Abstract: The invention features systems and methods for detecting and mitigating network attacks in a Voice-Over-IP (VoIP) network. A server is configured to receive information related to a mitigation action for a call. The information can include a complexity level for administering an audio challenge-response test to the call and an identification of the call. The server also generates i) a routing label based on the identification of the call, and ii) a script defining a plurality of variables that store identifications of a plurality of altered sound files for the audio challenge-response test. Each altered sound file is randomly selected by the server subject to one or more constraints associated with the complexity level. The server is further configured to transmit the script to a guardian module and the routing label to a gateway.

Abstract: A non-intrusive objective speech quality assessment is performed on a degraded speech signal. The methods are well suited for systems where random and bursty packet losses may occur and/or packet stream regeneration may also occur prior to speech signal quality assessment. In one embodiment received packetized speech is analyzed to determine to an overall final signal quality score. A limited set of trained neural networks, e.g., 5, corresponding to different signal features, each determine a signal feature quality score. A trained joint quality score determination module determines a joint quality score based on the signal feature quality scores. Packet loss is estimated based on received packet header information and/or detected gap durations. The determined joint quality score is adjusted, based on estimated packet loss information obtained from examining the speech signal, network level statistics and/or codec parameters to generate the final quality score.

Abstract: The invention features systems and methods for detecting and mitigating network attacks in a Voice-Over-IP (VoIP) network. A server is configured to receive information related to a mitigation action for a call. The information can include a complexity level for administering an audio challenge-response test to the call and an identification of the call. The server also generates i) a routing label based on the identification of the call, and ii) a script defining a plurality of variables that store identifications of a plurality of altered sound files for the audio challenge-response test. Each altered sound file is randomly selected by the server subject to one or more constraints associated with the complexity level. The server is further configured to transmit the script to a guardian module and the routing label to a gateway.

Abstract: The invention features systems and methods for detecting and mitigating network attacks in a Voice-Over-IP (VoIP) network. A server is configured to receive information related to a mitigation action for a call. The information can include a complexity level for administering an audio challenge-response test to the call and an identification of the call. The server also generates i) a routing label based on the identification of the call, and ii) a script defining a plurality of variables that store identifications of a plurality of altered sound files for the audio challenge-response test. Each altered sound file is randomly selected by the server subject to one or more constraints associated with the complexity level. The server is further configured to transmit the script to a guardian module and the routing label to a gateway.

Abstract: The invention features systems and methods for detecting and mitigating network attacks in a Voice-Over-IP (VoIP) network. A server is configured to receive information related to a mitigation action for a call. The information can include a complexity level for administering an audio challenge-response test to the call and an identification of the call. The server also generates i) a routing label based on the identification of the call, and ii) a script defining a plurality of variables that store identifications of a plurality of altered sound files for the audio challenge-response test. Each altered sound file is randomly selected by the server subject to one or more constraints associated with the complexity level. The server is further configured to transmit the script to a guardian module and the routing label to a gateway.

Abstract: A non-intrusive objective speech quality assessment is performed on a degraded speech signal. The methods are well suited for systems where random and bursty packet losses may occur and/or packet stream regeneration may also occur prior to speech signal quality assessment. In one embodiment received packetized speech is analyzed to determine to an overall final signal quality score. A limited set of trained neural networks, e.g., 5, corresponding to different signal features, each determine a signal feature quality score. A trained joint quality score determination module determines a joint quality score based on the signal feature quality scores. Packet loss is estimated based on received packet header information and/or detected gap durations. The determined joint quality score is adjusted, based on estimated packet loss information obtained from examining the speech signal, network level statistics and/or codec parameters to generate the final quality score.

Abstract: The invention features systems and methods for detecting and mitigating network attacks in a Voice-Over-IP (VoIP) network. A server is configured to receive information related to a mitigation action for a call. The information can include a complexity level for administering an audio challenge-response test to the call and an identification of the call. The server also generates i) a routing label based on the identification of the call, and ii) a script defining a plurality of variables that store identifications of a plurality of altered sound files for the audio challenge-response test. Each altered sound file is randomly selected by the server subject to one or more constraints associated with the complexity level. The server is further configured to transmit the script to a guardian module and the routing label to a gateway.

Abstract: Described are methods and apparatuses, including computer program products, for limiting server overload via client control. A first set of a plurality of requests are transmitted to a server at a first transmission rate during a first period of time. The first transmission rate is limited to be less than or equal to a first transmission limit rate. An overload value is determined based on whether at least two or more requests of the first set of requests for service satisfy an overload criterion. A second transmission limit rate is determined based on the overload value and the first transmission limit rate. A second set of a plurality of requests is transmitted to the server at a second transmission rate during a second period of time. The second transmission rate is limited to be less than or equal to the second transmission limit rate.

Abstract: Described are methods and apparatuses, including computer program products, for controlling server resources. An occupancy value of a buffer and a first utilization value of a first processor are measured. The buffer is configured to store one or more requests for service from at least a first client. The first processor is configured to receive and process the one or more requests from the buffer. A buffer size value is determined based on a processor throughput calculation, and a first service request limit for the first client is determined based on the occupancy value, the first utilization value, and the buffer size value.

Abstract: The invention features systems and methods for detecting and mitigating network attacks in a Voice-Over-IP (VoIP) network. A server is configured to receive information related to a mitigation action for a call. The information can include a complexity level for administering an audio challenge-response test to the call and an identification of the call. The server also generates i) a routing label based on the identification of the call, and ii) a script defining a plurality of variables that store identifications of a plurality of altered sound files for the audio challenge-response test. Each altered sound file is randomly selected by the server subject to one or more constraints associated with the complexity level. The server is further configured to transmit the script to a guardian module and the routing label to a gateway.

Abstract: Described are computer-based methods and apparatuses, including computer program products, for testing network elements in a communication network. A record file is received, comprising one or more record file elements, each record file element including data indicative of a request received by a network element in a network during normal operation. A virtual client is created for each of one or more identified sources. One or more regenerated requests are generated, each of the one or more regenerated requests being generated based on data in a corresponding record file element from the one or more record file elements. For each of the one or more regenerated requests, the virtual client associated with the regenerated request transmits the regenerated request to a subject network element to test the subject network element, wherein the one or more regenerated requests simulate requests received by the network element during normal operation.

Abstract: Computer-based methods and apparatuses, including computer program products, are described for detecting and limiting focused server overload in a network. A feedback message is received from a downstream server, wherein the feedback message includes a communication protocol statistic. The methods and apparatuses determine which of one or more counters that store a number of feedback messages received that include the statistic, from an array of counters, are associated with the downstream server using one or more hash functions based on information included in the feedback message. The one or more counters are incremented in response to the feedback message including the statistic. Using the one or more hash functions, a value of the number stored in the one or more counters is determined. The value is determined to be indicative of an overload episode in the network for the downstream server based on whether the value satisfies a predetermined criteria.

Abstract: Described are methods and apparatuses, including computer program products, for limiting server overload via client control. A first set of a plurality of requests are transmitted to a server at a first transmission rate during a first period of time. The first transmission rate is limited to be less than or equal to a first transmission limit rate. An overload value is determined based on whether at least two or more requests of the first set of requests for service satisfy an overload criterion. A second transmission limit rate is determined based on the overload value and the first transmission limit rate. A second set of a plurality of requests is transmitted to the server at a second transmission rate during a second period of time. The second transmission rate is limited to be less than or equal to the second transmission limit rate.

Abstract: Described are methods and apparatuses, including computer program products, for controlling server resources. An occupancy value of a buffer and a first utilization value of a first processor are measured. The buffer is configured to store one or more requests for service from at least a first client. The first processor is configured to receive and process the one or more requests from the buffer. A buffer size value is determined based on a processor throughput calculation, and a first service request limit for the first client is determined based on the occupancy value, the first utilization value, and the buffer size value.

Abstract: Described are methods and apparatus, including computer program products, for controlling time-sensitive data in a packet-based network. Data associated with a call is received, and the data includes an identifier associated with the data, a data source, or one or more data destinations. The data is associated with a logical trunk group selected from a plurality of logical trunk groups each in communication with the one or more data destinations over a packet-based network. The logical trunk group is selected based in part on the identifier. Calls through the packet-based network are managed based in part on the associated logical trunk group.

Abstract: A method and apparatus are disclosed for congestion management in a multi-branch Internet Protocol-based private branch exchange switch. The multi-branch Internet Protocol-based private branch exchange switch is interconnected through (i) a packet network referred to as the primary network, such as a wide area network, and (ii) an alternate network, such as the public switched telephone network. Packet phone adapters associated with each packet telephone unit monitor packet telephone calls and report delay information to communication servers. The communication server can reroute the packet telephony calls through the secondary network upon detection of congestion in the underlying primary network, thereby preserving voice quality. The packet phone adapter will discard records collected from calls whose duration is below a minimum value, to ensure reliable congestion information. Each communication server records reported voice quality of service information in a congestion control database.

Abstract: Described are methods and apparatus, including computer program products, for controlling time-sensitive data in a packet-based network. Data associated with a call is received, and the data includes an identifier associated with the data, a data source, or one or more data destinations. The data is associated with a logical trunk group selected from a plurality of logical trunk groups each in communication with the one or more data destinations over a packet-based network. The logical trunk group is selected based in part on the identifier. Calls through the packet-based network are managed based in part on the associated logical trunk group.

Abstract: Described are methods and apparatus, including computer program products, for hierarchically organizing logical trunk groups in a packet-based network. A first hierarchical group includes a first logical trunk group that is associated with a first trunk resource parameter. The first hierarchical group is associated with a group resource parameter, a portion of which is based on the trunk resource parameter. Data associated with a telephone call is associated with a logical trunk group. Transmission of the data through a packet-based network is based in part on the group resource parameter.

Abstract: Described are methods and apparatus, including computer program products, for defining logical trunk groups in a packet-based network. A plurality of logical trunk groups are defined for a first media gateway in communication with a packet-based network. Each of the plurality of logical trunk groups is associated with one or more media gateways in communication over the packet-based network with the first media gateway. Data associated with a call that is received or transmitted by the media gateway is associated with a first logical trunk group of the plurality of logical trunk groups.

Abstract: A method and apparatus are disclosed for alleviating congestion and overload in a distributed call-processing system interconnected through a packet based network. The illustrative Internet Protocol network includes a plurality of end terminals and distributed call processors. According to an aspect of the invention, the call processor will determine whether to process a call request or to forward the request to another call processor. Generally, the call processor will declare an overload condition if sufficient resources (including processing or memory resources) are not available to process a given call. If a call processor determines that it is too congested to process a call, the call processor enters an overload condition, selects an alternate call processor and forwards the request to the alternate call processor. Each call processor maintains an ordered list of call processors that indicates whether or not each call processor is overloaded.