Patent Application
20080273548
The present disclosure relates generally to the field of cable technologies for a communication network. In one example embodiment, the disclosure relates to a system and method to configure service groups in a cable network.
The Data Over Cable Service Interface Specification (DOCSIS) is an international cable modem standard that defines the communications and operations support interface requirements for data transmission over a cable system or network. In particular, DOCSIS specifies physical layer (PHY) aspects of cable modem transmissions as well as the Media Access Control (MAC) functionality used to access the cable transmission channels.
DOCSIS provides for a point to multipoint communications system in which downstream channels can service multiple cable modems through a continuous signal in the downstream direction, while TDMA burst signals are received from the cable modems in the upstream direction.
A Cable Modem Termination System (CMTS), which forms part of the headend of a cable network, has full ownership of the downstream traffic, which negates any negotiations for downstream transmissions. However, as multiple cable modems need to share access to the upstream channel, cable modems need to send requests through to the CMTS in order to be allocated a transmission time slot.
Channel bonding is a new feature that has been incorporated into DOCSIS 3.0. Channel bonding provides for the spreading of data transmissions over multiple radio frequency (RF) channels. This allows for a flexible way of increasing upstream and downstream throughput to subscribers.
The present disclosure is illustrated by way of example, and not limitation, in the figures of the accompanying drawings and in which like references indicate similar elements:
In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of an example embodiment of the present invention. It will be evident, however, to one skilled in the art that the present invention may be practiced without these specific details.
A method and apparatus for configuring service groups in a cable network is provided. The method may comprise identifying a primary downstream channel in a cable network and identifying a plurality of fiber nodes fed by the primary downstream channel. For each fiber node identified, the method may comprise identifying a set of downstream channels communicating with the fiber node. If one or more duplicate sets are identified, the one or more duplicate sets of downstream channels may be eliminated and a downstream service group may then be associated with each of the remaining sets of downstream channels. In an example embodiment, at least one Media Access Control (MAC) domain is automatically selected to correspond to the identified service groups.
Referring to
In the example system 10, the network devices are shown to be a cable modem termination system (CMTS) 12, which may form part of a cable company's headend, and a back office network 14. The CMTS 12 is used to provide high speed data services, e.g., cable internet and/or Voice over IP (VoIP) services to subscribers, by connecting Customer Premises Equipment (CPE) of the subscribers to a wide area network, such as the Ethernet 16.
In an example embodiment, the CMTS 12 is connected to a hybrid fiber/coaxial (HFC) system 18 of a HFC network 20 of a cable company. The HFC 20 is shown, in turn, to be connected to a plurality of user network devices or CPE (e.g., via cable modems (CMs) 22.1 to 22.3). The cable modems 22.1 to 22.3 are shown by way of example to connect the cable company's HFC network 20 to respective home networks 24. Each of home networks 24 are shown by way of example to terminate in CPEs 26.1, 26.2, 28.1, 30.1, 30.2 and 30.3. It will be appreciated that any number of CMs may be provided and that CPEs may be connected to the CMs.
In one example embodiment, the system 10 employs the Data Over Cable Service Interface Specification (DOCSIS) to define the communications and operations support interface requirements for data transmission over the cable system or network 10.
The “MAC domain” is defined in DOCSIS 3.0 as a subcomponent of the CMTS that provides data forwarding services to a set of downstream and upstream channels, while the “PHY channel” relates to layer 1 in the Open System Interconnection (OSI) architecture. This layer provides services to transmit bits or groups of bits over a transmission linked between open systems and may entail handshaking procedures. In an example embodiment, the HFC plant 50 is a broadband bidirectional shared-media transmission system that uses fiber trunks between a head-end and fiber nodes, with coaxial distribution (e.g., coaxial cables of a cable television network) from the fiber nodes to the customer network devices (e.g., the cable modems).
In an example configuration, and as shown in
A Cable modem service group, in DOCSIS 3.0, is the complete set of downstream and upstream channels within a single CMTS that a single cable modem could potentially receive or transmit. In many HFC deployments, a cable modem service group corresponds to a single fiber node. Usually, a cable modem service group serves multiple cable modems. A downstream service group, in DOCSIS 3.0, is the complete set of downstream channels from a single CMTS that could potentially reach a single cable modem. A downstream service group corresponds to a broadband forward carrier path signal from one CMTS.
The determination of service groups is an important aspect in channel bonding, which is a new feature of DOCSIS 3.0. Channel bonding is a logical process that combines the data packets received on multiple independent channels into one higher-speed data stream. Channel bonding can be implemented independently on upstream channels and downstream channels.
In an example embodiment, the configuration 48 between the DOCSIS MAC channel 46 and the DOCSIS PHY channel 50, and the configuration 52 between the DOCSIS PHY channel 50 and the HFC plant 54 may be configured by a user (e.g., a Mobile Switching Office (MSO)). This may be done by the user specifying the DOCSIS interfaces, e.g., the layer 1, 2 and 3 parameters associated with Transport Stream Identifier (TSID), as well as the bonding channels and the fiber nodes.
In order to assign multiple downstream channels to one or more cable modems, it may be necessary to first determine what downstream channels are available for use by a particular cable modem. Various complexities may arise to determine the appropriate protocol, e.g., in some configurations, certain downstream channels used to transmit data from the CMTS to the cable modems may be split to service many remote nodes, while other downstream channels may support fewer nodes. It will thus be appreciated that the set of downstream channels which can be received by a cable modem may accordingly vary depending on the fiber node to which the cable modem is attached. MSO databases may not accurately track the exact physical location of each cable modem by MAC address, making it difficult to determine exactly what downstream channels a particular cable modem can receive.
DOCSIS 3.0 addresses this problem by means of downstream service group resolution. In this process, the cable modem uses CMTS-provided information to determine the service group to which the cable modem belongs. The necessary information is contained in a message (called an MDD message broadcast) broadcast by the CMTS at least once every two seconds on primary-cable downstream channels. Upon receiving the MDD message broadcast, the cable modem notes the channel identification (ID) of the current channel, then tunes to other frequencies of the MDD and notes what (if any) channel IDs it finds on those channels. When the cable modem's discovered channel IDs and frequencies match one and only one of the per-service-group lists of channel IDs provided in the MDD, the cable modem identifies that service group as a “match” and conveys this information to the CMTS.
In order to execute the abovementioned process, it will be appreciated that the CMTS must first be configured to associate service groups with the cable modems. An example method and apparatus to self-discover MAC domain downstream service groups is described in more detail below.
Turning to
In an example embodiment, the CMTS 12 may include a fiber node identifier module 80, a channel identifier module 82, and a service group configuration module 84. The CMTS 12 may further include a Command Line Interface (CLI) module 86 and a memory 88 that may hold various tables necessary to support the functioning and/or configuration of the CMTS 12. The memory may also include instructions which, when executed, perform the methodology described herein.
The fiber node identifier module 80 may determine the physical downstream fiber node topology. In an example embodiment, the fiber node identifier module 80 may determine the topology by identifying a number of fiber nodes configured to communicate data between upstream and downstream network devices in a cable network. For example, the fiber node identifier module 80 may identify the number of fiber nodes (e.g., the fiber nodes of the HFC plant 54 of
The fiber node identifier module 80 may identify the number of fiber nodes by deriving the number of fiber nodes from the CLI module 86. In an example embodiment, the fiber node identifier module 80 may thus in an automated fashion obtain the CLI configuration which reflects the customer's HFC topology. A fiber node may describe the physical topology which is unique to the MSO and geographical location.
An example fiber node configuration may be as follows:
In an example embodiment, the channel identifier module 82 determines the radio frequency (RF) connector topology relating to channels to transmit or receive data over the number of fiber nodes. For example, the channel identifier module 82 may determine this RF connector topology by identifying a set of channels capable of transmitting or receiving data over each of the number of fiber nodes. The channel identifier module 82 may, for example, and referring back to
In an example embodiment, the channel identifier module 82 may identify the set of channels by deriving the selection of channels from the CLI module 86. The channel association may be unique to the MSO configuration and may be configured by CLI.
The service group configuration module 84 derives the service groups, e.g., the downstream service groups, from the information identified by the fiber node identifier module 80 and the channel identifier module 82. In an example embodiment, the service group configuration module 82 may associate a service group with each identified selection of channels in respect of each of the number of fiber nodes. The service group configuration module 84 may further record the number of fiber nodes, the identified selection of channels and the associated service groups or sets in a service group table. In an example embodiment, this service group table may be stored in the memory 88.
The information recorded in the service group table, an example of which is shown in
In the example embodiment shown in
The fiber node identifier module 80 of
As described below, the service group configuration module 84 may then associate a first service group with channels D1, D2, D3 and D4, a second service group with channels D1, D2, D5 and D6 and a third service group with channels D1 and D5. This information may then be recorded in a service group table 120 as shown by
In
As shown by block 142, a fiber node identifier module 80 may automatically identify primary downstream channels in the cable network such as a DOCSIS 3.0 network. In an example embodiment, the fiber node identifier module 80 includes software which, when executed, identifies the primary downstream channels by accessing a CLI module 88. For example, the method 140 may parse topology data in the CLI to identify a downstream channel with a “5/0/0”or “6/0/0”descriptor. A primary channels is a downstream channel from which a CM derives CMTS master clock timing for upstream transmission. In the example pseudo code above the primary channels are downstream Cable 5/0/0 and downstream Cable 6/0/0 channels. Thus, in an example embodiment a slot, subslot and unit of the downstream cable definition may be automatically investigated to identify primary capable downstream channels.
A channel identifier module 82 may identify a plurality of fiber nodes fed by the identified primary downstream channel as shown in block 144. In an example embodiment, the channel identifier module 82 may identify one or more primary downstream channels by accessing the CLI module 88 and deriving the plurality of channels from the CLI module 88.
As shown at block 146, for each fiber node identified, a set of downstream channels communicating with the fiber node is identified (see
By automatically discovering aspects the cable plant topology, as described above, less manual configuration of the parameters of a DOCSIS cable network is necessary, which may facilitate configuration of the network and may result in a reduction in the configuration errors by the Mobile Switching Office.
Returning to the example fiber node configuration shown in
The corresponding downstream channel configuration automatically derived from the CLI may be as follows:
The following is a further example of commands that may be incorporated in the fiber node identifier module 80 and the channel identifier module 82 in order to identify the fiber nodes and the channels that may transmit to the respective fiber nodes.
In the above example, “#cable fiber-node<1> may identify FN-A 112, FN-B 114, and FN-C 116 in
In an example embodiment, in order to identify duplicate sets of downstream channels in which two or more different fiber nodes are fed by the same downstream channels (e.g., see FN-C and FN-D in
Thus, in an example embodiment, a bitmap for each fiber node may be determined. Thereafter, duplicate bitmaps are identified and identical sets of downstream channels may be automatically eliminated. In the example shown in
In an example embodiment, the method 140 (see
The example computer system 200 includes a processor 202 (e.g., a central processing unit (CPU), a graphics processing unit (GPU) or both), a main memory 204 and a static memory 206, which communicate with each other via a bus 208. The computer system 200 may further include a video display unit 210 (e.g., a plasma display, a liquid crystal display (LCD) or a cathode ray tube (CRT)). The computer system 200 also includes an alphanumeric input device 212 (e.g., a keyboard), a user interface (UI) navigation device 214 (e.g., a mouse), a disk drive unit 216, a signal generation device 218 (e.g., a speaker) and a network interface device 220.
The disk drive unit 216 includes a machine-readable medium 222 on which is stored one or more sets of instructions and data structures (e.g., software 224) embodying or utilized by any one or more of the methodologies or functions described herein. The software 224 may also reside, completely or at least partially, within the main memory 204 and/or within the processor 202 during execution thereof by the computer system 200, the main memory 204 and the processor 202 also constituting machine-readable media.
The software 224 may further be transmitted or received over a network 226 via the network interface device 220 utilizing any one of a number of well-known transfer protocols (e.g., HTTP).
While the machine-readable medium 222 is shown in an example embodiment to be a single medium, the term “machine-readable medium” should be taken to include a single medium or multiple media (e.g., a centralized or distributed database, and/or associated caches and servers) that store the one or more sets of instructions. The term “machine-readable medium” shall also be taken to include any medium that is capable of storing, encoding or carrying a set of instructions for execution by the machine and that cause the machine to perform any one or more of the methodologies of the present application, or that is capable of storing, encoding or carrying data structures utilized by or associated with such a set of instructions. The term “machine-readable medium” shall accordingly be taken to include, but not be limited to, solid-state memories, optical and magnetic media, and carrier wave signals.
Although an embodiment has been described with reference to specific example embodiments, it will be evident that various modifications and changes may be made to these embodiments without departing from the broader spirit and scope of the invention. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense.
The Abstract of the Disclosure is provided to comply with 37 C.F.R. § 1.72(b), requiring an abstract that will allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the foregoing Detailed Description, it can be seen that various features are grouped together in a single embodiment for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed embodiments require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed embodiment. Thus the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separate embodiment.
