Multicast trees for virtual private local area network (LAN) service multicast

• US 7,558,219 B1
• Filed: 08/26/2005
• Issued: 07/07/2009
• Est. Priority Date: 08/30/2004
• Status: Active Grant

• Current Assignee: Juniper Networks Incorporated
• Original Assignee: Juniper Networks Incorporated
• Inventors: Rekhter, Yakov, Aggarwal, Rahul
• Primary Examiner(s): Kizou; Hassan
• Assistant Examiner(s): RENNER, BRANDON M
• Application Number:
  US11/212,932
• Time in Patent Office: 1,411 Days
• Field of Search: 370/338, 370/389, 370/392
• 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 virtual private local area network service (VPLS) multicast instances across a public network by utilizing multicast trees. In particular, the VPLS multicast instances transport layer two (L2) multicast traffic, such as Ethernet packets, between customer networks via the public network. The principles described herein enable VPLS multicast instances to handle high bandwidth multicast traffic. The principles also reduce the state and the overhead of maintaining the state in the network by removing the need to perform snooping between routers within the network.

Claims

1. A method comprising:

establishing a multicast tree comprising a point-to-multipoint (P2MP) label switched path (LSP) forming a P2MP tunnel, the P2MP tunnel having a source device providing an ingress to the P2MP tunnel and a plurality of destination devices providing a plurality of different egresses from the P2MP tunnel, wherein each of the destination devices belongs to at least one virtual private local area network service (VPLS) multicast instance; and

transmitting multicast data packets for the VPLS multicast instances from the source device through the P2MP tunnel to the destination devices on the multicast tree,

wherein establishing the multicast tree comprises;

discovering, with the source device, the VPLS multicast instances of which the destination devices are members;

mapping more than one of the discovered VPLS multicast instances to the multicast tree;

allocating an inner label with the source device for each of the more than one VPLS multicast instances mapped to the multicast tree;

advertising mapping information from the source device to the one or more destination devices, wherein the mapping information specifies which of the discovered VPLS multicast instances are mapped to the multicast tree;

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;

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, and

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 VPLS multicast instance with which the multicast data packet is associated.

2. The method of claim 1, wherein transmitting multicast data packets comprises transmitting the multicast data packets only for local VPLS multicast instances of the source device.

3. The method of claim 1, wherein transmitting multicast data packets comprises transmitting the multicast data packets for both local and remote VPLS multicast instances of the source device.

4. The method of claim 1, wherein the network comprises a multi-protocol label switching (MPLS) network.

5. The method of claim 1, wherein establishing the multicast tree comprises using a label switching protocol to establish the multicast tree, wherein the label switching protocol comprises one of the resource reservation protocol (RSVP) or the label distribution protocol (LDP).

6. The method of claim 1, wherein the multicast tree comprises one of a resource reservation protocol (RSVP) point to multi-point (P2MP) label switched path (LSP), a label distribution protocol (LDP) signaled P2MP LSP, or a protocol independent multicast (PIM) signaled P2MP LSP.

7. The method of claim 1, further comprising determining with the source device which of the discovered VPLS multicast instances to aggregate onto the multicast tree.

8. The method of claim 1, further comprising:

receiving, with one of the destination devices, the mapping information from the source device of the multicast tree;

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

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

9. The method of claim 8, further comprising creating a logical interface to the label space within the destination device that corresponds to the multicast tree.

10. 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 VPLS multicast instances that have destination devices requesting the multicast data packets; and

transmitting the encapsulated packet for the VPLS multicast instances on the multicast tree.

11. 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 switch interface (VSI) of the destination device that corresponds to the VPLS for which the multicast data packets were intended based on an inner label allocated by the source device that identifies the VPLS.

12. The method of claim 1, wherein transmitting the multicast data packets comprises transmitting multicast data packets of specific multicast groups that belong to the VPLS multicast instances from the source device to the one or more destination devices on the multicast tree.

13. A network device comprising:

a control unit that establishes a multicast tree comprising a label switched path (LSP) forming a point-to-multipoint (P2MP) tunnel, the P2MP tunnel having 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 destination devices belongs to at least one virtual private local area network service (VPLS) multicast instance;

an auto-discovery module that discovers the VPLS multicast instances of which the destination devices are members;

a binding module that maps more than one of the discovered VPLS multicast instances to the multicast tree; and

one or more output interfaces that transmit multicast data packets for the VPLS multicast instances through the P2MP tunnel on the multicast tree,

wherein the control unit allocates a different inner label for each of the more than one VPLS multicast instances mapped to the multicast tree that identifies the VPLS multicast instance and advertises mapping information to the one or more destination devices, wherein the mapping information specifies which of the discovered VPLS multicast instances are mapped to the multicast tree and includes the allocated inner labels to allow the destination devices to demultiplex the multicast data packets received over the multicast tree for the more than one VPLS multicast instances, and

wherein the control unit encapsulates each of the L3 multicast data packets with an outer label and one of the inner labels, wherein the outer label identifies a label space within the destination device that corresponds to the multicast tree.

14. The network device of claim 13, wherein the control unit transmits the multicast data packets only for local VPLS multicast instances of the source device.

15. The network device of claim 13, wherein the control unit transmits the multicast data packets for both local and remote VPLS multicast instances of the source device.

16. The network device of claim 13, wherein the network comprises a multi-protocol label switching (MPLS) network.

17. The network device of claim 13, wherein the label switching protocol comprises one of a resource reservation protocol (RSVP) or a label distribution protocol (LDP).

18. The network device of claim 13, wherein the multicast tree comprises one of a resource reservation protocol (RSVP) point to multi-point (P2MP) label switched path (LSP), a label distribution protocol (LDP) signaled P2MP LSP, or a protocol independent multicast (PIM) signaled P2MP LSP.

19. The network device of claim 13, further comprising:

an auto-discovery module within the control unit that discovers VPLS multicast instances of which of the plurality of destination devices are members; and

a binding module within the control unit that maps at least one of the discovered VPLS multicast instances to the multicast tree and advertises mapping information to the one or more destination devices.

20. The network device of claim 19, further comprising an aggregation module that determines which of the discovered VPLS multicast instances to aggregate onto the multicast tree.

21. The network device of claim 13, wherein the control unit transmits multicast data packets of specific multicast groups that belong to the VPLS multicast instances from the source device to the one or more destination devices on the multicast tree.

22. A computer-readable medium comprising instructions that cause a programmable processor to:

discover, with a source device, a plurality of virtual private local area network service (VPLS) multicast instances of which a plurality of destination devices are members;

establish a multicast tree comprising a label switched path (LSP) that forms a point-to-multipoint (P2MP) tunnel, the P2MP tunnel having 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 one or more destination devices belongs to at least one of the VPLS multicast instances;

map more than one of the discovered VPLS multicast instances to the multicast tree;

allocate a different inner label with the source device for each of the more than one VPLS multicast instances mapped to the multicast tree;

advertise mapping information from the source device to the one or more destination devices, wherein the mapping information specifies which of the discovered VPLS multicast instances are mapped to the multicast tree by the source device;

include 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 VPLS multicast instances;

encapsulate 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; and

transmit the encapsulated multicast data packets for the VPLS multicast instances from the source device through the P2MP tunnel to the destination devices on the multicast tree.

23. The computer-readable medium of claim 22, wherein the instructions that cause the programmable processor to transmit multicast data packets cause the programmable processor to transmit the multicast data packets only for local VPLS multicast instances of the source device.

24. The computer-readable medium of claim 22, wherein the instructions that cause the programmable processor to transmit multicast data packets cause the programmable processor to transmit the multicast data packets for both local and remote VPLS multicast instances of the source device.

25. The computer-readable medium of claim 22, wherein the instructions that cause the programmable processor to transmit multicast data packets cause the programmable processor to transmit multicast data packets of specific multicast groups that belong to the VPLS multicast instances from the source device to the one or more destination devices on the multicast tree.

26. A system comprising:

a source device within a network, wherein the source device provides an ingress to a point to multi-point (P2MP) tunnel, the P2MP tunnel comprising a label switched path (LSP) that forms a multicast tree a tunnel for transmitting multicast data packets for a plurality of different virtual private local area network service (VPLS) multicast instance;

one or more destination devices within the network that provide egresses to the P2MP tunnel, wherein each of the one or more destination devices belongs to at least one of a plurality of VPLS multicast instances;

wherein the source device allocates a different inner label for each of the plurality of different VPLS multicast instances and communicates the allocated inner labels to the destination devices,

wherein each of the destination devices maintain a label space that includes forwarding entries for the inner labels allocated by the source device,

wherein the source device encapsulates each of the multicast data packets with an outer label and one of the inner labels, wherein the outer label identifies the label space within the receiving destination device that corresponds to the P2MP tunnel, and the inner label identifies the VPLS multicast instance for which the multicast data packets are intended, and

wherein the destination devices demultiplex the multicast data packets received over the multicast tree for the plurality of different VPLS multicast instances 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.

27. The system of claim 26, wherein the multicast tree transmits multicast data packets of specific multicast groups that belong to the VPLS multicast instances from the source device to the one or more destination devices on the multicast tree.