Leo Nieuwesteeg

Bio: Leo Nieuwesteeg is an academic researcher from Cisco Systems, Inc.. The author has contributed to research in topics: Common-channel signaling & Call control. The author has an hindex of 3, co-authored 3 publications receiving 33 citations.

Multicast heartbeat signaling

Abstract: A mechanism that provides for communication of heartbeat signals from servers (call agents) to clients (gateways) in a packet telephony network environment. Clients listen for receipt of multicast heartbeats from any of the servers that may be part of a multicast group. A client assigned to a particular server for control messaging, upon failure to receive a response to a message sent to the assigned server and failure to receive a heartbeat from the assigned server, may select a second server from among the servers and re-send the message to the second server. Without receipt of heartbeat signals, the client defaults to a normal retry behavior for re-sending the message first to the assigned server a number of times before attempting to re-send the message to the second server. With receipt of the heartbeat from the second server, the client adopts an aggressive retry behavior by re-sending the message to the assigned server a lesser number of retries before attempting to re-send the message to the second server. The clients use the multicast heartbeats as a hint, allowing them to switch to the more aggressive retry behavior and consequently reduce the time to re-associate with a new server and re-establish a new security association (if IPsec is used), resulting in a drastic reduction in service delay due to server failures.

Scalable packet-switched call control signaling

Abstract: A packet-switched communication system, method for controlling packet-switched calls over such a system, and components of the system are disclosed. In one embodiment, the system provides a scalable implementation for handling H.323 calls. The H.323-required TCP signaling terminations are handled by distributed signaling gateways. Each signaling gateway backhauls the signaling content from these terminations to a central media gateway controller for processing. The media gateway controller uses an efficient gateway control protocol to control media gateways and/or media proxies that actually handle the media bearer channels associated with the backhauled H.323 signaling connections. The H.323 complexity can thus be concentrated in the media gateway controller, without requiring full H.323 functionality at the distributed gateways. Also, because the TCP signaling connections are remote from the media gateway controller, H.323 signaling redundancy can be provided at the media gateway controller.

Deferred invocation of communication services

Abstract: In one embodiment, a network device determines one or more conditions for invoking one or more real applications to the network device for a session This determination may be made at the initiation of the session, such as when a SIP INVITE message is received The one or more conditions allow real applications to be invoked when a future event satisfies the condition When it is determined that a condition is satisfied, a real application associated with the condition is then invoked Accordingly, conditions may be set for real applications that may be tested against future events that have not yet occurred This allows deferred invocation of real applications Accordingly, if real applications are not needed for a session, then they are not invoked But, when a real application is needed, it can be invoked

Communications system providing message aggregation features and related methods

Abstract: A communications system may include a plurality of source message servers for storing messages for delivery to a user, a target message server having a target message box associated therewith, and an aggregation server for periodically aggregating the messages from the source message servers to the target message box for retrieval by the user. The target message server may provide a delivery failure message to the aggregation server based upon a failure to deliver a message to the target message box. As such, the aggregation server may increase a period of sending messages to the target message box based upon a delivery failure message therefrom, and thereafter decrease the period of sending messages to the target message box based upon a successful delivery of a message thereto.

Voice over internet protocol real time protocol routing

Abstract: A method for call signaling and media flow in a network including receiving call signaling information from an originating Voice over Internet Protocol (VoIP) endpoint relaying the call signaling information to a destination VoIP endpoint, directing the originating VoIP endpoint to use a RTP media proxy and receiving a stream of media to the RTP media proxy from the originating VoIP endpoint.

Proxy server, communication system, communication method, and program

Abstract: A proxy server in an SIP network includes the common SIP proxy server function 11, the function of determining whether an SIP request and an SIP response received by the proxy server 10 belong to a call flow encountering a failure of the working SIP server 30, and the function of, when determination is made that they belong to a call flow encountering a failure, referring to the contents of the received SIP request and SIP response to specify a destination to which the SIP request and the SIP response are to be transmitted next.

Method and systems for redundant server automatic failover

Abstract: A method and systems for a redundant server automatic fail-over system (100) is provided. The system includes a plurality of client devices (106) communicatively coupled to a network (130) wherein the plurality of client devices each includes an active server identification location. The system also includes a first server system communicatively coupled to the network that is configured to operate as the active server (102) on the network wherein messages sent to the first server system are addressed to the first server system using the active server identification location on each client device. The system further includes a second server system communicatively coupled to the network that is configured to operate as a standby server (104) on the network and is configured to switch to being the active server on the network when it is determined that the first server system is unable to operate as the active server.

Registering an endpoint with a sliding window of controllers in a list of controllers of a survivable network

Abstract: Provided are methods, devices, and systems for maintaining a SIP survivable network. A SIP endpoint maintains an ordered list of the controllers that are available to it and registers with a subset containing the first N controllers in the list, where N is a plurality, but not all, of the controllers in the list, and obtains services from one or more of the controllers of the subset. If one of the controllers of the subset becomes unavailable, the endpoint registers with the (N+1)st controller in the list, thereby adding it to the subset. If and when the one controller becomes available again, the endpoint de-registers with the (N+1)st controller, thereby removing it from the subset, and if necessary re-registers with one controller. The subset thus forms a sliding window on the list.