Abstract: Hashing name resolution requests may be performed according to an identified routing policy. A query from a Domain Name System (DNS) resolver to lookup a name in a first collection of name records may be received. A hash function may be applied to the name to generate a hash value according to a routing policy for the first collection of name records that determines which name record in the first collection of name records is used to answer the query. A name record in the collection of name records may be identified according to a mapping request for the name record using the hash value and a value for the name record may be returned to the DNS resolver. The value for the name record may identify a second collection of name records to query as part of determining the network address at the DNS resolver.

Abstract: There are disclosed a system, a test head and a method for testing a device under test. Two or more test heads may be mated directly with respective connectors on the device under test. Each test head may include a traffic generator including a stateless packet builder to generate stateless traffic for transmission to the device under test, and a traffic receiver including a stateless packet analyzer to accumulate traffic statistics on stateless traffic received from the device under test. A server coupled to the two or more test heads via respective communications links, may generate stateful traffic for transmission to the device under test by the two or more test heads, and may process stateful traffic received from the device under test by the two or more test heads.

Abstract: Methods and test systems for reporting transmit bandwidth contention. A histogram representing transmit bandwidth demand for a network device may be built, the histogram including a plurality of bins representing for a plurality of contiguous time intervals of equal duration including a current time bin and plural future time bins. The histogram may be displayed and periodically updated.

Abstract: An impairment unit and method of emulating network impairments is disclosed. The impairment unit may receive network traffic and transmit impaired network traffic. Received packets may be stored in a memory physically partitioned into a plurality of memory blocks and logically partitioned into a plurality of buffers. At least one buffer may be associated with each of a plurality of predefined impairment classes. One or more buffer may be a limited-length queue. Memory blocks may be assigned to buffers on an as-needed basis. A classifier may determine respective impairment classes of the received packets. A number of memory blocks assigned to each limited-length queue may be limited to a respective predetermined maximum. An enqueue manager may store each received packet and associated metadata in the buffer associated with the respective impairment class. The enqueue manager may discard received packets if the associated limited-length queue is full.

Abstract: An impairment unit, method, and machine readable storage media for emulating network impairments. A first network interface may receive network traffic including a plurality of received packets. A classifier may determine an impairment class of each received packet based on test information contained within a payload portion of each received packet, the impairment class of each received packet being one of a plurality of impairment classes, each impairment class uniquely associated with a corresponding one of a plurality of impairment profiles. An impairment engine may impair each of the plurality of impairment classes in accordance with the corresponding impairment profile to provide impaired network traffic. A second network interface may transmit the impaired network traffic to the network.

Abstract: There are disclosed a system, a test head and a method for testing a device under test. Two or more test heads may be mated directly with respective connectors on the device under test. Each test head may include a traffic generator including a stateless packet builder to generate stateless traffic for transmission to the device under test, and a traffic receiver including a stateless packet analyzer to accumulate traffic statistics on stateless traffic received from the device under test. A server coupled to the two or more test heads via respective communications links, may generate stateful traffic for transmission to the device under test by the two or more test heads, and may process stateful traffic received from the device under test by the two or more test heads.

Abstract: Methods, apparatus, and computer readable storage media for accumulating traffic statistics. A traffic receiver may receive a packet and determine a flow identifier associated with the received packet. A hash function may be applied to the flow identifier to generate a memory pointer. One or more records may be retrieved from a statistics memory based on the memory pointer. A determination may be made if the flow identifier associated with the received packet matches a flow identifier value contained in one of the one or more retrieved records. When a match occurs, the retrieved record containing the matching flow identifier value may be updated and the updated record may be stored in the statistics memory.

Abstract: An impairment unit and method of emulating network impairments is disclosed. The impairment unit may receive network traffic and transmit impaired network traffic. Received packets may be stored in a memory physically partitioned into a plurality of memory blocks and logically partitioned into a plurality of buffers. At least one buffer may be associated with each of a plurality of predefined impairment classes. One or more buffer may be a limited-length queue. Memory blocks may be assigned to buffers on an as-needed basis. A classifier may determine respective impairment classes of the received packets. A number of memory blocks assigned to each limited-length queue may be limited to a respective predetermined maximum. An enqueue manager may store each received packet and associated metadata in the buffer associated with the respective impairment class. The enqueue manager may discard received packets if the associated limited-length queue is full.

Abstract: An impairment unit, method, and machine readable storage media for emulating network impairments. A first network interface may receive network traffic including a plurality of received packets. A classifier may determine an impairment class of each received packet based on test information contained within a payload portion of each received packet, the impairment class of each received packet being one of a plurality of impairment classes, each impairment class uniquely associated with a corresponding one of a plurality of impairment profiles. An impairment engine may impair each of the plurality of impairment classes in accordance with the corresponding impairment profile to provide impaired network traffic. A second network interface may transmit the impaired network traffic to the network.

Abstract: Methods and test systems for reporting transmit bandwidth contention. A histogram representing transmit bandwidth demand for a network device may be built, the histogram including a plurality of bins representing for a plurality of contiguous time intervals of equal duration including a current time bin and plural future time bins. The histogram may be displayed and periodically updated.

Abstract: Methods, apparatus, and computer readable storage media for accumulating traffic statistics. A traffic receiver may receive a packet and determine a flow identifier associated with the received packet. A hash function may be applied to the flow identifier to generate a memory pointer. One or more records may be retrieved from a statistics memory based on the memory pointer. A determination may be made if the flow identifier associated with the received packet matches a flow identifier value contained in one of the one or more retrieved records. When a match occurs, the retrieved record containing the matching flow identifier value may be updated and the updated record may be stored in the statistics memory.

Abstract: A method and apparatus for testing and measuring the performance of a network for delivering multimedia is disclosed. A multimedia source is divided into data packets according to a packetizing standard. Each data packet includes a header and a payload containing a portion of the multimedia. N data packets (N>0) are grouped together into a packet bundle. Then, instrumentation is inserted into the header of at least one data packet within the packet bundle. The instrumentation includes information used in determining performance characteristics of the network.

Abstract: A method and apparatus for measuring network performance. A stream of packets of encoded data, sent by a transmitter across a network, are received. The stream of packets includes (n+1) packets having transmittal timestamps from a clock local to the transmitter, where n is an integer greater than or equal to one. An (n+1)th transmittal timestamp and an nth transmittal timestamp are determined. A value is calculated based on the (n+1)th and the nth transmittal timestamps. The value corresponds to the size of a virtual buffer needed to store the packets during a measurement interval. The value is used to determine a performance measure for the network.

Abstract: A method and apparatus for measuring network performance. A packet from a stream of multimedia data packets is received from across a network during a measurement interval. The time interval from the start of the measurement interval to receiving the packet is measured. The response of a buffer to the received packet is determined. The level of the buffer just before the packet arrives is calculated, based on the time interval. The level of the buffer just after the packet arrives is calculated, based on the previous level. A performance measure for the network is determined based on at least one of the two levels.

Abstract: A method and apparatus for measuring network performance. A packet from a stream of multimedia data packets is received from across a network during a measurement interval. The time interval from the start of the measurement interval to receiving the packet is measured. The response of a buffer to the received packet is determined. The level of the buffer just before the packet arrives is calculated, based on the time interval. The level of the buffer just after the packet arrives is calculated, based on the previous level. A performance measure for the network is determined based on at least one of the two levels.

Abstract: A method and apparatus for measuring network performance. A stream of packets of encoded data, sent by a transmitter across a network, are received. The stream of packets includes (n+1) packets having transmittal timestamps from a clock local to the transmitter, where n is an integer greater than or equal to one. An (n+1)th transmittal timestamp and an nth transmittal timestamp are determined. A value is calculated based on the (n+1)th and the nth transmittal timestamps. The value corresponds to the size of a virtual buffer needed to store the packets during a measurement interval. The value is used to determine a performance measure for the network.

Abstract: A method and apparatus for testing and measuring the performance of a network for delivering multimedia is disclosed. A multimedia source is divided into data packets according to a packetizing standard. Each data packet includes a header and a payload containing a portion of the multimedia. N data packets (N>0) are grouped together into a packet bundle. Then, instrumentation is inserted into the header of at least one data packet within the packet bundle. The instrumentation includes information used in determining performance characteristics of the network.