METHODS AND APPARATUS TO IMPLEMENT MULTIPOINT AND REPLICATED COMMUNICATION PATHS USING UPSTREAM AND RECURSIVE DOWNSTREAM LABEL MAPPINGS

• US 20120027013A1
• Filed: 07/29/2010
• Published: 02/02/2012
• Est. Priority Date: 07/29/2010
• Status: Active Grant

• Current Assignee: AT&T Intellectual Property I LP (AT&T, Inc.)
• Original Assignee: AT&T Intellectual Property I LP (AT&T, Inc.)
• Inventors: Napierala, Maria
• Granted Patent: US 8,705,530 B2
• Time in Patent Office: Days
• US Class Current: 370/390
• CPC Class Codes: H04L 45/04 Interdomain routing, e.g. hierarchical routing
• CPC Class Codes: H04L 45/16 Multipoint routing
• CPC Class Codes: H04L 45/50 using label swapping, e.g. multi-protocol label switch [MPLS]
• CPC Class Codes: H04L 45/507 Label distribution

Abstract

Methods and apparatus to implement multipoint and replicated communication paths using upstream and recursive downstream label mappings are disclosed. An example method to aggregate multipoint communication paths disclosed herein comprises sending an upstream label assignment request to an upstream router in response to receiving a first downstream message for building a first inner multipoint communication path between a root node identified in the first downstream message and a leaf node originating the first downstream message, and receiving an upstream-assigned label from the upstream router in response to the upstream label assignment request, the upstream-assigned label to identify the first inner multipoint communication path among a plurality of inner multipoint communication paths conveyed via an outer multipoint communication path aggregating the plurality of inner multipoint communication paths.

Claims

1. A method to aggregate multipoint communication paths, the method comprising:

sending an upstream label assignment request to an upstream router in response to receiving a first downstream message for building a first inner multipoint communication path between a root node identified in the first downstream message and a leaf node originating the first downstream message; and

receiving an upstream-assigned label from the upstream router in response to the upstream label assignment request, the upstream-assigned label to identify the first inner multipoint communication path among a plurality of inner multipoint communication paths conveyed via an outer multipoint communication path aggregating the plurality of inner multipoint communication paths.

2. A method as defined in claim 1 wherein the first downstream message comprises a downstream-assigned label to identify the first inner multipoint communication path, and the method further comprises:

receiving a packet conveyed via the outer multipoint communication path;

determining whether a label stack included with the packet contains the upstream-assigned label; and

when the label stack contains the upstream-assigned label, swapping the upstream-assigned label with the downstream-assigned label to forward the packet to the leaf node.

3. A method as defined in claim 2 further comprising, when the label stack does not contain the upstream-assigned label, discarding the packet.

4. A method as defined in claim 1 wherein the first downstream message comprises a recursive multicast label distribution protocol (mLDP) message including a forwarding equivalency class (FEC) identifying the root node and the upstream router as the next-hop towards the root node, the FEC also including an opaque value type set to a first value to trigger sending of the upstream label assignment request.

5. A method as defined in claim 1 further comprising sending the upstream label assignment request and receiving the upstream-assigned label via a targeted label distribution protocol (LDP) session established with the upstream router.

6. A method as defined in claim 1 further comprising sending a second downstream message to build the outer multipoint communication path, the second downstream message identifying the upstream router as a root of the outer multipoint communication path.

7. A method as defined in claim 1 wherein the outer multipoint communication path and the first inner multipoint communication path are label switched paths (LSPs), the outer multipoint communication path resides in a core network, and wherein the method further comprises using a first protocol to build the outer multipoint communication path in the core network and a second protocol different from the first protocol to build a portion of the first inner multipoint communication path residing outside the core network.

8. A method as defined in claim 7 wherein the first protocol is mLDP and the second protocol is Protocol Independent Multicast (PIM) Source-Specific-Multicast (SSM), the first downstream message comprises a PIM join message identifying the root node as a source of an SSM channel, and the method further comprises processing configuration information to determine whether to send the upstream label assignment request in response to receiving the PIM join message.

9. A tangible article of manufacture storing machine readable instructions which, when executed, cause a machine to:

send an upstream label assignment request to an upstream router in response to receiving a first downstream message for building a first inner multipoint communication path between a root node identified in the first downstream message and a leaf node originating the first downstream message; and

receive an upstream-assigned label from the upstream router in response to the upstream label assignment request, the upstream-assigned label to identify the first inner multipoint communication path among a plurality of inner multipoint communication paths conveyed via an outer multipoint communication path aggregating the plurality of inner multipoint communication paths.

10. A tangible article of manufacture as defined in claim 9 wherein the first downstream message comprises a downstream-assigned label to identify the first inner multipoint communication path, and the machine readable instructions, when executed, further cause the machine to:

receive a packet conveyed via the outer multipoint communication path;

determine whether a label stack included with the packet contains the upstream-assigned label; and

when the label stack contains the upstream-assigned label, swap the upstream-assigned label with the downstream-assigned label to forward the packet to the leaf node.

11. A tangible article of manufacture as defined in claim 9 wherein the first downstream message comprises a recursive multicast label distribution protocol (mLDP) message including a forwarding equivalency class (FEC) identifying the root node and the upstream router as the next-hop towards the root node, the FEC also including an opaque value type set to a first value to trigger sending of the upstream label assignment request.

12. A tangible article of manufacture as defined in claim 9 wherein the machine readable instructions, when executed, further cause the machine to send a second downstream message to build the outer multipoint communication path, the second downstream message identifying the upstream router as a root of the outer multipoint communication path.

13. A tangible article of manufacture as defined in claim 9 wherein the outer multipoint communication path and the first inner multipoint communication path are label switched paths (LSPs), the outer multipoint communication path resides in a core network, and wherein the machine readable instructions, when executed, further cause the machine to use a first protocol to build the outer multipoint communication path in the core network and a second protocol different from the first protocol to build a portion of the first inner multipoint communication path residing outside the core network.

14. A tangible article of manufacture as defined in claim 13 wherein the first protocol is mLDP and the second protocol is Protocol Independent Multicast (PIM) Source-Specific-Multicast (SSM), the first downstream message comprises a PIM join message identifying the root node as a source of an SSM channel, and the machine readable instructions, when executed, further cause the machine to process configuration information to determine whether to send the upstream label assignment request in response to receiving the PIM join message.

15. A label switch router (LSR) comprising:

a packet transceiver to receive a packet conveyed via an outer multipoint communication path; and

a packet label swapper to;

determine whether a label stack included with the packet contains an upstream-assigned label assigned by an upstream LSR to identify a first inner multipoint communication path aggregated in the outer multipoint communication, the first inner multipoint communication path established between a root node and a leaf node, the leaf node served by the LSR; and

when the label stack contains the upstream-assigned label, swapping the upstream-assigned label with a first downstream-assigned label assigned by the leaf node to forward the packet to the leaf node.

16. An LSR as defined in claim 15 wherein the LSR is to discard the packet when the first inner multipoint communication path is not associated with any nodes served by the LSR.

17. An LSR as defined in claim 15 further comprising a message processor to:

send an upstream label assignment request to an upstream router in response to receiving a first downstream message including the first downstream-assigned label from the leaf node to build the first inner multipoint communication path; and

receive the upstream-assigned label from the upstream router in response to the upstream label assignment request, the upstream-assigned label to identify the first inner multipoint communication path among a plurality of inner multipoint communication paths aggregated via the outer multipoint communication path.

18. An LSR as defined in claim 17 wherein the first downstream message comprises a recursive multicast label distribution protocol (mLDP) message including a forwarding equivalency class (FEC) identifying the root node and the upstream router as the next-hop towards the root node, the FEC also including an opaque value type set to a first value to trigger sending of the upstream label assignment request, and wherein the message processor is to send the upstream label assignment request in response to determining that the opaque value type is set to the first value.

19. An LSR as defined in claim 17 wherein the message processor is to send the upstream label assignment request and receive the upstream-assigned label via a targeted label distribution protocol (LDP) session established with the upstream router.

20. An LSR as defined in claim 17 wherein the message processor is to send a second downstream message to build the outer multipoint communication path, the second downstream message identifying the upstream router as the root of the outer multipoint communication path.

21-40. -40. (canceled)