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Improving Convergence Speed and Scalability in OSPF: A Survey
Gagan Choudhury, Aman Shaikh, Mohd Soperi Mohd Zahid, Mukul Goyal, Emmanuel Baccelli, Hossein Hosseini, Kishore Trivedi
IEEE Communications Surveys and Tutorials,
2012.
[BIB]
{Open Shortest Path First (OSPF), a link state routing protocol, is a popular interior gateway protocol (IGP) in the Internet. Wide spread deployment and years of experience running the protocol have motivated continuous improvements in its operation as the nature and demands of the routing infrastructures have changed. Modern routing domains need to maintain a very high level of service availability. Hence, OSPF needs to achieve fast convergence to topology changes. Also, the ever-growing size of routing domains, and possible presence of wireless mobile adhoc network (MANET) components, requires highly scalable operation on part of OSPF to avoid routing instability. Recent years have seen significant efforts aimed at improving OSPF?s convergence speed as well as scalability and extending OSPF to achieve seamless integration of mobile adhoc networks with conventional wired networks. In this paper, we present a comprehensive survey of these efforts. }
Network monitoring and disaster detection,
Tue Apr 29 18:12:44 EDT 2008
A method of monitoring a network that includes a number of nodes interconnected by trunks has a step of obtaining processor usage data pertaining to a plurality of node processors, the processor usage data including information representative of a rate of usage of each of the plurality of node processors. The method also includes obtaining memory usage data pertaining to a plurality of memories, each of the plurality of memories associated with a node processor, the memory usage data including information representative of a rate of usage of each of the plurality of memories. The method further includes determining from the memory usage data and the processor usage data whether a network congestion event is occurring.
Network segmentation method,
Tue Oct 16 18:12:18 EDT 2007
A method includes obtaining first information indicative of instability of a data communication network. The method also includes isolating a first portion of a network from a second portion of the network responsive to the obtained first information. After a predetermined period of time, second information indicative of instability of the first portion is obtained. The method further includes isolating a first segment of the first portion from a second segment of the first portion responsive to the obtained second information.
Network having bandwidth sharing,
Tue Feb 13 18:11:53 EST 2007
A communication system includes a plurality of devices, such as cable modems, in communication with a station, such as a cable modem termination system, that provides efficient upstream bandwidth sharing.
Method and apparatus for managing voice call quality over packet networks,
Tue Sep 19 18:11:33 EDT 2006
The present invention relates to an apparatus and method for maintaining voice call quality over a packet network by providing optimal de-jitter buffer depth and rate of change of depth. Buffer depth and rate of change of buffer depth may be initially determined by classifying the incoming call. Classification of the incoming calls may be accomplished by categorizing calls into groups based on characteristics of the calls. The buffer depth and rate of change of depth may be further optimized at the start of calls based on voice-path delay and packet loss probability measurements over one or more calls of the same class such that the voice-path delay is minimized while maintaining a certain packet loss probability, the packet loss probability is minimized while maintaining a certain voice-path delay, or an R-factor, which is an objective measure of voice quality, is maximized.
Method for preventing overload condition in a circuit switched arrangement,
Tue Aug 29 18:11:32 EDT 2006
An arrangement where connections between a terminal and a switch are effected through a serial connection of shared, overloadable, resources, and where conventionally each of the resources has a given number of communication channels, provides for effective congestion control by converting one or more of the communications channels to one or more groups of enhanced signaling channels. The congestion control is effected by employing the enhanced signaling channels, which can carry audible signals, to determine whether to set up requested calls, based on a preselected congestion control process.
Link state network having weighted control message processing,
Tue Feb 28 18:10:56 EST 2006
A node in a network running a link-state routing protocol identifies certain routing control messages and stores the identified messages in separate queues. The queues are weighted such that each message type is allotted a predetermined amount of processing overhead to optimize the message processing by a node. In one embodiment, the node processor processes the queued messages in accordance with the entries in a weighted round robin polling table. An upper limit of processing time can be specified for each visit to a particular message queue.
Method for preventing overload condition in a circuit switched arrangement,
Tue Jan 17 18:10:47 EST 2006
A method for alleviating congestion problems in prior art networks delays provision of dial tone signals to terminals that are, likely, carrying out a re-dial attempt in excess of a preselected number of re-dial attempts. A determination that the terminal seeking to establish a connection is likely carrying out a re-dial attempt may be based on numerous factors, such as the time since the last time the terminal desired to establish a call, the duration of the last call, etc. The delay that is imposed is, advantageously, sensitive to the number of times the terminal has attempted a re-dial, and on other conditions, such as the cause of the failure to establish a connection, network congestion conditions, etc. In imposing the dial tone delay, identities of the terminals that are to receive a delayed dial tone are placed in a FIFO queue.
Network Protocol Having Staggered Recovery,
Tue Apr 26 18:10:21 EDT 2005
A network utilizing a link-state protocol includes a plurality of nodes with associated trunks that recover in a staggered manner. A first trunk associated with a first node is selected for recovery. After the first trunk is recovered, further trunks are selected such that N or less trunks recover at the same time until all trunks associated with the first node are selected for recovery. Node recovery is staggered at selected intervals to minimize or eliminate overload conditions. Staggered recovery in accordance with the present invention can reduce the likelihood of trunk loss due to excessive HELLO messages in an OSPF system and retransmission and retransmission lockout.
Method for preventing overload condition in a circuit switched arrangement,
Tue May 04 18:09:43 EDT 2004
A method that alleviates congestion problems in prior art networks by insuring that selected classes of calls have a reserved capacity, thus insuring a capability to service at least the selected level of traffic. In an illustrated embodiment, a selected capacity is reserved for voice calls, in contrast to data calls. When a connection request is made and there is unoccupied capacity, a voice call is always serviced, but a data call is serviced only if the number of established data connections is less than capacity of the path required for establishing a connection for the request, minus the capacity reserved for voice call.
Method and Apparatus for Transporting Private Line Traffic over an ATM Network,
Tue Apr 27 18:09:00 EDT 2004
A method and apparatus are provided to transport private line traffic over an ATM network. A first plurality of TDM private line traffic links, such as T1 or E1 circuits, are multiplexed to create a first rt-VBR virtual circuit such that the bandwidth of the first rt-VBR virtual circuit is not limited. A second plurality of TDM private line circuits are multiplexed to create a second rt-VBR virtual circuit such that the bandwidth of the second rt-VBR virtual circuit is not limited. This may be done by AAL2 multiplexing with substantially large SCR, PCR and MBS values and the removal of T1 frames that do not contain data (that is, frames that contain only frame delimiters). The first and second rt-VBR virtual circuits are combined for transport over a link in the ATM network. An overload control process may be performed based on the ATM network link utilization.
IEEE Fellow, 2009.
For contributions to design and analysis of telecommunication networks and routing protocols.
