or removed, a full set of links connecting the border node to every other border node can be affected. In this method, if there are N−1 nodes in the network and an Nth node is added, N2links must be advertised. Thus, this system is not scalable. Further, in some circumstances, one may not want to have the actual border node intra-domain topology advertised.

Alternatively, conventional methods may advertise the domain as a single virtual node, with no internal structure. This method is simple, but has the several disadvantages. For example, interfaces need to be renumbered to be unique in the context of the single virtual node, rather than using their original interface identifiers, which are only unique in the context of the associated border node. Thus, this method is administratively more complex. Additionally, no internal restrictions or metrics can be shown for the single virtual node, since nodes are not advertised with internal properties. This means that calculation of the end-to-end metric for a connection may not be accurate since it does not take into account the cost of crossing the domain, potentially leading to inefficient routing or failure to meet end-to-end path constraints.

SUMMARY OF THE INVENTION

Exemplary embodiments provide scalable, flexible, virtual network topologies and methods of generating such virtual network topologies to support multiple interconnected networks, which can have differing structures and capabilities.

Exemplary embodiments provide for a method for scalably advertising an abstracted form a network of nodes and links (e.g. an optical network, and the like) to external nodes or networks.

Further exemplary embodiments provide for the determination of virtual links to virtual node(s) (e.g. phantom hub node(s)) using characteristics of the domain such as predetermined subscriber levels, border node characteristics, and physical link characteristics, and advertising the virtual links.

Further exemplary embodiments provide for the determination of virtual links to virtual node(s) (e.g. phantom hub node(s)) using characteristics of the intra-domain connectivity between nodes and advertising the virtual links.

Further exemplary embodiments provide a system and method using one or more internal virtual node(s) (e.g. phantom hub nodes) connected to each border node, forming at least one virtual network topology representing the internal connectivity of the network.

Additional exemplary embodiments of the invention provide systems and methods that advertise a virtual network topology (e.g. the connectivity of the advertised network, and the like) without displaying the actual detailed physical topology (domain), and supporting source routing of connections using the network in an originating, transit or destination role.

Further areas of applicability of embodiments of the invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating exemplary embodiments, are intended for purposes of illustration only and are not intended to limit the scope of the invention.

DETAILED DESCRIPTION

The following description of aspects of the invention is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses. Aspects of the invention are disclosed in the following description and related drawings directed to specific embodiments of the invention. Alternate embodiments may be devised without departing from the spirit or the scope of the invention. Additionally, well-known elements of the invention will not be described in detail or omitted so as not to obscure the relevant details of the invention.

In networks where different routing protocols need to convert their topology into a common form, conventional protocols rely on extensive processing of all the connections and systems, which can necessitate advertising all the intra-domain links amongst nodes, which tends to slow down the path computation process and requires greater memory and processing power. Additionally it is not always desirable to advertise all of the intra-domain links to external domains (e.g., one's competitors) since this provides information that may be competitively useful, e.g., where high and low traffic demands can be found.FIG. 1illustrates a topology of an intra-domain network100, where all the intra-domain links (e.g.,141,143,145) and intra-domain virtual links (e.g.155) amongst the nodes (110,120,130,140,150, and the like) are advertised. A data originating node can use the routing information provided by the network100, stored in a node (e.g. the border nodes (BN), other intra-domain nodes, and the like) to route data from node to node (e.g. from node110to node140, through nodes144and146) through intra-domain links (e.g.141,143, and145) using the routing controller115and signal controller117.

The network information is communicated amongst each border node (e.g.110,120,130,140,150, and the like) using a logic control network121via logic control channels123. A border node is a node that has a link between at least two domains, where a domain can be a part of a network (e.g., telecommunication network). Logic control channels123can carry network information rather than voice and/or data messages.

At least one exemplary embodiment does not advertise all intra-domain links between nodes. A phantom hub node is generated and it's connectivity to border nodes and other intra-domain nodes are used to construct a virtual network topology with associated information (e.g. routing information) that can be advertised. In exemplary embodiments, the information advertised contains the connectivity of border nodes with at least one phantom hub node in a first domain. This information can be advertised to other domains seeking to route data through the first domain. The virtual network topology can comprise constructed intra-domain virtual links to/from the phantom hub node, to/from intra-domain nodes, which represent the actual intra-domain links between intra-domain nodes. One virtual link can represent many intra-domain links, reducing the amount of information needed to be advertised and facilitating the addition of additional border nodes.

In at least one exemplary embodiment the characteristics of one border node is used to calculate the virtual link between that node and a phantom hub node. Each node can calculate its respective virtual link and communicate each link to each border node to form a virtual network topology. Each border node can advertise the virtual links and virtual network topology to other nodes (e.g. data originating nodes).

In at least one other exemplary embodiment the characteristics of all border node(s) and links between the node(s) in the physical topology can be used to determine the virtual link between a select number of node(s) and at least one phantom hub node forming a virtual network topology. Each border node can advertise the virtual network topology (e.g. virtual link values) to other nodes (e.g. data originating nodes).

Various networks can utilize various embodiments. For example a constructed virtual network topology in accordance with at least one exemplary embodiment can be used to support virtual private network (VPN) services (where a particular customer gets connectivity only between their locations using some pre-defined subset of network resources). The VPN can be instantiated as a phantom hub node connecting border nodes that can connect to VPN customer sites, with the virtual link capacity set initially based on the service agreement with the VPN customer and thereafter updated to reflect that customer's usage of network resources. This provides the VPN customer with a simple virtual topology that they can access that still describes the connectivity and resources available to them. Accordingly, in further exemplary embodiments the virtual links connecting the phantom hub nodes to the intra-domain nodes can be established using predetermined virtual link values.

FIG. 2Aillustrates at least one exemplary embodiment of a virtual network topology200for a domain. A phantom hub node270can be created for each domain, and virtual links250and260can be formed between BNs (e.g.210,212,214,216, and218) and the phantom hub node270. The instantiation of the phantom hub node270can be accomplished by several methods (e.g., configure or hard code a phantom hub node id, generate a phantom link state advertisement (LSA) on behalf of phantom hub node and publish the LSA, and the like). The virtual network topology advertised can include nodes (e.g.210,212,214,216, and218, and the like), some or all of which can be border nodes, and virtual links (e.g.250,260, and the like) linked to phantom hub270. The representation of actual intra-domain links by a fewer number of advertised virtual links can reduce the amount of routing information advertised and hide details of the intra-domain network topology for security purposes.

The routing controller240can derive the virtual network topology of the intra-domain network. For example, virtual links250,260and phantom hub node270are a virtual representations of the physical intra-domain connectivity between intra-domain nodes,210and216through nodes211,213,215,217, and219via intra-domain links281–287. Thus in at least one exemplary embodiment the routing information containing connectivity information of virtual links250, and260, border nodes210and216, and phantom hub node270, can be advertised without the connectivity information of the actual intra-domain network topology.

The advertised routing information of the virtual network topology (phantom LSA) between border nodes210and216via the phantom hub270and virtual links250and260can be determined by a several different methods. For example, the LSA for virtual links250and260may advertise the combined total bandwidth available using the two paths having links (282,284,286,287) and (281,283,285), where the bandwidth for each path is the minimum of the bandwidth available on each link in the path. The LSA for the fully connected topology configuration inFIG. 1may use a similar method of deriving bandwidth for virtual links, however it requires a fully meshed set of virtual links with the accompanying disadvantages for scalability, as discussed herein. Alternatively, the LSA for virtual links250and260may advertise characteristics that have been determined by policy of the carrier offering the network service (e.g. subscription levels).

Referring toFIG. 1, since all border nodes are interconnected in the network topology (domain), when adding a new (Nth) border node, each border node needs to advertise virtual and/or intra-domain links to the new border node, resulting in N2intra-domain and/or virtual link advertisements. In contrast to having to calculate all of the additional intra-domain links when adding additional border nodes, exemplary embodiments of the invention comprising a phantom hub node can the virtual link between the added border node and the phantom hub node resulting in only 2 more intra-domain advertisements when adding a new (Nth) border node. As the number of border nodes increases, the use of a phantom hub node reduces the number of virtual link advertisements needed since only the virtual link information between the added border node and the phantom hub node would be needed.

Exemplary embodiments can have the phantom hub node as a border node. Additional exemplary embodiments can contain one or more Routing Controllers (RC), which can be nodes that serve to relay advertisements from external nodes or networks into the intra-domain network, and generate advertisements of the intra-domain network topology to send to external nodes or networks. The RCs can be configured in several arrangements (e.g. centralized routing control or distributed routing control, and the like). The virtual network topology information, an example of a representation of a domain, can be communicated to each border node (210,212,214,216, and218) via the control channel220. Additional exemplary embodiments can represent a portion of a domain instead of the whole domain.

Further exemplary embodiments can contain one or more signal controllers230(SC) that can change data into forms suitable (e.g. particular signaling protocols, parsing the data, amplification or modification of the data, filtering the data, forming signals from the data and the like) for the domain. Additionally the signal controller230can implement a signaling protocol (e.g., PNNI protocol, Optical Signaling and Routing Protocol (OSRP), and the like) that can cause the signal to be transmitted from one node to another within the domain along the route chosen by a routing protocol implemented by the routing controller240. The signaling protocol can start sending a signal by sending a setup message through the nodes along the chosen route. Once a data destination node receives the setup message, a cross-connect signal can be sent from the data destination node back to the originating node via the same route. Once the originating node receives the cross-connect signal, a connection can be established for data exchange between the nodes.

FIGS. 2B–2Dillustrate the two physical intra-domain link paths ofFIG. 2B,296and297corresponding respectively to the intra-domain link paths from nodes210,215,217,219,216through links282,284,286,287, and nodes210,211,213,216through links281,283,285. The physical intra-domain link paths296and297can be combined into a representative portion298of a virtual network topology. The portion298(virtual path) can be constructed using various methods, as discussed herein.

For example,FIG. 2Bshows an example bandwidth amongst various links between the nodes shown. In the exemplary embodiment shown, links282,286and287have bandwidths of 4 Gbps, while link284has a bandwidth of 6 Gbps. Likewise,FIG. 2Cillustrates the various bandwidths for the various links, with 5 Gbps for links281and285, and 3 Gbps for link283. Other types of routing information can be used besides bandwidth and the discussion herein of bandwidth should not be interpreted as limitative of the routing information used to determine link values or characteristics of the virtual links250and260(e.g. link path reliability, link delay, link available capacity, link minimum reservable capacity, link metric, destination address, priority, link color, link termination capabilities and the like).

FIG. 2Dillustrates at least one exemplary embodiment where the virtual path298, is representative of the link paths296and297using an average value of the bandwidth of both link paths296and297. Further exemplary embodiments can use other methods, several types of data, and computations, as discussed herein, to derive the virtual routing information for virtual path298. Other parameters may be determined by adding metrics on the associated real links, such as in the case of link metric, or by taking the minimum of the parameter values on the associated real links, such as in the case of minimum reservable capacity (i.e., the smallest quantum of capacity that may be reserved for an individual data flow).

FIGS. 2E–2Fillustrate a further example of two alternative physical intra-domain link paths276and277, where node211is no longer connected to node213as inFIG. 2Cbut instead to node217, and then from node217to213and to216. Intra-domain link paths276and277correspond respectively to the intra-domain link paths from nodes210,215,217,219,216through links282,284,286,287, and nodes210,211,217,213,216through links281,263,265,285. The physical intra-domain link paths276and277can be combined into a representative portion278(virtual path278) of a virtual network topology. The portion278can be constructed using various methods.

For example,FIG. 2Eshows an example bandwidth amongst various links between the nodes shown. In the exemplary embodiment shown, links282,286and287have bandwidths of 4 Gbps, while link284has a bandwidth of 6 Gbps. Likewise, the other various links have associated bandwidths, with 5 Gbps for links281and285, 3 Gbps for link263, and 4 Gbps for link265are illustrated (FIG. 2F). Other types of routing information can be used besides bandwidth and the discussion herein of bandwidth should not be interpreted as limitative of the routing information used to derive properties of the virtual links251and261(e.g. link path reliability, link delay, link available capacity, link minimum reservable capacity, link metric, destination address, priority, link color, link termination capabilities and the like).

FIG. 2Fillustrates at least one other exemplary embodiment where the virtual path278, is representative of the link paths276and277using the minimum value of the bandwidth of both link paths276and277. Further exemplary embodiments can use other methods, several types of data, and computations, as discussed herein, to derive the virtual routing information for virtual path278. In the exemplary embodiment shown the bandwidth for virtual link251is 3 Gbps, which is the minimum bandwidth of link paths276and277up to node217. In the example shown the bandwidth for the virtual link261is 4 Gbps, which is the minimum bandwidth for links paths276and277from node217to destination node216. In this example the phantom hub node271is associated with node217.

Those skilled in the art will appreciate that the embodiments shown herein are examples only, many variations fall within the intended scope of exemplary embodiments. For example weighted averages of properties can be used, minimum properties, predetermined virtual link values and the like. Further embodiments include the possibility of there being only one physical link between two nodes that can still be represented by a virtual link value. For example if the intra-domain physical link path297is the only physical link path between node210and216, the virtual link value can be a combination of the values along links281,283, and285using the techniques discussed for combining more than one physical link path (e.g. averaging the values, sum of the values, the minimum values, and the like), which includes using predetermined values (e.g. VPN subscription levels).

FIG. 3Aillustrates at least one further exemplary embodiment of a virtual network topology300. The control channel320can communicate the virtual routing information for the virtual network topology300to the border nodes310,312,314,316, and318. The routing controllers340and signal controllers330control the routing and signal transport through the network. The actual intra-domain connectivity remains but in at least one exemplary embodiment the advertisement of the connectivity between border nodes and actual intra-domain nodal connections and links can be replaced by the virtual network topology300. The virtual network topology300shows three phantom hub nodes370,372, and374, although exemplary embodiments are not limited to any particular number of phantom hub nodes. Phantom hub node370can be connected by virtual links350–354to each border node310,312,314,316, and318in a star connectivity pattern. Phantom hub node374can likewise be connected in a star connectivity pattern via virtual links391–395to each border node. However, phantom hub node372can be connected in a star connectivity pattern with only a subset of border nodes312,314, and318. Accordingly, the advertised virtual routing information for the sub virtual network topology (e.g. phantom hub node372, virtual links380–382, and border nodes312,314, and318) can represent connectivity between some border nodes, but not necessarily all border nodes.

Other configurations of the nodes, phantom hub nodes, virtual and physical links are possible (e.g. mesh topology, hybrid topology, tree topology, and the like). Additional variations can include the number of border nodes connected to a phantom hub node, the number of phantom nodes, and whether any, all or some of the phantom hub nodes are connected to at least one or all of the border nodes. Additionally, the phantom hub node can be a physical node (e.g., a border node). These variations are within the scope of exemplary embodiments of the invention.

FIG. 3Billustrates an example of a physical network represented by the virtual network topology301with phantom hub node370, border nodes310,312,314,316,318, and virtual links350–354, first shown inFIG. 3A. The physical network can have various configurations (full mesh, mesh, star, linear, ring, and the like).FIG. 3Billustrates a mesh configuration between physical nodes310,312,314,316,318,319, and332, with physical links341–348. As described above, the physical nodes and links can be represented as a virtual network topology that can be advertised. The virtual links350–354, and phantom hub node370can be determined via various methods in accordance with exemplary embodiments as discussed herein.

In at least one exemplary embodiment the characteristics intra-domain physical links connecting to a border node can be used by the border node to determine virtual links to a phantom hub node. The virtual link is then communicated to other nodes (e.g. border nodes) forming a virtual network topology that can be advertised. In other exemplary embodiments only the virtual link of the border node being queried is advertised. For example the following table (Table 1) provides example bandwidth values for each link.

In at least one exemplary embodiment the virtual link values can be calculated by adding all the bandwidth of links connected to each border node. Thus for this particular example the virtual link values to a phantom hub node are listed in Table 2.

Each virtual link value can be communicated to each other border node and advertised to a querying node or only the virtual link value for the node queried can be advertised.

In at least one further exemplary embodiment the minimum bandwidth of links connected to each intra-domain node (e.g. border node) can be used to determine the characteristic virtual link values (Table 3).

The border nodes can receive the virtual link values in Table 3 and can advertise the virtual values to querying nodes. Alternatively the border nodes can receive the data of the physical topology and calculate the virtual link values, for example as discussed herein, or can just use the characteristics of the values with each border node and advertise the value of that node with respect to the phantom hub node (for example the values in Table 2).

Additionally virtual link390can be constructed between phantom hub node370and at least one intra-domain node319not necessarily a border node. Thus in at least one embodiment, a virtual network topology is constructed for some of the intra-domain nodes, and an outside data originating node may communicate with a border node (e.g.,314), which can include advertising to the intra-domain nodes (e.g.,319) associated with the virtual network topology. The intra-domain nodes (e.g.,319) can advertise, the virtual network topology, as if they were border nodes. For example the phantom hub node370could have a virtual link390to an intra-domain node319that is not a border node. The intra-domain node319can be connected to various other intra-domain nodes.

Other methods of determining the virtual network topology are intended to be within the scope of embodiments of the invention, for example, minimum bandwidth, color, metrics, and the like.FIGS. 4A–6Rillustrate other examples of determining virtual link values in accordance with exemplary embodiments of the invention. Specifically,FIGS. 4A–6Rillustrate examples of methods of determining the virtual link values (characteristics) for virtual paths350,353, and354connecting border nodes310,316, and318with phantom hub node370.FIGS. 7A–7Iillustrate still more examples of embodiments that determine virtual link values. One of ordinary skill in the arts would recognize that many further examples fail within the scope of the present invention and the examples herein are not intended to be limitative.

FIGS. 4A–4Cillustrate three paths from border node310to318(note in this example all possible paths are not necessarily considered).FIG. 4Aillustrates the first path381, with nodes310,332,318, through links343and344with bandwidths 5 Gbps and 7 Gbps respectfully.FIG. 4Billustrates the second path382, with nodes310,332,314,316,318, through links343,347,346,345with bandwidths 5 Gbps, 7 Gbps, 3 Gbps, 5 Gbps, respectfully.FIG. 4Cillustrates the third path383, with nodes310,312,314,316,318, through links341,342,346,345with bandwidths 5 Gbps, 7 Gbps, 3 Gbps, 5 Gbps, respectfully. In at least one exemplary embodiment the virtual links361and364, connected to intermediate phantom hub node371, are assigned values associated with the minimum bandwidth along all three paths, 3 Gbps (FIG. 4D). Although for the example the minimum bandwidth is used, other methods (e.g. link average, weighted average, and the like) can be used. Additionally, those skilled in the art will appreciate that link values (characteristics) that are not susceptible to mathematical operations can be represented based on rules defined by the network operator.

The intermediate phantom hub nodes371and372along with associated virtual links361,362,364, and365can be combined to form the properties advertised for phantom hub node370and associated virtual links350,353, and354forming a virtual network topology389(FIGS. 4I–4K). In the example shown the minimum bandwidth of virtual links361and362is used, which happens to be the same 3 Gbps used for virtual link350. The values (3 Gbps) of the virtual links364and365are used for the virtual links354and353, respectfully. Although again the minimum bandwidth is used in the example, the maximum, average and other variations are intended to fall within the scope of exemplary embodiments. Further, embodiments of the invention do not require calculating intermediate phantom hub nodes. Instead, the values can be derived directly from the network topology information.

Additionally,FIGS. 5A–5Cillustrate the result of assigning the average values of the links to their respective virtual links and phantom hub nodes. In the exemplary embodiment shown inFIGS. 5A–5Cthe averages happen to be equal although such a result is not required. If the values of virtual link361and362were different the value that can be assigned to virtual link350can be the average of the two.

In further exemplary embodiments the phantom hub node can be associated with an intra-domain node (e.g. border node). Since all possible paths may not include the intra-domain node, virtual nodes and links can be derived to obtain effective paths (e.g.381′,383′, and the like). In the example shown inFIGS. 6A–6Q, in accordance with at least one exemplary embodiment, at least one path not including the intra-domain node intended to represent the phantom hub node is included, and at least one path including the intra-domain node is included. Not all of the paths are shown or used in the determination, as this example is provided as an illustration of another method to calculate virtual link values.

For example,FIGS. 6A,6C, and6D, illustrate the consideration of three paths from node310to node318, path381(FIG. 6A), path382(FIG. 6C), and path383(FIG. 6D). In this particular exemplary method, the paths that do not include the intra-domain node314(path381), that is intended to represent the phantom hub node370, are transformed into effective paths comprising a virtual node314′. For example, the first path381from node310to318derived into effective path381′ containing virtual node314′ and316′. In this example, a particular path (e.g.,382) containing the intra-domain node (e.g.,314) is chosen as the template. The other paths are derived to contain a similar path using virtual nodes as describe herein.

In the non-limitative example shown herein, path382is chosen to be a template that the other paths can match. Thus effective path381′ contains nodes310,332,314′,316′ and318. The second path382shown inFIG. 6Cincludes nodes310,332,314,316,318. The third path (FIG. 6D) contains nodes310,312,314,316and318.FIG. 6Eshows the effective path383′ having nodes and virtual nodes310,332′,314,316,318. Thus the path382and effective paths381′ and383′ have nodes310,332,314,316,318and/or virtual nodes316′,314′, and332′. The values associated with the virtual links between nodes and virtual nodes can be derived by various techniques as discussed above. For example the virtual link values between node310,332′ and314of virtual path383′ can be the average bandwidth between the nodes310and314of path383. In this particular version of an exemplary embodiment, effective path381′ (FIG. 6B), effective path383′ (FIG. 6E), and path382(FIG. 6C) are used. Each path includes the same nodes or equivalent virtual nodes, simplifying the calculation of averages in this particular non-limitative case.

FIGS. 6F–6Iillustrates the three paths from border node310to318.FIG. 6Fillustrates the first effective path381′, with nodes310,332,314′,316′,318, through links343with bandwidths 5 Gbps and link averages 7 Gbps respectfully.FIG. 6Gillustrates the second path382, with nodes310,332,314,316,318, through links343,347,346,345with bandwidths 5 Gbps, 7 Gbps, 3 Gbps, 5 Gbps respectfully.FIG. 6Hillustrates the third path383′, with nodes310,332′,314,316,318, through link averages 6 Gbps and links346,345with bandwidths 3 Gbps and 5 Gbps respectfully. In at least one exemplary embodiment the virtual links361and364, connected to intermediate phantom hub node314′, are assigned values associated with the average bandwidth along all three paths between nodes310and314or314′, 6 Gbps. Likewise the average, 5 Gbps, is used for virtual link364. Although for the example the average bandwidth is used, other methods (e.g. link average, weighted average, and the like) can be used. LikewiseFIGS. 6J–6Nillustrate the derivation of virtual path387′ and the combination of virtual path387′ with path385and386into virtual path388in a similar fashion as described above forFIGS. 6F–6I.

The intermediate phantom hub node314′ along with associated virtual links361,362,364, and365can be combined to form the properties advertised for phantom hub node370and associated virtual links350,353, and354forming a virtual network topology389(FIGS. 6O–6R). In the example shown the average bandwidth of virtual links361and362is used, 5.92 Gbps used for virtual link350. The values of the virtual links364and365are used for the virtual links354and353respectfully, 5 Gbps and 4.00 Gbps. Again, although the average bandwidth is used in the example, the maximum, minimum and other variations are intended to fall within the scope of embodiments of the invention.

FIGS. 7A–7Iis yet a further method in accordance with at least one exemplary embodiment. In this example paths between nodes that contain the particular node that is chosen to represent a phantom hub node are used. For example paths481(FIG. 7A),482(FIG. 7B), and483(FIG. 7C) are paths from node310to node314, where314has been chosen to be associated with a phantom hub node314′. In this example, the maximum through-put of the paths, 5 Gbps, from node310to node314is chosen to determine the virtual link value of virtual link350connecting node310with phantom hub node314′ (FIG. 7D), which in this example is also intra-domain node314.

Similarly paths485(FIG. 7E),486(FIG. 7F), and487(FIG. 7G) are paths between node318and node314. As above, using the maximum through-put, the virtual link value of 7 Gbps is chosen to determine the virtual link value of virtual link354connecting node318and the phantom hub node314′ (node314). The virtual link values associated with virtual links351and353(FIG. 71) can be determined in a similar manner and the resulting virtual network topology489is illustrated inFIG. 7I. Note that since node314is associated with the phantom hub node, virtual link352need not be determined.

Further, even though a physical node (e.g.,314) is used as the phantom hub node, the other methods for generating a phantom hub node and related virtual links described herein are applicable to this embodiment. However, those skilled in the art will appreciate that the link connecting the intra-domain node (e.g., border node314) does not need to be generated or advertised. For example, a predetermined virtual link value can be used to represent connectivity (e.g., links350–354) to the phantom hub node314′ (node314), thereby allowing additional nodes to be added with minimal computational effort.

Accordingly, at least one embodiment of the invention includes a system for advertising a representation of a domain (e.g., a domain can be considered to be an arbitrary network of interconnected network elements/nodes). The system comprises a first virtual link, a second virtual link, and at least one phantom hub node. The phantom hub node is coupled to a first intra-domain node by the first virtual link and coupled to a second intra-domain node by the second virtual link. The first and second virtual links can be determined based on characteristics of the domain, as discussed in the foregoing description. A first virtual link value and a second virtual link value are associated with the first virtual link and the second virtual link, respectively, and can be determined as discussed herein.

Referring toFIG. 8, at least one further exemplary embodiment uses abstracted intra-domain virtual links (e.g.,401,403,405,441and443) for portions of an intra-domain network topology. As discussed above intra-domain nodes and physical links can be replaced by phantom hub nodes and virtual links between intra-domain nodes. The intra-domain nodes can be border nodes.FIG. 8illustrates a representative inter-domain topology. As illustrated, there are one or more routing controllers (RCs) per domain, e.g.,417,427,433,437,451, which can be considered nodes in the control plane. The routing controllers serve to relay advertisements from external nodes or networks into the subject network (e.g.,400), and generate advertisements of the subject network topology to send to external nodes or networks. Nodes402,404,406,408,420,440,442, and446are connected by intra-domain links (e.g.,421,423,425,463). Nodes (e.g.402,404,406,408,431,435,439,455,457, and the like) representing portions of the network (460,470,480, and the like) can be represented as nodes and virtual links (e.g. nodes402,404,406and virtual links401,403,405, and470represented by a single virtual node420, and the like). For example, portion460can be abstract traffic-engineering (TE) links with centralized routing control470can be an abstract or virtual node with centralized routing control and480can be an abstract TE links with distributed routing control. Each of the portions460,470, and480can be considered domains, with the possibility that each domain can be represented by a virtual network topology as described above. As illustrated, the domain460can be represented by the virtual network topology composed of nodes402,406,408; virtual links401,403,405; and phantom hub node404.

At least one exemplary embodiment employs different options for deployment of the RCs and derivation of the abstract (virtual) topology. For example, a single RC can be used per network. each border node could have RC functionality. Further, combinations of sub-networks with single and/or multiple RC's per sub-network can be used. Further, the virtual topology could be derived from knowledge of the physical network topology (as can be provided through the use of a link state routing protocol within the subject network) and/or from advertisements generated by each border node.

In at least one exemplary embodiment of the invention, each border node can generate at least one phantom hub node (e.g., using techniques described above) and advertise one-way link capacity both to and from the phantom hub node(s). These advertisements can be received by all other border nodes and can be used to define the overall virtual network topology to be advertised to a connected external node or network.

In at least one exemplary embodiment of the invention, each border node can derive the presence of links from the phantom hub node(s) to other border nodes based on knowledge of the physical topology of the subject network. For example, the knowledge of the physical topology of the subject network can include a set of border nodes in the subject network, and the ability to reach any border node X from any other border node Y (e.g., border node310to border node316inFIG. 3). Thus, further exemplary embodiments do not require the communication of the topology of virtual links and phantom hub nodes between the various border nodes, instead each border node can derive the virtual topology and phantom hub node by itself.

Those skilled in the art will appreciated that other alternatives exist to generating the at least one phantom hub node, such as a central processor could generate the phantom hub node based on the known physical topology of the network or portion of the network. Additionally, as discussed above the phantom hub node can be assigned to a specific node in the network, such as one of the border nodes. Further, predetermined virtual link value(s) can be established between the at least a subset of the intra-domain nodes and phantom hub node (e.g., in the case of a VPN discussed above).

FIG. 9illustrates the use of a virtual network topology of domain510, which receives and/or transmits data between domains510,520, and530in accordance with at least one exemplary embodiment in a communication network500. Domain510represents a virtual network topology comprising a phantom hub node573in a star connectivity pattern with border nodes (e.g.561,575, and the like) and virtual links (e.g.570,572, and the like). To transmit data from the originating node561to domain530, Explicit Route Objects (ERO) can be generated through the path of561, phantom hub node573, border node575, through nodes581,583,585to node591. Likewise a ERO from domain530to510can have a path of591,585,583,581,575,573and561. Control channel574and540communicates the routing and signaling information between domains510,520, and530. However, when the data is actually transmitted through domain510, node573will typically be skipped, since it is a phantom node and internal routing data base containing the physical nodes and links will be used to route through domain570. Outside domain510, the routing control and signal control routes the data through inter-domain link576, node581, link582, node583, link584, and node585. The data is passed along inter-domain link586to node591, to domain530. Each domain can have various protocols and structures. Accordingly, the invention is not limited to the particular examples described herein.

FIG. 10illustrates the use of a virtual network topology of domain620, which passes data from domain610through the virtual network topology620to domain630. The originating domain610generates an ERO to reach domain620via nodes641,643, phantom node644,645, and647. Node641can pass data along inter-domain link613to border node643of domain620. The data is routed to its border node645of domain620via the physical links and nodes interconnecting border node643and645in domain620. Once again, phantom node644is typically not used (unless the phantom node is assigned to a physical node such as a border node used in the path). Border node645obtains routing and signaling information from domain630via control channels690and615. The data is then passed along inter-domain link617to border node647which then uses routing information of domain630to route the data to the designation node649. Each domain can have various protocols and structures and the originating and designation nodes can be intra-domain nodes and/or border nodes.

FIG. 11illustrates a flow chart illustrating another exemplary embodiment of the invention. As illustrated in accordance with at least one exemplary embodiment of the invention, a phantom hub node is instantiated, in block710and virtual link values are determined, in block720. For example, a first virtual link value is determined that represents connectivity between a first intra-domain node and the phantom hub node. Likewise, a second virtual link value is determined that represents connectivity between a second intra-domain node and the phantom hub node. As discussed above, the first and second virtual link values can be determined based on the link characteristics of the domain and/or at least one predetermined virtual link value. Each virtual link can use the same value or more than one predetermined value can be established and assigned to different virtual links. Further, the different virtual links can be to/from the same node to different phantom hub nodes. For example, a first virtual link to/from a first phantom hub node and a first border node can be generated using a first predetermined virtual link value. For example, the first predetermined virtual link value can be established by a service level agreement, such as in a VPN network. Additionally, a second virtual link connecting the first border node to a second phantom hub can be used to advertise a virtual topology of the domain to external networks. The second virtual link can be generated using a second predetermined value or any of the other methods described herein.

In at least one exemplary embodiment a representation of the domain (e.g., virtual network topology including the virtual link value) is advertised, in block730. As discussed above, the physical network topology can be represented by both a virtual network topology and a portion of the physical network topology not represented by the virtual network topology. Accordingly, the representation advertised is not limited to the virtual values and at least one embodiment of the invention can include advertising representations of a domain containing both virtual and a at least part of the physical topology not represented.

An example of instantiating a phantom hub node comprises each border node generating at least one intermediary phantom hub node, advertising a one-way link capacity both to and from the intermediary phantom hub node. The advertisements are received at the border nodes and are used to define an overall virtual network topology including the phantom hub node. Alternatively, instantiating the phantom hub node can comprise determining (by at least one border node) virtual links from the phantom hub node to other border nodes based on knowledge of the physical topology of the domain. Accordingly, each border node can generate a virtual network topology using the methods described herein and advertise the virtual network topology to external networks or nodes.

Further embodiments can additionally instantiate a second phantom hub node, where the second phantom hub node connects with less than all of the border nodes. In addition to instantiating the phantom hub nodes, embodiments can also advertise the first and second virtual link values to at least one of an external domain, network, and node, such as a border node.

The invention has been described in connection with a number of exemplary embodiments. To facilitate an understanding of the invention, many aspects of the invention were described in terms of sequences of actions. In at least one exemplary embodiment some actions can be performed by elements of a processor. Additionally, it will be recognized that in at least some embodiments, the various actions could be performed by specialized circuits (e.g., discrete logic gates interconnected to perform a specialized function, application specific integrated circuits (ASICS), and the like), by program instructions or computer program code being executed by one or more processors, or by a combination of both.

Moreover, at least one exemplary embodiment can be considered to be embodied entirely within any form of a computer readable storage medium having stored therein an appropriate set of computer instructions that would cause a processor to carry out the techniques described herein. Thus, the exemplary embodiment may be in tangible media, such as a floppy diskette, CD, DVD, hard drive, flash disk, magnetic tape, memory or any other computer-readable storage medium, wherein, when the program code is loaded into and executed by a processor, the processor becomes an apparatus for practicing an embodiment of the invention. Additionally, embodiments can include program instructions as a data signal transmitted via a transmission medium, such as over electrical wiring or cabling, through fiber optics, or via electromagnetic radiation, wherein, when the computer program code is loaded into and executed by a processor, the processor becomes an apparatus for practicing the embodiment of the invention. Accordingly, various aspects of the invention can be embodied in many different forms, and all such forms are contemplated to be within the scope of the invention. For some of the various aspects of the invention, some such forms of an embodiment can be referred to herein as “logic configured to”, “module configured to”, and/or “logic that” performs a described action.

Accordingly, at least one embodiment of the invention includes an apparatus comprising logic configured to generate a phantom hub node, logic configured to determine a first virtual link value, and logic configured to determine a second virtual link value. The virtual link values represent connectivity between the represented intra-domain nodes (e.g., border nodes) and the phantom hub node. The virtual link values can be determined based on characteristics of the domain (e.g., the physical topology, physical link parameter (e.g. bandwidth), and the like). Alternatively, the virtual link values can be determined using at least one predetermined virtual link value. For example, the predetermined virtual link value can be set for all links connecting intra-domain nodes (e.g., border nodes) to the phantom hub node. The predetermined virtual link value can be based on a service level agreement, such as related to a VPN service, or another value established by a network operator (e.g., minimum bandwidth, protection level, and the like) wherein the values are compatible with LSA's used in to represent the physical network. Further, the apparatus can further include logic configured to advertise the virtual link values to at least one of an external domain, network, and node.

Those skilled in the art will appreciate that the logic that forms the apparatus can be realized in variety of configurations, as discussed above. Accordingly, the apparatus can be realized in various network elements alone or in combination with other network elements. For example, the apparatus can be at least one of a routing controller (RC), a border node (or other intra-domain node), a sub-network, central processor, and the like. As discussed above, a single RC per network can be used. Alternatively, each border node could have RC functionality. Further, combinations of sub-networks with single and/or multiple RC's per sub-network can be used.

Other embodiments of the apparatus can include each border node including logic configured to generate at least one intermediary phantom hub node, logic configured to advertise one-way link capacity to/from the at least one intermediary phantom hub node, and logic configured to receive the advertisements from other border nodes and to use the advertisements to define an overall virtual network topology including at least one phantom hub node. Alternatively, embodiments can include at least one border node including logic configured to derive virtual links from the phantom hub node to other border nodes based on knowledge of the physical topology of the domain. Typically, intelligent nodes in a network will have information regarding the physical topology of the domain, which can be communicated to and stored at the node using known methods in the art.

In the exemplary examples herein, the term phantom hub node is used, where a phantom hub node is a type of virtual node. The scope of exemplary embodiments is intended to include virtual nodes. Thus the examples using phantom hub nodes are intended to apply for virtual nodes as well. For example, a virtual node can be use in cases where only some of the virtual links have a virtual node in common but not all. In at least one exemplary embodiment, a phantom hub node is a virtual node that is common to all virtual links connecting at least a portion of the intra-domain nodes. In this example if a portion of the intra-domain nodes connect via a phantom hub node, the remaining intra-domain nodes can connect via virtual links associated with separate virtual nodes, where not all of the virtual links forming a virtual network topology have the phantom hub node in common. Additionally, a virtual network topology can have a virtual node that is one or more of the physical nodes in the intra-domain topology.

Further exemplary embodiments can include reducing a first portion of a domain (e.g., physical network of interconnected nodes) into a virtual network topology, while a second portion represents a portion of the domain (e.g., physical network) not represented by the virtual network topology. In at least one exemplary embodiment the virtual network topology and the second portion are both advertised. Thus, a virtual network can represent sensitive portions of a physical network, while non-sensitive portions can be represented by their physical topology (e.g., link values and nodes).

The foregoing description of the invention is merely exemplary in nature. Accordingly, it should be appreciated that variations to those embodiments can be made by those skilled in the art without departing from the scope of the invention as defined by the following claims.