Method and apparatus for providing congruent multicast and unicast routing

• US 20080101360A1
• Filed: 10/25/2006
• Published: 05/01/2008
• Est. Priority Date: 10/25/2006
• Status: Active Grant

• Current Assignee: AT&T Corporation (AT&T, Inc.)
• Original Assignee: AT&T Corporation (AT&T, Inc.)
• Inventors: Napierala, Maria
• Granted Patent: US 7,626,984 B2
• Time in Patent Office: Days
• US Class Current: 370/390
• CPC Class Codes: H04L 12/1836 with heterogeneous network architecture
• CPC Class Codes: H04L 12/4641 Virtual LANs, VLANs, e.g. virtual private networks [VPN] LAN interconnection over a bridge based backbone H04L12/462; encapsulation techniques H04L12/4633; routing of packets H04L45/00; packet switches H04L49/00; virtual private networks for security H04L63/0272
• CPC Class Codes: H04L 45/04 Interdomain routing, e.g. hierarchical routing
• CPC Class Codes: H04L 45/50 using label swapping, e.g. multi-protocol label switch [MPLS]

Abstract

A method and apparatus for enabling congruent multicast and unicast routing in a Virtual Private Network (VPN) are disclosed. For example, the present method receives a request to join a multicast group to receive multicast data traffic by a receiver behind a remote Provider Edge (PE) router. The method then discovers a multicast source to allow said remote PE router to use a direct path to receive said multicast data traffic from a source.

Claims

1. A method for enabling congruent multicast and unicast routing in a Virtual Private Network (VPN), comprising:

receiving a request to join a multicast group to receive multicast data traffic from a receiver behind a remote Provider Edge (PE) router or a locally connect Customer Edge (CE) router; and

discovering a multicast source to allow said remote PE router or said locally connected CE router to use a direct path to receive said multicast data traffic from a source.

2. The method of claim 1, wherein said Virtual Private Network (VPN) is a Multi-Protocol Label Switching/Border Gateway Protocol (MPLS/BGP) multicast VPN.

3. The method of claim 2, wherein said discovering comprises:

receiving a PIM (*,G) Join message by a Provider Edge (PE) router with a Customer Rendezvous Point (C-RP) behind it from said remote PE router, where G is a multicast group;

sending said received PIM (*,G) Join message by said PE router with said C-RP behind it to said C-RP without forwarding multicast traffic on an interface that leads toward said VPN network; and

announcing said multicast source.

4. The method of claim 3, wherein said announcing comprises:

sending a PIM (S,G,rpt) Prune message by said PE router with a C-RP behind it to said C-RP when a first multicast packet is received from said multicast source by said PE router with a C-RP behind it, where S is a source of said multicast group;

sending a source announcement message by said PE router with a C-RP behind it to indicate said multicast source and its location to all other PE routers in said VPN; and

signaling an existence of said multicast source and a tunnel identifier to be used for (S,G) multicast traffic to said all other PE routers in said VPN by the PE router with said multicast source behind it when said PE router with said multicast source behind it receives said source announcement message from said PE router with a C-RP behind it.

5. The method of claim 4, wherein said source announcement message comprises a source address of said first multicast packet extracted from said first multicast packet.

6. The method of claim 3, wherein said discovering further comprises:

translating a PIM (*,G) Join message to a PIM (S,G) Join message by each PE router with a multicast group G receiver behind it; and

sending said PIM (S,G) Join message by said each PE router with a multicast group G receiver behind it to a best next hop router towards said multicast source; and

joining a tunnel for a (S,G) distribution tree announced by said best next hop router.

7. The method of claim 2, wherein said discovering comprises:

receiving a first PIM (S,G) Join message by a Provider Edge (PE) router with a multicast source behind it from said remote PE router or said locally connected CE router, where S is a multicast source and G is a multicast group;

announcing a tunnel to be used for (S,G) multicast traffic to all remote PE routers in said VPN by said PE router with said multicast source behind it; and

joining the tunnel for a (S,G) distribution tree announced by said a remote PE router with a multicast group receiver behind it only if said PE router with a multicast source behind it is a best next hop router from said remote PE router to said multicast source.

8. A computer-readable medium having stored thereon a plurality of instructions, the plurality of instructions including instructions which, when executed by a processor, cause the processor to perform the steps of a method for enabling congruent multicast and unicast routing in a Virtual Private Network (VPN), comprising:

receiving a request to join a multicast group to receive multicast data traffic from a receiver behind a remote Provider Edge (PE) router or a locally connect Customer Edge (CE) router; and

discovering a multicast source to allow said remote PE router or said locally connected CE router to use a direct path to receive said multicast data traffic from a source.

9. The computer-readable medium of claim 8, wherein said Virtual Private Network (VPN) is a Multi-Protocol Label Switching/Border Gateway Protocol (MPLS/BGP) multicast VPN.

10. The computer-readable medium of claim 9, wherein said discovering comprises:

receiving a PIM (*,G) Join message by a Provider Edge (PE) router with a Customer Rendezvous Point (C-RP) behind it from said remote PE router, where G is a multicast group;

sending said received PIM (*,G) Join message by said PE router with said C-RP behind it to said C-RP without forwarding multicast traffic on an interface that leads toward said VPN network; and

announcing said multicast source.

11. The computer-readable medium of claim 10, wherein said announcing comprises:

sending a PIM (S,G,rpt) Prune message by said PE router with a C-RP behind it to said C-RP when a first multicast packet is received from said multicast source by said PE router with a C-RP behind it, where S is a source of said multicast group;

sending a source announcement message by said PE router with a C-RP behind it to indicate said multicast source and its location to all other PE routers in said VPN; and

signaling an existence of said multicast source and a tunnel identifier to be used for (S,G) multicast traffic to said all other PE routers in said VPN by the PE router with said multicast source behind it when said PE router with said multicast source behind it receives said source announcement message from said PE router with a C-RP behind it.

12. The computer-readable medium of claim 11, wherein said source announcement message comprises a source address of said first multicast packet extracted from said first multicast packet.

13. The computer-readable medium of claim 10, wherein said discovering further comprises:

translating a PIM (*,G) Join message to a PIM (S,G) Join message by each PE router with a multicast group G receiver behind it; and

sending said PIM (S,G) Join message by said each PE router with a multicast group G receiver behind it to a best next hop router towards said multicast source; and

joining a tunnel for a (S,G) distribution tree announced by said best next hop router.

14. The computer-readable medium of claim 9, wherein said discovering comprises:

receiving a first PIM (S,G) Join message by a Provider Edge (PE) router with a multicast source behind it from said remote PE router or said locally connected CE router, where S is a multicast source and G is a multicast group;

announcing a tunnel to be used for (S,G) multicast traffic to all remote PE routers in said VPN by said PE router with said multicast source behind it; and

joining the tunnel for a (S,G) distribution tree announced by said a remote PE router with a multicast group receiver behind it only if said PE router with a multicast source behind it is a best next hop router from said remote PE router to said multicast source.

15. An apparatus for enabling congruent multicast and unicast routing in a Virtual Private Network (VPN), comprising:

means for receiving a request to join a multicast group to receive multicast data traffic from a receiver behind a remote Provider Edge (PE) router or a locally connect Customer Edge (CE) router; and

means for discovering a multicast source to allow said remote PE router or said locally connected CE router to use a direct path to receive said multicast data traffic from a source.

16. The apparatus of claim 15, wherein said Virtual Private Network (VPN) is a Multi-Protocol Label Switching/Border Gateway Protocol (MPLS/BGP) multicast VPN.

17. The apparatus of claim 16, wherein said discovering means comprises:

means for receiving a PIM (*,G) Join message by a Provider Edge (PE) router with a Customer Rendezvous Point (C-RP) behind it from said remote PE router, where G is a multicast group;

means for sending said received PIM (*,G) Join message by said PE router with said C-RP behind it to said C-RP without forwarding multicast traffic on an interface that leads toward said VPN network; and

means for announcing said multicast source.

18. The apparatus of claim 17, wherein said announcing means comprises:

means for sending a PIM (S,G,rpt) Prune message by said PE router with a C-RP behind it to said C-RP when a first multicast packet is received from said multicast source by said PE router with a C-RP behind it, where S is a source of said multicast group;

means for sending a source announcement message by said PE router with a C-RP behind it to indicate said multicast source and its location to all other PE routers in said VPN; and

means for signaling an existence of said multicast source and a tunnel identifier to be used for (S,G) multicast traffic to said all other PE routers in said VPN by the PE router with said multicast source behind it when said PE router with said multicast source behind it receives said source announcement message from said PE router with a C-RP behind it.

19. The apparatus of claim 18, wherein said source announcement message comprises a source address of said first multicast packet extracted from said first multicast packet.

20. The apparatus of claim 17, wherein said discovering means further comprises:

means for translating a PIM (*,G) Join message to a PIM (S,G) Join message by each PE router with a multicast group G receiver behind it; and

means for sending said PIM (S,G) Join message by said each PE router with a multicast group G receiver behind it to a best next hop router towards said multicast source; and

means for joining a tunnel for a (S,G) distribution tree announced by said best next hop router.