Transporting multicast over MPLS backbone using virtual interfaces to perform reverse-path forwarding checks

• US 20060221975A1
• Filed: 08/16/2005
• Published: 10/05/2006
• Est. Priority Date: 04/05/2005
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Lo, Alton, Boers, Arjen, Wijnands, Ijsbrand
• Granted Patent: US 8,089,964 B2
• Time in Patent Office: Days
• US Class Current: 370/395.500
• CPC Class Codes: H04L 12/18 for broadcast or conference , e.g. multicast
• CPC Class Codes: H04L 45/00 Routing or path finding of packets in data switching networks routing or path finding in wireless networks H04W40/00
• 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 45/60 Router architectures

Abstract

A mechanism is provided in which multicast reverse path forwarding can be performed at a provider network egress edge router wherein core routers of the provider network are not configured to support multicast protocols or point-to-multipoint LSPs. An embodiment of the present invention provides for the creation of virtual interfaces in the egress edge router element during configuration of a multicast connection in response to a subscriber request. A virtual interface will be associated with an upstream ingress edge router element and that ingress edge router element is provided a label associated with the virtual interface. Such a label can then be included in datastream packets transmitted through the provider network. The label can then be used by reverse path forward checking at the egress edge router element to ascertain whether the multicast datastream is being received by the correct upstream interface (e.g., the virtual interface associated with the ingress edge router element). In such a manner, core network router elements of the provider'"'"'s network need not be configured to process multicast transmissions as such, nor need the core router elements be configured to use the same network protocols as those used by the customer networks (e.g., customer networks can use IPv6 while the core network routers can use IPv4).

Claims

1. A method comprising:

receiving a first RPF-label and a first multicast packet;

determining an association of the first RPF-label with a first virtual interface; and

transmitting the first multicast packet if a source address within the first multicast packet is associated with the first virtual interface.

2. The method of claim 1 further comprising:

performing a reverse-path forwarding check to determine whether the source address is associated with the first virtual interface.

3. The method of claim 2 further comprising:

dropping the first multicast packet if the source address within the first multicast packet is not associated with the first virtual interface.

4. The method of claim 1, wherein

a data frame comprising the first RPF-label and first multicast packet is received from a non-multicast-enabled network element.

5. The method of claim 1 wherein said determining the association of the first RPF-label with the first virtual interface comprises:

comparing the first RPF-label to one or more entries in a table, wherein each entry in the table correlates an RPF-label to a virtual interface.

6. The method of claim 5, wherein

each virtual interface entered in the table is created in response to receiving a message to subscribe to a multicast datastream.

7. The method of claim 6, wherein

the message is a PIM JOIN for the multicast datastream.

8. The method of claim 6, wherein

each virtual interface entered in the table corresponds to an ingress router that is upstream toward a source of the multicast datastream.

9. A method comprising:

creating a first virtual interface, wherein

the first virtual interface corresponds to an ingress network element;

associating a first RPF-label with the first virtual interface; and

transmitting an identification of the first RPF-label to the ingress network element.

10. The method of claim 9 further comprising:

performing said creating in response to receiving a message requesting a multicast datastream, wherein

the ingress network element is upstream toward a source of the multicast stream.

11. The method of claim 9 further comprising:

storing said first RPF-label and an identifier of the first virtual interface in a table comprising one or more RPF-labels and virtual interface identifiers.

12. The method of claim 11 further comprising:

receiving a multicast packet and an associated second RPF-label;

comparing the second RPF-label with the one or more RPF-labels stored in the table; and

associating the multicast packet with a second virtual interface associated with the second RPF-label, in response to said comparing.

13. The method of claim 12 further comprising:

performing a reverse path forwarding (RPF) check on the multicast packet using the second virtual interface; and

transmitting the multicast packet if the second virtual interface is the first virtual interface.

14. A network routing apparatus comprising:

a plurality of network line cards, wherein

a first network line card of the plurality of network line cards is configured to receive a first RPF-label and a first multicast packet, and

a second network line card of the plurality of network line cards is configured to transmit the first multicast packet;

a switch fabric comprising a plurality of ports, wherein

each of the plurality of ports is-coupled to a corresponding one of the plurality of network line cards,

a first port is coupled to the first network line card, and

a second port is coupled to the second network line card; and

one or more processors coupled to the first network line card, wherein

the one or more processors are configured to determine an association of the first RPF-label with a first virtual interface, and

provide the first multicast packet to the second network line card if a source address within the first multicast packet is associated with the first virtual interface.

15. The network routing apparatus of claim 14, wherein

the one or more processors are further configured to compare the first RPF-label to one or more entries in a table, wherein

each entry in the table correlates an RPF-label to a virtual interface.

16. The network routing apparatus of claim 15, wherein

each virtual interface entered in the table corresponds to an ingress router that is upstream toward a source of a multicast datastream requested by a subscriber node coupled to the network routing apparatus.

17. A network routing apparatus comprising:

a plurality of network line cards, wherein

a first network line card of the plurality of network line cards is coupled to an ingress network element;

a switch fabric comprising a plurality of ports, wherein

each of the plurality of ports is coupled to a corresponding one of the plurality of network line cards, and

a first port is coupled to the first network line card;

a memory; and

one or more processors coupled to the first network line card and the memory, wherein

the one or more processors are configured to create a first virtual interface, wherein

the first virtual interface corresponds to the ingress network element, associate a first RPF-label with the first virtual interface, and transmit an identification of the first RPF-label to the ingress network element.

18. The network routing apparatus of claim 17 wherein the one or more processors are further configured to:

store the first RPF-label and an identifier of the first virtual interface in the memory, wherein

the memory comprises one or more RPF-labels and virtual interface identifiers;

compare a second RPF-label with the one or more RPF-labels stored in the memory, wherein

the second RPF-label is associated with a multicast packet received by the first network line card; and

associate the multicast packet with a second virtual interface associated with the second RPF-label.

19. The network routing apparatus of claim 18 wherein the one or more processors are further configured to:

perform a reverse path forwarding (RPF) check on the multicast packet using the second virtual interface; and

transmit the multicast packet if the second virtual interface is the first virtual interface.

20. A network routing apparatus comprising:

a plurality of network line cards, wherein

a first network line card of the plurality of network line cards is configured to receive a first RPF-label and a first multicast packet, and

a second network line card of the plurality of network line cards is configured to transmit the first multicast packet;

a switch fabric comprising a plurality of ports, wherein

each of the plurality of ports is coupled to a corresponding one of the plurality of network line cards,

a first port is coupled to the first network line card, and

a second port is coupled to the second network line card; and

means for determining an association of the first RPF-label with a first virtual interface; and

means for transmitting the first multicast packet if a source address within the first multicast packet is associated with the first virtual interface.

21. A network routing apparatus comprising:

a plurality of network line cards, wherein

a first network line card of the plurality of network line cards is coupled to an ingress network element;

a switch fabric comprising a plurality of ports, wherein

each of the plurality of ports is coupled to a corresponding one of the plurality of network line cards, and

a first port is coupled to the first network line card;

means for creating a first virtual interface, wherein

the first virtual interface corresponds to the ingress network element;

means for associating a first RPF-label with the first virtual interface; and

means for transmitting an identification of the first RPF-label to the ingress network element.