Patent Application
20060126595
Embodiments of the present invention relate to establishing a call bearing data between two endpoints. More specifically, embodiments of the present invention relate to establishing a call between two endpoints that are supported by separate media gateways, bypassing a core network.
A current trend in the telecommunications industry utilizes a decomposed voice over packet architecture in which a call control functionality is performed by one element and the actual bearing of data is accomplished by a second element. Prior to this decomposition technique, call control and call bearing were performed by one element, and the way that element worked was proprietary and unique to each telecommunications provider. Now, there are industry-wide standards, the call control element has been separated (logically, and in some cases physically as well) from the call bearing element, and telecommunications providers can work together to devise solutions to satisfy the constant demand on the telecommunications industry to provide faster and more complex services.
A media gateway is a network element that provides conversion between media (voice, video, data, etc.) and data packets carried over a core packet (IP, ATM, etc.) network. A media gateway supports a collection of endpoints. An endpoint sources and/or sinks one or more media streams.
In a conventional decomposed voice over packet architecture, an external call control element typically establishes a call between two endpoints on different media gateways via the core packet network. The call control element is logically external to the media gateway, while it may or may not reside in the same physical box or location. The external call control element is typically unaware of any possible connection between two endpoints other than the core packet network. It is possible that the two endpoints reside within the same network device or within different network devices that are in close proximity to one another. Alternative connections between endpoints are called alternate bearer possibilities, and may include such connections as ATM, virtual channel or TDM networks, pre-resolved IP paths, MPLS or VLAN networks or pseudo-wires, among others. In a decomposed voice over packet architecture, the external call control element is typically unaware of these alternate bearer possibilities.
In the prior art, however, it is known for the external call control element to discern that if a call originates and terminates on the same media gateway, there is a bearer possibility other than the core packet network. Media gateway control protocols including Media Gateway Control Protocol (MGCP), Trunking Gateway Control Protocol (TGCP), Network-based Call Signaling (NCS), Megaco/H.248 and SIP define syntax and semantics which allow the external call control element to specify an alternate bearer possibility when a call originates and terminates on the same media gateway. However, these constructs cannot be used in conjunction with endpoints which reside on different media gateways.
Embodiments of the present invention, a method and system for establishing a call between endpoints on different media gateways, are presented. Cluster attributes identifying alternate bearer possibilities are exchanged between media gateways as part of capabilities negotiation which occurs during call setup conducted by an external call control element over a core network. The media gateways analyze the cluster attributes to determine whether bearer possibilities exist apart from the core network. If an alternate bearer possibility exists, the alternate is employed and the call is established via the alternate bearer directly between the media gateways, thus bypassing the core network.
The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention:
Reference will now be made in detail to various embodiments of the invention, examples of which are illustrated in the accompanying drawings. While the invention will be described in conjunction with various embodiments, it will be understood that they are not intended to limit the invention to these embodiments. On the contrary, the invention is intended to cover alternatives, modifications and equivalents, which may be included within the spirit and the scope of the invention as defined by the appended claims. Furthermore, in the following detailed description of the present invention, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to one skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, components, structures and devices have not been described in detail so as to avoid unnecessarily obscuring aspects of the present invention.
Media gateway C [160] supports endpoints which are part of cluster 150, thus media gateway C [160] and media gateway B [120] are communicatively linked via link [161]. Media gateway C [160] and media gateway B [120] share an alternate bearer possibility [161]. Media gateway C [160] and media gateway A [110] do not support endpoints which are part of the same cluster. Media gateway A [110] and media gateway C [160] can communicate via core network 140. However, there is no alternate bearer possibility for establishing a call between endpoints supported by media gateway A [110] and endpoints supported by media gateway C [160].
Media gateway D [170] supports endpoints which are part of cluster 180. Cluster 180 does not share endpoints with cluster 150 or cluster 130. Endpoints supported by media gateway D [170] may participate in calls with endpoints in media gateway A [110], B [120] or C [160] via the core network [140], but there are no alternate bearer possibilities for such calls.
As illustrated at media gateway B [120], clusters may overlap. Endpoints supported by media gateway B [120] may have membership in cluster 150 and cluster 130. Clusters may also be nested (not depicted in
Referring to
a=X-cluster:<cluster ID type> <cluster ID Format> <cluster ID length> [<cluster Member ID>]
In this example, the cluster ID type sub-field is a text string giving the type of the cluster ID and cluster member ID. Cluster ID types may include Internet Protocol (IN), Asynchronous Transfer Mode (ATM), Multi-Protocol Label Switching (MPLS), Layer Two Tunneling Protocol (L2TP), etc. The cluster ID format sub-field is a text string giving the format of the cluster ID and cluster member ID. Cluster formats may include “IP4,” “IP6,” “NSAP,” “ASCII,” Label-Switched Path (LSP), pseudo-wire (PW), etc. The cluster ID length sub-field specifies the leftmost portion of the cluster member ID that constitutes the cluster ID. For example, with a cluster ID type/format of “IN IP4,” “IN IP6,” “ATM NSAP,” etc., the cluster ID length is expressed in terms of bits. With a cluster ID type/format of “STRING ASCII,” the cluster ID length is expressed in terms of ASCII characters.
The cluster member ID sub-field is an optional text string identifying the specific member within the cluster. The cluster member ID may be omitted if the <cluster ID type> and <cluster ID format> of the X-cluster attribute match the <network type> and <address type> of the standard connection data field:
c=<network type> <address type> <connection address>
The connection data field is taken from either the media description or the connection description, per the rules of RFC 2327. The <cluster member ID> sub-field is mandatory with a cluster ID type/format of “STRING ASCII.”
In one embodiment, the originating call leg 236 is established between endpoint A [201] and endpoint B [231] via the core network before it is determined whether or not media gateway A [210] and media gateway B [230] share an alternate bearer possibility. Once it is determined that an alternate bearer possibility exists, the originating call leg [260] is re-established via the alternate bearer.
Referring to
In one embodiment of the present invention, upon receiving cluster attribute 241, media gateway B [230] determines whether or not the terminating endpoint is a part of the cluster or clusters indicated by cluster attribute 241. Media gateway B [230] then sends establish response [250] to the call control element A [220] including cluster attribute 251 which indicates which cluster or clusters the terminating endpoint belongs to. Upon receiving cluster attribute 251, media gateway A [210] determines whether the originating endpoint belongs to any of the clusters indicated by cluster attribute 251. There may be one alternate bearer possibility, multiple alternate bearer possibilities, or no alternate bearer possibilities.
If the originating endpoint and the terminating endpoint share a cluster membership, e.g., they share one or more alternate bearer possibilities, originating call leg 260 is established via one of the alternate bearer possibilities, bypassing the core network. Terminating call leg 265 is also established via one of the alternate bearer possibilities, bypassing the core network. If there is no alternate bearer possibility, the terminating call leg would be established via the core network and through call control element A [220].
In one embodiment of the present invention, media gateway A [210] and media gateway B [230] are capable of determining which alternate bearer possibility presents the lowest cost option when there are multiple alternate bearer possibilities. Cost can be measured in terms of latency, bandwidth, equipment, etc. If the originating and terminating endpoints share membership in more than one cluster, originating call leg 260 is established via the most cost-efficient alternate bearer possibility, in this embodiment. However, it is not a requirement that the most cost-efficient solution be used.
A call leg may be modified with a new remote cluster attribute, for example in the case of call forwarding. The media gateways will maintain the alternate bearer or revert to the core packet network depending on the new cluster ID. As depicted in the call flow [300] in
Endpoints [e.g. 421] supported by originating media gateway A [410] are members of the same cluster as endpoints [e.g. 471] supported by terminating media gateway B [460]. If a call is desired between originating endpoint 420 and terminating endpoint 470, there is more than one way to establish the call. The call could be conducted by an external call control element [411] via core network 450, Utilizing embodiments of the present invention, the call is conducted by originating media gateway 410 and terminating media gateway 460 via alternate bearer 451. A call conducted in the latter manner would bypass core network 450.
Step 630 in
The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many modifications and variations are possible in light of the above teachings. The embodiments were chosen and described in order to best explain the principles of the invention and its practical application, to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the Claims appended hereto and their equivalents.
