Abstract: A switch responsive to a pressure differential, including a pressure response mechanism for providing a pressure response in response to the pressure differential and a device actuator arranged to interact with the pressure response mechanism and to utilize the pressure response of the pressure response mechanism to actuate a device. The device actuator actuates the device to an operative state when the pressure differential is below a lower pressure differential threshold, and may actuate the device to a non-operative state when the pressure differential is above an upper pressure differential threshold.

Abstract: Methods and apparatus are disclosed for generating fluid pulses in a fluid column, such as within a well. Various described example fluid pulse generators each have a valve structure including a plurality of rollers rotatable around axes that are oriented perpendicular or otherwise angled with respect to the flow direction, the rollers being arranged to collectively at least partially obstruct the cross-sectional area of the fluid conduit. The rotational positions of the rollers may be varied to change the degree of obstruction in the conduit, thereby to generate pressure pulses in the fluid column detectable at a location remote from the fluid pulse generator; these pressure pulses can be used to encode a signal received at the fluid pulse generator.

Abstract: Methods and apparatus are disclosed for generating fluid pulses in a fluid column, such as within a well. Various described example fluid pulse generators each have a valve structure including a plurality of rollers rotatable around axes that are oriented perpendicular or otherwise angled with respect to the flow direction, the rollers being arranged to collectively at least partially obstruct the cross-sectional area of the fluid conduit. The rotational positions of the rollers may be varied to change the degree of obstruction in the conduit, thereby to generate pressure pulses in the fluid column detectable at a location remote from the fluid pulse generator; these pressure pulses can be used to encode a signal received at the fluid pulse generator.

Abstract: A switch responsive to a pressure differential, including a pressure response mechanism for providing a pressure response in response to the pressure differential and a device actuator arranged to interact with the pressure response mechanism and to utilize the pressure response of the pressure response mechanism to actuate a device. The device actuator actuates the device to an operative state when the pressure differential is below a lower pressure differential threshold, and may actuate the device to a non-operative state when the pressure differential is above an upper pressure differential threshold.

Abstract: In at least some embodiments, a downhole tool includes a tool body defining a tool centerline, and a recessed ring guide intermediate to ends of the tool body. The downhole tool also includes an expander ring having an asymmetric wall thickness and rotatable around the recessed ring guide between a reduced tool profile orientation and an expanded tool profile orientation. The downhole tool also includes an actuator configured to rotate the expander ring between the reduced profile orientation and the expanded profile orientation.

Abstract: In at least some embodiments, a downhole tool includes a tool body defining a tool centerline, and a recessed ring guide intermediate to ends of the tool body. The downhole tool also includes an expander ring having an asymmetric wall thickness and rotatable around the recessed ring guide between a reduced tool profile orientation and an expanded tool profile orientation. The downhole tool also includes an actuator configured to rotate the expander ring between the reduced profile orientation and the expanded profile orientation.

Abstract: Methods and systems for identifying instability or a loop in a network. In one method, a first BPDU message is received at a switch indicating a topology change. The message includes a bridge identifier identifying a network device originating the first BPDU message. A second BPDU is generated at the switch and includes the bridge identifier identifying the network device originating the first BPDU message. The method further includes transmitting the second BPDU message indicating the topology change from the switch.

Abstract: A method for border nodes using the Border Gateway Protocol to advertise path updates to peer nodes in other domains involves calculating the update interval for each advertisement of an update of the same path to the same peer and advertising the update when the interval has expired. The update interval is the sum of the standard update interval and the unexpired portions of update intervals applied to previous unadvertised updates.

Abstract: Methods and systems for identifying instability or a loop in a network. In one method, a first BPDU message is received at a switch indicating a topology change. The message includes a bridge identifier identifying a network device originating the first BPDU message. A second BPDU is generated at the switch and includes the bridge identifier identifying the network device originating the first BPDU message. The method further includes transmitting the second BPDU message indicating the topology change from the switch.

Abstract: A novel technique is provided for preventing routing loops by disseminating Border Gateway Protocol (BGP) attribute information in an Open Shortest Path First (OSPF) configured network. Specifically, a new OSPF sub-type-length-value (TLV) is introduced for transporting a conventional BGP autonomous system (AS) path attribute through the OSPF-configured network. Like the BGP AS-path attribute, the new OSPF AS-path sub-TLV is configured to store a set of AS numbers corresponding to the AS path of one or more advertised routes. Thus, when a network device receives an OSPF link-state advertisement (LSA) containing the novel AS-path sub-TLV, the network device determines whether it resides in an autonomous system whose AS number is stored in the sub-TLV. If so, the network device does not install the LSA's advertised routes in its link-state database since the routes, if installed, could result in routing loops.

Abstract: A method is disclosed for providing automatic management of network routes, such as MPLS Layer 3 VPN routes. In one aspect, a method comprises creating and storing, in association with first information identifying a network element and second information identifying a customer entity that uses the network element, a maximum routes limit value representing a maximum number of routes that the network element is allowed to store, and a threshold routes limit value that is less than the maximum routes limit value; receiving a total routes value from the network element indicating that the network element has added, to a routing table of the network element, a number of routes equal to the total routes value; and in response to determining that the total routes value is greater than the threshold routes limit value, automatically performing a responsive action.

Abstract: A method for border nodes using the Border Gateway Protocol to advertise path updates to peer nodes in other domains involves calculating the update interval for each advertisement of an update of the same path to the same peer and advertising the update when the interval has expired. The update interval is the sum of the standard update interval and the expired portions of update intervals applied to previous unadvertised updates.