A hub featuring ports for attachment of stations to a LAN comprises concentration logic (14) for the handling of multiplexed incoming and outgoing Token-Ring and isochronous signal streams. The concentration logic comprises clock recovery logic (42) from incoming Token-Ring packet data stream (40), for regeneration of Differential Manchester encoded data on output (400), and recovering of Token-Ring clock (401). A cycle framing generator (43) receives a 125 us synchronization clock from the hub backplane (402), and the Token-Ring clock (401), and generates control signals (403) to each of the 10 ports. Each port is comprised of a port transmit interface (44), and a port receive interface (45). Data from a connected station is input (404) to port receive interface (45). Token-Ring packet Differential Manchester encoded data are output (406) to the next active port, specifically to its port transmit interface, along with a recovered strobe clock (405), while ISO data are output (407) to switch (46). The switch and other concentration logic receive a hub local clock (412). Isochronous traffic interchanges with the hub backplane through leads 410 and 411; between ports or between ports and the hub through leads 407 and 409. Data to a connected station is output (408) from port transmit interface (44). Differential Manchester encoded data are received (400) along with Token-Ring clock (401). Control signals are input (403). Isochronous data are received (409). Token-Ring packet Differential Manchester encoded data are finally output from the concentration logic (41).
A system comprised of a plurality of switches and time reference signals are provided for managing data transfer of data units during a time interval, comprised of a plurality of predefined time frames. During operation a plurality of sources as a Local Time Reference (LTR) signal that collectively constitute the equivalent of a common time reference (CTR) signal. The time reference signals are coupled to each of the switches, such that there is predefined time frames for transfer into and out from each of the respective switches responsive to the time reference signals.
The invention discloses a method and an apparatus for implementing the physical interface in a network element connected to a packet network such as Asynchronous Transfer Mode (ATM) network. With the solution of the invention, the physical interface functions can be integrated on one chip for more than one network port. The physical interface is provided between port bit streams at media speed and word data flow transferred onto/from a bus which is under the control of the network equipment. The solution of the invention includes grouping logics and storage elements by islands of more than one port. Furthermore, the logics and storage elements for statistical counting operations can be grouped for a processing generalized to all ports. Finally, the solution of the present invention takes into account two characteristics of the physical interface which are the different rates between network link media speed and bus access rate and the technology of the high density static imbedded RAMs used for hardware integration. The Flip/Flop pointer RAMs of Flip/Flop data RAMs are duplicated and some interface RAMs are created to transfer control data between the islands and the generalized processing logical blocks.
A hub port which maintains a constant phase in a datastream and reduces jitter transfer to an attached node port. The hub port includes circuitry for maintaining constant bit boundaries for all data transmitted along the hub loop from that hub port using an internal clock. In addition, the internal clock is used to reduce jitter transfer.
The problem with sharing or multi-tasking a single microprocessor across multiple ports is that it requires an elaborate and costly effort to adapt, modify, and rewriting of existing microcode. Extensive effort has gone into the development and testing of existing microcode that supports Token Ring. The re-use of the microcode, mostly in an "as is" condition is required to increase effectiveness and reduce costs. The present invention resolves these problems. It further describes a method that easily encapsulates existing hardware and allows the use of existing microcode to be extended to a multi-tasking environment, at a substantially reduced cost and with greater efficiency. Another embodiment of this invention describes a system and method to reuse a single existing Token Ring macro with embedded processor and microcode for multiple ports on a chip.
A distributed arbitration scheme for a network. Ports in a network device determine which port in a set of ports may broadcast a packet onto a bus in the network device. A method of transmitting data between a set of ports sharing a bus in hub is described. The set of ports includes a first port, and the method comprises the first port receiving a packet, the first port requesting the bus, and, if another port is requesting the bus, the first port transmitting the packet to the bus if the first port has not transmitted a packet later than the another port requesting the bus. A system using two clocks of different speeds in a network device. The hub has at least a port. The port has an internal data path having a first width. A bus is coupled to the port. The bus has a data path that has a second width. The second width is greater than the first width. The hub includes a first clock that has a first frequency and is coupled to circuitry in the port for clocking internal data transfers. The hub includes a second clock that has a second frequency less than the first frequency, and the second clock is coupled to circuitry in the port for qualifying data transfers with the bus.
