|Publication number||US20060165086 A1|
|Application number||US 11/387,942|
|Publication date||Jul 27, 2006|
|Filing date||Mar 23, 2006|
|Priority date||Mar 28, 2002|
|Also published as||US7079540|
|Publication number||11387942, 387942, US 2006/0165086 A1, US 2006/165086 A1, US 20060165086 A1, US 20060165086A1, US 2006165086 A1, US 2006165086A1, US-A1-20060165086, US-A1-2006165086, US2006/0165086A1, US2006/165086A1, US20060165086 A1, US20060165086A1, US2006165086 A1, US2006165086A1|
|Inventors||Marvin Wilson, Ren-Wei Liou, Thomas Georges, Harry Tang|
|Original Assignee||Wilson Marvin J, Ren-Wei Liou, Georges Thomas L, Harry Tang|
|Export Citation||BiBTeX, EndNote, RefMan|
|Referenced by (4), Classifications (4), Legal Events (1)|
|External Links: USPTO, USPTO Assignment, Espacenet|
1. Field of the Invention
The present invention relates to telecommunications systems and, more specifically, to systems and methods for provisioning resources in a broadband network.
2. Description of the Prior Art
Demand for in-home data and telephony services has grown dramatically in recent years and is expected to continue to increase. Accordingly, providers of data and telephony services have sought to design and deploy broadband networks with increased delivery capacity.
One broadband technology that has become particularly popular is digital subscriber lines (DSL). DSL offers increased data transfer rates and integrated telephony and data services using the existing public switched telephone network (PSTN), which previously was used exclusively for telephone voice communications.
As the demand for DSL service has grown, service providers have needed to build-out their infrastructure for providing DSL service. In particular, service providers have needed to quickly install large numbers of network elements devoted to providing DSL service. For example, service providers have needed to install large numbers of broadband access multiplexing elements, which generally include digital subscriber line access multiplexors (DSLAM's) and miniature remote access multiplexors (MINIRAM's). Installing, managing, and administering these quickly expanding, geographically distributed DSL networks has become increasingly complex, time consuming, and expensive.
One aspect of DSL network maintenance that is very cost and labor intensive is provisioning permanent virtual circuits (PVC's) in broadband access multiplexing elements. PVC's are permanent, “always on” connections between devices in the DSL network. A physical transmission path may be divided into a certain number of virtual paths. Each virtual path may be further divided into a certain number of virtual channels. Each PVC may be identified by a virtual path identifier (VPI) and a virtual channel identifier (VCI). At a multiplexing element, PVC's may be connected using VPI's and VCI's. Thus, it is necessary to assign a specific VPI and a VCI to each of the multiplexor's input ports. This is often a difficult task because multiplexors may often contain a very high quantity of inputs, and the number of VCI's and VPI's available is limited.
There are several existing methods for assigning a VPI and a VCI to each multiplexor input. One existing scheme assigns a VPI and a VCI to each input from an algorithm based on the rack, shelf, card and port to which that input path is connected. However, this scheme is ineffective because multiplexors often contain too many racks, shelves, cards, and ports.
Another existing scheme selects a new VPI and VCI for each “new” input. A “new” input is created each time a new subscriber requests DSL service. For each new input, an available VPI and VCI is selected from a pool of available VPI's and VCI's. When a VPI and a VCI is selected for the new input they are removed from the pool. If an existing subscriber wishes to have his or her service discontinued, then an existing connection must be deleted. When an existing connection is deleted the existing VPI and VCI are placed back in the pool. However, the effectiveness of this scheme is limited because attempts to delete a virtual circuit cross connection are often unsuccessful. Thus, despite attempts to delete it, a VPI and VCI may remain assigned to a given input even if that input is not actually used by a subscriber. When a new subscriber requests service, he or she may be assigned the same VPI and VCI as the connection that the service provider had previously attempted to remove. Therefore, the new subscriber's cross connection will fail.
Thus, a need exists in the art for systems and methods for provisioning virtual circuits in broadband access multiplexing elements that are suitable for the high quantity of multiplexor inputs and that eliminate the problem of service failure due to unsuccessful cross connection deletion attempts.
Accordingly, systems and methods for provisioning virtual circuits in broadband access multiplexing elements are disclosed. Systems and methods in accordance with the invention are operable in DSL networks comprising DSL line multiplexor devices such as for example, DSLAM's, and element management systems (EMS's) for managing the operation of these same multiplexor devices. As is explained in detail below, a DSL network may comprise a large number of EMS's, with each EMS having a large number of multiplexors that it is dedicated to managing. The DSL network may also comprise a network management system (NMS) that is responsible for managing the entire network. The NMS manages individual network elements by sending commands to the EMS dedicated to managing the particular element.
When a new subscriber requests DSL service, an available input port on a multiplexor is selected to serve as the line termination port for the subscriber's line. The NMS determines if the selected input port has been previously used. If the selected input port has not been previously used, then the NMS assigns to the input port a unique VPI and VCI selected from a pool of available VPI's and VCI's. The pool is unique to each multiplexor and is maintained by the NMS. The NMS then removes the selected VPI and VCI from the pool. If the selected input port has been previously used, then the NMS assigns to the input port its previous VPI and VCI. The NMS then sends commands to the EMS to connect the selected input port's assigned VPI and VCI to the output VPI and VCI.
The present invention will be better understood after reading the following detailed description of the presently preferred embodiments thereof with reference to the appended drawings, in which:
Systems and methods for provisioning virtual circuits in broadband access multiplexing elements in accordance with the invention are described below with reference to
Generally, applicants have invented systems and methods for provisioning virtual circuits in broadband access multiplexing elements. When a new subscriber requests DSL service, an available input port on a broadband access network multiplexing element such as, for example, a DSLAM, is selected to serve as the line termination port for the subscriber's line. The NMS determines if the selected input port has been previously used. If the selected input port has not been previously used, then the NMS assigns to the input port a unique VPI and VCI selected from a pool of available VPI's and VCI's. The pool is unique to each DSLAM and is maintained by the NMS. The NMS then removes the selected VPI and VCI from the pool. If the selected input port has been previously used, then the NMS assigns to the input port its previous VPI and VCI. The NMS then send commands to the EMS to connect the selected input port's assigned VPI and VCI to the output VPI and VCI.
Prior to explaining the details of an illustrative embodiment of the invention, it is useful to provide a description of a suitable exemplary environment in which the invention may be implemented.
Exemplary DSL Network Environment
1. Exemplary DSL Network
DSL is a technology that converts existing twisted-pair telephone lines into access paths for multimedia and high-speed data communications. DSL services promise to dramatically increase the speed of copper wire based transmission systems without requiring expensive upgrades to the local loop infrastructure. As used herein, xDSL refers to the numerous variations of DSL technology using the Bellcore acronyms such as ADSL (Asymmetric DSL), HDSL (high bit-rate DSL), RADSL (rate-adaptive DSL), and the like. New and improved versions of xDSL are in constant development and the invention is not intended to be limited to any single variation of the technology.
Most xDSL signals fall within the frequency range of 4 KHz to 2.2 MHz, with the range of 0 to 4 KHz reserved for the transmission of analog voice signals for plain old telephone service (POTS). The theoretical maximum amount of bandwidth between 4 KHz and 2.2 MHz is almost 70 Mbps of digital data spectrum. In practice however, only lab test conditions have ever reached higher than 60 Mbps and currently available products typically use 2 Mbps to 8 Mbps.
The different types of xDSL technologies may also be categorized as either symmetric EC xDSL or asymmetric (FDM) xDSL. A first class of EC xDSL includes Integrated Services Digital Network. (ISDN), High-Bit-Rate DSL (HDSL), and Single-Line DSL (SDSL). A second class of EC xDSL includes Asymmetric DSL (ADSL) and Rate Adaptive DSL (RADSL). The modulation technologies employed with the various types of xDSL include 2-binary 1-quaternary (2B1Q) for ISDN and HDSL, carrierless amplitude phase modulation (CAP) for HDSL, SDSL and RADSL, and discrete multi-tone modulation (DMT) for ADSL and RADSL.
Generally, DMT divides the upstream and downstream bands into smaller individual or discrete bands. The modems on either end listen to these discrete bands as smaller channels within the main upstream or downstream channel. Often, one of these smaller bands will be disrupted by noise, rendering the information carried within that band useless. Rather than toss away all the information sent at that instant across the entire upstream or downstream band, only that small part is lost and needs to be retransmitted.
With CAP, the overall amplitude or power of the signal is modulated. The signal is not safeguarded against noise and often suffers from lost information, which accounts in part for the lower transmission speeds of CAP-based DSL technologies. With amplitude modulation, there is also more loss over longer ranges. The benefits of CAP over DMT are that it is simpler in design and therefore cheaper, requires less power, and generates less heat. Both power consumption and heat are serious factors when it comes to housing many of these systems together (as in a central office). DMT however, often provides the best results and maintains the full bandwidth at its maximum range of 18,000 feet. CAP signals degrade quickly after 10,000 feet.
Typical xDSL systems are implemented as follows. At the customer premises a splitter is provided which separates the xDSL signals (i.e., digital data signals) from the POTS analog voice signals. The main purpose of the splitter is to shield ordinary telephones from the high frequency xDSL signals that can have disastrous effects on the telephone or human ear. The data line from the splitter connects to an xDSL modem and the analog line connects to the telephone. With xDSL Lite and some other product models, there is no external splitter or it is combined into the xDSL modem unit. An Ethernet line will usually link the xDSL modem to the customer premises PC.
The twisted pair from the customer premises connects to an xDSL access multiplexor such as, for example a DSLAM, typically located at the incumbent local exchange carrier (ILEC) central office (CO). The twisted pair from the customer premise may also pass through a neighborhood wiring distribution frame, which is a central point where the wire pairs from several customer premises come together, and/or an ILEC remote terminal before reaching the CO. Typically, a DSLAM is a multi-module unit that houses many CO-side xDSL modems within a single shelf much like the analog modern racks of today. At the DSLAM the voice and data lines are split out along separate paths. The digital data signal goes into either an ATM concentrator or an Internet Protocol router. The analog voice signals are connected to the CO phone switch. Thus, the digital data packets go through the router out to the Internet, and the analog voice signals go through the phone switch and into the public switched telephone network.
ADSL is one particularly promising and popular form of xDSL. ADSL can transmit up to 6 Mbps to a subscriber, and as much as 832 kbps or more in both the downstream and upstream directions. Such rates expand existing access capacity by a factor of 50 or more without the need to install new wiring or cabling. An ADSL circuit connects an ADSL modem on each end of a twisted-pair telephone line, creating three information channels—a high speed downstream channel, a medium speed duplex channel, depending on the implementation of the ADSL architecture, and a POTS or ISDN channel. The POTS/ISDN channel is split off from the digital modem by filters, thus guaranteeing uninterrupted POTS/ISDN, even if ADSL fails. The high speed channel ranges from 1.5 to 6.1 Mbps, while duplex rates range from 16 to 832 kbps. Each channel can be submultiplexed to form multiple, lower rate channels, depending on the system.
ADSL modems provide data rates consistent with North American and European digital hierarchies and can be purchased with various speed ranges and capabilities. The minimum configuration provides 1.5 or 2.0 Mbps downstream and a 16 kbps duplex channel; others provide rates of 6.1 Mbps and 64 kbps duplex. Products with downstream rates up to 8 Mbps and duplex rates up to 640 kbps are currently available. ADSL modems also can accommodate ATM transport with variable rates and compensation for ATM overhead, as well as IP protocols. Downstream data rates depend on a number of factors, including the length of the copper line, its wire gauge, presence of bridged taps, and cross-coupled interference. Line attenuation increases with line length and frequency, and decreases as wire diameter increases.
In addition to the layer 2 communications elements (e.g., asynchronous transfer mode (ATM) switches 108 and 109), layer 2/3 communications elements also form a part of broadband access network 101. Specifically, a plurality of layer 2/3 communications elements (e.g., ingress broadband gateways 120 a-n) reside after various layer 2 communications elements (e.g., ATM Switch 108) lying near ingress points for access device IP traffic (e.g., IP traffic from personal computer 103), and a plurality of layer 2/3 communications elements (e.g., egress broadband gateway 121 a) reside after layer 2 communications elements (e.g., ATM Switch 109) lying near egress points for access device IP traffic destined for ISP networks (e.g., ISP network 113) linked to broadband access network 101. In exemplary network 100, ATM switch 108 may comprise, for example, a Lucent CBX 500 multiservice WAN switch, and ATM switch 109 may comprise, for example, a Lucent GX 550 multiservice WAN switch. Ingress and egress broadband gateways 120, 121 comprise, for example, Nortel 5000 Broadband Service Nodes.
Each of the layer 2/3 communications elements in broadband access network 101 supports the creation of layer 3 communications sessions between various communications elements within and without network 101 using layer 3 protocols such as IP. The layer 2/3 communications elements also support the creation of virtual layer 2 communications sessions or “virtual PVCs (vPVCs)” using one or more of the following protocols: Point-to-Point Protocol (PPP) over Ethernet (PPPoE), PPP over ATM (PPPoA), Layer 2 Tunneling Protocol (L2TP), Point-to-Point Tunneling Protocol (PPTP), and/or Switched Multimegabit Data Service (SMDS) Interface Protocol (SIP). A PVC is a “permanent” virtual circuit and provides an “always on” connection whether the subscribers is actively using it or not. Thus, a series of three layer 2 virtual PVCs (e.g., vPVC1 a 125 a, vPVC2 a 126 a, and vPVC3 a 127 a) extend from an access device (e.g., ADSL modem 104) to an ISP (e.g., ISP network 113) through broadband access network 101 (versus having a single layer 2 PVC extending from an access device to an ISP as in other broadband access networks).
The first layer 2 vPVC (e.g., vPVC1 a 125 a) extends from an access device (e.g., ADSL modem 103) to one of the ingress layer 2/3 communications elements (e.g., ingress broadband gateway 120 a), and is the only vPVC devoted exclusively to a single IP subscriber. Typically the first layer 2 vPVC is a user authenticated PPP session. In one embodiment of the network 101 the first layer 2 vPVC is a user authenticated PPPoE session where the IP enabled device (or the operator thereof) supplies a username and domain (e.g., “user1@domain1”). Based on the domain provided, the first layer 2/3 communications element establishes a virtual layer 2 connection using L2TP over the remaining two layer 2 vPVCs to reach the appropriate ISP and the ISP provides the IP enabled device an IP address for obtaining IP based services. This model allows for the creation of access sessions with different ISPs depending on the domain provided by the IP enabled device. This model also allows IP services to be billed to a particular user on a per access session basis.
The second vPVC (e.g., vPVC2 a 126 a) extends from the foregoing ingress layer 2/3-communications element (e.g., Ingress Broadband Gateway 120 a) to one of the egress layer 2/3 communications elements (e.g., Egress Broadband Gateway 121 a). Through the use of a tunneling protocol such as L2TP, PPP aggregation occurs at the layer 2/3 ingress communications element and the multiple PPP communications sessions between access devices (e.g., access devices in homes 102 b-n) served by the ingress layer 2/3 communications element are funneled into the second vPVC. The third vPVC (e.g., vPVC3 a 127 a) extends from the foregoing egress layer 2/3 communications element (e.g., Egress Broadband Gateway 121 a) to the layer 2/3 communications element in the ISP network. In this embodiment of the invention the layer 2/3 communications element in the ISP network is an LNS capable router (e.g., layer 2/3 communications element 114). Again, through the use of a tunneling protocol such as L2TP, PPP aggregation occurs at the egress layer 2/3 communications element and the multiple PPP communications sessions from multiple L2TP IBG tunnels are concentrated onto a single L2TP tunnel by the egress broadband gateway and are funneled into the third virtual PVC. The third virtual PVC delivers a large (doubly aggregated) L2TP tunnel to the LNS router 114 where the PPP sessions are terminated and IP packets are once again routed normally.
As shown in
2. Provisioning Virtual Circuits in Broadband Access Multiplexing Elements
NMS 202 manages the algorithm that provisions virtual circuits in DSLAM's 107 a-n. NMS 202 selects a VPI and VCI for each new input to DSLAM's 107 a-n and sends commands to EMS's 201 a-m to connect the VPI and VCI of each new input to DSLAM's 107 a-n to the output of DSLAM's 107 a-n.
NMS 202 may be implemented on a generic computing system such as is shown in
If the selected input port has been previously used, then, at step 418, NMS 202 assigns to the input port its previous VPI and VCI. At step 420, NMS 202 sends commands to dedicated EMS 201 a-m to complete a connection between the selected DSLAM input and the DSLAM output.
If an existing subscriber's DSL service is canceled, the subscriber's connection is deleted. However, the VPI and VCI of the subscriber's input port remained assigned to that port and are not placed back in the pool of available VPI's and VCI's. Thus, a new subscriber's line on a different input port cannot be assigned the same VPI and VCI as the deleted connection. This eliminates the problem of service failure due to unsuccessful cross connection deletion attempts.
Thus, systems and methods for provisioning virtual circuits in broadband access multiplexing elements have been disclosed. These novel systems and methods comprise selecting a specific VPI and VCI for each new multiplexing element input from a pool of available VPI's and VCI's. Furthermore, these systems and methods eliminate the problem of service failure due to unsuccessful cross connection deletion attempts because a permanent VPI and VCI is assigned to each input port of the multiplexing element.
Those skilled in the art understand that computer readable instructions for implementing the above-described processes, such as those described with reference to
While the invention has been described and illustrated with reference to specific embodiments, those skilled in the art will recognize that modification and variations may be made without departing from the principles of the invention as described above and set forth in the following claims. For example, while the invention has been described in connection with provisioning of virtual circuits in DSLAM's, the systems and methods may be employed to plan other types of DSL multiplexing devices as well. Accordingly, reference should be made to the appended claims as indicating the scope of the invention.
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US7751412 *||Jan 22, 2003||Jul 6, 2010||Cisco Technology, Inc.||Virtual circuit automatic configuration|
|US7940773 *||Jan 18, 2008||May 10, 2011||Embarq Holdings Company, Llc||System, method and apparatus for automated ATM to ethernet provisioning|
|US8010594 *||Jun 18, 2008||Aug 30, 2011||Time Warner Cable Inc.||System and method for billing system interface failover resolution|
|US8126958||Jul 24, 2011||Feb 28, 2012||Time Warner Cable Inc.||System and method for billing system interface failover resolution|
|Oct 22, 2009||AS||Assignment|
Owner name: AT&T INTELLECTUAL PROPERTY I, L.P.,NEVADA
Free format text: CHANGE OF NAME;ASSIGNOR:AT&T DELAWARE INTELLECTUAL PROPERTY, INC.;REEL/FRAME:023448/0441
Effective date: 20081024