Traffic Switching In Hybrid Fiber Coaxial (HFC) Network

• US 20120257891A1
• Filed: 06/30/2011
• Published: 10/11/2012
• Est. Priority Date: 04/05/2011
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Boyd, Edward Wayne, Danzig, Joel I., Davis, Lawrence Drew, Bahm, Ernie
• Granted Patent: US 9,130,878 B2
• Time in Patent Office: Days
• US Class Current: 398/45
• CPC Class Codes: H04L 47/6215 Individual queue per QOS, rate or priority
• CPC Class Codes: H04Q 11/0067 Provisions for optical access or distribution networks, e.g. Gigabit Ethernet Passive Optical Network (GE-PON), ATM-based Passive Optical Network (A-PON), PON-Ring
• CPC Class Codes: H04Q 11/0071 Provisions for the electrical-optical layer interface

Abstract

Embodiments enable an Ethernet over Coaxial (EoC) Coaxial Media Converter (CMC) that implements only a subset of the functions (e.g., MAC and PHY) of a cable modem termination system (CMTS). The CMC sits between an optical line terminal (OLT) and a plurality of cable modems (CMs) that it serves. From the network management side at the OLT, the CMC appears and can be managed like an optical network unit (ONU). From the subscriber side, the CMC provides the same connectivity functions to the CMs as a CMTS and serves to terminate coaxial connections from the CMs.

Claims

1. A coaxial media converter (CMC), comprising:

an optical transceiver;

a first chip, coupled to the optical transceiver, that implements an Ethernet Passive Optical Network (EPON) Medium Access Control (MAC) layer;

a second chip, coupled to the first chip, that implements a Data Over Cable Service Interface Specification (DOCSIS) MAC layer; and

a DOCSIS physical layer (PHY) chip, coupled to the second chip.

2. The CMC of claim 1, wherein the first chip receives EPON MAC frames from the optical transceiver, removes EPON headers from the received EPON MAC frames, and forwards Ethernet frames encapsulated in the received EPON MAC frames to the second chip.

3. The CMC of claim 1, wherein the first chip receives Ethernet frames from the second chip, encapsulates the Ethernet frames into EPON MAC frames, and sends the EPON MAC flames to the optical transceiver.

4. The CMC of claim 1, wherein the second chip receives Ethernet frames from the first chip, encapsulates the Ethernet frames into DOCSIS MAC frames, and forwards the DOCSIS MAC frames to the DOCSIS PHY chip.

5. The CMC of claim 1, wherein the second chip receives DOCSIS MAC frames from the DOCSIS PHY chip, removes DOCSIS headers from the received DOCSIS MAC frames, and forwards Ethernet frames encapsulated in the DOCSIS MAC frames to the first chip.

6. The CMC of claim 1, wherein the first chip and the second chip are coupled via a Gigabit Media Independent Interface (GMII).

7. The CMC of claim 1, wherein the second chip comprises:

a Virtual Local Area Network (VLAN) switch; and

a plurality of queues, comprising a plurality of upstream queues and a plurality of downstream queues.

8. The CMC of claim 7, wherein the VLAN switch receives an Ethernet frame from the first chip and switches the Ethernet frame to an assigned queue of the plurality of downstream queues of the second chip.

9. The CMC of claim 8, wherein the VLAN switch processes a VLAN tag embedded in the Ethernet frame to map a cable modem index and a class of service (CoS) contained in the VLAN tag to a queue number, wherein the queue number identifies the assigned queue.

10. The CMC of claim 9, wherein the VLAN is inserted into the Ethernet frame by an optical line terminal (OLT), and wherein the cable modem index and the CoS identify respectively a destination cable modem CMC and a destination DOCSIS service flow at the cable modem for the Ethernet frame.

11. The CMC of claim 7, wherein the VLAN switch receives an Ethernet frame from a selected queue of the plurality of upstream queues, inserts a VLAN tag into the Ethernet frame based on the selected queue, and forwards the Ethernet frame to the first chip.

12. The CMC of claim 10, wherein the VLAN tag receives a queue number that identifies the selected queue, maps the queue number to a cable modem index and a class of service (CoS), and generates the VLAN tag from the cable modem index and the CoS.

13. A method for traffic switching from a cable modem to an optical line terminal (OLT), comprising:

receiving an Ethernet frame from the cable modem, the Ethernet frame associated with an upstream service flow from the cable modem;

retrieving a cable modem index associated with the cable modem and a class of service associated with the upstream service flow;

generating a tag based on the retrieved cable modem index and the class of service;

inserting the generated tag into the Ethernet frame; and

transmitting the Ethernet frame to the optical line terminal.

14. The method of claim 13, further comprising:

placing the Ethernet frame in a queue, wherein the queue is statically or dynamically assigned to the upstream service flow from the cable modem.

15. The method of claim 14, wherein said retrieving step comprises mapping via a lookup table a queue number of the queue to the cable modem index and the class of service.

16. The method of claim 13, wherein the tag is an IEEE Virtual Local Area Network (VLAN) tag.

17. The method of claim 13, further comprising:

appending a logical link identifier (LLID) field to the Ethernet frame based on the class of service associated with the upstream service flow.

18. A method for traffic switching from an optical line terminal (OLT) to a cable modem, comprising:

receiving an Ethernet frame from the OLT;

processing a tag contained in the Ethernet frame to retrieve a cable modem index and a class of service embedded in the tag;

determining from the retrieved cable modem index and the class of service a destination cable modem and a downstream service flow at the destination cable modem; and

transmitting the Ethernet frame to the destination cable modem.

19. The method of claim 18, wherein said determining step comprises mapping via a lookup table the retrieved cable modem index and the class of service to a queue number, wherein the queue number identifies a queue assigned to traffic destined to the downstream service flow at the destination cable modem.

20. The method of claim 18, wherein the tag is an IEEE Virtual Local Area Network (VLAN) tag.