Aggregate multicast trees for multicast virtual private networks

• US 8,121,056 B1
• Filed: 07/02/2009
• Issued: 02/21/2012
• Est. Priority Date: 08/30/2004
• Status: Active Grant

• Current Assignee: Juniper Networks Incorporated
• Original Assignee: Juniper Networks Incorporated
• Inventors: Aggarwal, Rahul, Rekhter, Yakov
• Primary Examiner(s): Vu, Huy
• Assistant Examiner(s): RENNER, BRANDON M
• Application Number:
  US12/497,078
• Time in Patent Office: 964 Days
• Field of Search: 370254-256, 370389-392
• US Class Current: 370/256
• CPC Class Codes: H04L 12/18 for broadcast or conference , e.g. multicast
• CPC Class Codes: H04L 12/1886 with traffic restrictions for efficiency improvement, e.g. involving subnets or subdomains
• 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

Abstract

Principles of the invention are described for providing multicast virtual private networks (MVPNs) across a public network that are capable of carrying high-bandwidth multicast traffic with increased scalability. In particular, the MVPNs may transport layer three (L3) multicast traffic, such as Internet Protocol (IP) packets, between remote sites via the public network. The principles described herein may reduce the overhead of protocol independent multicast (PIM) neighbor adjacencies and customer control information maintained for MVPNs. The principles may also reduce the state and the overhead of maintaining the state in the network by removing the need to maintain at least one dedicated multicast tree per each MVPN.

Claims

1. A method comprising:

establishing a multicast tree comprising a point-to-multipoint (P2MP) tunnel for transporting layer three (L3) multicast data packets through a network, wherein the P2MP tunnel includes a source device providing an ingress to the multicast tree and a plurality of destination devices providing a plurality of different egresses from the multicast tree, wherein each of the plurality of destination devices belongs to at least one of a plurality of multicast virtual private networks (MVPNs), and wherein establishing the multicast tree includes allocating a different inner label with the source device for each of the more than one MVPNs to which the destination devices belong, each of the inner labels identifying the respective MVPN; and

transmitting the L3 multicast data packets for a plurality of different MVPNs from the source device through the P2MP tunnel to the plurality of destination devices on the multicast tree by encapsulating each of the multicast data packets at the source device with an outer label and one of the inner labels, each of the inner label being selected by the source device based on the MVPN with which the multicast data packet is associated.

2. The method of claim 1, further comprising:

prior to establishing the multicast tree, discovering, with the source device, the destination devices that are members of the MVPNs;

mapping more than one of the discovered MVPNs to the multicast tree; and

advertising mapping information from the source device to the one or more destination devices, wherein the mapping information specifies which of the discovered MVPNs are mapped to the multicast tree by the source device.

3. The method of claim 2, further comprising:

with the source device, including the allocated inner labels within the mapping information advertised from the source device to the destination devices to allow the destination devices to demultiplex the multicast data packets received over the multicast tree for the more than one MVPNs; and

in response to the mapping information advertised by the source device, maintaining, within each destination device, a separate label space for the multicast tree, wherein the label space within each destination device includes forwarding entries for the inner labels allocated by the source device,

wherein transmitting the multicast data packets from the source device comprises encapsulating each of the multicast data packets at the source device with an outer label and one of the inner labels, wherein the outer label identifies the label space within the destination device that corresponds to the multicast tree, and wherein the inner label is based on the MVPN with which the multicast data packet is associated.

4. The method of claim 2, further comprising determining which of the discovered MVPNs to aggregate onto the multicast tree.

5. The method of claim 2, wherein discovering the MVPN memberships comprises receiving Border Gateway Protocol (BGP) membership advertisements from the one or more destination devices.

6. The method of claim 2, wherein discovering the MVPN memberships comprises discovering virtual routing and forwarding (VRF) instances configured for multicast of the one or more destination devices.

7. The method of claim 2, wherein advertising mapping information comprises sending Border Gateway Protocol (BGP) mapping advertisements to the one or more destination devices of the multicast tree.

8. The method of claim 2, wherein advertising mapping information comprises advertising an address of the source device of the multicast tree and an inner label allocated by the source device for each of the more than one MVPNs mapped to the multicast tree that identifies the MVPN.

9. The method of claim 8, further comprising including a tree identifier of the multicast tree, and a route target attribute of each of the more than one MVPNs mapped to the multicast tree in the mapping advertisement.

10. The method of claim 1, further comprising:

receiving mapping information from the source device of the multicast tree;

associating the multicast tree with one or more of the MVPNs to which the destination device belongs; and

creating a forwarding entry in the destination device that corresponds to the multicast tree.

11. The method of claim 10, further comprising creating a logical interface to a label space within the destination device that corresponds to the multicast tree.

12. The method of claim 1, wherein establishing the multicast tree comprises establishing the multicast tree using protocol independent multicast (PIM).

13. The method of claim 1, wherein establishing the multicast tree comprises establishing the multicast tree using a label switching protocol.

14. The method of claim 1, wherein transmitting multicast data packets comprises:

receiving the multicast data packets from a multicast source;

encapsulating the multicast data packets for the MVPNs that have destination devices requesting the multicast data packets; and

transmitting the encapsulated packet for the MVPNs on the multicast tree.

15. The method of claim 14, wherein encapsulating the multicast data packets comprises encapsulating the multicast data packets with an inner label and an outer label, wherein the outer label identifies a label space within the destination device that corresponds to the multicast tree, and the inner label identifies the MVPN for which the multicast data packets are intended.

16. The method of claim 14, wherein encapsulating the multicast data packets comprises encapsulating the multicast data packets using Internet Protocol (IP) encapsulation.

17. The method of claim 14, wherein encapsulating the multicast data packets comprises encapsulating the multicast data packets using Multi-Protocol Label Switching (MPLS) encapsulation.

18. The method of claim 1, further comprising:

receiving the multicast data packets from the source device of the multicast tree; and

sending the multicast data packets to a virtual routing and forwarding (VRF) of the destination device that corresponds to the MVPN for which the multicast data packets were intended based on an inner label allocated by the source device that identifies the MVPN.

19. The method of claim 1, further comprising:

receiving an encapsulated packet from the source device of the multicast tree;

performing a lookup on the outer label of the encapsulated packet to determine a forwarding entry within the destination device that corresponds to the multicast tree;

stripping the outer label from the encapsulated packet;

performing a lookup on the inner label of the encapsulated packet in the corresponding forwarding entry to determine a virtual routing and forwarding (VRF) that corresponds to the MVPN for which the multicast data packets are intended;

stripping the inner label from the encapsulated packet; and

sending the multicast data packets to the corresponding VRF of the MVPN.

20. The method of claim 1, wherein establishing the multicast tree comprises establishing a shared multicast tree, and wherein transmitting multicast data packets on the multicast tree comprises transmitting multicast data packets for both local and remote MVPNs of the source device to the one or more destination devices on the multicast tree.

21. The method of claim 1, wherein establishing the multicast tree comprises establishing a source multicast tree, and wherein transmitting multicast data packets on the multicast tree comprises transmitting multicast data packets only for local MVPNs of the source device to the one or more destination devices on the multicast tree.

22. A network device comprising:

a control unit that establishes a multicast tree comprising a point-to-multipoint (P2MP) tunnel for transporting layer three (L3) multicast data packets through a network, wherein the point-to-multipoint (P2MP) includes a source device providing an ingress to the P2MP tunnel and a plurality of destination devices providing a plurality of destinations for the P2MP tunnel within the network, wherein each of the destination devices belongs to at least one multicast virtual private network (MVPN), and wherein the control unit allocates a different inner label for the MVPNs to identify the MVPNs; and

one or more output interfaces that transmit the L3 multicast data packets for more than one of the MVPNs through the P2MP tunnel on the multicast tree, wherein the L3 multicast data packets are encapsulated with an outer label and one of the inner labels, each of the inner label being selected by the control unit based on the MVPN with which the multicast data packet is associated.

23. The network device of claim 22, further comprising:

an auto-discovery module that discovers MVPN memberships of the one or more destination devices; and

a binding module that maps more than one of the discovered MVPNs to the multicast tree and advertises mapping information to the one or more destination devices.

24. The network device of claim 23, wherein the network device comprises the source device of the P2MP tunnel.

25. The network device of claim 23, further comprising an aggregation module that determines which of the discovered MVPNs to aggregate onto the multicast tree.

26. The network device of claim 22, wherein the control unit:

receives mapping information from the source device of the multicast tree;

associates the multicast tree with one or more of the MVPNs to which the destination device belongs; and

creates a forwarding entry in the destination device that corresponds to the multicast tree.

27. The network device of claim 26, wherein the control unit creates a logical interface to a label space within the destination device that corresponds to the multicast tree.

28. The network device of claim 22, wherein the control unit:

receives the multicast data packets from a multicast source;

encapsulates the multicast data packets for the MVPNs that have destination devices requesting the multicast data packets; and

transmits the encapsulated packet for the MVPNs on the multicast tree.

29. The network device of claim 28, wherein the encapsulated packet comprises one of an Internet Protocol (IP) encapsulated packet or a Multi-Protocol Label Switching (MPLS) encapsulated packet.

30. The network device of claim 22, wherein the control unit:

receives the multicast data packets from the source device of the multicast tree; and

sends the multicast data packets to a virtual routing and forwarding (VRF) of the destination device that corresponds to the MVPN for which the multicast data packets were intended based on the inner label allocated by the source device that identifies the MVPN.

31. The network device of claim 22, wherein the control unit:

receives an encapsulated packet from the source device of the multicast tree;

performs a lookup on the outer label of the encapsulated packet to determine a forwarding entry within the destination device that corresponds to the multicast tree;

strips the outer label from the encapsulated packet;

performs a lookup on the inner label of the encapsulated packet in the corresponding forwarding entry to determine a virtual routing and forwarding (VRF) that corresponds to the MVPN for which the multicast data packets are intended;

strips the inner label from the encapsulated packet; and

sends the multicast data packets to the corresponding VRF of the MVPN.

32. The network device of claim 22, wherein the multicast tree comprises a shared multicast tree, and the control unit transmits multicast data packets for both local and remote MVPNs of the source device to the one or more destination devices on the multicast tree.

33. The network device of claim 22, wherein the multicast tree comprises a source multicast tree, and the control unit transmits multicast data packets only for local MVPNs of the source device to the one or more destination devices on the multicast tree.

34. A non-transitory computer-readable storage medium comprising instructions stored thereon that cause a programmable processor to:

establish a multicast tree comprising a point-to-multipoint (P2MP) tunnel for transporting layer three (L3) multicast data packets through a network, wherein the multicast tree includes a source device providing an ingress to the multicast tree and a plurality of destination devices providing egresses from the multicast tree, wherein each of the destination devices belongs to at least one multicast virtual private network (MVPN)), and wherein the instructions establish the multicast tree by allocating a different inner label for each of the MVPNs; and

transmit multicast data packets for a plurality of different MVPNs from the source device through the P2MP tunnel to the plurality of destination devices on the multicast tree by encapsulating each of the multicast data packets with an outer label and one of the inner labels, each of the inner label being selected based on the MVPN with which the multicast data packet is associated.

35. The non-transitory computer-readable medium of claim 34, further comprising instructions that cause the programmable processor to:

discover MVPN memberships of the one or more destination devices;

map more than one of the discovered MVPNs to the multicast tree; and

advertise mapping information to the one or more destination devices.

36. The non-transitory computer-readable medium of claim 34, further comprising instructions that cause the programmable processor to:

receive mapping information from the source device of the multicast tree;

associate the multicast tree with one or more of the MVPNs to which the destination device belongs; and

create a forwarding entry in the destination device that corresponds to the multicast tree.

37. The non-transitory computer-readable medium of claim 34, wherein the instructions that cause the programmable processor to transmit multicast data packets cause the programmable processor to:

receive the multicast data packets from a multicast source;

encapsulate the multicast data packets for the MVPNs that have destination devices requesting the multicast data packets; and

transmit the encapsulated packet for the MVPNs on the multicast tree.

38. The non-transitory computer-readable medium of claim 34, further comprising instructions that cause the programmable processor to:

receive the multicast data packets from the source device of the multicast tree; and

send the multicast data packets to a virtual routing and forwarding (VRF) of the destination device that corresponds to the MVPN for which the multicast data packets were intended based on the inner label that identifies the MVPN.

39. The non-transitory computer-readable medium of claim 34, further comprising instructions that cause the programmable processor to:

receive an encapsulated packet from the source device of the multicast tree;

perform a lookup on the outer label of the encapsulated packet to determine a forwarding entry within the destination device that corresponds to the multicast tree;

strip the outer label from the encapsulated packet;

perform a lookup on the inner label of the encapsulated packet in the corresponding forwarding entry to determine a virtual routing and forwarding (VRF) that corresponds to the MVPN for which the multicast data packets are intended;

strip the inner label from the encapsulated packet; and

send the multicast data packets to the corresponding VRF of the MVPN.

40. A system comprising:

a source device within a network, wherein the source device provides an ingress to a multicast tree comprising a point-to-multipoint (P2MP) tunnel that transmits layer three (L3) multicast data packets for more than one of the MVPNs;

one or more destination devices within the network that provide egresses to the P2MP tunnel, wherein each of the destination devices belongs to at least one multicast virtual private network (MVPN),

wherein the source device allocates a different inner label for each of the more than one MVPNs and communicates the allocated inner labels to the destination devices, and

wherein each of the multicast data packets received from the P2MP tunnel by the destination devices includes an inner label and an outer label, wherein the outer label identifies a label space within the receiving destination device that corresponds to the P2MP tunnel, and the inner label identifies the MVPN for which the L3 multicast data packets are intended, and

wherein the destination devices demultiplex the multicast data packets received over the multicast tree for the more than one MVPNs and select a virtual routing and forward (VRF) for forwarding the multicast data packets based on the different inner labels of the multicast data packets.