ETHERNET LAYER 2 PROTOCOL PACKET SWITCHING

• US 20080013547A1
• Filed: 10/19/2006
• Published: 01/17/2008
• Est. Priority Date: 07/14/2006
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Basavaraju, Muralidhara R., Klessig, Robert W., Raghavendran, Vijayakumar
• Granted Patent: US 8,085,790 B2
• Time in Patent Office: Days
• US Class Current: 370/395.53
• CPC Class Codes: H04L 12/4654 wherein a VLAN tag represents a customer VLAN, e.g. C-Tag
• CPC Class Codes: H04L 12/4658 wherein a VLAN tag represents a service provider backbone VLAN, e.g. B-Tag, S-Tag
• CPC Class Codes: H04L 12/467 Arrangements for supporting untagged frames, e.g. port-based VLANs
• CPC Class Codes: H04L 12/66 Arrangements for connecting between networks having differing types of switching systems, e.g. gateways

Abstract

In one embodiment, an apparatus includes an access node, and the access node includes ports. The access node is operable to perform downlink switching based upon a unique Provider Virtual Local Area Network tag (S-TAG) and a unique IEEE 802.1Q tag header (C-TAG) that is assigned to each port.

Claims

1. A method comprising:

assigning a Provider Virtual Local Area Network tag (S-TAG) and an IEEE 802.1Q tag header (C-TAG) to a group of ports to implement a N;

1 Virtual Local Area Network (VLAN) allocation scheme, the group of ports included in an access node that communicatively connects a Customer Edge (CE) device to a Provider Edge (PE) device; and

receiving a frame from the CE device, the frame containing a Layer 2 (L2) protocol packet; and

switching the frame based upon the S-TAG and the C-TAG.

2. The method of claim 1, wherein switching the frame based upon the S-TAG and the C-TAG comprises:

inserting a tag into the frame, the tag including the S-TAG and the C-TAG; and

forwarding the L2 protocol packet to a Provider Edge (PE) device based on the S-TAG.

3. The method of claim 2, wherein the L2 protocol packet comprises an Ethernet Local Management Interface (E-LMI) packet.

4. The method of claim 2, wherein the L2 protocol packet comprises one selected from the group consisting of a Cisco Discovery Protocol (CDP) packet, a UniDirectional Link Detection (UDLD) packet, a Port Aggregation Protocol (PAgP) packet, a Port Based Network Access Control (IEEE 802.1X) packet, and a Link Aggregation Control Protocol (LACP) packet.

5. The method of claim 2, wherein the access node comprises a Digital Subscriber Line Access Multiplexer (DSLAM).

6. An apparatus comprising an access node, the access node including ports, the access node operable to perform downlink switching based upon a unique Provider Virtual Local Area Network tag (S-TAG) and a unique IEEE 802.1Q tag header (C-TAG) that is assigned to each port.

7. The apparatus of claim 6, the access node operable to insert one or more tags into a frame received from a Customer Edge (CE) device, the tags including the S-TAG and the C-TAG.

8. The apparatus of claim 7, the access node operable to communicate with a Provider Edge (PE) device located at the edge of a Service Provider (SP) network using an uplink.

9. The apparatus of claim 8, wherein the SP network comprises a Metro Ethernet Network (MEN).

10. The apparatus of claim 8, the access node comprising a Digital Subscriber Line Access Multiplexer (DSLAM), the DSLAM operable to forward a Layer 2 (L2) protocol packet to the PE device based upon the S-TAG.

11. The apparatus of claim 10, wherein the L2 protocol packet comprises an Ethernet local Management Interface (E-LMI) packet.

12. Logic encoded in one or more tangible media for execution and when executed operable to:

insert a tag into a frame that is transmitted from a Customer Edge (CE) device, the tag including a Provider Virtual Local Area Network tag (S-TAG) and a IEEE 802.1Q tag header (C-TAG); and

perform downlink switching based upon the S-TAG and the C-TAG.

13. The logic of claim 12, wherein the performance of downlink switching based upon the S-TAG and the C-TAG comprises:

forwarding a Layer 2 (L2) protocol packet included in the frame to a Provider Edge (PE) device based upon the S-TAG; and

perform downlink switching based upon the C-TAG, the C-TAG including a unique value for a port of an access node.

14. The logic of claim 13, wherein the L2 protocol packet comprises an Ethernet Local Management Interface (E-LMI) packet.

15. The logic of claim 13, wherein the L2 protocol packet is selected from the group consisting of a Cisco Discovery Protocol (CDP) packet, a UniDirectional Link Detection (UDLD) packet, a Port Aggregation Protocol (PAgP) packet, a Port Based Network Access Control (IEEE 802.1×

) packet, and a Link Aggregation Control Protocol (LACP) packet.

16. The logic of claim 13, wherein the tag comprises:

a first two-byte Ethertype (Etype) field disposed adjacent to the S-TAG; and

a second two-byte Etype field disposed immediately between the S-TAG and the C-TAG.

17. The logic of claim 12, when executed further operable to implement a N:

1 Virtual Local Area Network (VLAN) allocation scheme.