Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L12/00—Data switching networks
  • H04L12/54—Store-and-forward switching systems 
  • H04L12/56—Packet switching systems
  • H04L12/5601—Transfer mode dependent, e.g. ATM
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L49/00—Packet switching elements
  • H04L49/60—Software-defined switches
  • H04L49/606—Hybrid ATM switches, e.g. ATM&STM, ATM&Frame Relay or ATM&IP
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04M—TELEPHONIC COMMUNICATION
  • H04M7/00—Arrangements for interconnection between switching centres
  • H04M7/12—Arrangements for interconnection between switching centres for working between exchanges having different types of switching equipment, e.g. power-driven and step by step or decimal and non-decimal
  • H04M7/1205—Arrangements for interconnection between switching centres for working between exchanges having different types of switching equipment, e.g. power-driven and step by step or decimal and non-decimal where the types of switching equipement comprises PSTN/ISDN equipment and switching equipment of networks other than PSTN/ISDN, e.g. Internet Protocol networks
  • H04M7/125—Details of gateway equipment
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L12/00—Data switching networks
  • H04L12/54—Store-and-forward switching systems 
  • H04L12/56—Packet switching systems
  • H04L12/5601—Transfer mode dependent, e.g. ATM
  • H04L2012/5638—Services, e.g. multimedia, GOS, QOS
  • H04L2012/5646—Cell characteristics, e.g. loss, delay, jitter, sequence integrity
  • H04L2012/5651—Priority, marking, classes
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L12/00—Data switching networks
  • H04L12/54—Store-and-forward switching systems 
  • H04L12/56—Packet switching systems
  • H04L12/5601—Transfer mode dependent, e.g. ATM
  • H04L2012/5638—Services, e.g. multimedia, GOS, QOS
  • H04L2012/5665—Interaction of ATM with other protocols
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L12/00—Data switching networks
  • H04L12/54—Store-and-forward switching systems 
  • H04L12/56—Packet switching systems
  • H04L12/5601—Transfer mode dependent, e.g. ATM
  • H04L2012/5678—Traffic aspects, e.g. arbitration, load balancing, smoothing, buffer management
  • H04L2012/5681—Buffer or queue management
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04Q—SELECTING
  • H04Q2213/00—Indexing scheme relating to selecting arrangements in general and for multiplex systems
  • H04Q2213/1302—Relay switches
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04Q—SELECTING
  • H04Q2213/00—Indexing scheme relating to selecting arrangements in general and for multiplex systems
  • H04Q2213/13034—A/D conversion, code compression/expansion
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04Q—SELECTING
  • H04Q2213/00—Indexing scheme relating to selecting arrangements in general and for multiplex systems
  • H04Q2213/1304—Coordinate switches, crossbar, 4/2 with relays, coupling field
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04Q—SELECTING
  • H04Q2213/00—Indexing scheme relating to selecting arrangements in general and for multiplex systems
  • H04Q2213/13196—Connection circuit/link/trunk/junction, bridge, router, gateway
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04Q—SELECTING
  • H04Q2213/00—Indexing scheme relating to selecting arrangements in general and for multiplex systems
  • H04Q2213/1329—Asynchronous transfer mode, ATM
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04Q—SELECTING
  • H04Q2213/00—Indexing scheme relating to selecting arrangements in general and for multiplex systems
  • H04Q2213/13292—Time division multiplexing, TDM
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04Q—SELECTING
  • H04Q2213/00—Indexing scheme relating to selecting arrangements in general and for multiplex systems
  • H04Q2213/13299—Bus
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04Q—SELECTING
  • H04Q2213/00—Indexing scheme relating to selecting arrangements in general and for multiplex systems
  • H04Q2213/1334—Configuration within the switch
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04Q—SELECTING
  • H04Q2213/00—Indexing scheme relating to selecting arrangements in general and for multiplex systems
  • H04Q2213/13341—Connections within the switch
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04Q—SELECTING
  • H04Q2213/00—Indexing scheme relating to selecting arrangements in general and for multiplex systems
  • H04Q2213/13389—LAN, internet

Definitions

• the present invention relates to telecommunications. More particularly, the present invention relates to a distributed telecommunications switching system and method.
• Telecommunications switching systems have been developed for transporting asynchronous transfer mode (ATM) and time division multiplex (TDM) traffic with limited traffic capacities.
• ATM asynchronous transfer mode
• TDM time division multiplex
• a typical digital switching system usually has a fixed rate subscriber bus capable of supporting TDM traffic only at a fixed bit rate.
• the traffic capacity can be increased only with conventional point-to-point time slot interchange connections which would limit the modularity and expandability of the system.
• a communications system which is capable of providing voice, video and data communications roughly comprises a time, division multiplex (TDM) fabric, an asynchronous transfer mode (ATM) fabric connected to the TDM fabric, an ATM cell bus connected to the ATM fabric, and a variable rate subscriber bus connected to the TDM fabric.
• TDM time, division multiplex
• ATM asynchronous transfer mode
• the system according to the present invention further comprises an interwor ing gateway connected between the TDM fabric and the ATM fabric .
• the variable rate subscriber bus is capable of accepting multiple TDM subscriber bus line cards or line units which operate at a variety of bit rates.
• the system further comprises a synchronous transport signal (STS) access controller connected to the TDM fabric.
• STS synchronous transport signal
• the ATM cell bus is capable of accepting multiple ATM line cards or line units.
• the ATM fabric is capable of supporting different modes of ATM fabric.
• the ATM fabric is capable of managing ATM traffic based upon a variety of ATM service parameters such as class of service (CoS) or quality of service (QoS) parameters in an ATM cell mode.
• the ATM fabric is also capable of supporting an ATM packet mode or frame relay mode .
• the common access platform according to the present invention is a scalable system which includes at least a primary bank comprising both ATM and TDM fabric.
• the system can be expanded by connecting one or more secondary banks to the primary bank through one or more stackplane buses.
• the stackplane bus comprises a plurality of ATM and TDM interfaces.
• the traffic capacity of the common access platform according to the present invention can thus be flexibly scaled up or down by adding or subtracting secondary banks from the platform.
• the stackplane bus provides modularity for interconnections between the primary and secondary banks .
• Fig. 1 illustrates a Common Access Platform High- Level Concept according to the invention.
• Fig. 2 illustrates a 2-Row Common Access Platform Shelf.
• Fig. 3 illustrates a 1-Row Common Access Platform Shelf, with all full-height line units.
• Fig. 4 illustrates the high-level architecture of a Common Access Platform, showing the backplane and stackplane bus concept.
• Fig. 5 is a Functional Diagram and shows the major interfaces within Common Access Platform.
• Fig. 6 illustrates 4 small line size applications of the Common Access Platform.
• Fig. 7 shows the DSLAM Configuration of the Common Access Platform.
• Fig. 8 shows Special Services Options in the Common Access Platform.
• Fig. 9 illustrates Universal Line Frame Configuration with Internet Redirect in the Common Access Platform.
• Fig. 10 illustrates Universal Line Frame with STM Transport in the Common Access Platform.
• Fig. 11 illustrates Universal Line Frame with ATM transport in the Common Access Platform.
• Fig. 12 illustrates Universal Line Frame with FR transport in the Common Access Platform.
• Fig. 13 illustrates Universal Line Frame with IP routing in the Common Access Platform.
• Fig.14 illustrates Platform Transport interfaces in the Common Access Platform.
• Fig. 15 illustrates the relationship of the Common Access Platform to a Litespan ® system.
• Fig. 16 shows a Residential User to ISP, PPP use of the Common Access Platform.
• Fig. 17 illustrates a Remote LAN Access using PPP use of the Common Access Platform.
• Fig. 18 compares a TDM mode of the Common Access Platform with a Frame Relay capable Common Access Platfo ⁇ rw
• the new common access platform is based on a scalable, distributed architecture with integrated data capabilities. It serves multiple remote terminals- (significantly more than Litespan ® - today) , greater intelligence is placed on the line or transport card reducing the complexity and cost of the common elements, and modular shelves are interconnected with a buss or "Stackplane" rather than the point-to-point TSI connections today.
• the system architecture is conceived to have an integrated ATM and TDM capability. Narrowband and other TDM based traffic use the system TSI, while all data traffic is transported-internally in ATM format.
• the system also allows for TDM adaptation to ATM and other types of data for applications such as circuit emulation, voice over
• the transport interfaces are DS1 (Tl/HDSL) , DS3, and
• DS1 transport cards may be physically the same as DS1 service cards.
• Fig. 1 illustrates the New
• the shelf is 6U high and can be divided into two rows. In this configuration, it can accept Litespan ® legacy TDM and ATM ADSL cards. It is expected that this shelf configuration be used in small NGDLC applications.
• Fig. 2 illustrates the 2 Row New Common Access Platform Shelf.
• ALU is an Alarm Unit
• AUX is an Auxiliary Unit
• LU is a Line Unit
• NCP is a Nodal Control Processor
• PS is a Power Supply
• TRAN is a Transport or Gateway Unit.
• Subscriber Bus 2 to 16 Mb/s Assignable TDM capacity Accepts all existing Litespan ® channel cards (including ADLU) Accepts quad-DSl and OLU cards
• BRX Broadband
• SONET/SDH bus 100 MHZ, point-to-point 0C-12/STM-4 capacity
• Full height cards are provided for ULF and central office data applications where high-density is required for POTS and a larger size line card facilitate advanced data capabilities. See Fig. 3, 1- Row New Common Access Platform Shelf, with all full- height line units.
• SONET/SDH bus 100 MHZ, point-to-point OC-12/STM-4 capacity
• Fig. 4 illustrates the high-level architecture showing the backplane and stackplane bus concept.
• Fig. 5 is a Functional Diagram and shows the major interfaces within the new platform.
• the new platform provides the ability to address issues with the current Litespan ® software architecture. The following are items that are considered in the development of the software architecture.
• the TL1 messages syntax is the same as Litespan ® . - A TL1 interface is needed to interface to the new system. Many of the TL1 commands currently supported in Litespan ® will need to be available on the new platform. To maintain a consistent interface and to leverage much of the work that has been done with the OSS, Litecraft and AMS, the front end of TL1 can be ported over to the new system, though the back end may change in the new architecture.
• Line cards with their own FLASH can receive a new image downloaded directly from AMS (Access Management System) .
• AMS Access Management System
• More intelligent Line cards It is an objective to be able to release line cards independently from the main software load. More intelligence in the line cards might enable this objective.
• Command and Alarm history logs To be able to historically browse events that happen when the system is not on line with AMS or other OSS, the ability to retrieve the history is provided.
• GR303 DSET software - DSET is the leader in regards to GR-303 interface software toolkit. Much development and testing effort has gone into the Litespan ® GR303 interface using the DSET software. That knowledge and effort is reused in the new platform.
• Service State Models There are several service state models in existence with TR-1093, TR-303 CMISE,
• the new platform's service state model captures all the service state models requirements.
• New features - the same philosophy discussed above of either porting existing work or using off- the-shelf code is utilized for the new features such as ATM, Frame Relay, IP, V5, etc.
• This new platform has the following functions for both ANSI and ETSI versions:
• the system has the following key capabilities:
• Banks may be daisy chained locally, extended optically, or over Tl/HDSL facilities to multiple remote nodes (number of remotes can be more than Litespan ® today) .
• V TR-8 Concentration on metallic interfaces, V TR-8, DS1-based GR-303, asynchronously mapped STS-1, and byte-synchronous OC-3 GR- 303 switch interfaces.
• a system can optionally be used in the central office to function as a COT supporting TR-57 interfaces,
• Integrated test systems within the HDT many small operators do not have PGTC or MLT test systems) decay It is likely to be compatible with test systems of the operator's choice (e.g. Hekiminan) and may even need to have some level of integrated functionality.
• Fig. 6 illustrates 4 small line size applications of the new common access platform.
• special services are provided through n x DSO as is ISDN support.
• the four applications are described as follows:
• RDT Remote Digital Terminal
• COT Central Office Terminal
• BCB Broadband Channel Bank
• the Broadband Channel Bank concept supports the new and preferred access network architecture for a fiber-to-the node topology. This pulls the distribution fiber back from the fiber- to-the-curb model to a position serving up to 500 homes. Distances from node to home are typically less 3,000 feet allowing "full service network" features to be offered via VDSL. With these distances, up to 26Mb/s data rate can be supported. VDSL has several advantages over ADSL at these distances which include: higher speeds, lower power, multiple services on the same drop (voice, data and video) , and opportunities for business services such as native LAN.
• FTTN topology within a business park or business condominium allows the operator to offer enhanced data service such as native LAN and ATM UNIs without stringing fiber directly to the business building.
• VDSL can run at symmetrical data rates of 6, 13, and 26 MB/s which extends the capabilities of traditional Tl over HDSL.
• This BCB will support the existing LS-2000 RDT configuration and can be remoted from the existing BFB as a standalone broadband channel bank within a CLE environment or street cabinet acting as a large ONU.
• the BCB In either configuration (new platform or subtending LS-2000/BFB) , the BCB has a small ATM fabric and accepts VDSL line cards in addition to all other line cards .
• DSLAMs are data only access devices traditionally delivering high-speed service via ADSL for Internet access.
• this generic DSLAM delivers data services via any variation of xDSL such as SDSL, HDSL and VDSL in addition to ADSL- full-rate (G.DMT) and ADSL-Lite
• the DSLAM shelf may be:
• a device that terminates a derived voice channel riding with the xDSL data stream as either voice over ATM, voice over IP, or other coding method and presents these voice channels to a switch interface.
• Future IP based service may be offered using a datagram mode.
• Fig. 7 shows the DSLAM Configuration.
• Specific value added data functions provided within the access network are Frame Relay aggregation, Frame Relay concentration, and Frame Relay to ATM interworking. As illustrated below, these functions simplify the network design. Economies of scale are provided by reducing the number of network elements (such as D4/D5, DCS 1:0 and fiber terminals) , reducing the number of dedicated links between data network and the access network, and providing by consolidation of switch ports (from many low-speed to a few high-speed ports) , and additionally provides a common management platform for all data services.
• network elements such as D4/D5, DCS 1:0 and fiber terminals
• Fig. 8 shows Special Services Options.
• the system has the following DSLAM capabilities:
• ATM over the following service interfaces full- rate DMT, G.Lite, IMA (inverse multiplexing of ATM) and HDSL) , • Following network interfaces for frame relay: IMT (inverse multiplexing over DS1) , DS3, OC-3 with migration path to OC-12,
• TDM based transport over the following service interfaces: ISDN, Tl, HDSL, SDSL, and DDS,
• Universal Line Frame concept is an extension of the narrowband local Class 5 switch line interface.
• the ULF provides the analog termination for the subscriber drop and provides concentrated GR-303 interface to the local switch.
• it provides fast Internet access with ADSL/DSLAM function, Internet redirect for the legacy dial-up modems, and VoIP gateway.
• the Internet redirect feature has the ability to offload the local switch from supporting long hold times associated with data calls to the public Internet. Call control for narrowband and data is under the direction of the Connection Control system as described later.
• V Supports high-density POTS card with 24 lines per card. Up to 16 cards or 384 lines are supported per bank.
• the POTS interface is LSSGR compliant in Gain, SRL, and ERL specifications for non-loaded drops.
• the system also supports high-density ISDN cards (24 lines per card) and DS1 cards (12 per card) .
• V " Provides GR-303 interface to switch over DSls, asynchronous STS- 1, and byte-synchronous OC-3.
• V Redirects Internet voiceband calls on a per call basis under the control of the external connection control system
• the class 5 makes an LNP query through SS#7 system and determines that the call needs to be redirected.
• the connection manager is connected to both the class 5 and the SS#7 system.
• the connection to the class 5 is to build a database correlating
• the connection to the SS#7 is to receive the redirect information. Once it has been established that the call is to be redirected to an
• connection manager issues a command over a TMC-like link between the connection manager and the system (for the Litespan ® , the interface is over an X.25 link to minimize development efforts.
• TMC-like interface may be best for the new system. It may be possible to eliminate the correlation table of CRVs and physical slots in the connection manager if TMC-like datalink channel is used. Redirected data calls are placed over DSls or SONET interfaces to ISP.
• Fig. 9 illustrates Universal Line Frame Configuration with Internet Redirect.
• IMA inverse multiplexing
• V ATM adaptation for voice over ATM and circuit emulation applications V ATM adaptation for voice over ATM and circuit emulation applications.
• an external multiplexer such as a SONET terminal may be used by the network operator.
• This arrangement provides a simple solution and transparency of service to the transport network, but requires the new platform to map all services via the STM interface and bandwidth usage is not optimized
• Fig. 10 illustrates Universal Line Frame with STM Transport .
• ATM transport has a similar effect to STM only interfaces. TDM based and other services must be adapted to ATM within the new platform before being presented to the transport network.
• Fig. 11 illustrates Universal Line Frame with ATM transport .
• Frame Relay transport is based on a TDM structure with n x 64 kb/s channels. This transport interface does not allow for high bandwidth services such as ATM and is the most limiting of all interfaces.
• Fig. 12 illustrates Universal Line Frame with FR transport.
• the IP interface facilitates a variety of service classifications.
• One such service interface is the possibility of ADSL unbundling on a per subscriber basis.
• This application requires the new platform to provide IP routing and Layer 3 processing. The same concept can be used with the Internet redirect application.
• Fig. 13 illustrates Universal Line Frame with IP routing.
• Fig. 14 illustrates the New Common Access Platform Transport interfaces.
• Customer Located Equipment can take the form of small to medium sized RDT sub-systems located on customer premises supporting high-density application for high-rise and multi-tenant buildings. With the short loop lengths from these systems, higher data rates are possible with VDSL or even direct Ethernet connections. For smaller line densities, the BRX or other ONUs can be deployed for the same but smaller function of a RDT.
• Channel Bank Assembly has a replacement Bank Control Unit (BCU) that provides the interface to the internal "stackplane" bus architecture of the new system.
• BCU Bank Control Unit
• the CBA is interconnected via a point-to-point arrangement since the legacy CBA does not allow the stackplane to flow-through to the next shelf
• V Broadband Fiber Bank (BFB) is maintained as the high-density optical distribution assembly for Fiber-to- the-Node and Fiber- to-the-Curb applications feeding BRX or ONU-48/96.
• the BFB has a replacement ATM Fiber bank Interface Unit (AFIU) that provides the interface with the internal "stackplane" bus architecture of the new system.
• AFIU ATM Fiber bank Interface Unit
• the BFB interconnects with the stackplane and provides the flow-through connection to other banks.
• V BRX is maintained as the fully integrated Optical Network Unit (ONU) providing narrowband and broadband service drops.
• the BRX is either fed directly from the new common access platform or by a BFB.
• AMS Access Management System
• the AMS therefore provides access management for both Litespan ® and the new system.
• Broadband Channel Bank functionality is added to existing Litespan ® -2000 and Litespan ® -2012 systems with the new common access platform connecting to the legacy Litespan ® TSI interface.
• the new platform has a special control interface to proxy the TSI signal and control information.
• the new common access platform (BCB function) has the ability to feed a number of BRX type ONUs along with the high-speed data services (xDSL up to VDSL) .
• the BCB is used at a RT site in a Fiber-to-the-Node or Fiber-to-the-Building application where the subscribers are within 3,000 feet.
• Fig. 15 illustrates the New Platform Relationship to Litespan ® .
• Operations are the glue that has the ability to bind together many dissimilar functional groups within the RBOC structure.
• a typical telco operations organization there are distinct workforces for DS0- based Special Services, DS-1-based IOF including DCS and fiber, DLC and OSP, and VF-based message services.
• This segregation of job functions is strictly controlled by union contract and results in a separation of services on network elements.
• message services and OSP can reside together but specials cannot be on the same bank as message.
• the IOF group manages IOF and fiber facilities. When a service has to be provisioned through different functional areas, a service contract will be written between the unions that allow one of them to assume responsibility. Usually the workforce with the cheaper rate will be chosen to show a "cost reduction".
• each grouping of network elements administered by a specific workforce has its own OS interface.
• a multi functional platform such as Litespan ® is used for integrated services as illustrated below, again separate workforces are involved.
• the Litespan ® solution does not offer the same physical separation.
• a strategic solution to the non-physical separation problem that faces the RBOC when they choose to use Litespan ® for integrated services is through the AMS.
• Logical partitions can be created within the software structure of AMS and Litespan ® that provides each workforce with its own and physically separate workstation and access to the integrated platform.
• the new platform amplifies the situation. It contains DLC functionality that is managed with legacy OSS, SNMP managed DSLAM and data capabilities, SONET-based management, and a management system for Internet redirect.
• V FTAM for file transfer
• TDM based services are supported internally by the TSI matrix very much like Litespan ® today.
• An enhancement to the database structure allows a greater number of remote terminals to be supported.
• a typical application that applies to the small scalable concept would use a GR-303 switch interface group across multiple remote nodes. These small nodes (100 to 200 lines) may be fed via a branching tree or a ring topology.
• two embodiments support TDM transport between nodes. These are: mapping the DSO traffic to VTI.5 payloads and allocating a fixed amount of OC bandwidth to TDM with the remainder for ATM. The drawback of this approach is that the bandwidth of the transport is not used efficiently if few TDM channels are in use.
• a more efficient mode and simpler system implementation from a software perspective is to convert the TDM traffic to ATM and run in a circuit emulation mode.
• This approach allows for dynamic bandwidth allocation between TDM and ATM of the OC link.
• the key differences are from a configuration standpoint.
• the advent of a GR-303 STS-1 Class 5 switch interface imposes an asynchronous VT mapping structure on the SONET transport.
• the primary application for the STS-1 switch interface is to feed multiple remotes via a fiber ring without requiring a COT. Therefore, a VT mapped payload between nodes would permit the new platform to interface directly with the switch are participate in the fiber distribution ring but with a relatively inefficient bandwidth for mixed TDM and ATM traffic.
• the new platform node-to-node links are transported via circuit emulation, the new platform can no longer participate in the ring unless a ring within a ring is provisioned.
• two nodal interfaces are foreseen: one being the bandwidth-optimized circuit emulation mode, the other being a VT mapped transport specifically for the STS-1 switch/ring interface.
• the basic ATM elements of service are defined as: a) Class of Service (CoS) which specifies which type of service or application that can be provided, b) Quality of Service (QoS) specifies how well a given service will perform, and c) Traffic Management which is the umbrella under which both QoS and CoS is specified.
• CoS Class of Service
• QoS Quality of Service
• Traffic Management which is the umbrella under which both QoS and CoS is specified.
• PCR Peak Cell Rate
• CDVT Cell Delay Variation Tolerance
• SCR Sustained Cell Rate
• MCS Maximum burst size
• CBR always carries the highest network priority with UBR being the lowest.
• VBR and ABR priority may be negotiated.
• Each ATM class of service has defined or negotiated attributes and is measured against them:
• Goodput is a measure of ATM cell traffic efficiency through the system fabric.
• Per VC Queuing allows a switch to independently hold the cells without impacting other connections.
• Fair-weighted Queuing is a mechanism for fairly servicing all virtual connection queues destined to a particular outgoing link while providing each with the requested QoS. Weighting applies to the switches ability to assign priority to certain service categories requiring low cell loss and low delay.
• Packet Discarding drops whole packets and not just individual cells to relieve congestion.
• the Packet represents the higher-layer application like TCP/IP.
• a corrupt cell in a TCP/IP packet would result in the client equipment rejecting the whole packet and requesting a retransmission, which results in further congestion, and a greater chance of more cells being discarded.
• the services are defined as:
• L2TP Access Concentration The purpose of L2TP tunneling is to group multiple PPP session and transports them over a layer 2 network to a particular destination. This allows the end users to use the widely deployed PPP protocol while eliminating the need for the access equipment to fully terminate the PPP sessions. It is an alternative being proposed within the Standards Forums in place of CPE devices using ATM interface with Q.2931 signaling and the access network functioning as a signaling node.
• LAC determines destination based on users domain name
• LAC encapsulates PPP session into pre-existing L2TP Session or generates new L2TP Session if one does not exist
• LAC Terminates Network based ATM/Frame Relay/Leased Line
• Fig. 16 shows Residential User to ISP, PPP.
• Virtual Private Networking appears as a standard Internet access connection to the new platform.
• the Client initiates a standard PPP session with the access system with the Client sending packets destined to the IP address of the corporate network.
• the LAC initiates a tunnel above that IP layer with traffic at this layer that may or may not be encrypted based on the client/corporate policy (see below) .
• the client now has to manage multiple network logins but this is common practice to provide the security demanded by most corporate networks _
• Fig. 17 illustrates Remote LAN Access using PPP.
• Frame Relay combines the statistical multiplexing and port sharing features of X.25 with the high speed and low delay characteristics of TDM circuit switching. Defined as a "packet-mode" service, Frame Relay organizes data into individually addressed units known as frames rather than placing it into fixed time slots. This gives Frame Relay statistical multiplexing and port sharing characteristics.
• Frame Relay is a data link protocol that can transport upper layer multi-protocol traffic.
• the new platform is based on two switching fabrics namely TDM and ATM.
• TDM TDM capable line cards exist for Litespan ® today. Thus it makes sense to leverage the existing line cards when it makes sense.
• DDS Frame Relay access
• BRI BRI
• Tl case a fractional Tl transport may be provisioned and the Litespan ® system may be provisioned to groom the DSOs.
• Fig. 18 compares a TDM mode new platform (top half of diagram below) with a Frame Relay capable new platform
• Type 1 consists of multiple low- speed Frame Relay aggregated into a non-channelized high-speed interface.
• An example is 24 x 64 Kb/s which are aggregated into a single non-channeled Tl. This configuration in effect provides a rate adaptation function between the Tl and the low-speed drop side ports .
• Type 2 is similar to Type 1, however, this mode permits the drop side bandwidth to exceed the DSl bandwidth.
• An example would be 48 x 64Kbps are concentrated into one DSl. In this case the sum of the committed information rate (CIR) must be less than 1.536 Mb/s.
• TDM Mode Supported for Frame Relay, Aggregation (TDM Mode)
• bonding may be required for 128kbps case.
• the frame relay aggregation module comprises a new network side card.
• the drop side cards are existing Litespan line cards.
• the module is compatible with existing Litespan TDM drop side cards as necessary and with FT1, DDS, BRI, etc.
• the frame relay concentration module comprises a new network side card.
• the drop side cards are existing Litespan line cards.
• the module is compatible with existing Litespan TDM drop side cards as necessary and with FT1, DDS, BRI, etc.
• Tl framer with 48 drop side HDLC controllers One network side HDLC controller
• the frame relay module roughly comprises:
• Frame Relay processing functions are located on a resource module (based on a multichannel HDLC controller) that can be added in a modular fashion to the system.
• a centralized gateway function between the TDM and ATM fabric is also provided in an embodiment. With a gateway, it is possibly to reuse existing TDM drop side cards. The gateway provides the inter-working function between TDM and ATM cards.
• Drop side is PRI, BRI, FT1 with NxDSO Network side is one HDLC T3 with 28 (aggregated) or up to 128 (concentrated) drop side HDLC controllers Traffic management for PVCs Network management/provisioning for PVCs
• Drop side is PRI, BRI, FT1 with NxDSO Network side consists of 1 HDLC HSSI/V.35 with 28 (aggregated) or up to 128
• Frame to ATM is becoming a common requirement at the edge of the network.
• an operator's network has an ATM core with several service level shells such as Frame Relay. Interworking between Frame and ATM can greatly streamline the network design and offer enhanced reliability due to the reduced number of network elements.
• the functions of ATM to Frame interworking are: Fra e Relay Forum and ATM forum interworking specifications for service and transport
• Drop side format is frame relay with many HDLC (up to 128 controllers) mapped to various physical ports PRI, BRI, FT1 with NxDSO, and xDSL
• Network side consists of ATM AAL5 SAR controller
• Transport functions are principally SONET based interfaces at the OC-3 and OC-12 rates with an upgrade path to OC-14. Concatenation is required for highspeed ATM streams. Both byte-synchronous and floating VT mapping is required. Configuration support required is follows:
• ETSI product requirements are different from those of the ANSI market. Some of the key differences are:
• Signal interfaces are based on a 2 Mb/s hierarchy vs. 1.5 Mb/s There are 30 message channels vs. 24
• Out of band signaling is used vs. robbed bit
• V5.1 and V5.2 switch interface 600 mm bank A full list of ETSI and international industry requirements is provided in References and Related Documents below.
• a new series of cabinets and enclosures are low cost and existing cabinets are optimized for 2 or 4 new platform shelves. Technologies such as Heat Pipes (exchangers) and lexan polycarbonates are used. Generally for the traditional RBOC market, TR-487 defines the housing requirements. However, when new markets are entered such as the CLECs, the requirements may be relaxed.
• Fiber-to-the-Node/Curb/Home (FTTN, FTTC, FTTH)
• Fiber-to-the-Node/Curb/Home defines the termination point of a fiber distribution feed to an optical network unit (ONU) where the service is then provided by copper twisted pair.
• ONUs are essentially small remote terminals served from an HDT.
• the above topology is covered by the umbrella term Fiber- in-the- Loop (FITTL) .
• FITTL Fiber- in-the- Loop
• the key difference between FTTN/C/H is the location and number of subscribers served. The distance from the ONU to the subscriber is inversely proportional to the effective data rate over the copper pair.
• FTTN serves hundreds of subscribers
• FTTC serves tens of subscribers
• FTTH serves units.
• FTTH is also known as FTTBuilding or Basement (FTTB) .
• IMA Inverse Multiplexed ATM
• LAC L2TP Access Concentrator
• LAC is a device attached to the switched network fabric (e.g. PSTN, ISDN, ATM) or co-located with a PPP end system capable of handling the L2TP protocol.
• the LAC needs only the media over which L2TP is to operate to pass traffic to one or more LNS's. It may tunnel any protocol carried within PPP.
• the LAC is the initiator of incoming calls and the receiver of outgoing calls.
• LNS L2TP Network Server
• An LNS operates on any platform capable of PPP termination.
• the LNS handles the server side of the L2TP protocol. Since L2TP relies only on the single media over which L2TP tunnels arrive, the LNS may have only a single LAN or WAN Interface, yet still be able to terminate calls arriving at any LAC's full range of PPP interfaces (asynchronous, synchronous ISDN, V.120, ADSL, etc.).
• the LNS is the initiator of outgoing calls and the receiver of incoming calls.
• Point-to-Point Protocol The point-to-point protocol is commonly used for dial- in connections to the public Internet.
• PPP is a link layer protocol used on a point-to-point basis for control of the link (Link Control Protocol, LCP) , network-layer control, authentication, and compression. These capabilities require a point-to- point relationship between peers such as client PC and network server.
• the Point-to-Point Protocol provides a standard method for transporting multiprotocol datagrams over point-to-point links and is now used with ADSL.
• a tunnel is a defined by an LNS-LAC pair.
• the tunnel carries PPP datagrams between the LAC and the LNS. Many sessions can be multiplexed over a single tunnel.
• a control connection operating in-band over the same tunnel controls the establishment, release, and maintenance of sessions and of the tunnel itself.
• a tunnel is sometimes referred to as a control connection.
• CDV Cell Delay Variation CDVT Cell Delay Variation Tolerance
• VCC Virtual Channel Connection VCI Virtual Channel Identifier

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• 1999
  • 1999-08-18 AU AU56843/99A patent/AU5684399A/en not_active Abandoned
  • 1999-08-18 EP EP99943817A patent/EP1104644A4/de not_active Withdrawn
  • 1999-08-18 WO PCT/US1999/019093 patent/WO2000011880A2/en active Application Filing

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