Multiplex communications – Diagnostic testing – Path check
Reexamination Certificate
1999-05-27
2004-04-06
Vu, Huy D. (Department: 2665)
Multiplex communications
Diagnostic testing
Path check
C370S251000, C370S390000
Reexamination Certificate
active
06717914
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to data communications networks and more particularly relates to a system for probing selected Switched Virtual Circuits (SVCs) in a connection oriented network such as an Asynchronous Transfer Mode (ATM) network.
BACKGROUND OF THE INVENTION
Asynchronous Transfer Mode
Currently, there is a growing trend to make Asynchronous Transfer Mode (ATM) networking technology the base of future global communications. ATM has already been adopted as a standard for broadband communications by the International Telecommunications Union (ITU) and by the ATM Forum, a networking industry consortium.
ATM originated as a telecommunication concept defined by the Comite Consulatif International Telegraphique et Telephonique (CCITT), now known as the ITU, and the American National Standards Institute (ANSI) for carrying user traffic on any User to Network Interface (UNI) and to facilitate multimedia networking between high speed devices at multi-megabit data rates. ATM is a method for transferring network traffic, including voice, video and data, at high speed. Using this connection oriented switched networking technology centered around a switch, a great number of virtual connections can be supported by multiple applications through the same physical connection. The switching technology enables bandwidth to be dedicated for each application, overcoming the problems that exist in a shared media networking technology, like Ethernet, Token Ring and Fiber Distributed Data Interface (FDDI). ATM allows different types of physical layer technology to share the same higher layer—the ATM layer.
ATM uses very short, fixed length packets called cells. The first five bytes, called the header, of each cell contain the information necessary to deliver the cell to its destination. The cell header also provides the network with the ability to implement congestion control and traffic management mechanisms. The fixed length cells offer smaller and more predictable switching delays as cell switching is less complex than variable length packet switching and can be accomplished in hardware for many cells in parallel. The cell format also allows for multi-protocol transmissions. Since ATM is protocol transparent, the various protocols can be transported at the same time. With ATM, phone, fax, video, data and other information can be transported simultaneously.
ATM is a connection oriented transport service. To access the ATM network, a station requests a virtual circuit between itself and other end stations, using the signaling protocol to the ATM switch. ATM provides the User Network Interface (UNI) which is typically used to interconnect an ATM user with an ATM switch that is managed as part of the same network.
The current standard solution for routing in a private ATM network is described in Private Network Node Interface (PNNI) Phase
0
and Phase
1
specifications published by ATM Forum. The previous Phase
0
draft specification is referred to as Interim Inter-Switch Signaling Protocol (IISP). The goal of the PNNI specifications is to provide customers of ATM network equipment some level of multi-vendor interoperability.
SVC Traffic Analysis
Networks that are connection oriented typically have two stages for connecting network users from point to point. The first stage in the establishment of the colnection utilizes some form of signaling mechanism and in the second stage, data is transferred via the connection established in the first stage.
An example of such as connection oriented network is an ATM network. ATM networks utilize a signaling protocol that is derived from the Q.93B standard to provide network users a service for establishing a connection to another network user. This connection is termed a Switched Virtual Connection (SVC) and, once created, is used as the data path between the users that have been connected.
The connection originator uses the signaling protocol to convey the service details it is requesting the network to provide, e.g., destination address (i.e. the called address), calls of service, traffic descriptor, protocol which is to be used by the virtual connection, network transit, etc. In addition, the originator provides information about itself, in particular, its own address (i.e. the calling address).
Once the network receives the request from the originator user, it attempts to find a route to the destination that has sufficient resources to fulfill the specific characteristic requirements of the request as provided by the originating user. If the network finds a satisfactory route with the necessary resources to establish the connection, and if the called user also has sufficient resources to establish the connection, the connection is then established. Once the route is established, data can flow between source and destination over the connection.
Such a network may carry another type of connection known as a Permanent Virtual Circuit (PVC) which are typically established under manual management control. The service provided by PVCs and SVCs are the same, with the difference being their method of establishment.
In the course of network operations, SVCs may be constantly created and torn down. SVC connections may be created very quickly and last for a relatively short lifetime duration, i.e., hundreds, of milliseconds, seconds, etc., before being removed. In the event a network manager desires to capture SVC traffic for purposes of analysis, the specific SVC must first be identified, and data somehow routed to the management station. Normally, this must be done manually, without effecting the original data path, and without any synchronization in time with the establishment of the SVC and the data being transferred over it. Although it is possible for a network manager to capture data from the SVC, the establishment of the capture mechanism may take many tens of minutes depending on the type and sophistication of the management tools available. During this time the SVC may have already been established and removed making its capture impossible using current techniques.
It would therefore be desirable to have a capture mechanism that can be utilized by a network management station and that is capable of capturing very, short lived SVCs without interfering or effecting the flow of data over the SVC from calling to called users.
SUMMARY OF THE INVENTION
The present invention is a system for probing one or more SVCs that enables a network management station to setup a probe event in advance before a SVC is created. Upon the creation of the SVC, the data is captured and sent to the network management station without any further intervention required. Note that the system of the present invention is applicable to any connection-oriented network that utilizes signaling to establish connections between network users.
The invention establishes a SVC probe in two stages. In the first stage, a SVC originator is configured with a probing IE containing parameters to be included in the SETUP request message when SVCs are established. The probing IE is generated by the network management station and sent to the SVC originator using standard SNMP techniques. A unique identifier is included as one of the parameters in the probing IE. It is used by the probing switch to detect a SVC that is to be probed.
A PVC is established to the switch containing one or more SVCs that are to be probed. A probing port is configured on the switch and a range of VPI/VCIs are assigned to the port. The same unique identifier is configured in the switch to be probed.
In operation, the switches along the path, attempt to find a match between the unique identifier included in the SETUP request message and that previously configured by the management station. If a match is found, a multicast connection is configured in the switch and traffic from the SVC originator is directed toward both the destination and the probing port. Likewise, traffic from the destination is directed toward both the SVC originator and the probing port. In this fashion, the SVC t
3Com Corporation
McDonnell & Boehnen Hulbert & Berghoff
Philpott Justin
Vu Huy D.
Zaretsky Howard
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