System and method for providing support for multipoint L2VPN services in devices without local bridging

• US 8,228,928 B2
• Filed: 11/17/2009
• Issued: 07/24/2012
• Est. Priority Date: 01/19/2006
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Parandekar, Harshavardhan, Sajassi, Ali, Dhar, Sanjay
• Primary Examiner(s): Vu, Huy D
• Assistant Examiner(s): Beyen, Zewdu A
• Application Number:
  US12/620,390
• Publication Number:
  US 20100061379A1
• Time in Patent Office: 980 Days
• Field of Search: None
• US Class Current: 370/401
• CPC Class Codes: H04L 12/2859 Point-to-point connection between the data network and the subscribers encapsulation H04L12/4633; virtual LANs H04L12/4641; routing of packets H04L45/00
• CPC Class Codes: H04L 12/2898 Subscriber equipments DSL modems H04M11/062; cable modems H04L12/2801
• CPC Class Codes: H04L 12/465 wherein a single frame includes a plurality of VLAN tags

Abstract

A network device has a network interface to allow the device to send and receive traffic across a network. The device also has a cable connection to allow the device to exchange data with at least one cable modem and a processor to associate a cable interface and cable service identifier with a cable modem; receive a packet from the cable modem; and insert a layer 2 network identifier, the identifier comprising two service provider VLAN (SP-VLAN) tags, into the packet. The processor in the network device identifies a virtual trunk interface based on the outer SP-VLAN tag and identifies the virtual private network based on the inner SP-VLAN tag.

Claims

1. A method comprising:

receiving a packet from a cable modem;

identifying a cable interface and cable service identifier associated with the cable modem;

inserting a layer 2 (L2) network identifier into the packet, the L2 network identifier comprising inner and outer Service Provider Virtual Local Area Network (SP-VLAN) tags to be used within a service provider network to bridge the packet across the service provider network, wherein the inner SP-VLAN tag represents a customer VPN in a multipoint L2VPN service wherein the inner SP-VLAN tag is associated with a particular bridge group, wherein the outer SP-VLAN tag represents a single attachment circuit and wherein the outer SP-VLAN tag is associated with a virtual interface trunk;

wherein the inner SP-VLAN tag and the outer SP-VLAN tag are added to the packet upon entry into the service provider network;

and

transmitting the double SP-VLAN tagged packet to an upstream network device;

wherein the inner SP-VLAN tag and the outer SP-VLAN tag are removed from the packet prior to exiting the service provider network.

2. The method of claim 1, further comprising:

wherein a number inner SP-VLAN tags is based on a number of upstream network devices in the VPN; and

wherein a number of outer SP-VLAN tags is based on a number of service flows available to the customer nodes of the VPN.

3. The method of claim 1 further comprising:

forwarding and routing the SP-VLAN tagged packet;

identifying a virtual trunk interface based on the outer SP-VLAN tag, wherein the virtual trunk interface is associated with the cable service identifier;

removing the outer SP-VLAN tag to form a single SP-VLAN tagged packet; and

forwarding the single SP-VLAN tagged packet to a downstream network device based on the inner SP-VLAN tag.

4. The method of claim 3, wherein the upstream and downstream network devices comprise a same device.

5. A system comprising:

an ingress CMTS configured to map at least one attachment circuit to an outer SP-VLAN tag of a double SP-VLAN tagged packet,

wherein an inner SP-VLAN tag represents a broadcast domain and the outer SP-VLAN tag uniquely identifies a single attachment circuit on the ingress CMTS in the broadcast domain;

wherein, if a packet arrives at the ingress CMTS with a customer edge VLAN (CE-VLAN) tag in a header, the ingress CMTS adds the inner and outer SP-VLAN tags without removing the CE-VLAN tag from the header;

wherein the inner SP-VLAN tag represents a customer VPN in a multipoint L2VPN service and is associated with a particular bridge group;

wherein the outer SP-VLAN tag is associated with a virtual interface trunk;

wherein the inner SP-VLAN tag and the outer SP-VLAN tag are added to the packet upon entry into a service provider network and wherein the inner SP-VLAN tag and the outer SP-VLAN tag are removed from the packet prior to exiting the service provider network.

6. The system of claim 5, wherein the broadcast domain is a customer VPN.

7. The system of claim 5, further comprising:

an upstream aggregation node comprising a plurality of virtual trunk interfaces, wherein each of the virtual trunk interfaces corresponds to an attachment circuit.

8. The system of claim 7, wherein a number of the plurality of virtual trunk interfaces is equal to a number of attachment circuits the ingress CMTS associates for a particular customer VPN.

9. The system of claim 8, wherein if the packet is received on a physical interface of the upstream aggregation node, then the upstream aggregation node interprets the SP-VLAN outer tag as a virtual trunk interface identifier and removes the SP-VLAN outer tag from the packet.

10. The system of claim 9, wherein the upstream aggregation node is further configure to build a layer 2 (L2) Forwarding Database including a MAC address and SP-VLAN inner tag associated with a virtual trunk interface.

11. The system of claim 10, wherein the upstream aggregation node is further configured to flood the packet to a virtual trunk interface identified.

12. The system of claim 8, wherein the upstream aggregation node is further configured to use the packet comprising the SP-VLAN inner tag without the SP-VLAN outer tag to bridge the packet across a network to an egress aggregation node, wherein the egress aggregation node is configured to add a new SP-VLAN outer tag based on an egress virtual trunk interface identifier.

13. The system of claim 5, comprising an egress aggregation node configure to forward the packet to an egress CMTS.

14. The system of claim 13, wherein the packet includes the SP-VLAN inner tag and a new SP-VLAN outer tag, wherein the egress CMTS is configured to map the packet back to an attachment circuit, remove the SP-VLAN inner tag and the new SP-VLAN outer tag, and forward the packet.

15. A system comprising:

means for accessing a configuration file, wherein the configuration file includes information for associating a cable modem (CM) with a particular customer VPN and an SP-VLAN inner tag, wherein the inner SP-VLAN tag is associated with a bridge group;

means for adding the SP-VLAN inner tag to a packet upon ingress into a service provider network;

means for discovering a customer VPN in the configuration file;

means for selecting and adding an SP-VLAN outer tag corresponding to the customer VPN to the packet from a plurality of available tags, wherein the plurality of available tags is limited to a number of tags associated with corresponding attachment circuits associated with the customer VPN, wherein the outer SP-VLAN tag is associated with a virtual trunk interface;

means for transmitting the packet on an egress interface to an upstream aggregation node; and

means for removing the inner SP-VLAN tag and the outer SP-VLAN tag from the packet prior to exiting the service provider network.

16. The system of claim 15, further comprising means for assigning Service Identifiers (SID) to one or more active service flows corresponding to the CM, wherein the SIDs are available to a CMTS upon receipt of a packet from the CM.

17. The system of claim 16, further comprising means for maintaining an upstream mapping table for mapping the SP-VLAN outer and inner tags and an egress interface to an upstream aggregation node associated with the SID.

18. The system of claim 15, wherein a number of the plurality of available tags corresponds to a maximum number of attachment circuits for any VPN at a CMTS.

19. The system of claim 16, further comprising means for initiating a plurality of free SP-VLAN outer tags corresponding to the customer VPN.

20. The system of claim 15, further comprising:

means for assigning Service Identifiers (SID) to one or more active service flows corresponding to the CM, wherein the SIDs are available to a CMTS upon receipt of a packet from the CM; and

means for maintaining an upstream mapping table for mapping the SP-VLAN outer and inner tags and an egress interface to an upstream aggregation node associated with the SID.