Integrated network switching hub and bus structure

Details Integrated network switching hub and bus structure Integrated network switching hub and bus structure

1998-07-14

2001-05-01

Auve, Glenn A. (Department: 2181)

Electrical computers and digital data processing systems: input/

Intrasystem connection

Bus access regulation

C710S120000, C370S362000

Reexamination Certificate

active

06226705

ABSTRACT:

FIELD OF THE INVENTION
This invention relates generally to computer networks. In particular it pertains to a relatively low cost network switching hub and bus structure integrated into an integrated circuit chip, which improves network performance by increasing bandwidth and reducing collisions.
BACKGROUND OF THE INVENTION
Personal computers (PCs) have permeated nearly all levels of society and business, creating a need to link individual PCs into networks to more efficiently utilize and share resources. Computer networks are becoming increasingly popular in low-cost, performance-oriented computing environments.
One very popular type of network used to link PCs or workstations is called a local area network (LAN). LANs and other types of networks permit the sharing of resources such as software, printers, modems, and other peripherals among PC workstations operating as nodes on the network.
FIG. 1
illustrates a simple and conventional LAN, generally designated by the reference numeral
100
. Network
100
comprises a plurality of PC workstations
112
a
through
112
e,
each connected by a communication link
113
a
through
113
e
respectively to an associated hub
114
. Communication links in such networks are typically two-conductor cables, wherein a potential across the two conductors is varied in a manner representing sequential binary data. Such a link is termed a serial link.
Hubs, such as hub
114
, in networks are used to connect multiple workstations for routing through a single link to a server. In
FIG. 1
, PC workstations
112
a
through
112
e
are all connected to server
116
through link
115
. Hubs typically have a limited number of input ports, so the number of workstations that can be connected is limited as well. Typically the input ports are arranged in groups of 8, 16, 32, 64 and so forth. Further network capacity can be added by connecting multiple hubs, such as hub
118
(shown in dashed lines) to the one file server, and the additional hubs may then be connected to other multiple workstations (not shown). Other network variations include addition of multiple file servers connected in different arrangements to multiple hubs.
File server
116
in this example, and generally in the art, comprises a set of sheared high-capacity mass storage devices, such as hard disks. Such file servers are often special PCs that have higher performance capability and more and larger capacity hard disks than do individual workstations
112
a
through
112
e.
The shared disk space on such file servers typically stores software applications which spreads the cost of the hard disk over more than one user, thereby permitting more efficient use of resources.
File server
116
in this example may also contain routers (not shown) for communication and connection to different network protocols such as Ethernet™, Asynchronous Transfer Mode (ATM), and Fiber Distributed Data Interface (FDDI), among others. The output of file server
116
is coupled to shared peripherals such as a network modem
118
, a laser printer
120
, and other peripherals represented by element number
122
. All workstations
112
a
through
112
e
on the network share access to the peripherals connected to server
116
.
It will apparent to those with skill in the art that the example of
FIG. 1
is but one of many network arrangements known in the art.
There are some limitations of a conventional LAN
100
as described above. For example, communication over link
115
is shared by all of the workstations, and if many workstations are attempting to communicate at once, bandwidth may be a problem, slowing communication. By way of example, coaxial lines used in many networks have a maximum data transfer rate of 10 megabytes per second (Mb/s). The maximum data transfer rate, which is related to bandwidth, ultimately determines the maximum number of workstations that can be adequately handled by the network. Overloading a network can result in lost connections, communication delays, slow system response, timeouts, and slow file transfer times. All of these situations decreases the efficiency of the network, and become very annoying to network users.
Another limitation of conventional LANs such as LAN
100
, is that communication collisions may occur between multiple workstations requesting access to the network. In commonly used network protocols such as Ethernet™, one way that collisions are handled is by processing one request at-a-time while buffering other requests in a first-in-first-out (FIFO) buffer. Since access is granted one-workstation-at-a time, other stations are required to wait, thereby decreasing efficiency. Networks with heavy traffic tend to have many collisions which may drop efficiency to unacceptable levels.
The problems of inefficient communication are exacerbated by addition of more workstations to the network and increased use of bandwidth-hungry applications such as color publishing and document imaging. So networks that had adequate bandwidth when installed may be outdated simply by software development.
Another way to add bandwidth is by increasing the number of switching hubs. This solution often results in segmenting a single large network into multiple smaller networks, which decreases the amount of traffic that travels over any given communication link and thereby increases the bandwidth available to each individual user. Statistics and traffic patterns can be further analyzed for adjustments for optimal network performance.
Another disadvantage of conventional networks is the relatively high cost of multi-port hubs. By way of example, a 32 or even 16 port hub for some networks can cost in the range of about 32K to 100K dollars, a substantial investment for any user. Also conventional hubs are typically separate units in an enclosure with a dedicated power supply and controlling electronics, adding to clutter and adding to cost.
What is needed is a switchable hub that is relatively low cost, compact, and increases network performance by increasing bandwidth and reducing collisions. As will be described hereinafter, the present invention provides a method and apparatus to meet these objectives.
SUMMARY OF THE INVENTION
In a preferred embodiment of the present invention an integrated circuit (IC) switching hub is provided, comprising a parallel bus implemented as traces on the IC; a plurality of data ports, each coupled to the on-chip bus, for receiving and sending data; a plurality of direct switching elements, one implemented at each data port between the port and the bus; and an arbitrator controller connected by a first control line to each of the direct switching elements. The arbitrator controller is adapted to control the direct switching elements between the ports to switch data from any first port to any second port among the plurality of data ports.
In some embodiments the data ports are serial ports, and each port includes an adapter for translating to the parallel on-chip bus. In other embodiments the data ports are parallel ports. In one embodiment at least one port is a PCI standard parallel port adapted for communication with a PCI bus. In still other embodiments there may be plural pairs of external data ports wherein one of the external data ports is adapted for connecting the IC switching hub to a second IC switching hub.
The direct switching elements may queue switch transistors implemented in one layer on the chip, connections implemented in another layer.
In another aspect of the invention a method for switching data onto a bus of an integrated circuit switching hub is provided, comprising steps of (a) receiving data at an external port of the switching hub; (b) connecting the port to the bus by data lines through a set of direct switching elements; and (c) switching data onto the bus by operating the direct switching elements by an on-chip arbitrator controller. In this method, in some embodiments the direct switching elements are queue switch transistors, one for each bus line. Also in some embodiments the ports are serial ports, and include adaptors for trans

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