Management communication bus for networking devices

Details Management communication bus for networking devices Management communication bus for networking devices

1996-03-29

2001-03-06

Auve, Glenn A. (Department: 2781)

Electrical computers and digital data processing systems: input/

Intrasystem connection

Bus access regulation

C710S105000, C710S109000, C710S113000, C710S120000, C709S208000, C712S020000

Reexamination Certificate

active

06199133

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to the field of networking devices, and more particularly to a management communication bus for networking devices.
DESCRIPTION OF THE RELATED ART
There are many different types of networks and network systems for sharing files and resources or for otherwise enabling communication between two or more computers. Networks may be categorized based on various features and functions, such as message capacity, range over which the nodes are distributed, node or computer types, node relationships, topology or logical and/or physical layout, architecture based on cable type and data packet format, access possibilities, etc. For example, the range of a network refers to the distance over which the nodes are distributed, such as local-area networks (LANs) within an office or floor of a building, wide-area networks (WANs) spanning across a college campus, or a city or a state, global-area networks (GANs) spanning across national boundaries, etc. The architecture of a network generally refers to the cabling or media and media access used as well as the packet structure of the data transmitted across the media. Various architectures are common, including Ethernet using coaxial, twisted pair or fiber-optic cables for operation at 10 megabits per second (Mbps) (e.g. 10Base-T, 10Base-F) or fast Ethernet operating at 100 Mbps (e.g. 100Base-T, 100Base-FX). ARCnet (Attached Resource Computer Network) is a relatively inexpensive network architecture using coaxial, twisted pair or fiber-optic cables for operation at 2.5 Mbps. Token Ring or Token Bus uses special IBM cable or fiber-optic cable for operation between 1-16 Mbps. Of course, many other types of networks are known and available.
Each network generally includes two or more computers, often referred to as nodes or stations, which are coupled together through selected media and various other network devices for relaying, transmitting, repeating, translating, filtering, etc., the data between the nodes. The term “network device” generally refers to the computers and their network interface cards (NICs) as well as various other devices on the network, including repeaters, bridges, switches, routers, brouters, to name a few examples.
It is desired to monitor and/or configure each of the network devices for purposes of managing that network. For example, it may be desired to enable or disable and configure each of the ports of a multi-port device, such as a repeater. Also, it may be desired to monitor the status of the ports or to monitor and retrieve statistical data about one or more ports on a network device. Thus, management data must be communicated between the network devices. Each of the network devices may be configured to communicate with other network devices through their respective network channels and protocols for purposes of management. However, if the network channels or protocols are incompatible, then some type of converter or bridge device would be required to enable such communication. For example, a bridge would typically be required to enable a 10Base-T and a 100Base-T device to communicate with each other. Such converter devices add significant and undesirable cost to the system. Furthermore, such communication is typically packetized requiring additional overhead to encode the data into packets and send the data on its network to another device. The receiving device must then retrieve the packet and decode the data, which requires additional overhead. More importantly, it is not desired to consume valuable time and resources on the respective networks by increasing traffic with management functions. Also, not all of the network devices are sources or destinations of data and simply receive and re-send data. For example, an Ethernet repeater does not receive and decode packets, but simply repeats the packet on its other ports. Thus, the repeater would require modification of its network logic to enable management functions.
One possible solution is to add a common network protocol to each of the devices, such as ARCnet or the like, so that each device becomes a node on a separate management network. However, such a network must be relatively inexpensive and yet have enough data throughput to achieve the desired management functions. Although ARCnet is a relatively inexpensive architecture, it requires significant overhead for encoding and decoding packets and inserting wait states, thereby decreasing actual overall data throughput to approximately 1 Mbps.
Another possible solution is to incorporate a known input/output (I/O) bus structure to all of the network devices, such as the 8-bit PC bus, the industry standard architecture (ISA) or AT bus, the Extended ISA (EISA) bus, the Micro Channel Architecture ® by IBM (MCA), the peripheral component interconnect (PCI) bus, etc. Each of these bus structures provide memory mapped transactions and would enable sufficient throughput for the desired management functions of network devices. However, such bus structures are also relatively expensive and require a significant amount of bus signals. An 8-bit PC bus, for example, requires at least 31 pins or signals, and the 16-bit ISA bus adds at least 18 more pins to the PC bus. The EISA bus adds 55 signals to the ISA bus. The MCA bus includes at least 46 pins for its basic 8-bit section.
Another possible solution is to use a serial channel for communications. However, serial communications are relatively expensive for the amount of data throughput available. Common throughput rates are 9600, 14,400, 19,200 and 28,800 bits at unit density (baud). Higher baud and/or bit rates may be available, but at significant increase in cost.
It is desired to provide a management communication scheme for managing network devices at the desired data throughput without adding significant cost to a network system.
SUMMARY OF THE INVENTION
A management communication bus according to the present invention enables management of a plurality of network devices of a network system. The network system includes at least one bus master device and at least one slave device, where the bus master and slave devices are distributed within the network devices as desired. Thus, each network device includes a slave device or a bus master device or both. The bus includes several state signals for defining at least three states for arbitration, for slave identification, for asserting an address and for asserting data corresponding to the address. The bus further includes several data signals for transferring information data depending upon the different states, where the information data includes bus request, slave identification, the address and the data corresponding to the address. In the preferred embodiment, the bus includes a clock signal for purposes of synchronization. The clock signal is preferably approximately eight megahertz (MHz). Also, the bus preferably includes two state signals for defining at least four states, and eight data signals, where a bus master accesses up to 16 kilobytes (KB) of data per slave at a data throughput rate of 1.14 Mbps.
Preferably, arbitration and slave identification occurs during a first state, an address is asserted in two portions during second and third states, respectively, and a data cycle is performed during a fourth state. During the first address state, the controlling bus master device asserts a cycle definition signal on a bus data signal to indicate whether the operation is a read or a write cycle. During the second address state, a slave device being accessed may assert a busy signal on a bus data signal to indicate that the slave device is busy, where the bus master keeps the bus in the second address state until the slave device is ready to proceed to the data cycle. Each bus master includes an interface to the bus to step through each of the states thereby controlling each cycle. The bus master preferably asserts only one of the state signals at a time.
Preferably, a plurality of bus masters and slave devices are coupled to the bus, each including an interface

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