Cisco Technology, Inc.

Christian Cassar

Jesper Skriver

Isidoros Kouvelas

Stewart Frederick Bryant

Fabio Rodolfo Maino

Dino Farinacci

Darrel Jay Lewis

John Mullooly

Gregg Schudel

Rajiv Asati

Mark L Hendrickson

Fang Yang

Giles Douglas Yorke Heron

Robert Marcin Raszuk

Neil Alasdair James Jarvis

Kathy Xia Ke

Matthew James Collins

Crispin Nicholas Dent-Young

Alan J Cheilek

Kenneth A Patton

Willem Maria Verrydt

In one embodiment, a method includes identifying a change in network topology at a network device, transmitting a test packet from the network device to determine if an adjacent network device located in a backup path has converged following the network topology change, and updating a forwarding information base at the network device in response to the network topology change if a response to the test packet indicates that the adjacent network device has converged. An apparatus and logic are also disclosed herein.

Loop-free convergence in communication networks

In one embodiment, a method includes receiving at a first network device in a first virtual private network, a packet destined for a second network device in communication with a second virtual private network, and transmitting the packet over the second network, wherein the packet is encapsulated for transmittal on a tunnel extending from the first network device to the second network device. The first network device is in communication with a system operable to map and encapsulate the packet and provide an overlay that traverses over the second virtual private network. An apparatus and logic are also disclosed herein.

Interconnecting virtual private networks

In one embodiment, a method includes discovering at a first edge device in a first network that a multicast source has moved from the first network to a second network, the first edge device in communication through a core network with a plurality of edge devices belonging to a multicast group comprising the multicast source, transmitting from the first edge device to a second edge device in the second network, a join request for the multicast group comprising the multicast source at the second network, receiving multicast traffic for the multicast group at the first edge device on a transient multicast tree extending from the second edge device to the plurality of edge devices, and forwarding the multicast traffic to the plurality of edge devices. An apparatus and logic are also disclosed herein.

Fast convergence with multicast source mobility

An example method for independently verifying a transit point in a network environment is provided and includes receiving, at a transit point in a packet network, at least two radio signals from corresponding different radio sources, receiving, at the transit point, a sampling request in an packet message, and transmitting in another packet message a sample of the at least two radio signals such that by comparing the sample with an expected sample, a location of the transit point is determined. The expected sample can comprise another sample of the at least two radio signals that would have been received by the transit point at an expected location at a time of receipt of the sampling request, and if the expected sample matches the sample, the transit point is determined to be at the expected location.

Independently verifying a transit point in a network environment

In one embodiment, a device receives a payload encapsulated in an Internet Protocol (IP) transport header having a time-to-live (TTL) value, and decapsulates the payload while maintaining the TTL value. In response to determining that a destination of the payload is not attached to the device, the device may then re-encapsulate the payload in a new IP transport header with a new TTL value that is less than the maintained TTL value, and transmits the re-encapsulated payload toward the destination. In this manner, loops in overlay networks may be prevented based on eventual expiration of the TTL value of the IP transport header, accordingly.

Breaking loops in overlay networks using an IP transport header

In one embodiment, a clock on a network device is initialized, and then a first timing message is received at the network device from a reference device having a first timestamp indicating when the first timing message was transmitted from the reference device. The network device may then determine and store a one-way delay from the first timestamp to a first time at which the first timing message was received at the network device. In response to restarting the clock, the network device may receive a second timing message from the reference device having a second timestamp indicating when the second timing message was transmitted from the reference device. The network device may then calibrate the clock such that a second time at which the network device received the second timing message is the second timestamp plus the stored one-way delay.

Recalibration of precision clocks in a computer network

In one embodiment, an angular distance calculation technique may enable an intermediate node, such as a route reflector, to render customized best path selection decisions to destination address prefixes and advertise those decisions to its intermediate peering nodes, i.e., route reflector clients, in an autonomous system of a computer network. That is, the route reflector may execute a routing protocol, such as BGP, to select and advertise a next hop (e.g., an address prefix of an egress point of the autonomous system) associated with a customized best path to a route reflector client based on an angular distance between the route reflector client and the egress point. In this manner, the route reflector client may route data traffic destined to a destination address prefix utilizing the egress point associated with the customized best path to that prefix.

Angular distance calculation for BGP best path selection

A method of constructing a forwarding database for a data communications network comprising a plurality of network components and supporting at least first and second topologies having one or more common network components is described. The forwarding database includes a plurality of entries providing forwarding information for data destined for a related network component. The method comprises the step, performed at a constructing network component, of deriving topology dependent forwarding information for data destined for a network component. The method further comprises the step of including the topology dependent forwarding information at the related forwarding database entry.

Method of constructing a forwarding database for a data communications network

A method and apparatus for redirecting network traffic through a multipoint tunnel overlay network using distinct network address spaces for the overlay and transport networks. In an IP implementation, redirecting traffic to be tunneled across a network comprises deriving the transport IP address of a multipoint tunnel endpoint from the network IP address by making the transport address numerically equivalent to the network address, the transport address being in an address space distinct from the address space of the network address. Traffic is redirected by changing the address space of the next hop in a received routing advertisement.

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Hampton, United Kingdom

Christian Cassar