Multiplex communications – Diagnostic testing – Of a repeater
Reexamination Certificate
1998-05-14
2001-07-31
Cangialosi, Salvatore (Department: 2661)
Multiplex communications
Diagnostic testing
Of a repeater
C251S315040
Reexamination Certificate
active
06269082
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to hybrid frame relay/asynchronous transfer mode (ATM) networks and ATM networks, and more particularly to a system and method for creating multiple logical channels on a single virtual circuit across a hybrid frame relay/ ATM network or an asynchronous transfer mode network, and for performing network diagnostics.
BACKGROUND OF THE INVENTION
Modem communications networks often include a number of paths or links that are interconnected to route voice, video, and/or data (hereinafter collectively referred to as “data”) traffic from one location of the network to another. At each location, an interconnect node couples a plurality of source nodes and destination nodes to the network. In some cases, the sources and destinations are incorporated in a private line network that may include a series of offices connected together by leased-lines with switching facilities and transmission equipment owned and operated by the carrier or service provider and leased to the user. This type of network is conventionally referred to as a “circuit-switching network.” Accordingly, a source node of one office at one location of the network may transmit data to a destination node of a second office located at another location of the network through their respective switching facilities.
At any given location, a large number of source nodes may desire to communicate through their respective switching facilities, or interconnect node, to destination nodes at various other locations of the network. The data traffic from the various source nodes is first multiplexed through the source switching facility, then demultiplexed at the destination switching facility and finally delivered to the proper destination node. A variety of techniques for efficiently multiplexing data from multiple source nodes onto a single circuit of the network are presently employed in private line networks. For instance, time division multiplexing (“TDM”) affords each source node full access to the allotted bandwidth of the circuit for a small amount of time. The circuit is divided into defined time segments, with each segment corresponding to a specific source node, to provide for the transfer of data from those source nodes, when called upon, through the network.
Other data communications systems, in contrast, have not been as successful employing multiplexing techniques to enhance network efficiency further. In particular, frame-relay networks offer far fewer alternatives than their circuit-switching network counterparts. Frame-relay networks are often referred to as “packet-switching networks.” Packet-switching networks, as opposed to circuit-switching networks, allow multiple users to share data network facilities and bandwidth rather than providing a specific amount of dedicated bandwidth to each user, as in TDM. Instead, packet switches divide bandwidth into connectionless, virtual circuits. As is known, virtual circuit bandwidth is consumed only when data is actually transmitted. Otherwise, the bandwidth is not used. In this way, packet-switching networks essentially mirror the operation of a statistical multiplexer (whereby multiple logical users share a single network access circuit).
One problem, however, with such traditional virtual circuits relates to the throughput efficiency in frame-relay and other packet-switching networks. For instance, a one-to-one correspondence exists between applications and frame-relay virtual circuits, there being no inherent mechanism in today's frame-relay standards for transporting end-to-end data management. Internet Engineering Task Force Request for Comments (“ETF RFC”) 1490 “Multiprotocol Interconnect Over Frame Relay,” herein incorporated by reference, provides the ability to multiplex protocols, but forces the end-to-end data management data and the data communicated on to a single logical channel on a given virtual circuit. Additionally, IETF RFC 1490 protocol headers appear on every single frame transmitted over the circuit.
A second problem with traditional frame relay networks is that they are limited by the data rates that are achievable. Specifically, in order to achieve data transmission rates greater than 1.5 Mbps (mega bits per second), most network service providers use Asynchronous Transfer Mode (ATM) which can provide data transmission rates of up to 44 Mbps. However, current data transmission using an ATM network or a hybrid ATM/frame relay network is without acceptable systems and methods to perform diagnostics that are compatible with existing frame relay networks across the virtual circuit.
SUMMARY OF THE INVENTION
The present invention is directed to a system and method for creating multiple logical channels on a single virtual circuit in a hybrid ATM/frame relay or ATM network, and for performing network diagnostics. The present invention provides for a single primary channel and multiple secondary channels which may be employed to communicate data across a hybrid ATM/frame relay or ATM network. The ATM DSU in the network comprises a microprocessor, a serial communications controller (SCC) circuit, segment assembler/reassembler (SAR) circuit, and a memory coupled to a common local interface such as a data bus. The ATM data service unit (DSU) transmits and receives data, respectively, to and from the ATM network through the SAR circuit. Likewise, the ATM DSU transmits and receives data, respectively, to and from one or more data communication devices through the SCC circuit.
Stored in the memory is operating logic to perform several tasks including creating the secondary channels by adding a secondary channel flag octet and secondary header octet at the beginning of the user information field of the data frame to be communicated. The secondary channel flag and secondary header are added by the DSU's in the system. Since the secondary channel information is added to the user information field, the logical channels created thereby are transparent to the virtual circuit itself. Data frames that are communicated via the primary channel do not receive the secondary channel flag or the secondary header. If the first octet of the user information field of a data frame to be communicated across the primary channel is equal to the secondary channel flag, then an additional secondary channel flag octet is added after this first octet. Upon encountering the two secondary channel flag octets, a receiving DSU will throw out one of them and pass on the remaining octet as user data to the primary channel destination. Note that a data frame which is sent on the primary channel features no additional overhead, thereby saving on transmission costs.
Accordingly, there is also provided a method for communicating a data frame across a hybrid ATM/frame relay or ATM network via multiple logical circuits. The method comprises the steps of determining the primary or secondary logical channel which is to be used to transmit a data frame. If the data frame is to be communicated on the primary channel, the system performs the steps of determining whether the first octet of the user data field is equal to the secondary channel flag, and, adding an additional channel flag after the first octet if the first octet is equal to the secondary channel flag. If the first octet of the user data field is not equal to the secondary channel flag, then the data frame is communicated across the network as is. If the data frame is to be communicated on any one of the plurality of secondary channels, then the steps of adding a secondary channel flag and a secondary header to the user information field of the data frame, and, transmitting the data frame across the network are performed. Upon receiving the data frame, the DSU performs the steps of determining whether the data frame is assigned to the primary or one of the plurality of secondary channels. If assigned to the primary channel, the step of transmitting the data frame to the primary channel destination is performed. If the first octet of the user information field of the dat
Lester, Jr. Lee Hampton
Mawhinney Ted Nodine
Mundwiler Richard Allen
Cangialosi Salvatore
Paradyne Corporation
Thomas Kayden Horstemeyer & Risley LLP
LandOfFree
System and method for multiplexing a frame relay virtual... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with System and method for multiplexing a frame relay virtual..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and System and method for multiplexing a frame relay virtual... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2487548