Multiplex communications – Channel assignment techniques – Carrier sense multiple access
Reexamination Certificate
1997-12-05
2001-12-11
Nguyen, Chau (Department: 2663)
Multiplex communications
Channel assignment techniques
Carrier sense multiple access
C370S462000
Reexamination Certificate
active
06330248
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention relates to transmitting packet data on a high speed network, more specifically to methods and systems for transmitting data from a media access controller (MAC) layer onto a physical layer of a full-duplex network operating at data rates of at least one gigabit per second.
2. Background Art
Local area networks use a network cable or other media to link stations on the network. Each local area network architecture uses a media access control (MAC) that sends data packets to a physical layer transceiver for transmission on the network media.
The Ethernet protocol ISO/IEC 8802-3 (ANSI/IEEE standard 802.3, 1993 edition) defines a half-duplex media access mechanism that permits all stations to access the network channel with equality. The half-duplex mechanism typically operates at either 10 MB/s, or 100 MB/s. A full-duplex environment has also been proposed for Ethernet networks, referred to as IEEE 802.3x, Full-Duplex with Flow Control—Working Draft (0.3). The full-duplex environment provides a two-way, point-to-point communication link between two networks stations using the switched hub, for example at 100 MB/s, so that two stations can simultaneously transmit and receive Ethernet data packets between each other without collision.
The IEEE 802.3z Task Force is currently defining standards for the operation of a shared (i.e., half-duplex) and full-duplex gigabit Ethernet. The standard will describe a media access control (MAC) layer, a reconciliation layer, a gigabit-media independent interface (GMII), and physical media dependent sublayers that will implement the physical layer (PHY) of the proposed networks. The proposed networks will enable users to implement Ethernet links capable of operating at a data rate of 1 gigabit per second in half-duplex mode and 2 gigabits per second in full-duplex mode.
Currently, the Fast Ethernet standard describes a media independent interface (MII) that is used to connect Fast Ethernet MAC layer devices to the Fast Ethernet devices, enabling users to implement Ethernet links operating at 100 MB/s half-duplex, and 200 MB/s full-duplex.
There currently is no means for users to implement Ethernet links that operate in the range of data rates that exceed 200 MB/s and are lower than 1 gigabit per second. In addition, efforts at implementing a physical data link at gigabit transmission rates is very expensive, since the current state of technology does not permit use of copper links for gigabit data rate transmissions. Hence, only fiber optics can be used to transmit data at gigabit data rates.
One arrangement for implementing physical layer data links that provide gigabit transmission rates is disclosed in commonly assigned, co-pending application Ser. No. 08/912,235, filed Aug. 15, 1997, entitled “ARRANGEMENT FOR TRANSMITTING HIGH SPEED PACKET DATA FROM A MEDIA ACCESS CONTROLLER ACROSS MULTIPLE PHYSICAL LINKS” now U.S. Pat. No.6,094,439. The disclosed arrangement uses a modified reconciliation layer between the media access controller and the physical layer to transmit at least a portion of the packet data from the media access controller onto multiple media interface links. Use of multiple media interface links provides higher data transmission rates in a cost effective manner by simultaneously transmitting different serial data streams on multiple media interface links, effectively increasing the data rate.
SUMMARY OF THE INVENTION
There is a need for an economic arrangement that specifically identifies implementation functions necessary to enable load allocation of high speed data frames across multiple lower-speed physical links.
There is also a need for an arrangement that specifies an architecture necessary to implement allocation of high speed data frames across multiple transmission links based on the respective priority of the data frames and the availability of the transmission links.
These and other needs are attained by the present invention, where data frames received by a media interface from a high speed media access controller are transmitted on selected media interface links based on path selection arbitration logic in the media interface.
According to one aspect of the present invention, a method of transferring a data frame output from a media access controller of an originating network node to a destination network node, comprises establishing a plurality of first media interface links each configured for transmitting data at a first data rate to respective physical layer links in communication with the destination network node, receiving the data frame in a media interface from the media access controller via a second media interface link at a second data rate higher than the first data rate, and transmitting the received data frame from the media interface for transmission on a selected one of the first media interface links according to a path selection arbitration logic in the media interface. Transmission of data frames received from a media access controller onto media interface links at a lower data rate enables transmission of data from a high speed media access controller in an economic manner by distributing the data frames along multiple lower-rate transmission paths. Moreover, transmission based on the path selection arbitration logic provides a virtual switch fabric below the media access control layer that manages the high speed data frame traffic across multiple lower-speed transmission links.
Another aspect of the present invention provides an apparatus for transmitting a data frame received from a media access controller via a first media interface link at a first transmission rate, comprising a plurality of transmit buffers configured for storing data to be output to a respective plurality of second media interface links, the second media interface links each configured for sending and receiving data at a second data rate less than the first data rate, a first media interface controller having path selection arbitration logic for selectively storing the received data frame in a selected one of the transmit buffers, and a second media interface controller configured for outputting the data stored in each of the transmit buffers based on a corresponding number of stored bytes exceeding a prescribed threshold and an availability of the corresponding second media interface link.
Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
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Kalkunte Mohan V.
Krishna Gopal S.
Merchant Shashank C.
Advanced Micro Devices , Inc.
Lee Chiho Andrew
Nguyen Chau
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