US20070286200A1 - Fault tolerant atm-based distributed virtual tandem switching system and method - Google Patents

Fault tolerant atm-based distributed virtual tandem switching system and method Download PDF

Info

Publication number
US20070286200A1
US20070286200A1 US11/739,250 US73925007A US2007286200A1 US 20070286200 A1 US20070286200 A1 US 20070286200A1 US 73925007 A US73925007 A US 73925007A US 2007286200 A1 US2007286200 A1 US 2007286200A1
Authority
US
United States
Prior art keywords
iwf
sms
unit
data network
signaling
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
US11/739,250
Inventor
Haifeng Bi
George Allen
Randy BEAMON
Alice CARLSON
Weijing Chen
Janice DOERNER
Mehran Esfandiari
Gary GIBBONS
Paul KASCHUBE
Bruce NANCE
John PINCH
Tina Sigarto
Barbara Smith
Matthew Stafford
George YOUNG
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
AT&T Labs Inc
Original Assignee
AT&T Labs Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US09/287,092 external-priority patent/US6169735B1/en
Application filed by AT&T Labs Inc filed Critical AT&T Labs Inc
Priority to US11/739,250 priority Critical patent/US20070286200A1/en
Publication of US20070286200A1 publication Critical patent/US20070286200A1/en
Abandoned legal-status Critical Current

Links

Images

Classifications

    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00Data switching networks
    • H04L12/54Store-and-forward switching systems 
    • H04L12/56Packet switching systems
    • H04L12/5601Transfer mode dependent, e.g. ATM
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04QSELECTING
    • H04Q11/00Selecting arrangements for multiplex systems
    • H04Q11/04Selecting arrangements for multiplex systems for time-division multiplexing
    • H04Q11/0428Integrated services digital network, i.e. systems for transmission of different types of digitised signals, e.g. speech, data, telecentral, television signals
    • H04Q11/0478Provisions for broadband connections
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04JMULTIPLEX COMMUNICATION
    • H04J2203/00Aspects of optical multiplex systems other than those covered by H04J14/05 and H04J14/07
    • H04J2203/0001Provisions for broadband connections in integrated services digital network using frames of the Optical Transport Network [OTN] or using synchronous transfer mode [STM], e.g. SONET, SDH
    • H04J2203/0046User Network Interface
    • H04J2203/0048Network termination, e.g. NT1, NT2, PBX
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04JMULTIPLEX COMMUNICATION
    • H04J2203/00Aspects of optical multiplex systems other than those covered by H04J14/05 and H04J14/07
    • H04J2203/0001Provisions for broadband connections in integrated services digital network using frames of the Optical Transport Network [OTN] or using synchronous transfer mode [STM], e.g. SONET, SDH
    • H04J2203/0064Admission Control
    • H04J2203/0066Signalling, e.g. protocols, reference model
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04JMULTIPLEX COMMUNICATION
    • H04J2203/00Aspects of optical multiplex systems other than those covered by H04J14/05 and H04J14/07
    • H04J2203/0001Provisions for broadband connections in integrated services digital network using frames of the Optical Transport Network [OTN] or using synchronous transfer mode [STM], e.g. SONET, SDH
    • H04J2203/0073Services, e.g. multimedia, GOS, QOS
    • H04J2203/0078Support of N-ISDN
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00Data switching networks
    • H04L12/54Store-and-forward switching systems 
    • H04L12/56Packet switching systems
    • H04L12/5601Transfer mode dependent, e.g. ATM
    • H04L2012/5614User Network Interface
    • H04L2012/5618Bridges, gateways [GW] or interworking units [IWU]
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00Data switching networks
    • H04L12/54Store-and-forward switching systems 
    • H04L12/56Packet switching systems
    • H04L12/5601Transfer mode dependent, e.g. ATM
    • H04L2012/5625Operations, administration and maintenance [OAM]
    • H04L2012/5627Fault tolerance and recovery
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00Data switching networks
    • H04L12/54Store-and-forward switching systems 
    • H04L12/56Packet switching systems
    • H04L12/5601Transfer mode dependent, e.g. ATM
    • H04L2012/5629Admission control
    • H04L2012/563Signalling, e.g. protocols, reference model
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00Data switching networks
    • H04L12/54Store-and-forward switching systems 
    • H04L12/56Packet switching systems
    • H04L12/5601Transfer mode dependent, e.g. ATM
    • H04L2012/5638Services, e.g. multimedia, GOS, QOS
    • H04L2012/5646Cell characteristics, e.g. loss, delay, jitter, sequence integrity
    • H04L2012/5652Cell construction, e.g. including header, packetisation, depacketisation, assembly, reassembly
    • H04L2012/5653Cell construction, e.g. including header, packetisation, depacketisation, assembly, reassembly using the ATM adaptation layer [AAL]
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00Data switching networks
    • H04L12/54Store-and-forward switching systems 
    • H04L12/56Packet switching systems
    • H04L12/5601Transfer mode dependent, e.g. ATM
    • H04L2012/5638Services, e.g. multimedia, GOS, QOS
    • H04L2012/5663Support of N-ISDN
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00Data switching networks
    • H04L12/54Store-and-forward switching systems 
    • H04L12/56Packet switching systems
    • H04L12/5601Transfer mode dependent, e.g. ATM
    • H04L2012/5638Services, e.g. multimedia, GOS, QOS
    • H04L2012/5671Support of voice
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00Data switching networks
    • H04L12/54Store-and-forward switching systems 
    • H04L12/56Packet switching systems
    • H04L12/5601Transfer mode dependent, e.g. ATM
    • H04L2012/5687Security aspects
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L49/00Packet switching elements
    • H04L49/55Prevention, detection or correction of errors
    • H04L49/557Error correction, e.g. fault recovery or fault tolerance

Definitions

  • the present invention relates to the field of telecommunications. More particularly, the present invention relates to reliably constructing and operating asynchronous transfer mode (ATM)-based telecommunications networks.
  • ATM asynchronous transfer mode
  • Tandem replacement using voice trunking over ATM (VTOA) technology is one application of an ATM distributed network system architecture.
  • the architecture represents a new paradigm of networking that requires rethinking of how to run networks.
  • An important consideration is how to construct and operate the new ATM-based virtual tandem switch as reliably as possible and, definitely, no less reliably than current time division multiplexed (TDM) tandems.
  • TDM time division multiplexed
  • the ATM-based virtual tandem system impacts system reliability.
  • the virtual tandem improves system reliability by distributing its components geographically, localizing the impact of failures.
  • a greater number of network elements is involved, and thus the number of occurrences of element failures may increase.
  • the virtual tandem is designed to serve an entire metropolitan area, it is imperative for the virtual tandem's design to meet the highest level of survivability.
  • the present invention identifies potential failure points in the virtual tandem and provides solutions to reduce and survive failures.
  • the solutions place design and engineering requirements upon equipment vendors and companies operating the virtual tandem. It is therefore a primary object of the present invention to employ these requirements for use in the design of the network elements and for engineering the networks.
  • standard call processing employs end offices 10 connected via tandem trunks 12 , direct trunks 14 , or both tandem trunks 12 and direct trunks 14 .
  • Each trunk 12 , 14 is a digital service level 0 (DS0), operating at 64 kbps, that is transmitted between the switching offices 10 in a time division multiplexed manner.
  • DS0 digital service level 0
  • Each end office 10 connects to its neighboring end office 10 and the tandem office 16 using separate trunk groups. In this system, trunk groups are forecasted and pre-provisioned with dedicated bandwidth, which may lead to inefficiency and high operations cost.
  • a new voice trunking system using ATM technology has been proposed in U.S. patent application Ser. No. 09/287,092, entitled “ATM-Based Distributed Virtual Tandem Switching System.”
  • voice trunks from end office switches 20 , 26 are converted to ATM cells by a first or second trunk inter-working function (T-IWF) device 22 , 24 .
  • the T-IWFs 22 , 24 are distributed to each end office 20 , 26 , and are controlled by a centralized control and signaling inter-working function (CS-IWF) device 28 .
  • the CS-IWF 28 performs call control functions as well as conversion between the narrowband Signaling System No. 7 (SS7) protocol and a broadband signaling protocol.
  • SS7 narrowband Signaling System No. 7
  • the T-IWFs 22 , 24 , CS-IWF 28 , and the ATM network 30 form the ATM-based distributed virtual tandem switching system.
  • VTOA voice trunking over ATM
  • trunks are no longer statistically provisioned as DS0 time slots. Instead, the trunks are realized through dynamically established switched virtual connections (SVCs), thus eliminating the need to provision separate trunk groups to different destinations, as done in TDM-based trunking networks.
  • SVCs switched virtual connections
  • FIG. 1 shows a conventional TDM telecommunications network architecture
  • FIG. 2 shows a known virtual trunking over ATM telecommunications network architecture
  • FIG. 3 shows a CS-IWF complex architecture, according to one aspect of the present invention
  • FIG. 4 shows an end office architecture and its relationship with an ATM network, according to another aspect of the present invention.
  • FIG. 5 shows an SMS connected to an ATM network, according to a further aspect of the present invention.
  • the present invention is directed to improving the reliability of the VTOA system.
  • the present invention identifies potential failure points of the VTOA system and provides various configurations to minimize the impact of failures.
  • a control and signaling interworking function (CS-IWF) complex for use within a VTOA system that communicates with mated signaling transfer points.
  • the VTOA system includes an ATM network including multiple ATM switches and multiple trunk interworking functions (T-IWFs).
  • the CS-IWF complex includes multiple CS-IWF units connected to at least two of the ATM switches and connected to at least one of the signaling transfer points.
  • Each CS-IWF unit has multiple processors with at least one processor compensating for a failed processor.
  • a CS-IWF unit fails, at least one other CS-IWF unit compensates for the failed CS-IWF unit.
  • the processor(s) compensating for the failed processor cooperate with the CS-IWF unit(s) compensating for the failed CS-IWF unit so that the CS-IWF complex survives simplex failures.
  • the CS-IWF complex includes multiple signaling link sets. Each link set connects the CS-IWF complex to one of the mated STPs.
  • the CS-IWF complex may also include multiple signaling gateways that connect to each of the CS-IWF units. Each signaling gateway connects to one of the mated STPs. The multiple signaling gateways minimize isolation of the CS-IWF units when a link failure occurs.
  • the CS-IWF complex also includes multiple ATM links that connect each CS-IWF unit to multiple ATM switches.
  • the multiple processors within each CS-IWF unit operate in an active/standby mode.
  • the multiple processors operate in a load sharing mode.
  • At least one of the CS-IWF units is located in a building separate from a building housing at least one other of the CS-IWF units.
  • a single point code identifies the CS-IWF complex.
  • an end office building for use with a VTOA system.
  • the VTOA system includes an ATM network including interconnected ATM switches, and at least one CS-IWF complex.
  • the end office building includes multiple T-IWFs, which are part of the VTOA system.
  • Each T-IWF has multiple processors with at least one processor compensating for a failed processor.
  • at least one T-IWF absorbs at least a portion of a failed T-IWF's workload.
  • the end office building also includes a switch that distributes calls among the T-IWFs in a load sharing manner.
  • the processor(s) compensating for the failed processor cooperate with the T-IWF(s) absorbing at least a portion of the failed T-IWF's workload so that the end office building survives simplex failures.
  • the end office building also includes at least one add/drop multiplexor (ADM) that connects the multiple T-IWFs to the ATM network.
  • ADM add/drop multiplexor
  • each T-IWF also includes an optical interface for connecting to the ADM.
  • the optical interface supports SONET 1+1 automatic protection switching.
  • At least one T-IWF connects to a first ATM switch that is different from a second ATM switch to which another T-IWF connects.
  • each end office building connects to multiple ATM switches so that if one ATM switch fails, the end office building remains connected to the ATM network.
  • a method for recovery from a failing ATM link in a VTOA system.
  • the VTOA system includes an ATM network having multiple ATM switches interconnected by ATM links, multiple T-IWFs, and at least one CS-IWF complex.
  • the method includes delaying recovery action in the ATM network for a predetermined duration while SONET recovery of the link is attempted. If the SONET recovery is successful, a call path through the ATM network stays up. If the SONET recovery is unsuccessful, existing calls carried by the failed ATM link are dropped.
  • the predetermined duration is 100 milliseconds.
  • a switch management system for use within a VTOA system.
  • the VTOA system includes an ATM network including a least one ATM switch, multiple T-IWFs, and at least one CS-IWF complex.
  • the switch management system includes multiple switch management system units. At least one of the switch management system units is a backup unit for at least one primary switch management system unit. Each switch management system unit provides application redundancy within itself. Consequently, the switch management system survives simplex failures.
  • the primary switch management system unit is located in a building separate from a building housing the backup switch management system unit.
  • each switch management system unit is connected to multiple ATM switches.
  • a method for restoring functions of a failed switch management system operating within a VTOA system.
  • the VTOA system includes an ATM network including multiple ATM switches, multiple T-IWFs, and at least one CS-IWF complex.
  • the method includes restoring essential surveillance of the VTOA system; restoring billing functions of the VTOA system; restoring full surveillance capability of the VTOA system; restoring configuration management of the VTOA system; and restoring performance management of the VTOA system.
  • a VTOA system includes an ATM network having multiple interconnected ATM switches. Also provided are multiple mated signaling transfer points that communicate with the VTOA system.
  • the VTOA system also includes at least one CS-IWF complex including multiple CS-IWF units connected to at least two of the ATM switches and connected to at least one of the signaling transfer points. Each unit has multiple processors that share load resulting from failure of one of the processors.
  • at least one end office building is provided for interaction with the VTOA system. Each end office building includes multiple T-IWFs, each having multiple processors.
  • a switch is also provided in the end office building(s) to distribute calls among the multiple T-IWFs in a load sharing manner.
  • the VTOA system also includes a switch management system including multiple switch management system units. At least one of the switch management system units is a backup unit for at least one primary switch management system unit. Each switch management system unit provides application redundancy within itself. Consequently, the VTOA system survives simplex failures. According to another embodiment, there are at least two completely disjointed routes between any two end points.
  • a method for communicating over a VTOA system.
  • the VTOA system includes a CS-IWF complex, an ATM network containing multiple ATM switches, and a signaling network.
  • Multiple end office buildings are provided for interaction with the VTOA system.
  • Each end office building includes a switch and multiple T-IWFs, which are part of the VTOA system.
  • the method includes transmitting a signal from the switch to the T-IWFs in a load sharing manner; and transmitting from the T-IWFs to the ATM switches in a load sharing manner.
  • communications survive a simplex failure in the VTOA system.
  • CS-IWF failure CS-IWF failure
  • T-IWF failure T-IWF failure
  • ATM network failure ATM network failure
  • SMS failure SMS failure.
  • a simplex failure is the occurrence of a single network element failure, in contrast to simultaneous failures of multiple network elements. To survive means that, in the event of a simplex failure, the network must be able to continue to operate and recover on its own either to its normal or to a compromised level of performance.
  • the CS-IWF is the most critical element of the new virtual tandem because failure of the CS-IWF impacts the entire serving area. Thus, failure of the CS-IWF is not acceptable, and therefore the CS-IWF requires the highest level of reliability.
  • Exemplary CS-IWF units include the Connection Gateway from Lucent Technologies Inc, and the Succession Call Server, from Nortel Networks Corporation.
  • FIG. 3 shows a design for a reliable CS-IWF complex 300 that includes multiple CS-IWF units 310 , 320 , 330 .
  • each CS-IWF complex 300 serving a metropolitan area is assigned a single point code, regardless of how many individual CS-IWF units 310 , 320 , 330 the complex 300 contains.
  • FIG. 3 a general case is depicted where the CS-IWF complex 300 includes of n CS-IWFs 310 , 320 , 330 for reasons of reliability or processing capacity.
  • each CS-IWF unit 310 , 320 , 330 must be highly reliable.
  • redundant processors are provided within each CS-IWF 310 , 320 , 330 for protection against processor failure.
  • FIG. 3 processor 0 311 , 321 , 331 and processor 1 312 , 322 , 332 are shown, although one of ordinary skill in the art will realize that more processors can be added without departing from the scope of the present invention.
  • the redundant processors may operate in an active/standby mode or in a load sharing mode.
  • Each CS-IWF complex 300 must contain spare capacity for protection.
  • n CS-IWF units 310 , 320 , 330 In general, in a CS-IWF complex 300 of n units, up to k (k>1) out of the n CS-IWF units 310 , 320 , 330 must be provided for the purpose of protection. The objective is that the loss of one CS-IWF 310 unit has no impact on the call handling capacity of the CS-IWF complex 300 as a whole. In the active/standby mode, n ⁇ k CS-IWFs 310 , 320 are active, and k operate in standby mode.
  • all n CS-IWFs 310 , 320 , 330 run at levels less than maximum such that if one of the CS-IWFs 310 should fail, its processing load can be absorbed by the remaining CS-IWFs 320 , 330 .
  • all components of a CS-IWF complex 300 are not provided at the same physical location. As a result, the loss of one physical location does not shut down the entire network. In this embodiment, the components can be connected via either dedicated or networked links. All components of the CS-IWF complex 300 are NEBS level 3 compliant. See GR-63-CORE, (Network Equipment—Building System [NEBS] Requirements: Physical Protection)—A module of LSSGR, FR-64; TSGR, FR-440; and NEBSFR, FR-2065; GR-1089-CORE, (Electromagnetic Compatibility and Electrical Safety Generic.
  • GR-63-CORE Network Equipment—Building System [NEBS] Requirements: Physical Protection
  • Criteria for Network Telecommunications Equipment A module of LSSGR, FR-64; and TSGR, FR-440; and SR-NWT-002550, (Technical Considerations for NEBS-2000), the disclosures of which are expressly incorporated by reference in their entireties, for more about NEBS level 3.
  • STPs typically include mated pairs 370 , 380 operating in a load-sharing manner to increase reliability.
  • a CS-IWF complex 300 maintains, at a minimum, two signaling link sets, one with each of the local mated STPs 370 , 380 .
  • the CS-IWF units 310 , 320 , 330 are connected with the signaling link sets in a configuration that minimizes the possibility of any CS-IWF unit 310 , 320 , 330 being isolated from the signaling network as a result of a link or link-set failure.
  • a non-limiting example of such interconnection using signaling gateways 350 , 360 is shown in FIG. 3 .
  • the CS-IWF complex must support low-speed signaling links (e.g., 56 kbps to operate with SS7) with the ability to migrate to high-speed links (e.g., T1 or T1 ATM).
  • Each CS-IWF complex 300 bridges between narrowband and broadband signaling.
  • the narrowband signaling may be in the form of SS7 ISUP messages
  • the broadband signaling may be standard-based broadband signaling, for example ATM UNI or PNNI.
  • the signaling gateways 350 , 360 are part of the CS-IWF complex 300 and distribute SS7 signaling to each CS-IWF unit 310 , 320 , 330 .
  • the signaling gateways 350 , 360 form an interconnection network that connects STPs 370 , 380 to CS-IWF units 310 , 320 , 330 .
  • the signaling gateways are a distribution vehicle.
  • An exemplary signaling gateway is the Connection Gateway Signaling Node, manufactured by Lucent Technologies, Inc.
  • each CS-IWF 310 , 320 , 330 maintains an ATM link with two different ATM switches 390 , 395 in the ATM network so that the CS-IWF complex 300 can communicate with T-IWFs, other CS-IWFs and the SMS (not shown in FIG. 3 ).
  • the ATM switches 390 , 395 are on separate SONET rings.
  • the well known 1+1 automatic protection switching (APS) is not required.
  • each T-IWF is highly reliable, i.e., nearly always available. Therefore, according to one embodiment, the critical components (e.g., processor) within a T-IWF are redundant to achieve this object.
  • Exemplary T-IWFs include the 7R/E Trunk Access Gateway, from Lucent Technologies Inc.; and the Succession Multi-service Gateway 4000 (MG 4000), from Nortel Networks Corporation.
  • FIG. 4 illustrates an exemplary architecture of an end office building 400 and its relationship to an ATM network 475 .
  • a class 5 end office building (EO) 400 includes a switch 402 , associated T-IWFs 404 , 406 , 408 , which should be NEBS level 3 compliant, and a SONET add/drop multiplexer (ADM) 410 .
  • Exemplary switches include class 5 switches such as: the Lucent Technologies Inc. 1AESS; the Lucent Technologies Inc. 5ESS; the Ericsson AXE-10; and/or the Northern Telecom (Nortel) DMS-100 switches.
  • FIG. 1AESS the Lucent Technologies Inc. 1AESS
  • the Lucent Technologies Inc. 5ESS the Lucent Technologies Inc. 5ESS
  • the Ericsson AXE-10 the Northern Telecom (Nortel) DMS-100 switches.
  • Nortel Northern Telecom
  • FIG. 4 a general case is shown where multiple T-IWF units 404 , 406 , 408 , are deployed in an end office building 400 for reasons of reliability or capacity.
  • switch 402 and ATM switches 420 , 430 shown in FIG. 4 are not co-located in the same end office building 400 , such co-location may occur in other end office buildings.
  • a class 5 switch having traffic volume requiring only one T-IWF is still connected with two T-IWFs for protection. Consequently, loss of one T-IWF does not isolate the class 5 switch. Furthermore, a class 5 switch must be able to maintain as few as one trunk group regardless of the number of T-IWFs by which it is served. According to an embodiment, the class 5 switch 402 distributes its calls among the T-IWFs 404 , 406 , 408 in a load-sharing manner. Thus, loss of one of the T-IWFs 404 , 406 , 408 may degrade the trunking capacity of the class 5 switch 402 , but will not isolate the class 5 switch 402 .
  • the optical interface on the T-IWF 404 , 406 , 408 for connecting with the SONET add/drop multiplexer (ADM) 410 (or an ATM switch 420 , 430 when an ATM switch 420 , 430 is located in the same end office building 400 ) supports the SONET 1+1 Automatic Protection Switching (APS) scheme, although deployment of this feature is optional.
  • the ADM 410 connects the T-IWFs 404 , 406 , 408 to the ATM switches 420 , 430 at the ATM layer via links 440 , 450 .
  • the links 440 , 450 are preferably SONET rings that connect the T-IWFs 404 , 406 , 408 to ATM switches 420 , 430 in a load sharing manner.
  • Exemplary ADMs are manufactured by Fujitsu, Lucent Technologies Inc., and Nortel.
  • Each T-IWF 404 , 406 , 408 serving a given end office building 400 does not connect to the ATM network at the same ATM switch 420 , 430 . Rather, each T-IWF 404 , 406 , 408 is single-homed to an ATM switch 420 , 430 , while each end office building 400 is multi-homed to multiple ATM switches 420 , 430 , preferably on separate SONET rings 440 , 450 . This configuration prevents the end office building 400 from becoming totally disconnected from the ATM network in the event of an ATM host 420 , 430 failure, although the T-IWFs 404 , 406 , 408 connected to the failed ATM switch 420 , 430 may be impacted.
  • the SONET transport network 440 , 450 employs unidirectional path switched ring (UPSR) or bi-directional line switched ring (BLSR).
  • UPSR unidirectional path switched ring
  • BLSR bi-directional line switched ring
  • the ATM layer virtual path protection capability in a SONET/ATM hybrid transport node may be supported.
  • the ATM VP ring functionality may be integrated into the T-IWF 404 , 406 , 408 and the ATM switches 420 , 430 .
  • ATM virtual path (VP) ring functionality is either integrated with or separated from the T-IWF 404 , 406 , 408 to achieve the potential benefits of ATM layer VP protection and transport layer efficiency.
  • ATM switches are not protected with redundant ATM switches; nor are ATM virtual connections carrying bearer channels protected with redundant virtual connections.
  • the 1+1 protection of user network interface (UNI) interfaces on ATM switches is not universally deployed.
  • no attempt (such as virtual connection re-routing) will be made at the ATM layer to save calls in progress that are impacted by an ATM equipment or link failure.
  • the 1+1 protection enables SONET recovery by directing traffic from a failed ring, e.g., a cut ring, to a properly functioning ring. That is, two devices are connected by two rings (one active ring and one standby ring) in the usual manner. When the active ring fails, the standby ring is activated.
  • the network In order to eliminate single points of total failure in the ATM network, the network must be constructed so that between any two end points at least two completely disjointed routes traverse the ATM network. Consequently, the ATM switches are able to intelligently route calls in this network, e.g., by balancing the call load between disjointed routes to reduce the impact of failure as well as to improve network performance. The balanced intelligent routing is performed in a known manner.
  • An ATM link failure occurs as result of a transport facility failure, such as a fiber cut.
  • the ATM network therefore relies on known protection schemes in the transport network to recover from such a failure.
  • the ATM switch detects a link failure, the ATM switch delays recovery action for a predetermined time period, preferably 100 ms, during which time the SONET layer recovery is attempted. If the transport layer successfully recovers, then the impact of the failure will only be a momentary degradation of the voice connections, and the connected call paths stay up. If the transport layer fails to recover from such a link failure, then existing calls being carried by the link are dropped. The ATM switches on both ends of the failed link will then flag the associated ports as unavailable, and future calls will automatically avoid the failed link until it is repaired. After the link is repaired, no manual intervention is required in order for traffic to resume using that link, as is well known.
  • ATM switching equipment failures only include failures of non-redundant components, such as un-protected interface cards, or a whole switch.
  • Exemplary ATM switches include the MainStreetXpress 36170 Multiservices Switch or 670 RSP, both manufactured by Newbridge Networks Corporation; the GX 550 Smart Core ATM Switch, manufactured by Lucent Technologies Inc.; and the Passport 15000 Multiservice Switch, manufactured by Nortel Networks Corporation.
  • common equipment in an ATM switch such as the switching fabric, the control processor, the power supply, wiring, fuses, alarms, etc. are redundant. Consequently, failure of one such unit has no impact on the operation or the performance of the ATM switch.
  • Redundant interface cards are not provided. Thus, when an un-protected interface card or port fails, calls being carried by that interface card or port are dropped. The ATM switches connected via the failed interface card or port will then flag the associated card or port as unavailable, and future calls will automatically avoid using the failed card or port until it is repaired. After the card or port is repaired, minimal manual intervention will be required in order for traffic to resume using that card or port, as is well known.
  • redundant ATM switches are not provided.
  • an ATM switch does not have a standby.
  • calls being carried by the ATM switch are dropped.
  • the ATM network will then flag the failed switch as unavailable, and future calls will automatically avoid this switch until it is repaired.
  • minimal manual intervention will be required in order for traffic to resume using that ATM switch, as is well known.
  • FIG. 5 shows a single switch management system (SMS) unit 500 .
  • the SMS is the element layer manager of the ATM-based virtual tandem. It communicates with the T-IWFs and the CS-IWF, and the legacy operation support systems (OSS). Essentially, it controls management of the distributed switch and acts as a man-machine interface enabling a human user to view and control the overall behavior of the VTOA. According to one embodiment, it communicates with other network management systems involved in the virtual tandem, such as the operation support system of the ATM network.
  • the SMS can be located either in a central office or in a data center, and should be NEBS level 3 compliant. Exemplary SMSs include the OneLink Manager, from Lucent Technologies Inc., and the Succession Network Manager, from Nortel Networks Corporation.
  • the SMS includes a primary SMS unit 500 and a backup SMS unit (not shown) that takes over if the primary SMS unit 500 fails. That is, the primary and the backup SMS units operate in an active/standby mode.
  • the backup SMS unit may support multiple primary SMS units 500 , as dictated by engineering and operational network requirements, and must be located in a different building from the building housing the primary SMS unit 500 .
  • each SMS unit 500 maintains dual ATM links 510 , 520 with two different ATM switches 530 , 540 , preferably on separate SONET rings.
  • the dual links 510 , 520 allow control communications with the backup SMS unit, the T-IWFs, and the CS-IWF.
  • each switch management system unit has management connectivity to other VTOA system elements provided by paths through the ATM network.
  • Each SMS unit must provide application redundancy within itself, with automatic, transparent switch over in the event of failure of the active SMS application. Redundancy may be accomplished by providing a backup processor in each physical platform and/or providing backup software applications. For example, two applications may run side by side in a single processor, or separately in two processors, or the second application may begin in the second processor when the first application fails. Consequently, if part of one physical platform fails, the remaining portion of the physical platform is configured so that it can compensate for the failed portion.
  • the switch of its load to the other unit must be accomplished with minimal manual actions, ideally no actions and preferably no more than a system administrator approaching the physical platform and issuing necessary instructions to the SMS through a computer terminal. Failure of the active unit must have minimal impact on an operations user of an SMS graphical user interface (GUI). For example, the operations user should not have to re-boot the computer or re-log in to the computer to continue using the GUI. Slower processing of commands is acceptable, and alarms and/or notifications of the switchover are necessary.
  • GUI graphical user interface
  • the SMS as a system restores its operation in the following sequence:
  • Each SMS unit has its own continually updated database.
  • Each database is synchronized with the other VTOA databases.
  • the database enables the five functions discussed above and includes such information as the system users, networking software, the network inventory, security, etc. Awareness of the network topology is also provided by the database.
  • the methods described herein are intended for operation as software programs running on a computer processor.
  • Dedicated hardware implementations including, but not limited to, application specific integrated circuits, programmable logic arrays and other hardware devices can likewise be constructed to implement the methods described herein.
  • the software implementations of the present invention can be stored on a tangible storage medium such as a magnetic or optical disk, read-only memory or random access memory and be produced as an article of manufacture.

Abstract

A System and method for reducing and surviving failures in a voice trunking over ATM (VTOA) environment includes a CS-IWF complex having a plurality of interconnected CS-IWF units, each unit having a plurality of processors. An end office building may also be provided for interaction with the VTOA system. The end office building includes multiple T-IWFs, and a switch that distributes calls among the T-IWFs in a load sharing manner. Each T-IWF has a plurality of processors and is part of the VTOA system. A switch management system is also provided in the VTOA system. In order to reduce and survive failures, the switch management system includes a plurality of switch management system units. At least one of the switch management system units is a backup unit for a primary switch management system unit. Each switch management system unit provides application redundancy within itself.

Description

    CROSS-REFERENCE TO RELATED APPLICATIONS
  • The present application is a continuation application of pending U.S. patent application Ser. No. 09/534,308, filed on Mar. 23, 2000, which is a continuation-in-part of U.S. patent application Ser. No. 09/287,092, filed on Apr. 7, 1999, to George C. ALLEN Jr. et al., entitled “ATM-Based Distributed Virtual Tandem Switching System,” issued as U.S. Pat. No. 6,169,735, on Jan. 2, 2001, which claims the benefit of U.S. Provisional Patent Application No. 60/083,640, filed on Apr. 30, 1998, entitled “ATM-Based Distributed Virtual Tandem Switching System” to ALLEN et al., the disclosures of which are expressly incorporated herein by reference in their entireties.
  • BACKGROUND OF THE INVENTION
  • 1. Field of the Invention
  • The present invention relates to the field of telecommunications. More particularly, the present invention relates to reliably constructing and operating asynchronous transfer mode (ATM)-based telecommunications networks.
  • 2. Background Information
  • Tandem replacement using voice trunking over ATM (VTOA) technology, described in U.S. patent application Ser. No. 09/287,092, to George C. ALLEN Jr. et al., entitled “ATM-based Distributed Virtual Tandem Switching System,” filed on Apr. 7, 1999, is one application of an ATM distributed network system architecture. The architecture represents a new paradigm of networking that requires rethinking of how to run networks. An important consideration is how to construct and operate the new ATM-based virtual tandem switch as reliably as possible and, definitely, no less reliably than current time division multiplexed (TDM) tandems.
  • The ATM-based virtual tandem system impacts system reliability. On one hand, the virtual tandem improves system reliability by distributing its components geographically, localizing the impact of failures. On the other hand, a greater number of network elements is involved, and thus the number of occurrences of element failures may increase. Because the virtual tandem is designed to serve an entire metropolitan area, it is imperative for the virtual tandem's design to meet the highest level of survivability.
  • The present invention identifies potential failure points in the virtual tandem and provides solutions to reduce and survive failures. The solutions, in turn, place design and engineering requirements upon equipment vendors and companies operating the virtual tandem. It is therefore a primary object of the present invention to employ these requirements for use in the design of the network elements and for engineering the networks.
  • With reference to FIG. 1 of the drawings, standard call processing employs end offices 10 connected via tandem trunks 12, direct trunks 14, or both tandem trunks 12 and direct trunks 14. Each trunk 12, 14 is a digital service level 0 (DS0), operating at 64 kbps, that is transmitted between the switching offices 10 in a time division multiplexed manner. Each end office 10 connects to its neighboring end office 10 and the tandem office 16 using separate trunk groups. In this system, trunk groups are forecasted and pre-provisioned with dedicated bandwidth, which may lead to inefficiency and high operations cost.
  • A new voice trunking system using ATM technology has been proposed in U.S. patent application Ser. No. 09/287,092, entitled “ATM-Based Distributed Virtual Tandem Switching System.” In this system, shown in FIG. 2, voice trunks from end office switches 20, 26 are converted to ATM cells by a first or second trunk inter-working function (T-IWF) device 22, 24. The T-IWFs 22, 24 are distributed to each end office 20, 26, and are controlled by a centralized control and signaling inter-working function (CS-IWF) device 28. The CS-IWF 28 performs call control functions as well as conversion between the narrowband Signaling System No. 7 (SS7) protocol and a broadband signaling protocol. The T-IWFs 22, 24, CS-IWF 28, and the ATM network 30 form the ATM-based distributed virtual tandem switching system. According to this voice trunking over ATM (VTOA) architecture, trunks are no longer statistically provisioned as DS0 time slots. Instead, the trunks are realized through dynamically established switched virtual connections (SVCs), thus eliminating the need to provision separate trunk groups to different destinations, as done in TDM-based trunking networks.
  • BRIEF DESCRIPTION OF THE DRAWINGS
  • The present invention is further described in the detailed description that follows, by reference to the noted plurality of drawings by way of non-limiting examples of preferred embodiments of the present invention, in which like reference numerals represent similar parts throughout several views of the drawings, and in which:
  • FIG. 1 shows a conventional TDM telecommunications network architecture;
  • FIG. 2 shows a known virtual trunking over ATM telecommunications network architecture;
  • FIG. 3 shows a CS-IWF complex architecture, according to one aspect of the present invention;
  • FIG. 4 shows an end office architecture and its relationship with an ATM network, according to another aspect of the present invention; and
  • FIG. 5 shows an SMS connected to an ATM network, according to a further aspect of the present invention.
  • DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
  • In view of the foregoing, the present invention is directed to improving the reliability of the VTOA system. The present invention identifies potential failure points of the VTOA system and provides various configurations to minimize the impact of failures.
  • According to an embodiment of the present invention, a control and signaling interworking function (CS-IWF) complex is provided for use within a VTOA system that communicates with mated signaling transfer points. The VTOA system includes an ATM network including multiple ATM switches and multiple trunk interworking functions (T-IWFs). The CS-IWF complex includes multiple CS-IWF units connected to at least two of the ATM switches and connected to at least one of the signaling transfer points. Each CS-IWF unit has multiple processors with at least one processor compensating for a failed processor. When a CS-IWF unit fails, at least one other CS-IWF unit compensates for the failed CS-IWF unit. The processor(s) compensating for the failed processor cooperate with the CS-IWF unit(s) compensating for the failed CS-IWF unit so that the CS-IWF complex survives simplex failures.
  • According to another embodiment, the CS-IWF complex includes multiple signaling link sets. Each link set connects the CS-IWF complex to one of the mated STPs. The CS-IWF complex may also include multiple signaling gateways that connect to each of the CS-IWF units. Each signaling gateway connects to one of the mated STPs. The multiple signaling gateways minimize isolation of the CS-IWF units when a link failure occurs. The CS-IWF complex also includes multiple ATM links that connect each CS-IWF unit to multiple ATM switches.
  • In one embodiment, the multiple processors within each CS-IWF unit operate in an active/standby mode. Alternatively, the multiple processors operate in a load sharing mode.
  • Preferably, at least one of the CS-IWF units is located in a building separate from a building housing at least one other of the CS-IWF units. Furthermore, a single point code identifies the CS-IWF complex.
  • According to an embodiment of the present invention, an end office building is provided for use with a VTOA system. The VTOA system includes an ATM network including interconnected ATM switches, and at least one CS-IWF complex. The end office building includes multiple T-IWFs, which are part of the VTOA system. Each T-IWF has multiple processors with at least one processor compensating for a failed processor. Moreover, at least one T-IWF absorbs at least a portion of a failed T-IWF's workload. The end office building also includes a switch that distributes calls among the T-IWFs in a load sharing manner. Thus, the processor(s) compensating for the failed processor cooperate with the T-IWF(s) absorbing at least a portion of the failed T-IWF's workload so that the end office building survives simplex failures.
  • According to another embodiment, the end office building also includes at least one add/drop multiplexor (ADM) that connects the multiple T-IWFs to the ATM network. Preferably, each T-IWF also includes an optical interface for connecting to the ADM. The optical interface supports SONET 1+1 automatic protection switching.
  • In one embodiment, at least one T-IWF connects to a first ATM switch that is different from a second ATM switch to which another T-IWF connects. Thus, each end office building connects to multiple ATM switches so that if one ATM switch fails, the end office building remains connected to the ATM network.
  • According to another embodiment of the present invention, a method is provided for recovery from a failing ATM link in a VTOA system. The VTOA system includes an ATM network having multiple ATM switches interconnected by ATM links, multiple T-IWFs, and at least one CS-IWF complex. The method includes delaying recovery action in the ATM network for a predetermined duration while SONET recovery of the link is attempted. If the SONET recovery is successful, a call path through the ATM network stays up. If the SONET recovery is unsuccessful, existing calls carried by the failed ATM link are dropped. Preferably, the predetermined duration is 100 milliseconds.
  • According to a further embodiment of the present invention, a switch management system (SMS) is provided for use within a VTOA system. The VTOA system includes an ATM network including a least one ATM switch, multiple T-IWFs, and at least one CS-IWF complex. The switch management system includes multiple switch management system units. At least one of the switch management system units is a backup unit for at least one primary switch management system unit. Each switch management system unit provides application redundancy within itself. Consequently, the switch management system survives simplex failures.
  • Preferably, the primary switch management system unit is located in a building separate from a building housing the backup switch management system unit. In addition, each switch management system unit is connected to multiple ATM switches.
  • According to yet another embodiment of the present invention, a method is provided for restoring functions of a failed switch management system operating within a VTOA system. The VTOA system includes an ATM network including multiple ATM switches, multiple T-IWFs, and at least one CS-IWF complex. The method includes restoring essential surveillance of the VTOA system; restoring billing functions of the VTOA system; restoring full surveillance capability of the VTOA system; restoring configuration management of the VTOA system; and restoring performance management of the VTOA system.
  • According to yet another embodiment of the present invention, a VTOA system includes an ATM network having multiple interconnected ATM switches. Also provided are multiple mated signaling transfer points that communicate with the VTOA system. The VTOA system also includes at least one CS-IWF complex including multiple CS-IWF units connected to at least two of the ATM switches and connected to at least one of the signaling transfer points. Each unit has multiple processors that share load resulting from failure of one of the processors. In addition, at least one end office building is provided for interaction with the VTOA system. Each end office building includes multiple T-IWFs, each having multiple processors. A switch is also provided in the end office building(s) to distribute calls among the multiple T-IWFs in a load sharing manner. The VTOA system also includes a switch management system including multiple switch management system units. At least one of the switch management system units is a backup unit for at least one primary switch management system unit. Each switch management system unit provides application redundancy within itself. Consequently, the VTOA system survives simplex failures. According to another embodiment, there are at least two completely disjointed routes between any two end points.
  • According to yet another embodiment of the present invention, a method is provided for communicating over a VTOA system. The VTOA system includes a CS-IWF complex, an ATM network containing multiple ATM switches, and a signaling network. Multiple end office buildings are provided for interaction with the VTOA system. Each end office building includes a switch and multiple T-IWFs, which are part of the VTOA system. The method includes transmitting a signal from the switch to the T-IWFs in a load sharing manner; and transmitting from the T-IWFs to the ATM switches in a load sharing manner. Thus, communications survive a simplex failure in the VTOA system.
  • According to the present invention, the following failure points are analyzed: CS-IWF failure; T-IWF failure; ATM network failure; and SMS failure. Each of these failure scenarios is discussed below along with survivability measures to protect against and survive these failures. Each solution, discussed below, guarantees that the network will survive all simplex failures. A simplex failure is the occurrence of a single network element failure, in contrast to simultaneous failures of multiple network elements. To survive means that, in the event of a simplex failure, the network must be able to continue to operate and recover on its own either to its normal or to a compromised level of performance.
  • CS-IWF
  • The CS-IWF is the most critical element of the new virtual tandem because failure of the CS-IWF impacts the entire serving area. Thus, failure of the CS-IWF is not acceptable, and therefore the CS-IWF requires the highest level of reliability. Exemplary CS-IWF units include the Connection Gateway from Lucent Technologies Inc, and the Succession Call Server, from Nortel Networks Corporation.
  • FIG. 3 shows a design for a reliable CS-IWF complex 300 that includes multiple CS- IWF units 310, 320, 330. According to the present invention, each CS-IWF complex 300 serving a metropolitan area is assigned a single point code, regardless of how many individual CS- IWF units 310, 320, 330 the complex 300 contains. In FIG. 3, a general case is depicted where the CS-IWF complex 300 includes of n CS- IWFs 310, 320, 330 for reasons of reliability or processing capacity. A special case occurs when n=2, in which case two CS-IWFs 310, 320 operate in a load sharing or active/standby mode.
  • According to an object of the present invention, each CS- IWF unit 310, 320, 330 must be highly reliable. To achieve this objective, redundant processors are provided within each CS- IWF 310, 320, 330 for protection against processor failure. In FIG. 3, processor 0 311, 321, 331 and processor 1 312, 322, 332 are shown, although one of ordinary skill in the art will realize that more processors can be added without departing from the scope of the present invention. The redundant processors may operate in an active/standby mode or in a load sharing mode.
  • Each CS-IWF complex 300 must contain spare capacity for protection. The specific architecture of the CS-IWF complex 300 dictates the spare processing capacity required. For example, in a complex 300 where n=2, if one CS-IWF 310 fails, the remaining CS-IWF 320 must be able to handle the load of the CS-IWF 310 that failed. If three CS- IWFs 310, 320, 330 are provided, any two remaining CS-IWFs 320, 330 should be able to handle the load of the failed CS-IWF 310. Thus, a CS-IWF complex 300 must contain at least two CS-IWF units 310, 320. In general, in a CS-IWF complex 300 of n units, up to k (k>1) out of the n CS- IWF units 310, 320, 330 must be provided for the purpose of protection. The objective is that the loss of one CS-IWF 310 unit has no impact on the call handling capacity of the CS-IWF complex 300 as a whole. In the active/standby mode, n−k CS-IWFs 310, 320 are active, and k operate in standby mode. In the load-sharing mode, all n CS- IWFs 310, 320, 330 run at levels less than maximum such that if one of the CS-IWFs 310 should fail, its processing load can be absorbed by the remaining CS-IWFs 320, 330.
  • In an embodiment, all components of a CS-IWF complex 300 are not provided at the same physical location. As a result, the loss of one physical location does not shut down the entire network. In this embodiment, the components can be connected via either dedicated or networked links. All components of the CS-IWF complex 300 are NEBS level 3 compliant. See GR-63-CORE, (Network Equipment—Building System [NEBS] Requirements: Physical Protection)—A module of LSSGR, FR-64; TSGR, FR-440; and NEBSFR, FR-2065; GR-1089-CORE, (Electromagnetic Compatibility and Electrical Safety Generic. Criteria for Network Telecommunications Equipment)—A module of LSSGR, FR-64; and TSGR, FR-440; and SR-NWT-002550, (Technical Considerations for NEBS-2000), the disclosures of which are expressly incorporated by reference in their entireties, for more about NEBS level 3.
  • As is well known, STPs typically include mated pairs 370, 380 operating in a load-sharing manner to increase reliability. To take advantage of the mated STP's reliability and to further improve the CS-IWF complex's 300 reliability, a CS-IWF complex 300 maintains, at a minimum, two signaling link sets, one with each of the local mated STPs 370, 380. Moreover, within a CS-IWF complex 300, the CS- IWF units 310, 320, 330 are connected with the signaling link sets in a configuration that minimizes the possibility of any CS- IWF unit 310, 320, 330 being isolated from the signaling network as a result of a link or link-set failure. A non-limiting example of such interconnection using signaling gateways 350, 360 is shown in FIG. 3. The CS-IWF complex must support low-speed signaling links (e.g., 56 kbps to operate with SS7) with the ability to migrate to high-speed links (e.g., T1 or T1 ATM).
  • Each CS-IWF complex 300 bridges between narrowband and broadband signaling. For example, the narrowband signaling may be in the form of SS7 ISUP messages, and the broadband signaling may be standard-based broadband signaling, for example ATM UNI or PNNI.
  • The signaling gateways 350, 360 are part of the CS-IWF complex 300 and distribute SS7 signaling to each CS- IWF unit 310, 320, 330. The signaling gateways 350, 360 form an interconnection network that connects STPs 370, 380 to CS- IWF units 310, 320, 330. In other words, the signaling gateways are a distribution vehicle. An exemplary signaling gateway is the Connection Gateway Signaling Node, manufactured by Lucent Technologies, Inc.
  • In another embodiment, each CS- IWF 310, 320, 330 maintains an ATM link with two different ATM switches 390, 395 in the ATM network so that the CS-IWF complex 300 can communicate with T-IWFs, other CS-IWFs and the SMS (not shown in FIG. 3). Preferably the ATM switches 390, 395 are on separate SONET rings. Further, it is not necessary for all CS- IWFs 310, 320, 330 to connect to the same two ATM switches 390, 395. According to this embodiment, the well known 1+1 automatic protection switching (APS) is not required.
  • T-IWF
  • It is an object of the present invention that each T-IWF is highly reliable, i.e., nearly always available. Therefore, according to one embodiment, the critical components (e.g., processor) within a T-IWF are redundant to achieve this object. Exemplary T-IWFs include the 7R/E Trunk Access Gateway, from Lucent Technologies Inc.; and the Succession Multi-service Gateway 4000 (MG 4000), from Nortel Networks Corporation.
  • FIG. 4 illustrates an exemplary architecture of an end office building 400 and its relationship to an ATM network 475. In FIG. 4, a class 5 end office building (EO) 400 includes a switch 402, associated T- IWFs 404, 406, 408, which should be NEBS level 3 compliant, and a SONET add/drop multiplexer (ADM) 410. Exemplary switches include class 5 switches such as: the Lucent Technologies Inc. 1AESS; the Lucent Technologies Inc. 5ESS; the Ericsson AXE-10; and/or the Northern Telecom (Nortel) DMS-100 switches. In FIG. 4 a general case is shown where multiple T- IWF units 404, 406, 408, are deployed in an end office building 400 for reasons of reliability or capacity. Although the switch 402 and ATM switches 420, 430 shown in FIG. 4 are not co-located in the same end office building 400, such co-location may occur in other end office buildings.
  • According to the present invention, a class 5 switch having traffic volume requiring only one T-IWF is still connected with two T-IWFs for protection. Consequently, loss of one T-IWF does not isolate the class 5 switch. Furthermore, a class 5 switch must be able to maintain as few as one trunk group regardless of the number of T-IWFs by which it is served. According to an embodiment, the class 5 switch 402 distributes its calls among the T- IWFs 404, 406, 408 in a load-sharing manner. Thus, loss of one of the T- IWFs 404, 406, 408 may degrade the trunking capacity of the class 5 switch 402, but will not isolate the class 5 switch 402.
  • The optical interface on the T- IWF 404, 406, 408 for connecting with the SONET add/drop multiplexer (ADM) 410 (or an ATM switch 420, 430 when an ATM switch 420, 430 is located in the same end office building 400) supports the SONET 1+1 Automatic Protection Switching (APS) scheme, although deployment of this feature is optional. The ADM 410 connects the T- IWFs 404, 406, 408 to the ATM switches 420, 430 at the ATM layer via links 440, 450. The links 440, 450 are preferably SONET rings that connect the T- IWFs 404, 406, 408 to ATM switches 420, 430 in a load sharing manner. Exemplary ADMs are manufactured by Fujitsu, Lucent Technologies Inc., and Nortel.
  • Each T- IWF 404, 406, 408 serving a given end office building 400 does not connect to the ATM network at the same ATM switch 420, 430. Rather, each T- IWF 404, 406, 408 is single-homed to an ATM switch 420, 430, while each end office building 400 is multi-homed to multiple ATM switches 420, 430, preferably on separate SONET rings 440, 450. This configuration prevents the end office building 400 from becoming totally disconnected from the ATM network in the event of an ATM host 420, 430 failure, although the T- IWFs 404, 406, 408 connected to the failed ATM switch 420, 430 may be impacted. Preferably, the SONET transport network 440, 450 employs unidirectional path switched ring (UPSR) or bi-directional line switched ring (BLSR). In order to protect against both ATM and SONET layer failures, the ATM layer virtual path protection capability in a SONET/ATM hybrid transport node may be supported. Further, the ATM VP ring functionality may be integrated into the T- IWF 404, 406, 408 and the ATM switches 420, 430. According to another embodiment, ATM virtual path (VP) ring functionality is either integrated with or separated from the T- IWF 404, 406, 408 to achieve the potential benefits of ATM layer VP protection and transport layer efficiency.
  • ATM Network
  • An example ATM network environment, as relevant to the analysis of the failure scenarios, is now discussed. However, if an ATM network having a different configuration is provided, alternate CS-IWF, T-IWF, SMS, etc. configurations from those presently described may be preferred. In the exemplary ATM network, ATM switches are not protected with redundant ATM switches; nor are ATM virtual connections carrying bearer channels protected with redundant virtual connections. The 1+1 protection of user network interface (UNI) interfaces on ATM switches is not universally deployed. In the absence of the ATM VP ring capability, no attempt (such as virtual connection re-routing) will be made at the ATM layer to save calls in progress that are impacted by an ATM equipment or link failure.
  • The 1+1 protection enables SONET recovery by directing traffic from a failed ring, e.g., a cut ring, to a properly functioning ring. That is, two devices are connected by two rings (one active ring and one standby ring) in the usual manner. When the active ring fails, the standby ring is activated.
  • In order to eliminate single points of total failure in the ATM network, the network must be constructed so that between any two end points at least two completely disjointed routes traverse the ATM network. Consequently, the ATM switches are able to intelligently route calls in this network, e.g., by balancing the call load between disjointed routes to reduce the impact of failure as well as to improve network performance. The balanced intelligent routing is performed in a known manner.
  • An ATM link failure occurs as result of a transport facility failure, such as a fiber cut. The ATM network therefore relies on known protection schemes in the transport network to recover from such a failure. In the event that the ATM switch detects a link failure, the ATM switch delays recovery action for a predetermined time period, preferably 100 ms, during which time the SONET layer recovery is attempted. If the transport layer successfully recovers, then the impact of the failure will only be a momentary degradation of the voice connections, and the connected call paths stay up. If the transport layer fails to recover from such a link failure, then existing calls being carried by the link are dropped. The ATM switches on both ends of the failed link will then flag the associated ports as unavailable, and future calls will automatically avoid the failed link until it is repaired. After the link is repaired, no manual intervention is required in order for traffic to resume using that link, as is well known.
  • According to the present invention, ATM switching equipment failures only include failures of non-redundant components, such as un-protected interface cards, or a whole switch. Exemplary ATM switches include the MainStreetXpress 36170 Multiservices Switch or 670 RSP, both manufactured by Newbridge Networks Corporation; the GX 550 Smart Core ATM Switch, manufactured by Lucent Technologies Inc.; and the Passport 15000 Multiservice Switch, manufactured by Nortel Networks Corporation. In an embodiment, common equipment in an ATM switch, such as the switching fabric, the control processor, the power supply, wiring, fuses, alarms, etc. are redundant. Consequently, failure of one such unit has no impact on the operation or the performance of the ATM switch.
  • Redundant interface cards, however, are not provided. Thus, when an un-protected interface card or port fails, calls being carried by that interface card or port are dropped. The ATM switches connected via the failed interface card or port will then flag the associated card or port as unavailable, and future calls will automatically avoid using the failed card or port until it is repaired. After the card or port is repaired, minimal manual intervention will be required in order for traffic to resume using that card or port, as is well known.
  • In the exemplary ATM network, redundant ATM switches are not provided. In other words, an ATM switch does not have a standby. Thus, in the event of a total ATM switch failure, such as loss of the building, calls being carried by the ATM switch are dropped. The ATM network will then flag the failed switch as unavailable, and future calls will automatically avoid this switch until it is repaired. After the ATM switch is repaired, minimal manual intervention will be required in order for traffic to resume using that ATM switch, as is well known.
  • SMS
  • FIG. 5 shows a single switch management system (SMS) unit 500. The SMS is the element layer manager of the ATM-based virtual tandem. It communicates with the T-IWFs and the CS-IWF, and the legacy operation support systems (OSS). Essentially, it controls management of the distributed switch and acts as a man-machine interface enabling a human user to view and control the overall behavior of the VTOA. According to one embodiment, it communicates with other network management systems involved in the virtual tandem, such as the operation support system of the ATM network. The SMS can be located either in a central office or in a data center, and should be NEBS level 3 compliant. Exemplary SMSs include the OneLink Manager, from Lucent Technologies Inc., and the Succession Network Manager, from Nortel Networks Corporation.
  • According to an embodiment, the SMS includes a primary SMS unit 500 and a backup SMS unit (not shown) that takes over if the primary SMS unit 500 fails. That is, the primary and the backup SMS units operate in an active/standby mode. The backup SMS unit may support multiple primary SMS units 500, as dictated by engineering and operational network requirements, and must be located in a different building from the building housing the primary SMS unit 500.
  • As seen in FIG. 5, each SMS unit 500 maintains dual ATM links 510, 520 with two different ATM switches 530, 540, preferably on separate SONET rings. The dual links 510, 520 allow control communications with the backup SMS unit, the T-IWFs, and the CS-IWF. In other words, each switch management system unit has management connectivity to other VTOA system elements provided by paths through the ATM network.
  • Each SMS unit must provide application redundancy within itself, with automatic, transparent switch over in the event of failure of the active SMS application. Redundancy may be accomplished by providing a backup processor in each physical platform and/or providing backup software applications. For example, two applications may run side by side in a single processor, or separately in two processors, or the second application may begin in the second processor when the first application fails. Consequently, if part of one physical platform fails, the remaining portion of the physical platform is configured so that it can compensate for the failed portion.
  • In the event of failure of the active SMS unit 500, the switch of its load to the other unit must be accomplished with minimal manual actions, ideally no actions and preferably no more than a system administrator approaching the physical platform and issuing necessary instructions to the SMS through a computer terminal. Failure of the active unit must have minimal impact on an operations user of an SMS graphical user interface (GUI). For example, the operations user should not have to re-boot the computer or re-log in to the computer to continue using the GUI. Slower processing of commands is acceptable, and alarms and/or notifications of the switchover are necessary.
  • If the active SMS unit 500 fails, the SMS as a system restores its operation in the following sequence:
      • 1. Essential surveillance such as status and critical alarms;
      • 2. Billing functions;
      • 3. Full surveillance capability;
      • 4. Configuration management;
      • 5. Performance management.
        Essential surveillance refers to capabilities such as determining-whether the VTOA switch is functional or non-functional, and determining the overall health of individual components of the network. Billing is self explanatory. Full surveillance refers to capabilities such as viewing all state changes within the system, viewing alarms and events, e.g., a card within a component that failed, etc. Configuration management refers to capabilities such as rearranging equipment and adding new connections. Performance management refers to capabilities such as collecting data for such tasks as engineering or growth of the network.
  • Each SMS unit has its own continually updated database. Each database is synchronized with the other VTOA databases. The database enables the five functions discussed above and includes such information as the system users, networking software, the network inventory, security, etc. Awareness of the network topology is also provided by the database.
  • Although the invention has been described with reference to several exemplary embodiments, it is understood that the words that have been used are words of description and illustration, rather than words of limitation. Changes may be made within the purview of the appended claims, as presently stated and as amended, without departing from the scope and spirit of the invention in its aspects. Although the invention has been described with reference to particular means, materials and embodiments, the invention is not intended to be limited to the particulars disclosed; rather, the invention extends to all functionally equivalent structures, methods, and uses such as are within the scope of the appended claims.
  • In accordance with various embodiments of the present invention, the methods described herein are intended for operation as software programs running on a computer processor. Dedicated hardware implementations including, but not limited to, application specific integrated circuits, programmable logic arrays and other hardware devices can likewise be constructed to implement the methods described herein. It should also be noted that the software implementations of the present invention can be stored on a tangible storage medium such as a magnetic or optical disk, read-only memory or random access memory and be produced as an article of manufacture.

Claims (20)

1. A control and signaling interworking function (CS-IWF) system interacting with a virtual trunking system, the CS-IWF system performing call control functions for transmitting voice across a data network in the virtual trunking system, the CS-IWF system comprising:
a plurality of CS-IWF units, each of the plurality of CS-IWF units being connected to at least one data network switch, each of the plurality of CS-IWF units having a plurality of processors, at least one of the plurality of processors being configured to compensate for a failed processor, at least one CS-IWF unit being configured to absorb at least a portion of a workload associated with a failed CS-IWF unit, enabling the virtual trunking system to survive a simplex failure; and
a plurality of signaling gateways, each of the plurality of signaling gateways being connected to at least one of a pair of mated signaling transfer points (STPs), through a plurality of signaling link sets, and each of the plurality of CS-IWF units;
wherein the CS-IWF units are configured to interface narrowband signaling and broadband signaling for call processing and control within the data network.
2. The system of claim of 1, wherein calls originating and terminating within a public switched telephone network (PSTN) are transmitted through the data network.
3. The system of claim of 1, wherein the at least one data network switch comprises an ATM switch.
4. The system of claim of 1, further comprising a plurality of data network links that connect each of the plurality of CS-IWF units to the at least one data network switch.
5. The system of claim of 1, wherein each of the plurality of CS-IWF units operates one of an active mode or standby mode.
6. The system of claim of 1, wherein the plurality of CS-IWF units are configured to operate in a load-sharing mode.
7. The system of claim of 1, wherein the CS-IWF system is identifiable by a single point code.
8. A control and signaling interworking function (CS-IWF) device, performing call control functions for transmitting voice across a data network, comprising at least one data network switch, in a virtual trunking system, the CS-IWF device comprising:
at least one processor, configured to compensate for a failed processor in the CS-IWF device or in at least one additional CS-IWF device;
a first interface for interfacing with the at least one additional CS-IWF device, the CS-IWF device being configured to absorb at least a portion of a workload of the at least one additional CS-IWF device, enabling the virtual trunking system to survive a simplex failure; and
a second interface for interfacing with a plurality of signaling gateways, each of the plurality of signaling gateways being connected to at least one of a pair of mated signaling transfer points (STPs), through a plurality of signaling link sets;
wherein each of the CS-IWF device and the at least one additional CS-IWF device are configured to interface narrowband signaling and broadband signaling for call processing and control within the data network.
9. The CS-IWF device of claim 8, further comprising:
a third interface for providing call processing and control information to an originating trunking interworking function (T-IWF) unit and a terminating T-IWF unit over the data network, wherein each T-IWF unit has a plurality of processors and each T-IWF unit is capable of dynamically establishing an end-to-end connection to another T-IWF unit, so that calls originating or terminating within a public switched telephone network (PSTN) may be transmitted through the data network.
10. The CS-IWF device of claim 8, wherein the data network comprises an Asynchronous Transfer Mode (ATM) network.
11. The CS-IWF device of claim 8, wherein the data network comprises at least two disjointed routes between two end points.
12. The CS-IWF device of claim 8, wherein the CS-IWF device operates in one of an active mode or standby mode.
13. A fault-tolerant switch management system (SMS) for controlling a plurality of distributed switches in a virtual trunking system, the SMS comprising:
at least one backup SMS unit configured to operate in a standby mode when a primary SMS unit is operational and to operate in an active mode, performing functions of the at least one primary SMS unit, when the at least one primary SMS unit fails, the at least one primary SMS unit and the at least one backup SMS unit being connected to a data network through at least one data network switch, the connection allowing control communication among a trunking interworking function (T-IWF) complex, a control and signaling interworking function (CS-IWF) complex and at least one of the primary SMS unit and the backup SMS unit;
wherein the CS-IWF complex comprises a plurality of CS-IWF units configured to interface narrowband signaling and broadband signaling for call processing and control within the data network so that telephone calls originating or terminating within a public switched telephone network (PSTN) may be transmitted through the data network, and
wherein the T-IWF complex comprises a plurality of T-IWF units, each of the plurality of T-IWF units having a plurality of processors, each T-IWF unit being capable of dynamically establishing an end-to-end connection to another T-IWF unit.
14. The fault-tolerant switch management system (SMS) of claim 13, wherein each of the plurality of T-IWF units connect to the data network through at least one add/drop multiplexor (ADM).
15. The fault-tolerant switch management system (SMS) of claim 13, the data network comprising at least two disjointed routes between two end points.
16. The fault-tolerant switch management system (SMS) of claim 13, wherein the SMS is located in one of a central office (CO) or a data center.
17. The fault-tolerant switch management system (SMS) of claim 13, wherein the SMS is Network Equipment Building Systems (NEBS) level 3 compliant.
18. The fault-tolerant switch management system (SMS) of claim 13, wherein the backup SMS unit is located at a location that is physically separate from the location of the primary SMS unit.
19. The fault-tolerant switch management system (SMS) of claim 13, wherein each of the at least one primary SMS unit and the at least one backup SMS unit comprises a database storing at least one of a system user, a networking software, a network inventory and security information.
20. The fault-tolerant switch management system (SMS) of claim 13, wherein the connection to the at least one data network switch comprises a multi-homed connection.
US11/739,250 1998-04-30 2007-04-24 Fault tolerant atm-based distributed virtual tandem switching system and method Abandoned US20070286200A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US11/739,250 US20070286200A1 (en) 1998-04-30 2007-04-24 Fault tolerant atm-based distributed virtual tandem switching system and method

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US8364098P 1998-04-30 1998-04-30
US09/287,092 US6169735B1 (en) 1998-04-30 1999-04-07 ATM-based distributed virtual tandem switching system
US09/534,308 US7227837B1 (en) 1998-04-30 2000-03-23 Fault tolerant virtual tandem switch
US11/739,250 US20070286200A1 (en) 1998-04-30 2007-04-24 Fault tolerant atm-based distributed virtual tandem switching system and method

Related Parent Applications (1)

Application Number Title Priority Date Filing Date
US09/534,308 Continuation US7227837B1 (en) 1998-04-30 2000-03-23 Fault tolerant virtual tandem switch

Publications (1)

Publication Number Publication Date
US20070286200A1 true US20070286200A1 (en) 2007-12-13

Family

ID=32512175

Family Applications (5)

Application Number Title Priority Date Filing Date
US09/534,308 Expired - Fee Related US7227837B1 (en) 1998-04-30 2000-03-23 Fault tolerant virtual tandem switch
US09/705,793 Expired - Fee Related US6757278B1 (en) 1998-04-30 2000-11-06 Secure ATM-based distributed virtual tandem switching system and method
US10/813,052 Expired - Fee Related US7136378B2 (en) 1998-04-30 2004-03-31 Secure ATM-based distributed virtual tandem switching system and method
US11/531,916 Expired - Fee Related US7843932B2 (en) 1998-04-30 2006-09-14 Secure ATM-based distributed virtual tandem switching system and method
US11/739,250 Abandoned US20070286200A1 (en) 1998-04-30 2007-04-24 Fault tolerant atm-based distributed virtual tandem switching system and method

Family Applications Before (4)

Application Number Title Priority Date Filing Date
US09/534,308 Expired - Fee Related US7227837B1 (en) 1998-04-30 2000-03-23 Fault tolerant virtual tandem switch
US09/705,793 Expired - Fee Related US6757278B1 (en) 1998-04-30 2000-11-06 Secure ATM-based distributed virtual tandem switching system and method
US10/813,052 Expired - Fee Related US7136378B2 (en) 1998-04-30 2004-03-31 Secure ATM-based distributed virtual tandem switching system and method
US11/531,916 Expired - Fee Related US7843932B2 (en) 1998-04-30 2006-09-14 Secure ATM-based distributed virtual tandem switching system and method

Country Status (1)

Country Link
US (5) US7227837B1 (en)

Families Citing this family (56)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6169735B1 (en) * 1998-04-30 2001-01-02 Sbc Technology Resources, Inc. ATM-based distributed virtual tandem switching system
US7227837B1 (en) * 1998-04-30 2007-06-05 At&T Labs, Inc. Fault tolerant virtual tandem switch
US6744768B2 (en) * 1999-07-14 2004-06-01 Telefonaktiebolaget Lm Ericsson Combining narrowband applications with broadband transport
WO2001054362A1 (en) * 2000-01-20 2001-07-26 Mci Worldcom, Inc. Intelligent policy server system and method for bandwidth control in an atm network
US6343065B1 (en) * 2000-01-20 2002-01-29 Sbc Technology Resources, Inc. System and method of measurement-based adaptive caching of virtual connections
US6724801B1 (en) * 2000-04-05 2004-04-20 Nortel Networks Limited Method and system enabling communications between a switched telephone network and a wireless network
FI20002124A (en) * 2000-09-27 2002-03-28 Nokia Corp Changing channel properties
US7079551B2 (en) * 2000-10-05 2006-07-18 Kiribati Wireless Ventures, Llc Private network link verification procedure in free space optical communication network
US7016369B2 (en) * 2000-12-22 2006-03-21 Telefonaktiebolaget Lm Ericsson (Publ) Binding information for telecommunications network
GB2373131A (en) 2001-03-09 2002-09-11 Marconi Comm Ltd Telecommunications networks
US7050414B2 (en) * 2001-06-22 2006-05-23 Lucent Technologies Inc. Method and apparatus for setting up a call over a packet-based transport network
US7539198B1 (en) * 2002-06-26 2009-05-26 Cisco Technology, Inc. System and method to provide node-to-node connectivity in a communications network
US20040190531A1 (en) * 2002-08-20 2004-09-30 Pierre-Yves Sibille Bearer connection signaling in a distributed architecture
US8078756B2 (en) * 2003-06-03 2011-12-13 Cisco Technology, Inc. Computing a path for an open ended uni-directional path protected switched ring
EP1649706A4 (en) * 2003-07-18 2011-05-11 Kodiak Networks Inc Premium voice services for wireless communications systems
US7693069B2 (en) * 2003-07-28 2010-04-06 Alcatel-Lucent Usa Inc. Method, apparatus and system for improved inter-domain routing convergence
US7978707B2 (en) * 2004-04-01 2011-07-12 Alcatel Lucent Method and apparatus for securely establishing L3-SVC connections
US20110183659A1 (en) * 2009-12-04 2011-07-28 Kodiak Networks, Inc. Community group client and community auto discovery solutions in a wireless communications network
US9485787B2 (en) 2005-05-24 2016-11-01 Kodiak Networks, Inc. Method to achieve a fully acknowledged mode communication (FAMC) in push-to-talk-over-cellular (PoC)
US10178513B2 (en) 2004-11-23 2019-01-08 Kodiak Networks, Inc. Relay-mode and direct-mode operations for push-to-talk-over-cellular (PoC) using WiFi-technologies
US10367863B2 (en) 2004-11-23 2019-07-30 Kodiak Networks Inc. Method for providing dynamic quality of service for push-to-talk service
US9137646B2 (en) 2004-11-23 2015-09-15 Kodiak Networks, Inc. Method and framework to detect service users in an insufficient wireless radio coverage network and to improve a service delivery experience by guaranteed presence
US8676189B2 (en) * 2008-01-24 2014-03-18 Kodiak Networks, Inc. Converged mobile-web communications solution
US9088876B2 (en) 2012-02-01 2015-07-21 Kodiak Networks, Inc. WiFi interworking solutions for push-to-talk-over-cellular (PoC)
US10057105B2 (en) 2004-11-23 2018-08-21 Kodiak Networks, Inc. Architecture framework to realize push-to-X services using cloudbased storage services
US10116691B2 (en) 2004-11-23 2018-10-30 Kodiak Networks, Inc. VoIP denial-of-service protection mechanisms from attack
US8369829B2 (en) * 2010-03-03 2013-02-05 Kodiak Networks, Inc. Prepaid billing solutions for push-to-talk in a wireless communications network
US10750327B2 (en) 2004-11-23 2020-08-18 Kodiak Networks Inc Method for multiplexing media streams to optimize network resource usage for push-to-talk-over-cellular service
US9913300B2 (en) 2011-12-14 2018-03-06 Kodiak Networks, Inc. Push-to-talk-over-cellular (PoC)
US8670760B2 (en) 2008-01-24 2014-03-11 Kodiak Networks, Inc. Converged mobile-web communications solution
US8036692B2 (en) * 2005-08-08 2011-10-11 Kodiaks Networks, Inc. Brew platform enabling advanced voice services (AVS) including push-to-talk, push-to-conference and push-to-message on wireless handsets and networks
US7853279B2 (en) * 2006-04-26 2010-12-14 Kodiak Networks, Inc. Advanced features on a real-time exchange system
US10111055B2 (en) 2004-11-23 2018-10-23 Kodiak Networks, Inc. Optimized methods for large group calling using unicast and multicast transport bearer for PoC
US8958348B2 (en) * 2008-10-20 2015-02-17 Kodiak Networks, Inc. Hybrid push-to-talk for mobile phone networks
US7689238B2 (en) * 2005-08-03 2010-03-30 Kodiak Networks, Inc. Architecture and implementation of closed user groups and limiting mobility in wireless networks
US20080298345A1 (en) * 2007-05-30 2008-12-04 Llija Hadzic Cross-connect for emulated circuit-base communications
US20090041205A1 (en) * 2007-08-10 2009-02-12 Tekelec Methods, systems, and computer program products for detecting and mitigating ping call events in a communications network
WO2010117815A1 (en) * 2009-03-30 2010-10-14 Kodiak Networks, Inc. Enhanced group calling features for connected portfolio services in a wireless communications network
US8984503B2 (en) * 2009-12-31 2015-03-17 International Business Machines Corporation Porting virtual images between platforms
EP2599326B1 (en) 2010-05-21 2015-10-21 Kodiak Networks, Inc. Predictive wakeup for push-to-talk-over-cellular (poc) call setup optimizations
US8352415B2 (en) * 2010-06-15 2013-01-08 International Business Machines Corporation Converting images in virtual environments
US20130279375A1 (en) * 2012-04-20 2013-10-24 Motorola Solutions, Inc. Method and apparatus for enabling interoperability between a broadband network and a narrowband network
EP3025529B1 (en) 2013-07-23 2018-04-11 Kodiak Networks, Inc. Radio access network aware service push-to-talk-over-cellular networks
US9276815B2 (en) 2013-12-27 2016-03-01 Dell Products L.P. N-node virtual link trunking (VLT) systems management plane
US9264347B2 (en) 2013-12-27 2016-02-16 Dell Products L.P. N-node virtual link trunking (VLT) systems control plane
US9680702B1 (en) * 2014-06-02 2017-06-13 Hrl Laboratories, Llc Network of networks diffusion control
US10362074B2 (en) 2015-02-03 2019-07-23 Kodiak Networks, Inc Session management and notification mechanisms for push-to-talk (PTT)
US10609138B2 (en) 2015-05-07 2020-03-31 Kodiak Networks Inc. System and method for mobile data synchronization
DE112016004558B4 (en) 2015-10-06 2023-01-05 Kodiak Networks, Inc. SYSTEM AND METHOD FOR PTTING PTT OVER LTE
AU2016336539B2 (en) 2015-10-06 2019-04-18 Kodiak Networks, Inc. System and method for media encoding scheme (MES) selection
WO2017070551A1 (en) 2015-10-23 2017-04-27 Kodiak Networks Inc. System and method for content messaging
WO2017185032A1 (en) 2016-04-22 2017-10-26 Kodiak Networks, Inc. System and method for push-to-talk (ptt) key one-touch calling
US10555370B2 (en) 2016-09-28 2020-02-04 Kodiak Networks, Inc. System and method for push-to-talk (PTT) in high latency networks
US10257669B2 (en) 2016-12-01 2019-04-09 Kodiak Networks, Inc. PTX data analytic engine notifying group list of detected risk event
US10630529B2 (en) 2016-12-29 2020-04-21 Kodiak Networks, Inc. System and method for push-to-talk (PTT) in mobile edge computing (MEC)
US10341823B2 (en) 2016-12-30 2019-07-02 Kodiak Networks Inc. System and method for direct mode push to talk communication protocols

Citations (66)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5260978A (en) * 1992-10-30 1993-11-09 Bell Communications Research, Inc. Synchronous residual time stamp for timing recovery in a broadband network
US5363369A (en) * 1993-03-31 1994-11-08 At&T Bell Laboratories System for inter packet community communication
US5392402A (en) * 1993-06-29 1995-02-21 Bell Communications Research, Inc. Broadband intelligent telecommunications network and method employing a resource system to support network services
US5428607A (en) * 1993-12-20 1995-06-27 At&T Corp. Intra-switch communications in narrow band ATM networks
US5434854A (en) * 1993-12-27 1995-07-18 At&T Corp. System for communicating digital cellular data between a cell site and a switching system or another cell site
US5434853A (en) * 1993-12-27 1995-07-18 At&T Corp. System and method for providing soft handoff of a cellular mobile-to-mobile call
US5438565A (en) * 1993-03-31 1995-08-01 At&T Corp. Packet switch to provide code division, multiple access cellular service
US5459722A (en) * 1994-06-30 1995-10-17 At&T Ipm Corp. Asynchronous transfer mode (ATM) transport of voice-band signals
US5483527A (en) * 1994-12-21 1996-01-09 At&T Corp. Terminal adapter for interfacing an ATM network with a STM network
US5513174A (en) * 1994-12-07 1996-04-30 At&T Corp. Telecommunication system with detection and control of packet collisions
US5539884A (en) * 1993-05-20 1996-07-23 Bell Communications Research, Inc. Intelligent broadband communication system and method employing fast-packet switches
US5568475A (en) * 1994-12-21 1996-10-22 Lucent Technologies Inc. ATM network architecture employing an out-of-band signaling network
US5581551A (en) * 1993-12-21 1996-12-03 Siemens Aktiengesellschaft Method for transmitting digital signals in an ATM communication network
US5619500A (en) * 1994-09-01 1997-04-08 Digital Link Corporation ATM network interface
US5623491A (en) * 1995-03-21 1997-04-22 Dsc Communications Corporation Device for adapting narrowband voice traffic of a local access network to allow transmission over a broadband asynchronous transfer mode network
US5638365A (en) * 1994-09-19 1997-06-10 International Business Machines Corporation Dynamically structured data transfer mechanism in an ATM network
US5680437A (en) * 1996-06-04 1997-10-21 Motorola, Inc. Signaling system seven distributed call terminating processor
US5684800A (en) * 1995-11-15 1997-11-04 Cabletron Systems, Inc. Method for establishing restricted broadcast groups in a switched network
US5703876A (en) * 1994-05-05 1997-12-30 Christie; Joseph Michael ATM transport system
US5710769A (en) * 1996-02-29 1998-01-20 Lucent Technologies Inc. Merging the functions of switching and cross connect in telecommunications networks
US5719863A (en) * 1995-01-26 1998-02-17 Siemens Aktiengesellschaft Method and arrangement for fast through-connect of virtual connections in ATM communications systems
US5757783A (en) * 1995-06-15 1998-05-26 Lucent Technologies Inc. Method and apparatus for routing ATM cells in an AD-ATM LAN
US5781320A (en) * 1996-08-23 1998-07-14 Lucent Technologies Inc. Fiber access architecture for use in telecommunications networks
US5796836A (en) * 1995-04-17 1998-08-18 Secure Computing Corporation Scalable key agile cryptography
US5825750A (en) * 1996-03-29 1998-10-20 Motorola Method and apparatus for maintaining security in a packetized data communications network
US5867571A (en) * 1996-02-23 1999-02-02 Lucent Technologies Inc. Method and arrangement for establishing call connections in a telecommunications network using a virtual transport server
US5883893A (en) * 1996-09-10 1999-03-16 Cisco Technology, Inc. ATM voice transport protocol
US5889773A (en) * 1996-11-27 1999-03-30 Alcatel Usa Sourcing, L.P. Method and apparatus for placing time division multiplexed telephony traffic into an asynchronous transfer mode format
US5898673A (en) * 1997-02-12 1999-04-27 Siemens Information And Communication Networks, Inc. System and method for prevention of cell loss due to quality of service contracts in an ATM network
US5914956A (en) * 1997-02-03 1999-06-22 Williams; Joel R. Cache for improving the connection capacity of a communications switch
US5930238A (en) * 1997-07-10 1999-07-27 General Datacomm Asynchronous transfer mode (ATM) multicast tree delivery switching
US5943321A (en) * 1997-08-20 1999-08-24 General Datacomm Inc. Circuit set-up and caching for multimedia multipoint servers
US5953316A (en) * 1997-04-17 1999-09-14 The Trustees Of Columbia University In The City Of New York Reservation method and system for asynchronous transfer mode communications
US5956334A (en) * 1997-02-10 1999-09-21 At & T Corporation Method for interfacing a telephony and an ATM network to establish voice communication
US5991301A (en) * 1994-05-05 1999-11-23 Sprint Communications Co. L.P. Broadband telecommunications system
US5991746A (en) * 1997-02-05 1999-11-23 General Datacomm, Inc. Billing system utilizing a modified file transfer protocol for collecting non-file MIB tables for billing in an ATM network
US6009100A (en) * 1997-09-12 1999-12-28 Lucent Technologies Inc. Asynchronous transfer mode switching system
US6028933A (en) * 1997-04-17 2000-02-22 Lucent Technologies Inc. Encrypting method and apparatus enabling multiple access for multiple services and multiple transmission modes over a broadband communication network
US6031840A (en) * 1995-12-07 2000-02-29 Sprint Communications Co. L.P. Telecommunications system
US6035405A (en) * 1997-12-22 2000-03-07 Nortel Networks Corporation Secure virtual LANs
US6049531A (en) * 1997-07-14 2000-04-11 At&T Corp Real-time multimedia conferencing over an ATM network using an intelligent ATM ADSL modem and ADSL access
US6101183A (en) * 1996-06-21 2000-08-08 Lucent Technologies Inc. Method and apparatus for crossconnecting transmission members in the outside distribution plant of a telecommunications network
US6119170A (en) * 1997-12-29 2000-09-12 Bull Hn Information Systems Inc. Method and apparatus for TCP/IP multihoming on a host system configured with multiple independent transport provider systems
US6118759A (en) * 1996-10-28 2000-09-12 Fujitsu Limited Network system and frame relay switch
US6134235A (en) * 1997-10-08 2000-10-17 At&T Corp. Pots/packet bridge
US6141339A (en) * 1997-04-04 2000-10-31 Sprint Communications Company, L.P. Telecommunications system
US6151315A (en) * 1997-06-02 2000-11-21 At&T Corp Method and apparatus for achieving fabric independent routing technique
US6169735B1 (en) * 1998-04-30 2001-01-02 Sbc Technology Resources, Inc. ATM-based distributed virtual tandem switching system
US6195333B1 (en) * 1996-10-28 2001-02-27 Fujitsu Network Communications, Inc. Unframed isochronous shaping method to reduce delay and delay variation in a CBR transmission system
US6195714B1 (en) * 1998-06-08 2001-02-27 Nortel Networks Limited System for transferring STM calls through ATM network by converting the STM calls to ATM and vice versa at the edge nodes of ATM network
US6252952B1 (en) * 1999-12-30 2001-06-26 At&T Corp Personal user network (closed user network) PUN/CUN
US6275493B1 (en) * 1998-04-02 2001-08-14 Nortel Networks Limited Method and apparatus for caching switched virtual circuits in an ATM network
US6282194B1 (en) * 1998-09-23 2001-08-28 Nortel Networks Limited Transit trunk subnetwork system
US20010036188A1 (en) * 1998-01-20 2001-11-01 Telefonaktiebolaget L M Ericsson Multi-service circuit for telecommuncations
US20020009086A1 (en) * 2000-01-20 2002-01-24 Gallant John K. Intelligent network and method for providing voice telephony over ATM and private address translation
US6343065B1 (en) * 2000-01-20 2002-01-29 Sbc Technology Resources, Inc. System and method of measurement-based adaptive caching of virtual connections
US20020071394A1 (en) * 1997-11-17 2002-06-13 Adc Telecommunications, Inc. System and method for electronically identifying connections of a cross-connect system
US20020075855A1 (en) * 1998-05-11 2002-06-20 At&T Corp. Method and apparatus for a remote signaling and call processing in a telecommunications network
US6470018B1 (en) * 1997-05-09 2002-10-22 Sprint Communications Company L.P. System and method for connecting a call
US6510164B1 (en) * 1998-11-16 2003-01-21 Sun Microsystems, Inc. User-level dedicated interface for IP applications in a data packet switching and load balancing system
US6563918B1 (en) * 1998-02-20 2003-05-13 Sprint Communications Company, LP Telecommunications system architecture for connecting a call
US6643282B1 (en) * 1994-05-05 2003-11-04 Sprint Communications Company L.P. Method, system and apparatus for telecommunications control
US20040022237A1 (en) * 1998-11-20 2004-02-05 Level 3 Communications, Inc. Voice over data telecommunications network architecture
US6757278B1 (en) * 1998-04-30 2004-06-29 Sbc Technology Resources, Inc. Secure ATM-based distributed virtual tandem switching system and method
US6782004B1 (en) * 1998-11-09 2004-08-24 Lucent Technologies Inc. Intelligent network signaling using an open system protocol
US6870827B1 (en) * 1997-03-19 2005-03-22 Verizon Services Corp. Voice call alternative routing through PSTN and internet networks

Family Cites Families (33)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US64129A (en) * 1867-04-23 To all whom it may concern
US75855A (en) * 1868-03-24 Improved composition pavements for streets
US93947A (en) * 1869-08-24 Improved rock-drilling apparatus
US9086A (en) * 1852-06-29 And wm
US36188A (en) * 1862-08-12 Improved can for oils,, varnishes, scc
US4076223A (en) 1975-12-31 1978-02-28 Pennsylvania Engineering Corporation Enclosure for steel converting apparatus
JPH05122240A (en) 1991-10-24 1993-05-18 Fujitsu Ltd Vpi vci allocation system in atm transmission
US5365524A (en) 1992-11-06 1994-11-15 At&T Bell Laboratories Establishing telecommunications call paths between clustered switching entities
JP2646948B2 (en) 1992-12-25 1997-08-27 日本電気株式会社 Signaling method in packet network
JP2518515B2 (en) 1993-05-27 1996-07-24 日本電気株式会社 High-speed connection setup packet switch
US5490140A (en) 1994-09-30 1996-02-06 International Business Machines Corporation System and method for providing ATM support for frame relay DTEs with a terminal adapter
IT1274350B (en) 1994-12-06 1997-07-17 Angeletti P Ist Richerche Bio INTERLEUCHINA-6 (IL-6) ANTAGONISTS, WHICH CONSIST OF SOLUBLE FORMS OF THE ALFA RECEPTOR OF IL-6, CHANGED IN THE INTERFACE THAT LINKS TO GP 130
JPH08186585A (en) * 1995-01-05 1996-07-16 Fujitsu Ltd Atm switchboard
JP2921424B2 (en) 1995-01-13 1999-07-19 日本電気株式会社 ATM electronic exchange network system and electronic exchange used in the system
US5845211A (en) 1995-01-13 1998-12-01 Bell South Corporation Wireless digital network
US5683365A (en) * 1995-06-07 1997-11-04 Johnson & Johnson Medical, Inc. Tip protection device
GB9603398D0 (en) 1996-02-17 1996-04-17 Plessey Telecomm Broadband/narrowband interworking
JP3600353B2 (en) 1996-03-15 2004-12-15 富士通株式会社 Voice information service device connected to ATM network
US5926464A (en) 1996-04-04 1999-07-20 Lucent Technologies Inc. Customer telecommunication interface device with built-in network features
US6487200B1 (en) * 1996-04-04 2002-11-26 At&T Corp. Packet telephone system
JPH09275400A (en) * 1996-04-04 1997-10-21 Hitachi Ltd Atm exchange system
US6122255A (en) * 1996-04-18 2000-09-19 Bell Atlantic Network Services, Inc. Internet telephone service with mediation
US6122275A (en) 1996-09-26 2000-09-19 Lucent Technologies Inc. Real-time processing for virtual circuits in packet switching
US6005859A (en) * 1996-12-19 1999-12-21 Northern Telecom Limited Proxy VAT-PSTN origination
US6070243A (en) * 1997-06-13 2000-05-30 Xylan Corporation Deterministic user authentication service for communication network
US6055232A (en) 1997-08-15 2000-04-25 Alcatel Usa Sourcing, L.P. Telecommunications network architecture deploying intelligent network services in a legacy network
US7406084B2 (en) * 1997-09-19 2008-07-29 Nokia Siemens Networks Gmbh & Co. Kg Flexible software architecture for a call processing system
US6084956A (en) * 1997-09-19 2000-07-04 Nortel Networks Corporation SS7 mediation for data network call setup and services interworking
US6175622B1 (en) * 1998-02-10 2001-01-16 Northern Telecom Limited Virtual private network for a telephone network
US6263212B1 (en) * 1998-02-17 2001-07-17 Alcatel Usa Sourcing, L.P. Short message service center
ATE358406T1 (en) 2000-05-23 2007-04-15 Sbc Techn Res Inc ATM BASED DISTRIBUTED NETWORK SWITCHING SYSTEM
WO2002037779A1 (en) 2000-11-06 2002-05-10 Sbc Technology Resources, Inc. Secure atm-based distributed virtual tandem switching system and method
US6557278B1 (en) * 2002-03-27 2003-05-06 Kuo-Ying Huang Ornament card

Patent Citations (74)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5260978A (en) * 1992-10-30 1993-11-09 Bell Communications Research, Inc. Synchronous residual time stamp for timing recovery in a broadband network
US5363369A (en) * 1993-03-31 1994-11-08 At&T Bell Laboratories System for inter packet community communication
US5438565A (en) * 1993-03-31 1995-08-01 At&T Corp. Packet switch to provide code division, multiple access cellular service
US5539884A (en) * 1993-05-20 1996-07-23 Bell Communications Research, Inc. Intelligent broadband communication system and method employing fast-packet switches
US5392402A (en) * 1993-06-29 1995-02-21 Bell Communications Research, Inc. Broadband intelligent telecommunications network and method employing a resource system to support network services
US5428607A (en) * 1993-12-20 1995-06-27 At&T Corp. Intra-switch communications in narrow band ATM networks
US5581551A (en) * 1993-12-21 1996-12-03 Siemens Aktiengesellschaft Method for transmitting digital signals in an ATM communication network
US5434854A (en) * 1993-12-27 1995-07-18 At&T Corp. System for communicating digital cellular data between a cell site and a switching system or another cell site
US5434853A (en) * 1993-12-27 1995-07-18 At&T Corp. System and method for providing soft handoff of a cellular mobile-to-mobile call
US5703876A (en) * 1994-05-05 1997-12-30 Christie; Joseph Michael ATM transport system
US5991301A (en) * 1994-05-05 1999-11-23 Sprint Communications Co. L.P. Broadband telecommunications system
US6643282B1 (en) * 1994-05-05 2003-11-04 Sprint Communications Company L.P. Method, system and apparatus for telecommunications control
US5459722A (en) * 1994-06-30 1995-10-17 At&T Ipm Corp. Asynchronous transfer mode (ATM) transport of voice-band signals
US5619500A (en) * 1994-09-01 1997-04-08 Digital Link Corporation ATM network interface
US5638365A (en) * 1994-09-19 1997-06-10 International Business Machines Corporation Dynamically structured data transfer mechanism in an ATM network
US5513174A (en) * 1994-12-07 1996-04-30 At&T Corp. Telecommunication system with detection and control of packet collisions
US5483527A (en) * 1994-12-21 1996-01-09 At&T Corp. Terminal adapter for interfacing an ATM network with a STM network
US5568475A (en) * 1994-12-21 1996-10-22 Lucent Technologies Inc. ATM network architecture employing an out-of-band signaling network
US5719863A (en) * 1995-01-26 1998-02-17 Siemens Aktiengesellschaft Method and arrangement for fast through-connect of virtual connections in ATM communications systems
US5623491A (en) * 1995-03-21 1997-04-22 Dsc Communications Corporation Device for adapting narrowband voice traffic of a local access network to allow transmission over a broadband asynchronous transfer mode network
US5796836A (en) * 1995-04-17 1998-08-18 Secure Computing Corporation Scalable key agile cryptography
US5757783A (en) * 1995-06-15 1998-05-26 Lucent Technologies Inc. Method and apparatus for routing ATM cells in an AD-ATM LAN
US5684800A (en) * 1995-11-15 1997-11-04 Cabletron Systems, Inc. Method for establishing restricted broadcast groups in a switched network
US6031840A (en) * 1995-12-07 2000-02-29 Sprint Communications Co. L.P. Telecommunications system
US5867571A (en) * 1996-02-23 1999-02-02 Lucent Technologies Inc. Method and arrangement for establishing call connections in a telecommunications network using a virtual transport server
US5710769A (en) * 1996-02-29 1998-01-20 Lucent Technologies Inc. Merging the functions of switching and cross connect in telecommunications networks
US5825750A (en) * 1996-03-29 1998-10-20 Motorola Method and apparatus for maintaining security in a packetized data communications network
US5680437A (en) * 1996-06-04 1997-10-21 Motorola, Inc. Signaling system seven distributed call terminating processor
US6101183A (en) * 1996-06-21 2000-08-08 Lucent Technologies Inc. Method and apparatus for crossconnecting transmission members in the outside distribution plant of a telecommunications network
US5781320A (en) * 1996-08-23 1998-07-14 Lucent Technologies Inc. Fiber access architecture for use in telecommunications networks
US5883893A (en) * 1996-09-10 1999-03-16 Cisco Technology, Inc. ATM voice transport protocol
US6195333B1 (en) * 1996-10-28 2001-02-27 Fujitsu Network Communications, Inc. Unframed isochronous shaping method to reduce delay and delay variation in a CBR transmission system
US6118759A (en) * 1996-10-28 2000-09-12 Fujitsu Limited Network system and frame relay switch
US5889773A (en) * 1996-11-27 1999-03-30 Alcatel Usa Sourcing, L.P. Method and apparatus for placing time division multiplexed telephony traffic into an asynchronous transfer mode format
US5914956A (en) * 1997-02-03 1999-06-22 Williams; Joel R. Cache for improving the connection capacity of a communications switch
US5991746A (en) * 1997-02-05 1999-11-23 General Datacomm, Inc. Billing system utilizing a modified file transfer protocol for collecting non-file MIB tables for billing in an ATM network
US5956334A (en) * 1997-02-10 1999-09-21 At & T Corporation Method for interfacing a telephony and an ATM network to establish voice communication
US5898673A (en) * 1997-02-12 1999-04-27 Siemens Information And Communication Networks, Inc. System and method for prevention of cell loss due to quality of service contracts in an ATM network
US6870827B1 (en) * 1997-03-19 2005-03-22 Verizon Services Corp. Voice call alternative routing through PSTN and internet networks
US6141339A (en) * 1997-04-04 2000-10-31 Sprint Communications Company, L.P. Telecommunications system
US6028933A (en) * 1997-04-17 2000-02-22 Lucent Technologies Inc. Encrypting method and apparatus enabling multiple access for multiple services and multiple transmission modes over a broadband communication network
US5953316A (en) * 1997-04-17 1999-09-14 The Trustees Of Columbia University In The City Of New York Reservation method and system for asynchronous transfer mode communications
US6470018B1 (en) * 1997-05-09 2002-10-22 Sprint Communications Company L.P. System and method for connecting a call
US6151315A (en) * 1997-06-02 2000-11-21 At&T Corp Method and apparatus for achieving fabric independent routing technique
US5930238A (en) * 1997-07-10 1999-07-27 General Datacomm Asynchronous transfer mode (ATM) multicast tree delivery switching
US6049531A (en) * 1997-07-14 2000-04-11 At&T Corp Real-time multimedia conferencing over an ATM network using an intelligent ATM ADSL modem and ADSL access
US5943321A (en) * 1997-08-20 1999-08-24 General Datacomm Inc. Circuit set-up and caching for multimedia multipoint servers
US6009100A (en) * 1997-09-12 1999-12-28 Lucent Technologies Inc. Asynchronous transfer mode switching system
US6134235A (en) * 1997-10-08 2000-10-17 At&T Corp. Pots/packet bridge
US20020071394A1 (en) * 1997-11-17 2002-06-13 Adc Telecommunications, Inc. System and method for electronically identifying connections of a cross-connect system
US6035405A (en) * 1997-12-22 2000-03-07 Nortel Networks Corporation Secure virtual LANs
US6119170A (en) * 1997-12-29 2000-09-12 Bull Hn Information Systems Inc. Method and apparatus for TCP/IP multihoming on a host system configured with multiple independent transport provider systems
US20010036188A1 (en) * 1998-01-20 2001-11-01 Telefonaktiebolaget L M Ericsson Multi-service circuit for telecommuncations
US6563918B1 (en) * 1998-02-20 2003-05-13 Sprint Communications Company, LP Telecommunications system architecture for connecting a call
US6275493B1 (en) * 1998-04-02 2001-08-14 Nortel Networks Limited Method and apparatus for caching switched virtual circuits in an ATM network
US20040179531A1 (en) * 1998-04-30 2004-09-16 Sbc Technology Resources, Inc. Secure ATM-based distributed virtual tandem switching system and method
US6757278B1 (en) * 1998-04-30 2004-06-29 Sbc Technology Resources, Inc. Secure ATM-based distributed virtual tandem switching system and method
US6345048B1 (en) * 1998-04-30 2002-02-05 Sbc Technology Resources, Inc. ATM-based distributed virtual tandem switching system
US6389011B2 (en) * 1998-04-30 2002-05-14 Sbc Technology Resources, Inc. ATM-based distributed virtual tandem switching system
US6765903B1 (en) * 1998-04-30 2004-07-20 Sbc Technology Resources, Inc. ATM-based distributed network switching system
US6219348B1 (en) * 1998-04-30 2001-04-17 Sbc Technology Resources, Inc. ATM-based distributed virtual tandem switching system
US6169735B1 (en) * 1998-04-30 2001-01-02 Sbc Technology Resources, Inc. ATM-based distributed virtual tandem switching system
US20020093947A1 (en) * 1998-04-30 2002-07-18 Sbc Technology Resources, Inc. ATM-based distributed virtual tandem switching system
US20020075855A1 (en) * 1998-05-11 2002-06-20 At&T Corp. Method and apparatus for a remote signaling and call processing in a telecommunications network
US6195714B1 (en) * 1998-06-08 2001-02-27 Nortel Networks Limited System for transferring STM calls through ATM network by converting the STM calls to ATM and vice versa at the edge nodes of ATM network
US6282194B1 (en) * 1998-09-23 2001-08-28 Nortel Networks Limited Transit trunk subnetwork system
US6782004B1 (en) * 1998-11-09 2004-08-24 Lucent Technologies Inc. Intelligent network signaling using an open system protocol
US6510164B1 (en) * 1998-11-16 2003-01-21 Sun Microsystems, Inc. User-level dedicated interface for IP applications in a data packet switching and load balancing system
US20040022237A1 (en) * 1998-11-20 2004-02-05 Level 3 Communications, Inc. Voice over data telecommunications network architecture
US6252952B1 (en) * 1999-12-30 2001-06-26 At&T Corp Personal user network (closed user network) PUN/CUN
US20020064129A1 (en) * 2000-01-20 2002-05-30 Sbc Technology Resources, Inc. System and method for measurement-based adaptive caching of virtual connections
US20020061101A1 (en) * 2000-01-20 2002-05-23 Hall Thomas Glenn Intelligent network and method for providing voice telephony over ATM and closed user groups
US6343065B1 (en) * 2000-01-20 2002-01-29 Sbc Technology Resources, Inc. System and method of measurement-based adaptive caching of virtual connections
US20020009086A1 (en) * 2000-01-20 2002-01-24 Gallant John K. Intelligent network and method for providing voice telephony over ATM and private address translation

Also Published As

Publication number Publication date
US7136378B2 (en) 2006-11-14
US7843932B2 (en) 2010-11-30
US6757278B1 (en) 2004-06-29
US20070008977A1 (en) 2007-01-11
US20040179531A1 (en) 2004-09-16
US7227837B1 (en) 2007-06-05

Similar Documents

Publication Publication Date Title
US7227837B1 (en) Fault tolerant virtual tandem switch
Wu Emerging technologies for fiber network survivability
US6616350B1 (en) Method and apparatus for providing a more efficient use of the total bandwidth capacity in a synchronous optical network
US7046619B2 (en) Method and system for bi-directional path switched network
US7660238B2 (en) Mesh with protection channel access (MPCA)
US8116196B2 (en) Shared mesh signaling method and apparatus
EP0994635B1 (en) Method and apparatus for data transmission in synchronous optical networks
CA2249149C (en) A communication system having narrowband to broadband connectivity
US6327260B1 (en) Controlled routing to a plurality of signaling interfaces at a single telephonic switch
Sosnosky Service applications for SONET DCS distributed restoration
Flanagan Fiber network survivability
US20030041208A1 (en) Network element with redundant switching matrix
Krishnan et al. Improved survivability with multi-layer dynamic routing
KR20120005540A (en) Protection of user data transmission through a transport network
Veitch et al. ATM network resilience
US20040221058A1 (en) Nested protection switching in a mesh connected communications network
US20060050631A1 (en) Reconfigurable apparatus providing 1:N and 1:1 equipment redundancy for high speed broadband interfaces with 1‘and 1:N automatic protection switching
Van Landegem et al. A self-healing ATM network based on multilink principles
US8675667B1 (en) Systems and methods for forming and operating robust communication networks for an enterprise
JPH0918492A (en) Atm communication network and failure restoration method
EP0592153A2 (en) Telecommunications system with redundant SS7 signaling interfaces
MacDonald et al. Requirements of optical layer network restoration
Jones et al. Sprint long distance network survivability: today and tomorrow
JP2002044148A (en) Method for routing traffic in network
Gryseels et al. Common pool survivability for meshed SDH-based ATM networks

Legal Events

Date Code Title Description
STCB Information on status: application discontinuation

Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION