Rad Data Communications Ltd.

Rad Data Communication Ltd.

Alon Geva

Yaakov Stein

Gabriel Zigelboim

Ron Insler

Ehud Malik

A method for measuring one-way delays in a communications network, the method comprising: maintaining, at a third node having a reference clock, a first virtual clock state emulating a first node clock located at a first node and a second virtual clock state emulating a second node clock located at a second node; registering a timeset comprising transmission and reception times at the first node and the second node, respectively, for each packet of a plurality of packets that are transmitted from the first node to the second node and reflected from the second node back to the first node; converting times in the timeset, responsive to the first and/or second virtual clocks, into times in accordance with the reference clock; calculating, for each packet of the plurality of packets, a forward one-way delay (FOWD) and a reverse one-way delay (ROWD), responsive to the converted timeset.

One-way packet delay measurement

A method of determining packet loss ratio between two communications nodes, the method comprising: transmitting at least one loopback packet configured to be propagated from a first node through a second and third nodes back to the first node; upon traversal of the second node inserting into the loopback packet a first counter for a number of packets sent from the second node to the third node prior to receiving the loopback packet; upon traversal of the third node inserting into the loopback packet a second counter for a number of packets received by the third node from the second node prior to receiving the loopback packet; upon return of the loopback packet to the first node, determining a packet loss ratio between the second and third nodes responsive to the first counter number and the second counter number inserted into the loopback packet.

Triangle loopback

A method for measuring one-way delays in a communications network, the method comprising: maintaining a virtual clock state comprising information for converting times measured with respect to remote clocks into times as would be measured with respect to a local reference clock; registering, for each packet of the plurality of packets in a communications session between the first and second nodes, a timeset comprising transmission and reception times at the first and second nodes; converting, responsive to the virtual clock, times in the timeset measured with respect to the first node clock or the second node clock, into times as would be measured with respect to the reference clock; calculating, for each packet of the series of packets, a forward one-way delay (FOWD) from the first node to the second node and a reverse one-way delay (ROWD) from the second node to the first node, responsive to the converted timeset.

Apparatus for synchronizing a local clock to a master clock, the apparatus comprising: at least one port for receiving and transmitting packets; a local clock; and a packet inspector that uses time from the local clock to timestamp packets received at a port of the at least one port, copies timing information from the received packets if the packets are timing distribution packets that are transmitted between a master clock and a slave clock in order to synchronize the slave clock to the master clock, and forwards the received packets for transmission from a port of the at least one port towards a packet destination that is not a packet source from where the packets originate, wherein the local clock uses the copied timing information and timestamps to synchronize the local clock to the master clock.

Timing over packet demarcation entity

A method of characterizing a communications channel between two communications nodes, the method comprising: determining at least one feature of a communications path between a first communications node and a second communications node; determining at least one feature of a communications path between the first communications node and a third communications node; transmitting at least one packet from the first node to propagate through the second and third nodes and return to the first node; and determining at least one feature of the communications channel between the second and third nodes responsive to receiving the packet at the first node, the at least one determined feature of the first node and the second node, and/or information comprised in the packet.

Apparatus for providing timing information, the apparatus comprising: a primary reference time clock (PRTC) that provides a reference time of day (ToD) and a reference frequency; a packet master clock that receives the ToD and reference frequency and is configured to distribute timing to a slave clock in accordance with a timing over packet procedure responsive to the ToD and the reference frequency; and a housing that houses the PRTC and packet master clock which may be plugged into a conventional small form factor (SFP) compliant cage to connect the packet master clock to a packet switched network (PSN).

Pluggable packet master clock

Apparatus for monitoring a packet switched network, the apparatus comprising: at least one port for receiving and transmitting packets; a local clock; and a packet inspector that uses time from the local clock to timestamp packets received at a port of the at least one port, and additionally copies timing information from received timing distribution packets, which are transmitted from a master clock to a slave clock in order to discipline the slave clock, and forwards the received packets for transmission from a port of the at least one port; wherein the apparatus uses the timestamp of a received timing distribution packet and the copied timing information to monitor timing distribution performance of the network.

A method and system in which a Digital Subscriber Line Access Multiplexer (DSLAM) that is part of a DSL (Digital Subscriber Line) system is able to provide synchronous services to end user equipment connected to the DSLAM via a DSL link and Customer Premises Equipment (CPE). A sniffer device having direct or indirect access to a Primary Reference Clock (PRC) of the DSL system calculates the phase difference between the PRC and the DSLAM's Local Timing Reference (LTR). The phase difference is sent to the CPEs requiring accurate reference clock frequency. The CPEs are able to derive the PRC from the phase difference information transmitted by the sniffer device thus enabling synchronous end user equipment operation.

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Hod Hasharon, Israel

Alon Geva