Patent Application
20070280234
Examples of embodiments of the invention will now be described in greater detail with reference to the accompanying drawings, in which:
In embodiments of the present invention, a layer 2 switched connection is used as a control channel for communicating control signals across a switched network, the control signals being for controlling the communication of multicast data. An exemplary embodiment of the layer 2 switched connection is an SVC (Switched Virtual Circuit) over an ATM network. In some embodiments a P2MP switched connection is established in response to receiving, over the control channel, a request for a multicast channel. The multicast data for that multicast channel is sent over the P2MP switched connection.
Referring to
Non-limiting examples of the network element 100 include a provider edge; a router; a server; a DSLAM (Digital Subscriber Line Access Multiplexer); and a BRAS.
In use, embodiments of the network element 100 are part of a system. Referring to
In some embodiments, the switched network 260 supports both P2P (Point-to-Point) and P2MP (Point-to-Multipoint) communications. Non-limiting examples of the network 260 include an ATM (Asynchronous Transfer Mode) network; an Ethernet; a Frame Relay network; and an MPLS (Multiple Protocol Label Switch) network. By using a SVC over an ATM network for the control channel, for example, there is no requirement that every node in the network comprise a table of the multicast channel addresses because the SVC is switched automatically at each node when given the VPI/VCI of the called network element. An IGMP Report containing a source IP address and an IP Group address is passed over the layer 2 control channel to the upstream router, such as the BRAS, where a P2MP SPVC is launched based on the information in the Report. In addition, an inherent feature of SVCs is the ability to switch to a back-up circuit should there be a failure along the SVC. This provides additional stability to the control channel in embodiments of the present invention. In some embodiments of the invention, the SVC is a P2P circuit.
Where the network is an ATM network, some embodiments of the network element 100 are configured to implement ATM NNI (Network-Network Interface) signalling protocols, such as PNNI (Private Network-Network Interface) signalling. In some embodiments, the network element 100 supports ATM AINI (ATM Internet Interface) signalling links.
In some embodiments of the present invention, the multicast data comprises data for an IPTV (Internet Protocol Television) multicast channel.
Referring now to
In some embodiments of the present invention, the network protocol module 320 of the network element 300 is also configured to establish the layer 2 P2MP connection in response to the multicast protocol module 310 receiving a report requesting the selected multicast channel.
As with the network element 100, embodiments of the network element 300 are used in a system. Referring now to
In some embodiments, the network element 350 is further connected to a downstream network element, such as a DSLAM, a set-top box, etc and the network element 300 receives multicast data from a source through a multicast enabled network. In some embodiments, the network element 350 receives requests for a particular multicast channel from the downstream network element. If that channel is not being received by the network element 350 already, it passes on the request to the network element 300 over the SVC 345 and the multicast protocol module 310 receives the request. If the channel is already being received at the network element 300, the multicast protocol module 310 instructs the network protocol module to transmit data for the channel to the network element 350. If the channel is not being received at the network element 300, the multicast protocol module 310 will send a request for the channel upstream and instruct the network protocol module 320 to transmit data for the channel to the network element 350. In response to receiving instructions to transmit multicast data to the network element 350, the network protocol module 320 establishes the SPVC 370 and sends the data. When the data is received at the network element 350, it is forwarded to the downstream network element.
In some embodiments, the network element is also configured to communicate with a further network element over a PVC (Permanent Virtual Circuit) control channel. Referring to
Now referring to
In some embodiments, the first network element 610 has a table mapping the IP multicast address to a source ATM endpoint that the multicast channel is coming in on. Additionally, the table can map the multicast channel to a VPI/VCI at the second network element 620, i.e. the destination node for the multicast data. The drawback of having the second network element's VPI/VCI on a table at the first network element is that all destination nodes will have to use the same VPI/VCI for the same multicast channels.
To enable destination nodes to use different VPI/VCI for different channels, a table could be in place at the second network element 620, the table specifying which VPI/VCI for each channel. In this case, when the SPVC 670 is launched, the called party number would specify “wildcard” VPI/VCI, triggering the second network element 620 to use its VPI/VCI values from the table.
In some embodiments of the present invention, the network element 610 and/or the network element 620 have a similar configuration to the network element 100 described with reference to
In some embodiments, the SVC control channel 650 is an IGMP control channel. In some embodiments, the first network element 610 and the second network element 620 each comprise an IGMP protocol module to which the SVC IGMP control channel is connected. In some embodiments, the first network element and the second network element each comprise a network protocol module in communication with the IGMP protocol module. In some embodiments, the network protocol module of the first network element 610 establishes the SPVC 670.
In some embodiments, the first network element 610 receives the multicast data from a multicast source through an IP (Internet Protocol) network.
An exemplary system will now be described with reference to
In some embodiments the method described with reference to
In some embodiments, the method described with reference to
The methods according to embodiments of the present invention may be implemented using hardware, software or combinations thereof. Accordingly, one embodiment of the present invention comprises a computer readable medium having computer readable instructions stored thereon for implementing any of the methods described herein.
According to one embodiment of the present invention, an upstream router and a downstream router support signalling over a switched network that separates the two routers. In such cases, to implement a method according to one embodiment of the present invention, the following steps are carried out:
Provisioning both the upstream router and the downstream router to become a provider edge to a switched network and use a network protocol to gain access to the switched network that connects the two routers;
Establishing a SVC-IGMP control channel between the downstream router and the upstream router through the switched network. Exemplary ways of establishing the control channel parameters include using an algorithm such as the “higher router IP address” or using explicit provisioning to determine the calling and called party sides. In some embodiments, the SVC-IGMP endpoints are provisioned by an operator at both routers. The determination of called/calling sides may be from upstream router, whereby the control channel is a Router mode IGMP control channel or from the downstream router, whereby the control channel is a. Host mode IGMP control channel.
Transporting IGMP messages between the downstream router and upstream router over the established SVC-IGMP control channel; and
When the downstream router sends a REPORT message to the upstream router, triggering the upstream router to establish a P2MP SPVC with the root originating from the upstream router and the P2MP leaf terminating at the downstream router.
In some embodiments the upstream router and/or the downstream router do not support signalling over the switched network. In these cases an extra network element is introduced between the router(s) and the switched network to establish the SVC control channel and the SPVC across the switched network. In some embodiments, the extra network element is an edge node for the switched network that is adjacent to the router that does not support signalling over the switched network. One manner of implementing these embodiments is as follows:
Establishing a PVC-IGMP control channel between the edge node and the router. In some embodiments, this is done only on the downstream side or the upstream side of the switched network. In other embodiments, a PVC-IGMP control channel is established both on downstream side and one on the upstream side. For purposes of this example only, the remainder of this method assumes that a PVC-IGMP control channel is established on both sides;
Establishing a SVC-IGMP control channel between the downstream edge node and upstream edge node;
When the downstream router sends a REPORT message requesting a multicast channel towards the downstream edge node over the downstream PVC-IGMP control channel, the downstream edge node forwards the message towards the upstream edge node via the SVC-IGMP control channel;
When the upstream edge node receives the REPORT message, it will establish a P2MP SPVC with a root originating from the upstream edge node and a P2MP leaf terminating at downstream edge node;
If IGMP proxy is required, the upstream edge node will also forward the REPORT message toward the upstream router to allow it to make its own crossed-connection in order to feed the multicast stream for the channel toward the upstream edge node.
The methods of embodiments of the present invention may be implemented on any embodiments of the network elements and in any of the systems described herein. Embodiments of the methods described herein are implemented using hardware, software or combinations thereof.
What has been described is merely illustrative of the application of the principles of the invention. Other arrangements and methods can be implemented by those skilled in the art without departing from the spirit and scope of the present invention.
