HK1169762A - Method and system for unified network management on fiber optics coaxial hybrid network - Google Patents

Description

Unified network management system and method for fiber coaxial hybrid network

Cross Reference to Related Applications

This patent application has priority to U.S. provisional patent application No.61/472,010 (attorney docket No. 2875.5530000), filed on 5/4/2011, which is incorporated herein by reference in its entirety.

Technical Field

The present invention relates generally to Hybrid Fiber Coaxial (HFC) networks.

Background

A fiber-coaxial hybrid network is a network that combines fiber optic lines (fiber optic lines) and coaxial cables. HFC networks are commonly used by cable television (CATV) users to provide television and high-speed data access.

A Passive Optical Network (PON) is a single shared fiber that uses inexpensive optical splitters (optical splitters) to split the single fiber into individual fibers to satisfy individual users. An Ethernet Passive Optical Network (EPON) is a PON based on the ethernet standard. EPONs can provide a simple, manageable coupling to ethernet-based IP devices at the client and central office (central office). As with other gigabit ethernet media, EPONs are well suited to carry packet traffic.

HFC networks today typically include PON (e.g., EPON) crossovers (spans). The PON flying lead may extend all the way to the network users in the case of an Optical Network Unit (ONU) with Fiber To The Home (FTTH). For example, in the case of a standard Cable Modem (CM), or a coaxial cable span (coax span) coupled to the subscriber.

Disclosure of Invention

According to one aspect, there is provided a system for unified (unified) management of fiber coupled Optical Network Units (ONUs) and coaxial coupled Cable Modems (CMs) in a fiber coaxial Hybrid (HFC) network, comprising:

a Network Management System (NMS) having a host interface for issuing management instructions to an ONU of the HFC fiber coupling or a CM of the coaxial cable coupling;

an Ethernet Passive Optical Network (EPON) Optical Line Terminal (OLT) module coupled to the NMS for generating an EPON Operations Administration Maintenance (OAM) message based on management instructions issued by the NMS; and

a Coaxial Media Converter (CMC) coupled to the CM to receive the EPON OAM message and convert the EPON OAM message to a cable service interface data Specification (DOCSIS) OAM message when the EPON OAM message is issued to the CM.

Preferably, the host interface uses a generic management command format when issuing management commands to either the ONU coupled to the optical fiber or the CM coupled to the coaxial cable.

Preferably, the generic management instruction format includes a tag field to indicate whether the management instruction is for an ONU for optical fiber coupling or a CM for coaxial cable coupling.

Preferably, the host interface is further configured to issue a management instruction to the CMC, wherein the host interface uses the generic management instruction format when issuing the management instruction to the CMC.

Preferably, the EPON OAM message includes a CM context (context) field when the NMS issues a management instruction for the CM.

Preferably, the CMC terminates an EPON OAM logical link with the EPON OLT module.

Preferably, the CM supports DOCSIS OAM protocol.

Preferably, the NMS and the OLT module are located in separate subsystems.

Preferably, the NMS and the EPON OLT module are integrated within an OLT system.

Preferably, the NMS is a standard EPON OLT NMS.

Preferably, the NMS is a proprietary (proprietary) EPON OLT NMS.

Preferably, the NMS is a non-EPON OLT NMS.

Preferably, the system further comprises an OLT mediation (mediation) module that translates (translate) between the non-EPON OLT NMS and the EPON OLT module.

Preferably, the NMS is a DOCSIS NMS, wherein the OLT mediation module comprises a DOCSIS Mediation Layer (DML) module.

Preferably, the OLT broker module is integrated within the EPON OLT module.

According to one aspect, there is provided a method for unified (unified) management of fiber coupled Optical Network Units (ONUs) and coaxial coupled Cable Modems (CMs) in a fiber coaxial Hybrid (HFC) network, comprising:

receiving instructions from a Network Management System (NMS) for an ONU of the HFC fiber coupled or a CM of a coaxial cable coupling;

generating an Ethernet Passive Optical Network (EPON) Operations Administration Maintenance (OAM) message based on the management instruction, wherein the EPONOAM message includes a CM context field when the management instruction is a CM for the coax coupling;

when the management instruction is a CM for the coax coupling, an EPON OAM message is sent to a Coax Media Converter (CMC) serving the CM.

Preferably, the host interface uses a generic management command format when issuing management commands to either the ONU coupled to the optical fiber or the CM coupled to the coaxial cable.

Preferably, the NMS is a non-EPON OLT NMS, the method further comprising,

translating management instructions from the NMS into EPON Optical Line Terminal (OLT) host interface instructions.

Preferably, the method further comprises the step of,

converting (convert) the EPON OAM messages into Cable service interface data Specification (DOCSIS) OAM messages.

Preferably, the method further comprises the step of,

sending the EPON OAM message directly to the fiber-coupled ONU when the management instruction is for the fiber-coupled ONU.

Drawings

The accompanying drawings, which are incorporated herein and form a part of the specification, illustrate the present invention and, together with the description, further serve to explain the principles of the invention and to enable a person skilled in the pertinent art to make and use the invention.

FIG. 1 is a schematic diagram of a conventional cable network;

FIG. 2 is a schematic diagram of a conventional Hybrid Fiber Coax (HFC) network;

fig. 3 is a schematic diagram of an exemplary EPON (ethernet passive optical network) -DOCSIS (cable service interface data specification) EoC (ethernet over coaxial) HFC according to an embodiment of the present invention;

FIG. 4 is a schematic diagram of an exemplary EPON to DOCSIS EoC conversion, according to an embodiment of the present invention;

FIG. 5 is a schematic diagram of an exemplary implementation of a DOCSIS media-over-coax converter (CMC) according to an embodiment of the present invention;

FIG. 6 is another exemplary implementation of a DOCSIS CMC in accordance with embodiments of the present invention;

FIG. 7 is a schematic diagram of exemplary upstream and downstream Virtual Local Area Network (VLAN) switching, according to an embodiment of the present invention;

fig. 8 is a schematic diagram of an exemplary VLAN tag according to an embodiment of the present invention;

FIG. 9 is a flow diagram of a method for traffic switching according to an embodiment of the present invention;

FIG. 10 is a flow diagram of a method for traffic switching according to an embodiment of the present invention;

FIG. 11 is a schematic diagram of exemplary OLT (optical line terminal) downstream traffic processing according to an embodiment of the present invention;

FIG. 12 is a schematic diagram of exemplary OLT upstream traffic processing according to an embodiment of the present invention;

fig. 13 is a schematic diagram of an exemplary network of hybrid FTTH (fiber to the home) ONUs (optical network units) and coaxially coupled Cable Modems (CMs);

FIG. 14 is a schematic diagram of an exemplary modified host interface instruction in accordance with an embodiment of the present invention;

fig. 15 is a schematic diagram of an exemplary modified OAM (operation administration maintenance) message according to an embodiment of the present invention;

fig. 16 is a schematic diagram of an exemplary view of a unified EPON OLT management interface in accordance with an embodiment of the present invention;

fig. 17 is a schematic diagram of an exemplary network architecture according to an embodiment of the present invention.

The present invention will be described with reference to the accompanying drawings. In general, the drawing in which an element first appears is representatively illustrated by the leftmost digit(s) in the corresponding reference number.

Detailed Description

Fig. 1 is a schematic diagram of a conventional high-speed wired network 100. The conventional network 100 includes a Central Office (CO) or hub 102. The Central Office (CO) or hub 102 serves a Cable Modem (CM) group (population) with multiple CM (and set-top box) subscribers. On the subscriber side, the CO/hub 102 is coupled to a coaxial cable network 112 through a Cable Modem Termination System (CMTS). The coaxial cable network 112 couples the CO/hub 102 to the CM group 116. On the high speed network side, the CO/hub 102 is coupled by a CMTS 104 to a mass data link 118, which data link 118 couples the CO/hub 102 to an Internet Protocol (IP) network (e.g., the Internet) 110. In practice, the CO/hub 102 may include multiple CMTSs 104 (e.g., up to 10) to support the cable modem set 116 served by the CO/hub. In addition, the CO/hub 102 may be coupled to the IP network via a plurality of mass data links 118.

As shown in fig. 1, CMTS 104 includes a radio frequency coaxial cable interface 106 and a high speed (e.g., ethernet) interface 108. The rf coax interface 106 transmits rf signals to and from the CM group 116. The rf coaxial cable interface 106 may be coupled to multiple coaxial cables to aggregate traffic from multiple CM users using a combiner 114. The combiner 114 is located further downstream of the coaxial cable network 100. Typically, traffic between the CMTS 104 and CM group 116 is transported in ethernet frames encapsulated within DOCSIS (cable service interface data specification) frames, e.g., ethernet interface 108 transports IP traffic to or from IP110 network.

Typically, the CMTS 104 serves CM groups. The number of CM groups ranges from a few thousand to a hundred thousand (e.g. 5000-. In addition, the CMTS includes layer 3(L3) switches (i.e., network routing units) that perform IP packet routing. In the case of a CMTS coupled to a network, for example, the CMTS includes an L3 switch that implements OSPF (open shortest Path first) routing protocol. Also, the CMTS 104 is a large, complex, and expensive network component.

Fig. 2 is a schematic diagram of a conventional Hybrid Fiber Coaxial (HFC) network 200. Legacy network 200 includes a Central Office (CO) or hub 202, which Central Office (CO) or hub 202 services CM group 210. On the subscriber side, the CO/hub 202 is coupled to a Passive Optical Network (PON)206 through an Optical Line Terminal (OLT), the PON206 coupling the CO/hub to a CM bank 210. On the high-speed network side, the CO/hub 202 is coupled to a mass data link 118, as with the conventional network 100 described above. The data link 118 couples the CO/hub 102 to an IP network (e.g., the Internet) 110.

The CO/hub 202 may include more than one OLT204 to support the CM group 210 serviced by the CO/hub 202. Each OLT204 is coupled to a respective fiber optic line and serves a CM segment (segment)212 of a respective CM group 210. The OLT204 may implement a standard IEEE (institute of electrical and electronics engineers) ethernet network based on a PON (epon) standard protocol (IEEE 802.3), or other data based on a PON protocol (e.g., Gigabit Passive Optical Network (GPON) or broadband PON (bpon)). In addition, the generic OLT204 supports both layer 3 switching and layer 2 switching.

The coupling between the CM group 210 and the OLT202 is accomplished through a hybrid fiber-coax network. As shown in fig. 2, the PON206 extends to the perimeter of the individual CM segments 212 of the CM group 210, and then a separate coaxial cable coupling 208 is made to each CM subscriber of each CM segment 212. For example, fiber optic lines may be towed to a multi-tenant building (multi-tenant building) and then separate coaxial cable couplings will be made with each apartment of the multi-tenant building.

When CM210 is a standard cable modem (i.e., incapable of operating the PON's data link layer), the coaxial cable coupling 208 from the CM will terminate in the same manner as in a conventional coaxial cable network (e.g., cable network 100). Similarly, as shown in FIG. 2, for each CM segment 212 of a CM group 210, one CMTS 104 is placed to terminate the coaxial cable coupling 208 from the CM segment. The CMTS 104 may implement DOCSIS or any other EoC (standard or non-standard) protocol. In addition, the CMTS 104 performs layer 3 switching as described above.

The conventional structure of the network 200 exists today in various cable network markets. When CM segments 212 are in a queue of thousands of CM subscribers, as shown in fig. 2, CMTS 104 is set up to terminate coaxial cable coupling, which may be economically justifiable for cable network operators. However, in certain markets (e.g., china), the number of CM users coupled to a particular CMTS 104 is very small (on the order of hundreds), which makes this solution costly and ineffective for network operators. An alternative solution is to remove the CMTS 104 from the architecture by upgrading the CM210 in its entirety to the PON CM so that only physical layer conversion is required from the coaxial coupling 208 to the PON 206. However, this alternative is also expensive and may not be feasible.

Embodiments of the present invention, as described further below, allow removal of a CMTS from the above-described HFC architecture without requiring an upgrade to the network subscriber's CM (or set-top box). According to an embodiment, the CMTS is configured with a small-sized EoC (e.g., DOCSIS MoCA (multimedia over coax alliance), etc.) media over coax converter (CMC). The CMC performs only a subset of the functions previously performed by the CMTS and additional switching functions as described below. In one embodiment, the CMC performs only EoC Media Access Control (MAC) and physical layer (PHY, and may vary in size depending on the number of CMs to be serviced by the CMC from the OLT network management aspect, the CMC appears and can manage like an Optical Network Unit (ONU). from the customer aspect, the CMC provides the same coupling functionality on the coax as the CMTS and serves to terminate coax coupling from the CM.

Embodiments of the present invention will be described below. As may be recognized by those of ordinary skill in the pertinent art based on the teachings herein, the embodiments are not limited to the examples described herein. For example, embodiments will be described with reference to EPON-DOCSIS HFC. However, embodiments are not limited to such PON or EoC technologies, and any other combination of PON/EoC may be used. Furthermore, exemplary implementations of hardware circuitry and/or software for enabling embodiments are provided for illustration only and not for limitation.

Fig. 3 is a schematic diagram of an exemplary EPON-DOCSIS HFC network 300 according to an embodiment of the present invention. As shown in fig. 3, exemplary network 300 includes OLT302 and CMC 304. The CMC304 serves the CM section 212. The CM section 212 includes a plurality of CMs and set-top boxes.

OLT302 and CMC304 are coupled through PON 206. In an embodiment, OLT302 and CMC304 communicate over PON206 with an EPON. CMC304 replaces CMT in the conventional architecture depicted in fig. 2. Thus, as shown in FIG. 2, CMC304 is coupled to individual CMs in CM section 212 via coaxial cable coupling 208. In one embodiment, EoC technology, such as DOCSIS, is used on the coaxial cable coupling 208.

Accordingly, CMC304 bridges the PON technology utilized on PON206 and the EoC technology utilized on coaxial cable coupling 208. In particular, CMC304 suspends the PON protocol and translates traffic into the EoC protocol. Wherein the PON protocol is used by OLT302 and the EoC protocol is used by CM 212. In an embodiment, CMC304 bridges EPON and DOCSIS to enable end-to-end communication over the HFC network between EPON OLT302 and DOCSIS 212.

CMC304 is shaped like an ONU of an HFC network located across PON 206. Thus, CMC304 may be configured by OLT302 in the same manner as an ONU. On the coax span of the HFC network, CM304 provides traffic scheduling to CM2121 through allocated time slots (timelocks) and aggregates traffic from CM212 onto the PON LLID (logical link identification). Additionally, CMC304 needs to provide DOCSIS management (e.g., configuration files, SNMP, etc.) to CM2121 to simulate its operation in a end-to-end DOCSIS network.

Fig. 4 is a schematic diagram of an exemplary EPON to DOCSIS EoC conversion, according to an embodiment of the present invention. In particular, example 400 illustrates some of the network layers, functions, or modules executing in CMC304 in accordance with an embodiment. It will be appreciated by those skilled in the art and informed by the teachings herein that other network layers and/or functions may be implemented based on the particular PON and EoC technology used for HFC networks. In addition, the MC304 may perform more or fewer layers, functions and/or modules, if desired.

In example 400, CMC304 includes EPON interface 402 and DOCSIS interface 404. In an embodiment, EPON interface 402 performs an EPON physical layer (including power control function 406, line coding function 408, EPON framing (framing) function 410), an EPON MAC sublayer 412, a subset of EPON data link layer functions (including link layer encryption function 414 (e.g., china perturbation) EPON MPCP 416, and EPON DBA 418), and OAM (operation administration maintenance) functions 420.

The DOCSIS interface 404 also performs the DOCSIS physical layer (performs, for example, QAM (quadrature amplitude modulation) function 422 for downstream communications, SCDMA (synchronous code division multiple access) function 424 for upstream communications, channel bonding function 426 for supporting channel bonding (bonding) described by DOCSIS3.0, FEC (forward error correction) function 428, and DOCSIS framing function 430)), DOCSIS mac sublayer 432, a subset of DOCSIS data link layer functions (including DES (data encryption standard)) encryption function 434, DOCSIS QoS (quality of service) 436, and DOCSIS SCH (scheduling) function 438), and DOCSIS OAM function 440.

According to embodiments, CMC304 may perform more or fewer layers, functions, and/or modules as it continues to provide bridging from EPONs to DOCSIS, and vice versa. Notably, according to an embodiment, while CMC304 may perform certain data link layer functions as described above, CMC304 does not perform layer 2 switching (sometimes referred to in the art as "bridging"). In general, CMC304 requires a layer 2 MAC address bridge that uses a MAC Destination Address (DA) to look up the switching decisions.

FIG. 5 is a schematic illustration of a DOCSIS of a media over coax converter (CMC)304 in accordance with an exemplary implementation 500 of an embodiment of the present invention. DOCSIS CMC304 is located between OLT302 and DOCISCM 442. As shown in fig. 5, exemplary DOCSIS CMC implementation 500 includes, among other components: an optical burst transceiver (optical burst transceiver)502, an EPON MAC chip 504, a DOCSIS EoC MAC chip 506, and one or more DOCSIS EoC physical layer chips 508. It will be appreciated by those skilled in the art and informed by the teachings herein that in other implementations, one or more of the EPON MAC, DOCSIS EoC MAC and DOCSIS EoC physical layer chips may be integrated into a single chip.

The optical pulse transceiver 502 is coupled to an optical fiber line. This fiber line couples DOCSIS CMC304 and OLT 302. Accordingly, in downstream communications, the optical pulse transceiver 502 receives an EPON physical layer encoded signal from the OLT 302. From the EPON physical layer encoded signal, transceiver 502 generates and transmits an EPON MAC frame to EPON MAC chip 504. In upstream communications, transceiver 502 receives EPON MAC frames, which are transmitted over a fiber-optic line using EPON physical layer signals, from an EPON MAC chip 504.

The EPON MAC chip 504 executes the EPON MAC layer. In one embodiment, EPON MAC chip 504 supports downstream transmission rates of 1 or 2Gbps (gigabytes per second) and upstream transmission rates of 1 Gbps. The EPON MAC chip 504 terminates an EPON MAC link with the EPON MAC layer of the OLT 302. Thus, in downstream communications, EPON MAC chip 504 receives EPON MAC frames from transceiver 502 and removes the EPON header from the received EPON MAC frames before transmitting the Ethernet encapsulated frames to DOCSIS EoC chip 506. In upstream communications, DOCSIS EoC chip 504 receives ethernet frames from DOCSIS EoC chip 506, where DOCSIS EoC chip 504 encapsulates the received ethernet frames inside by appending appropriate EPON headers (e.g., LLIDs assigned to CMC304) to the ethernet frames and sends the frames to optical pulse transceivers 502 for transmission to OLT302 over fiber optic lines.

The DOCSIS EoC chip 506 and EPON MAC chip 504 perform the same function, with reference only to the coax side of CMC 304. In particular, the DOCSIS EoC chip 506 implements the DOCSIS MAC layer. DOCSIS EoC chip 506 terminates the DOCSIS MAC link with DOCSIS CM 442. In downstream communications, DOCSIS EoC chip 506 receives Ethernet frames from EPON MAC chip 504, adds appropriate DOCSIS headers to the Ethernet frames to generate DOCSIS MAC frames, and sends the DOCSIS MAC frames to DOCSIS EoC PHY chip 508 for transmission of the frames over coax to DOCSIS CM 442. In upstream communications, the DOCSIS EoC chip 506 receives a DOCSIS MAC frame from the DOCSIS EoC PHY chip 508, removes a DOCISIS header from the received epon MAC frame, and transmits the encapsulated ethernet frame to the EPONN MAC chip 504.

The DOCSIS EoC chip 508 enables data transmission/reception of coaxial cable. In downstream communications, the DOCSIS EoC PHY chip 508 receives DOCSIS MAC frames from the DOCSIS EoC MAC chip 506, which are transmitted over the coax using DOCSIS PHY signal transmission. In upstream communications, the DOCSIS EoC PHY chip 508 receives DOCSIS PHY encoded signals from the CM 442, generates DOCSIS MAC frames from the DOCSIS EoC PHY chip 508 and forwards the DOCSIS MAC frames to the EPONOC MAC chip 506.

As shown in fig. 5, the EPONN MAC chip 504 and the DOCSIS EoC MAC chip 506 may have associated flash or Random Access Memory (RAM), such as a flash unit 518, a DDR (double speed) memory unit 520, and a flash unit 522. Also, on the coax side of CMC304, conventional analog circuits (e.g., upstream amplifier chain 510, downstream amplifier chain 512, digital-to-analog converter 514, and phase-locked loop 516) may be used with PHY chip 508 to enable transmission and reception on the coax. It will be appreciated by those skilled in the art in light of the teachings herein that CMC304 may be implemented in ways other than exemplary implementation 500.

Figure 6 is a schematic diagram of a further exemplary implementation 600 of a DOCSIS CMC in accordance with an embodiment of the present invention. For simplicity, some elements of CMC304 (already described in fig. 5) are not shown in exemplary implementation 600.

As shown in FIG. 6, in an exemplary implementation 600, an EPON MAC chip 504 is coupled to a DOCSIS EoC MAC chip 506 via a GMII (media independent interface to gigabit) interface 604. A Central Processing Unit (CPU)602 controls the DOCSIS EoC MAC chip 506 through an interface 606. In addition, the CPU602 controls the epon MAC chip 504 through in-band OAM messages exchanged by the DOCSIS EoC MAC chip 506.

The DOCSIS EoC MAC chip 506 executes as an FPGA (field programmable Gate array). In one embodiment, the DOCSIS EoC MAC chip 506 includes a VLAN (virtual local area network) switch 608, a multi-queue 610, and a scheduler 612.

VLAN switch 608 performs VLAN switching of ethernet frames between EPON MAC chip 504 and queue 610. According to an embodiment, VLAN switching on VLAN switch 608 is enabled by inserting a VLAN tag (e.g., IEEE VLAN, S-VLAN (server virtual local area network)) in ethernet frames communicated between OLT302 and CMC 304. When inserted by OLT302, the VLAN tag identifies for the ethernet frame the destination Cable Modem (CM) (using the CM index) and the class of service (CoS) of the ethernet frame. Likewise, when inserted by CMC304, the VLAN tag identifies for the ethernet frame the originating Cable Modem (CM) (using the CM index) and class of service (CoS) of the ethernet frame. According to embodiments, the VLAN identification may be inserted into the ethernet frame (e.g., before the ethertype/Size field) or at the start of the ethernet frame.

According to an embodiment, VLAN switching at CMC304 by VLAN switch 608 includes VLAN tag to queue number mapping/translation, and vice versa. Fig. 7 is a schematic diagram of an exemplary upstream and downstream VLAN exchange according to an embodiment of the present invention.

As shown in fig. 7, in upstream communication (i.e., from CMC304 to OLT 302), VLAN switch 608 receives a queue number 702, which represents the sequence number of the upstream queue (from queue 610) from which ethernet frames are transmitted. The VLAN switch 608 invokes a queue allocator LUT 704 to retrieve the CM index (i.e., CM) and CoS currently allocated to the queue whose queue number is 702. The VLAN switch 608 then generates a VLAN tag (or a portion of the VLAN tag) from the CM index and the CoS (in fig. 7, the CM index is referred to as "CNU #" and the CoS is referred to as "service"), inserts the generated VLAN tag into an ethernet frame, and transmits the ethernet frame to the EPON MAC chip 504. EPON MAC chip 504 uses the CoS from the ethernet frame to map the frame onto an LLID (different LLIDs apply to different CoS), which is added to the ethernet as part of the EPON header before being transmitted onto the fiber optic line.

In downstream communications (i.e., from the CMC304 to the CM), the VLAN switch receives an ethernet frame with a VLAN tag 708 embedded by the OLT 302. (note that EPON MAC chip 504 removes the EPON header before transmitting the frame to the DOSIS EoCMAC chip 506). VLAN switch 608 strips VLAN tag 708 (or a portion thereof) from the ethernet frame and invokes the queue distributor look-up table to retrieve (by reverse search) the queue number 710 based on the CM index and the CoS included in the VLAN tag. Queue number 710 is the number of downstream queues (starting from queue 610) that are currently assigned to CoS included in the CM index and VLAN identification.

In one embodiment, CMC304 supports up to 512 CMs. Thus, the DOSIS EoC MAC chip 506 includes 1024 queues in each direction (upstream and downstream). CMC304 may be configured to allocate 2 upstream and 2 downstream queues for each CM, such that each CM has 2 CoS (i.e., service flows). In another embodiment, CMC304 dynamically allocates its queues 610 to support the dynamic service flows currently coming from the CM. Thus, the CM can be allocated as many queues as possible to support availability-based service flows.

Fig. 8 is a schematic diagram of an exemplary VLAN tag 800 for enabling VLAN switching at CMC304 in accordance with an embodiment of the present invention. The exemplary VLAN tag 800 is an IEEE S-VLAN (serving VLAN) tag having a 16-bit TPID (tag protocol identification) field 802 set to 0x88A8, a 3-bit service field 804 identifying the CoS of the frame, a fixed CFI (standard format indicator) bit 806 set to 0, a 12-bit VLAN ID (identifier) (VID) field 808 identifying the CM index of the source/destination CM, where the VID field 808 has a fixed 3-bit portion and a variable portion (at least 9 significant bits).

As described above, the VLAN switching scheme at CMC304 maps CM indices and CoS pairs with queues, and vice versa. Accordingly, each CM coupled to CMC304 must be assigned a unique CM index (e.g., between integers 0 and 511) when the CM is coupled to or registered with CMC 304. The CMC304 always identifies a CM as long as the CM is coupled to the CMC. If a CM and CMC are disconnected or reset, their CM index is released and may be assigned to another CM. When a CM is coupled to CM304 and re-registered with CMC304, the CM is assigned another CM index, which may or may not be the same as the previous CM index.

On the OLT side, OLT302 must know the CM index assigned to the CM joining the network. To do so, OLT302 checks the source address of the inbound ethernet frame. After OLT302 determines that its MAC source address is unknown (e.g., not present in its MAC Data Address (DA) look-up table), the ethernet frame is examined to obtain the VLAN tag inserted by CMC 304. As described above, CMC304 tags the ethernet frame with a VLAN tag that includes a CM index of the source CM (organizing CM). OLT302 then creates an entry in its MAC DA look-up table to associate the CM index included in the previously unknown MAC address and VLAN tag. OLT302 may then generate a VLAN tag with a CM index to insert into an ethernet frame that is destined for a MAC address.

Since CM indices may be reassigned when a CM is disconnected, OLT302 must spy on the arrival and departure of CMs from CMC 304. Upon receiving the CM leave message, OLT302 clears all known MAC addresses associated with the detached CM.

Referring back to FIG. 6, the DOCSIS EoC MAC chip 506 also includes a scheduler 612. Scheduler 612 provides traffic scheduling by allocating time slots to CMs connected to CMC 304. Additionally, scheduler 612 may put traffic into aggregation queue 610 based on the CoS of the inbound traffic. The scheduler 612 enables CoS-based aggregation of LLIDs of the fiber lines to the OLT 302. Information on how to configure the scheduler 612 can be received through messages from the ONU SLAs (service level agreement). Note that CMC304 terminates the OAM link (typically between the OLT and the ONUs). CMC304 is therefore able to check OAM SLA information and program its hardware accordingly. In addition, CMC304 may in turn send instructions (via standard DOSIS instructions) to specific CMs to instruct the CMs to queue and shape as needed to meet the SLA end-to-end.

Fig. 9 is a flow diagram 900 of a method for traffic switching according to an embodiment of the present invention. Process 900 is performed at a CMC (e.g., in CM 304) to switch upstream traffic from the CM to the OLT. As shown in fig. 9, process 900 begins at step 902, which includes receiving an ethernet frame from a cable modem. The Ethernet frame is associated with an upstream service flow from the cable modem. In one embodiment, step 902 further comprises placing the ethernet frames in a queue, wherein the queue is statically or dynamically assigned to an upstream service flow from the cable modem. Step 904 includes retrieving a cable modem index associated with the cable modem and a service class associated with the upstream service flow. In one embodiment, step 904 mirrors (via a look-up table) the queue number of the queue that placed the ethernet frame in step 902 to the cable modem index and class of service.

Step 906 includes generating a label based on the retrieved index and service class of the cable modem. In one embodiment, the tag is an IEEE VLAN tag. The tag has a service class field and a cable modem index field.

Step 908 includes inserting the generated tag into an ethernet frame. In one embodiment, the tag is added (append) to an ethernet frame. In another embodiment, the tag is inserted within an ethernet frame.

Step 910 includes suspending a Logical Link Identification (LLID) to the ethernet frame based on a service class associated with the upstream service flow.

Finally, step 912 includes transmitting the ethernet frame to the optical line terminal according to the LLID.

Fig. 10 is a flow diagram 1000 of another method for traffic switching according to an embodiment of the present invention. Process 1000 is performed at a CMC (e.g., in CM 304) to switch downstream traffic from the CM to the OLT. As shown in fig. 10, process 1000 begins at step 1002 by receiving an ethernet frame from an optical line terminal.

Step 1004 includes processing a tag included in the ethernet frame to retrieve a cable modem index and a service class embedded in the tag. In one embodiment, the tag is an IEEE VLAN tag having a class of service field and a cable modem index field.

Step 1006 includes determining a target cable modem and a downstream service flow for the target cable modem from the retrieved cable modem index and service class. In one embodiment, step 1006 mirrors (via a look-up table) the cable modem index and the class of service into a queue number, where the queue number identifies the queue assigned to the traffic. The traffic is destined for a service flow downstream of the target cable modem. In the cable modem, queues are statically or dynamically assigned to downstream service flows.

Finally, step 1008 includes sending the ethernet frames to the destination cable modem, and in one embodiment step 1008 further includes queuing the ethernet frames. The queue is assigned to a downstream service flow in the target cable modem.

As described above, the CMC304 (and DOCSIS EoC MAC chip 506) does not perform layer 2 switching, typically requiring layer 2 MAC address bridging using MAC target address (DA) lookups for switching decisions. Instead, as described above, simple VLAN-based switching is used at CMC304, and layer 2 switching (typically done by the CMTS) is performed at OLT 302. As described above, OLT302 has existing layer 3 and layer 2 switching capabilities. Thus, only minimal modifications are required at OLT302 to enable VLAN-based switching at CMC 304.

Exemplary traffic processing performed at OLT302 according to an embodiment is described below. The traffic processing may be performed by the host interface at OLT 302. In an embodiment, the various CMs may be emulated as destinations in the OLT host interface and may be identified by their MAC addresses in the OLT host interface. In an embodiment, up to 64 CMCs and 4000 destinations are supported by a single OLT.

The ONUs coupled to OLT302 have their respective domains in the OLT host interface. The CMC coupled to OLT302 is considered an ONU and therefore also has the OLT domain in the OLT host interface. However, traffic destined for the CMC is determined by the network carrier using a network S-VLAN tag (unlike the VLAN tag described above, the VLAN tag is inserted between CMC304 and OLT 302). The network S-VLAN tag is mapped to the OLT domain (which is the CMC domain serving the CM destination).

Fig. 11 is a schematic diagram of an exemplary OLT downstream (i.e., from OLT302 to CMC304) traffic processing procedure in accordance with an embodiment of the present invention. As shown in fig. 11, the process begins at step 1102, where step 1102 includes the domain selection module selecting an OLT domain (i.e., CMC) for traffic based on a VID (virtual local area network ID) field of a network S-VLAN tag. In step 1104, a CMC VLAN tag is added to the ethernet frame and the service field is set according to the required CoS. Then, a layer 2 switching based on said selected OLT domain is performed in step 1106. In particular, the layer 2 mac da lookup in the selected OLT domain is performed over ethernet frames. The layer 2 DA looks up a particular destination (i.e., CM) that maps to the selected frame. Finally, in step 1108, the VID field of the CMC VLAN tag is set to the CM index associated with the particular destination in step 1006 and the appropriate LLID is set for that destination.

Fig. 12 is an exemplary OLT upstream (i.e., from OLT302 to the IP network) traffic processing procedure in accordance with an embodiment of the present invention. As shown in fig. 12, the process begins at step 1202, where the destination selection module determines the destination of the traffic (i.e., the CM destination) based on the LLID from the CMC and the VID field of the CMC insertion VLAN tag. In step 1204, a destination rule is applied, comprising: a queue (from a set of queues associated with the tag) is selected based on the service field (CoS) of the CMC insert VLAN tag. An ACL (access control list) lookup is then performed in step 1206 and the ethernet frame with the MAC address looked up by the ACL is placed in the OLT domain serving the destination. In step 1208, the VLAN tag is deleted from the ethernet frame according to the domain rules for the OLT domain.

The embodiments described above thus enable traffic bridging between PON (e.g., EPON) and EoC (e.g., DOCSIS) technologies. Accordingly, the OLT may simultaneously serve the fiber-coupled ONUs and CMs over the same PON. However, the fiber-coupled ONUs and CMs are designed to operate with different Network Management Systems (NMSs) for configuration and setup. For example, a standard DOCSIS CM is designed to operate with the SNMP (simple network management protocol) adopted by DOCSIS. On the other hand, the EPON standard has defined a NMS based on a layer 2 OAM protocol that can be specified by operators of EPONs (e.g., china telecom, NTT, time warner, etc.).

Thus, in order to operate an EPON-DOCSIS EoC network with hybrid fiber coupled ONUs (e.g., FTTH) and coax coupled CMs, two types of management capabilities must be provided. However, having to modify the OLT to support DOCSIS management separately would be costly and ineffective, for example, in addition to existing EPON management. Rather, it is desirable that the embodiments further described below enable a unified network management system at the OLT to manage the ONUs and CMs (requiring minor modifications to existing EPON management currently applied to the OLT). As described further below, embodiments enable such a unified NMS with minor modifications/additions to existing OLT software and EPON management protocols, and a simple conversion from EPON management to DOCSIS management at the CMC. Thus, a standard DOCSIS CM can be managed using a standard EPON OLT NMS.

Embodiments will be described below with reference to an exemplary HFC having a hybrid FTTH ONU and a CM coupled coaxial cable. Those skilled in the art will appreciate that embodiments are not limited to the exemplary networks described herein. Further, embodiments may be described using an example implementation that may enable unified network management at the OLT. These exemplary embodiments are provided for purposes of illustration and are not intended to be limiting. Furthermore, those skilled in the art will appreciate that embodiments are applicable to any PON or EoC technology and are not limited to EPON and DOCSIS described in the examples below.

Fig. 13 is a schematic diagram of an exemplary network 1300 with a hybrid FTTH ONU and a CM coupled coaxial cable in accordance with an embodiment of the present invention. The exemplary network 1300 includes an OLT1302, CMC304, ONU1304, and a plurality of CMs 212 located in the CO/hub 202.

As shown in fig. 13, CMC304 is located, for example, in a basement of multi-tenant building 1306. In this manner, the EPON side of the network is as far as possible to the customer, while the coaxial side of the network provides only a short coaxial coupling between the CMC112 and the CMCs 304 and CMs 212 of the individual apartments located in the multi-tenant building 1306. In one embodiment, CM212 is a standard DOCSIS CM.

ONU1304 is coupled to OLT1302 via an all-fiber link comprising fiber lines 206 and 1308. ONU1304 may enable FTTH service to be provided to home 1310 by having fiber optic line 1308 reach the boundary of the living room of home 1310 (e.g., a box on the outside wall of home 1310).

According to an embodiment, a network operator of the exemplary network 1300 may manage/service the FTTH ONUs 1304 and CMs 212 at the OLT1302 using a unified network management system. This includes end-to-end configuration, management, and QoS with a single interface available to both fiber and coaxial cable users.

In an embodiment, OLT1302 supports an EPON OLT Network Management System (NMS). An EPONOLT NMS employs a layer 2 OAM protocol (hereinafter referred to as "EPONOAM") defined by EPON operators. The EPON OAM protocol defines EPON OAM messages that may be used to manage and provision ONUs. Furthermore, the EPON OLT NMS has a host interface that allows a network operator to manage the ONUs with the NMS. The host interface provides various host interface commands to a network operator that can be used to send specific EPON OAM messages to the ONUs.

According to an embodiment, an EPON OLT NMS may be modified to enable the EPON OLT to manage CMs and ONUs using the same host interface and the same EPON OAM protocol information. In particular, embodiments include modifying a host interface of an EPON OLT NMS and an EPON OAM protocol used by the NMS to enable unified management of ONUs and CMs. Exemplary embodiments of these modifications are described below. Based on the teachings herein one skilled in the art should appreciate that these modifications can be implemented in various other ways that are also within the scope of the embodiments of the invention.

FIG. 14 illustrates an exemplary modified host interface command 1400 according to an embodiment of the invention. Specifically, as shown in FIG. 14, the host interface commands are modified to add support for the CM context (context). In one embodiment, the modification may be accomplished by adding a "tag" field that can be used to indicate whether the host interface command is for an ONU or CM. The tag field is set to the CM ID if the host interface is for an ONU. The tag field is set to the CM ID if the host interface command is for a CM. Since the CMC includes ONUs, the CMC may be addressed with its ONU ID. In this manner, the same host interface commands may be used for the ONU, CMC, and CM with minor modifications.

If the host interface command is intended for the CM (as determined by the CM tag), the EPON OAM message (generated as a result of the host interface command) generated thereby is intended for the CM. Thus, in an embodiment, when an EPON OAM message is intended for a CM, the EPON OAM protocol message is modified to include CM context support.

Fig. 15 illustrates an exemplary modified EPON OAM message 1500 in accordance with an embodiment of the present invention. As shown in fig. 15, EPON OAM messages are modified to increase support for CM context by adding a "CM context" field to the EPON OAM messages. The CM context field indicates the CM to which the EPON OAM message is intended. In this manner, with minor modifications, the EPON OAM protocol used by OLT1302 to manage ONUs (e.g., ONU1304) may be extended to also manage CMs (e.g., CM 212). Based on the teachings herein, those skilled in the art will appreciate that the respective modifications may also be implemented in the OLT logic to enable adding CM context to EPON OAM protocol messages as desired.

The expected CM reception of EPON OAM messages may or may not support EPON OAM. In the case where the CM supports EPON OAM, CMC304 simply forwards unmodified EPON OAM messages to the CM. In this case, the EPON OAM link (from OLT1302) terminates at the CM itself. On the other hand, when a CM does not support EPON OAM (as is the case with a standard DOCSIS CM, for example), CMC304 terminates the OAM link with OLT1302 and translates the EPON OAM messages into OAM messages supported by the CM (e.g., DOCSIS OAM messages or SNMP commands). This is illustrated in fig. 4, for example, fig. 4 shows that the CMC may convert between an exemplary 802.3ah (epon) OAM protocol, which is a layer 2 OAM protocol, and a DOCSIS OAM protocol, and vice versa.

Thus, according to an embodiment, when a modified EPON OAM message (including the CM context field) is received by CMC304, CMC304 processes the CM context field to determine the CM to which the EPON OAM message is destined. CMC304 may then determine whether an EPON OAM message needs to be converted to a DOCSIS OAM message before sending the OAM message to the intended CM acceptor.

Thus, as described above, seamless and complete management of ONUs and CMs may be enabled using the same EPON OLT NMS. This includes end-to-end configuration, management, and QoS with a single interface available to the ONU and CM users.

Fig. 16 illustrates an exemplary diagram 1600 of a unified EPON OLT management interface in accordance with an embodiment of the present invention. As shown in fig. 16, the management interface displays a hierarchical view of the managed network. The parent node (parent point) of the hierarchy is the OLT1602 where the NMS resides. The sub-nodes of the hierarchy include ONUs (e.g., ONU 1604) and CMCs (e.g., CMC 1606). And the grandchild node in the hierarchy includes a CM (e.g., CM 1608) serviced by the CMC. Nodes in any network (whether OLT1602, ONU1604, CMC 1606 or 1608) can be managed by clicking on the respective lists of nodes in the hierarchical structure graph. The node list includes, for example, the node type (i.e., OLT, ONU, CMC, CM), the serial number of the node device, and the address associated with the node. The management interface provides the same end-to-end configuration, management and QoS service functions for the ONU and the CM. For example, as shown in fig. 16, the management interface enables the same LLID assignment function, SLA provisioning, queue and port filtering configuration, VLAN rules, data for ONU1604 and CM 1608.

Embodiments are not limited to the use of an EPON OLT MNS as described above. Indeed, according to an embodiment, said NMS at the OLT may be any NMS the network operator wishes to use. To make this feasible, embodiments provide an OLT mediation layer that converts the NMS used to an EPON OLT NMS supported by CMC 304. CMC304, as described above, may then be translated back to the NMS protocol supported by the CM. For example, according to an embodiment, a network operator may use docissms (snmp) to manage an EPON-DOCSIS EoC network as described above. This is illustrated in fig. 17, fig. 17 showing an exemplary network architecture 1700 according to an embodiment of the present invention.

As shown in fig. 17, in exemplary architecture 1700, OTL 1702 manages multiple ONUs 1710. Additionally, OTL 1702 may manage multiple CMCs (not shown in fig. 17) that serve multiple CMs (not shown in the figure) coupled to DOCSIS EoC. The OLT1702 therefore manages an EPON-DOSIS EoC network having ONUs (e.g., FTTH) coupled to a hybrid fiber and a CM coupled to a coaxial cable.

OLT 702 is itself managed by dossis NMS 1708. The DOSIS NMS 1708 uses the same SNMP manager, system record server, TFTP (common File transfer protocol) server, etc. as the standard DOCSIS manager. Therefore, NMS 1708 manages OLT1702 in the same manner as it manages the CMTS. In practice, NMS 1708 does not need to know that it is managing the OLT or that the OLT is managing the network with a hybrid FTTH ONU and coaxial cable CM.

To make this feasible, in one embodiment, OLT1702 is modified as shown in FIG. 17. In particular, the OLT1702 includes a standard EPON OLT1704 and a DML (DOCSIS interposer) module 1706. Those skilled in the art will appreciate that the DML1706 may be integrated within the standard logic of the OLT1704 or provided as a separate interface between the NMS 1708 and the OLT 1704. The DML1706 may be implemented in hardware or software as understood by those skilled in the art.

Thus, the DML1706 interface is located between DOCSIS NMS 1708 and EPON OLT1704, and in particular, DML1706 translates from EPON OAM to EPON OAM and vice versa. It is noted that CMC304 performs a secondary conversion from EPON OAM to DOCSIS OAM when the OAM message is destined for a CM. For example, in an embodiment, DML1706 will perform the same OAM conversion functions performed by CMC 304.

Accordingly, embodiments enable a network operator to use any (and single) NMS that wishes to manage a CM coupled to a hybrid FTTH OUN and coaxial cable. For example, a cable company operator may wish to use a DOSIS NMS (which the cable company operator has used to manage its DOSIS network) to manage such a hybrid network. As with the embodiments described above, the cable company operator is allowed to do so by simply adding a DML module between the NMS and the OLT. On the other hand, a telephone company operator (satisfied with using an EPON OLT NMS with minimal OLT/OAM protocol modifications) can manage the same hybrid network using an unmodified EPON OLTNMS.

The description of the invention describes the execution of certain important functions by means of functional blocks. For ease of description, these functional block boundaries are specifically defined herein. Their boundaries may also be redefined, provided that these functions are made operational.

The foregoing description of the specific embodiments will so fully reveal the general nature of the invention that others can, by applying knowledge within the skill of the art, readily modify and/or adapt for various applications such specific embodiments, without undue experimentation, without departing from the general concept of the present invention. Therefore, such adaptations and modifications are intended to be within the meaning and range of equivalents of the disclosed embodiments, based on the teaching and guidance presented herein. It is to be understood that the phraseology or terminology herein is for the purpose of description and not of limitation, such that the terminology or phraseology of the present specification is to be interpreted by the skilled artisan in light of the teachings and guidance.

The breadth and scope of an embodiment of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.

Claims (10)

1. A system for unified management of fiber-coupled optical network units and coaxial-coupled cable modems in a hybrid fiber-coaxial network, comprising:

a network management system having a host interface for issuing management instructions to a fiber-coupled optical network unit of the hybrid fiber-coaxial network or to the coaxial cable-coupled cable modem;

the Ethernet passive optical network optical line terminal module is coupled with the network management system and used for generating an Ethernet passive optical network operation management maintenance message based on a management instruction issued by the network management system; and

the coaxial cable media converter is coupled with the cable modem and used for receiving the Ethernet passive optical network operation management maintenance message when the Ethernet passive optical network operation management maintenance message is issued to the cable modem and converting the Ethernet passive optical network operation management maintenance message into an operation management maintenance message with a cable service interface data specification.

2. The system of claim 1, wherein the host interface uses a generic management command format when issuing management commands to either the optical network unit coupled to the optical fiber or the cable modem coupled to the coaxial cable.

3. The system of claim 2, wherein the generic management instruction format comprises a tag field to indicate whether the management instruction is for the optical network unit coupled to the optical fiber or the cable modem coupled to the coaxial cable.

4. The system of claim 2, wherein the host interface is further configured to issue management commands to the coax media converter, wherein the host interface uses the generic management command format when issuing management commands to the coax media converter.

5. The system of claim 1, wherein the Ethernet passive optical network operation management maintenance message includes a cable modem context field when the network management system issues a management instruction for the cable modem.

6. The system of claim 1, wherein the coax media converter terminates an ethernet passive optical network operation administration maintenance message logical link with the ethernet passive optical network optical line termination module.

7. The system of claim 1, wherein the cable modem supports a cable service interface data specification operation administration maintenance protocol.

8. The system of claim 1, wherein the network management system and the optical line termination module are located in separate subsystems.

9. The system of claim 1, wherein the network management system and the ethernet passive optical network optical line termination module are integrated within an optical line termination system.

10. A method for unified management of fiber-coupled optical network units and coaxial-coupled cable modems in a fiber-coaxial hybrid network, comprising:

receiving instructions from a network management system for a fiber-coupled optical network unit or a coaxial cable-coupled cable modem of the hybrid fiber-coaxial network;

generating an Ethernet passive optical network operation management maintenance message based on the management instruction, wherein the Ethernet passive optical network operation management maintenance message comprises a cable modem context field when the management instruction is a cable modem for the coaxial cable coupling;

when the management instruction is a cable modem for the coaxial cable coupling, sending an Ethernet passive optical network operation management maintenance message to a coaxial cable media converter serving the cable modem.