WO2001069850A2

WO2001069850A2 - Non-fault tolerant network nodes in a multiple fault tolerant network

Info

Publication number: WO2001069850A2
Application number: PCT/US2001/007405
Authority: WO
Inventors: Jiandong Huang; Jay W. Gustin; Ronald J. Freimark; Tony J. Kozlik; Sejun Song
Original assignee: Honeywell International Inc.
Priority date: 2000-03-10
Filing date: 2001-03-08
Publication date: 2001-09-20
Also published as: EP1262040A2; AU4911401A; US6901443B1; DE60130873T2; ATE375650T1; CN1428030A; JP2004500778A; CN1185828C; EP1262040B1; DE60130873D1; AU2001249114B2; CA2402872A1; WO2001069850A3

Abstract

The present invention provides a method an apparatus for facilitating communication with non-fault tolerant network nodes in a fault-tolerant network environment. In various embodiments, a network address or network location of any network nodes present on a network that are not fault-tolerant is determined and stored, and data intended for the detected non-fault-tolerant network nodes is routed only over that network to which the non-fault-tolerant network node is connected. In further embodiments, the fault-tolerant network comprises a primary and redundant network with fault tolerant network nodes that are attached to each network; a non-fault-tolerant network node that is attached to either the primary or redundant network is then operable to communicate with any fault-tolerant network node via data sent over only the network to which the non-fault-tolerant network node is connected.

Description

Non-Fault Tolerant Network Nodes in a Multiple Fault Tolerant Network

Field of the Invention

The invention relates generally to computer networks, and more specifically

to a method and apparatus providing non-fault tolerant network node operability in

a fault-tolerant network.

Notice of Copending Applications

This application is related to the following copending applications, which

are hereby incorporated by reference:

"Fault Tolerant Networking", serial number 09/188,976; and

Atty. docket number 256.044usl

Background of the Invention

Computer networks have become increasingly important to communication

and productivity in environments where computers are utilized for work.

Electronic mail has in many situations replaced paper mail and faxes as a means of

distribution of information, and the availability of vast amounts of information on

the Internet has become an invaluable resource both for many work-related and

personal tasks. The ability to exchange data over computer networks also enables

sharing of computer resources such as printers in a work environment, and enables

centralized network-based management of the networked computers.

For example, an office worker's personal computer may run software that is

installed and updated automatically via a network, and that generates data that is

printed to a networked printer shared by people in several different offices. The

network may be used to inventory the software and hardware installed in each personal computer, greatly simplifying the task of inventory management. Also,

the software and hardware configuration of each computer may be managed via the

network, making the task of user support easier in a networked environment.

Networked computers also typically are connected to one or more network

servers that provide data and resources to the networked computers. For example,

a server may store a number of software applications that can be executed by the

networked computers, or may store a database of data that can be accessed and

utilized by the networked computers. The network servers typically also manage

access to certain networked devices such as printers, which can be utilized by any

of the networked computers. Also, a server may facilitate exchange of data such as

e-mail or other similar services between the networked computers.

Connection from the local network to a larger network such as the Internet

can provide greater ability to exchange data, such as by providing Internet e-mail

access or access to the World Wide Web. These data connections make

conducting business via the Internet practical, and have contributed to the growth

in development and use of computer networks. Internet servers that provide data

and serve functions sucn as e-commerce, streaming audio or video, e-mail, or

provide other content rely on the operation of local networks as well as the Internet

to provide a path between such data servers and client computer systems.

But like other electronic systems, networks are subject to failures.

Misconfiguration, broken wires, failed electronic components, and a number of

other factors can cause a computer network connection to fail, leading to possible

inoperability of the computer network. Such failures can be minimized in critical

networking environments such as process control, medical, or other critical applications by utilization of backup or redundant network components. One example is use of a second network connection to critical network nodes providing

the same function as the first network connection. But, management of the

network connections to facilitate operation in the event of a network failure can be

a difficult task, and is itself subject to the ability of a network system or user to properly detect and compensate for the network fault. Furthermore, when both a

primary and redundant network develop faults, exclusive use of either network will

not provide full network operability.

One solution is use of a method or apparatus that can detect and manage the

state of a network of computers utilizing redundant communication channels. Such

a system incorporates in various embodiments nodes which are capable of

detecting and managing the state of communication channels between the node and

each other fault-tolerant network node to which it is connected. In some

embodiments, such network nodes employ a network status data record indicating the state of each of a primary and redundant network connection to each other

node, and further employ logic enabling determination of an operable data path to

send and receive data between each pair of nodes.

But, such networks will desirably include nodes which do not have full

fault-tolerant capability. One common example of such a non-fault-tolerant

network node is a standard office laser printer with a built-in network connection.

What is needed is a method and apparatus to facilitate communication with non-

fault-tolerant network nodes in such a fault-tolerant network system.

Summary of the Invention

The present invention provides a method and apparatus for operation of non-fault tolerant network nodes in a fault-tolerant network environment. In some

embodiments, a network address or network location of any network nodes present

on a network that are not fault-tolerant is determined and stored, and data to be sent

to the detected non-fault-tolerant network nodes is routed only over that network to

which the non-fault-tolerant network node is connected. In various further

embodiments, the fault-tolerant network comprises a primary and redundant

network with fault tolerant network nodes that are attached to each network; a non-

fault-tolerant network node that is attached to either the primary or redundant

network is then operable to communicates with any fault-tolerant network node via

data sent over only the network to which the non-fault-tolerant network node is

connected.

Brief Description of the Figures

Figure 1 shows a diagram of a fault-tolerant computer network with

multiple fault-tolerant network nodes having primary and redundant network

connections and having multiple non-fault-tolerant network nodes, consistent with

an embodiment of the present invention.

Figure 2 shows a flowchart of a method of managing communication with

non-fault-tolerant network nodes in a fault-tolerant computer network, consistent

with an embodiment of the present invention.

Detailed Description

In the following detailed description of sample embodiments of the invention, reference is made to the accompanying drawings which form a part

hereof, and in which is shown by way of illustration specific sample embodiments

in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is

to be understood that other embodiments may be utilized and that logical,

mechanical, electrical, and other changes may be made without departing from the

spirit or scope of the present invention. The following detailed description is,

therefore, not to be taken in a limiting sense, and the scope of the invention is

defined only by the appended claims.

The present invention provides a method and apparatus for managing

communication with non-fault-tolerant network nodes in a fault-tolerant network.

The invention is capable in various embodiments of identifying the network

location and address of non-fault tolerant network nodes, and of routing data only

over certain portions of the network to communicate with the non-fault-tolerant

network node. The network in some embodiments comprises a primary and a

redundant network having connections to each fault-tolerant network node, and the

invention comprises routing information to non-fault-tolerant network nodes

connected to either the primary or redundant network via only that network to

which the non-fault-tolerant network node is connected.

The invention in various forms is implemented within an existing network

interface technology, such as Ethernet. In one such embodiment, the fault-tolerant

network comprises two Ethernet connections connected to each fault-tolerant

computer or node — a primary network connection and a redundant network

connection. It is not critical for purposes of the invention which connection is the

primary connection and which is the redundant connection, as the connections are

physically and functionally similar. In the example embodiment discussed here,

the primary and redundant network connections are interchangeable and are named primarily for the purpose of distinguishing the two networks from each other. Each of the primary and redundant networks also may have one or more non-fault-

tolerant network nodes attached, and communication with such non-fault-tolerant

networks is facilitated by the present invention.

Figure 1 illustrates an exemplary fault-tolerant network with fault-tolerant

network nodes 101, 102 and 103. A primary network 104 and a redundant network

105 link each node to the other nodes of the network, as indicated by the lines

connecting the nodes to each of the networks. Non-fault tolerant network nodes

are also connected to each network, including non-fault-tolerant network node 106

connected to the primary network 104 and non-fault-tolerant network node 107

connected to redundant network 105.

The fault-tolerant network connections linking the fault-tolerant network

nodes are configured such that the fault-tolerant network nodes can communicate with each other despite multiple network faults, such as by use in some

embodiments of particular node-to-node communication rules and network status

monitoring capability within each node. The communication rules in various

embodiments of a fault-tolerant network facilitate determination of a network path

between each pair of nodes based on the network status data stored in and

communicated between each fault-tolerant network node. Each fault-tolerant

network node of such a system must be able to recognize non-fault-tolerant

network nodes and adapt its communication rules for communicating with non-

fault-tolerant network nodes such as nodes 106 and 107 of the example network of

Figure 1.

In a typical single network configuration, data intended for a network node is simply sent over the network to the intended node. But, where multiple networks are combined to form a fault-tolerant network capable of compensating

for multiple faults such as the network of Figure 1, data intended for a single non-

fault-tolerant network node such as node 106 or 107 is desirably sent over the

specific network to which the non-fault-tolerant network node is connected.

In some embodiments of the invention, data intended for a non-fault-

tolerant network node such as non-fault-tolerant network node 106 is simply

broadcast or transmitted over both the primary network 104 and the redundant

network 105, ensuring that the data is sent to the network to which the non-fault-

tolerant network node is connected. Such a system does not require tracking

addresses or locations of non-fault-tolerant network nodes, and simply relies on the network interface adapters of the redundant network 105 to filter out the extra data.

But, such a configuration is reliant on the ability of the nodes connected to the

redundant network 105 to ignore the data intended for a network node not attached

to that network, and further wastes network bandwidth on the redundant network.

Other embodiments of the invention comprise maintaining an address table

of detected non-fault-tolerant network nodes that are present on both the primary

network 104 and the redundant network 105, and further associating each address

or non-fault-tolerant network node with the network on which the node address

was detected. In some embodiments of the invention, detection of the non-fault-

tolerant network node address comprises monitoring for and intercepting Internet

Protocol (IP) Address Resolution Protocol (ARP) packets that are sent by each

node in certain IP-compatible network configurations. For example, each ARP

packet in an Ethernet network contains the Media Access Control (MAC) address that uniquely identifies the node transmitting the IP ARP packet. The intercepted MAC address of each non-fault-tolerant network node is then recorded along with the network on which the non-fault-tolerant network node is detected. In other embodiments, other network hardware and communication protocols may be used for the same purpose, and are within the scope of the invention.

To send data from a fault-tolerant network node to a non-fault-tolerant network node in such embodiments of the invention, the address of the desired node is found in the stored address records of the sending fault-tolerant network node, and the associated network is determined. For example, if fault-tolerant network node 101 initiates a data transfer to non-fault-tolerant network node 106, node 101 searches its stored address records and finds the address of node 106, and further finds that the address data for node 106 was received on the primary network 104 rather than the redundant network 105. Node 101 then sends the data intended for node 106 only over network 104, eliminating the need to send the same data over redundant network 105 and use additional network bandwidth.

In further embodiments of the invention, fault-tolerant network nodes such as node 101 use the network status data indicating the ability of that node to communicate with other fault-tolerant network nodes to reroute data intended for a non-fault-tolerant network node around a network fault. This is achieved in some embodiments by initially sending the data on the network on which the non-fault- tolerant network node does not reside and using a selected fault-tolerant network node to transfer the sent data to the network on which the non-fault-tolerant network node resides at a point on the non-fault-tolerant network node's network such that the fault on the non-fault-tolerant network node's network is not between the transferring node and the non-fault-tolerant receiving node. Other

embodiments exist in which data can be rerouted across the fault-tolerant networks

to avoid multiple faults, and are within the scope of the invention.

In further embodiments, data sent to non-fault-tolerant network nodes is

sent over all networks in the fault-tolerant network system rather than sent over a

single network if the record containing address and network data for non-fault-

tolerant network nodes does not contain data on the intended destination non-fault-

tolerant network node. Sending such data comprises sending or replicating the data

on both the primary and redundant network of the example network discussed

above and shown in Figure 1.

Figure 2 is a flowchart of a method of managing communication between

fault-tolerant network nodes and non-fault-tolerant network nodes in a fault-

tolerant network such as the example network of Figure 1. At 201, each fault-

tolerant network node determines the network address of any non-fault-tolerant

network nodes present on each network to which the fault-tolerant network node is

connected. This may be achieved in any suitable manner, including searching for

IP ARP packets or other identifying data transmitted by the non-fault-tolerant

network nodes. At 202, each fault-tolerant network node further determines the

network on which each non-fault-tolerant network node exists. In some embodiments, this simply comprises detecting which network adapter in the

detecting fault-tolerant network node detected the IP ARP packet or other

identifying data. At 203, the fault-tolerant network nodes each store the data

determined at 201 and 202. The address and network data for each non-fault- tolerant network node are associated with each other in the stored data in one embodiment, so that looking up a record for a particular non-fault-tolerant network node results in retrieval of both the network address of the node and the network on

which the node resides. In various embodiments, the process of determination of

network addresses and networks associated with each non-fault-tolerant network

node and the storing of this data is a continuous process, and occurs even during

other operations such as execution of other blocks of the flowchart of Figure 2.

At 204, a fault-tolerant network node initiates sending data to a non-fault-

tolerant network node. At 205, the stored data is searched for the address and

network of the non-fault-tolerant network node. At 206, a decision is made based

on determination of whether the address and network data for the non-fault-tolerant

network node are present in the stored data. If the address and network data are present in the stored data, the data to be sent is sent from the fault-tolerant network

node to the non-fault-tolerant network node over only that network to which the

stored data indicates the non-fault-tolerant network node is connected at 207. In

other embodiments, the data is sent indirectly via one or more intermediate nodes

to the non-fault-tolerant network node, to avoid one or more network faults. If the

address and network data are not present in the stored data, the data to be sent is

sent over all networks to which the sending fault-tolerant network node is

connected to ensure that the intended non-fault-tolerant network node receives the

data. In the example of Figure 1, the data would be sent over both the primary

network 104 and the redundant network 105.

The present invention provides a method and apparatus that enable a

network with primary and redundant network connections to manage routing of

data to non-fault-tolerant network nodes within the network. Some embodiments of the invention incorporate a data record within each fault-tolerant network node

that contains detected address and network data for each non-fault-tolerant network

node, and which then is used by the fault-tolerant network node to determine over

which network data mtended for a specific non-fault-tolerant network node should

be sent. In some embodiments, the invention includes rerouting data that cannot be

transferred directly from a fault-tolerant network node to a non-fault-tolerant

network node due to a network fault, and comprises routing the data to one or more

intermediate nodes which are able to facilitate communication between the nodes.

Although specific embodiments have been illustrated and described herein,

it will be appreciated by those of ordinary skill in the art that any arrangement

which is calculated to achieve the same purpose may be substituted for the specific

embodiments shown. This application is intended to cover any adaptations or variations of the invention. It is intended that this invention be limited only by the

claims, and the full scope of equivalents thereof.

Claims

1. A method of managing communication witli non-fault tolerant network nodes in

a fault-tolerant computer network, comprising:

determining network addresses of network nodes present in a plurality of

networks that are not fault-tolerant and are connected to only a single network;

deteraiining the network on which each non-fault tolerant network node

exists;

storing the detected network address data of the non-fault tolerant network

nodes and storing associated network data comprising the network on which the non-fault tolerant network node exists therewith; and

sending data intended for a non-fault tolerant network node over only the

network on which the non-fault tolerant network node has been determined to

exist.

2. The method of claim 1, wherein determining the network addresses of non-

fault-tolerant network nodes comprises detection of network address information

that the non-fault-tolerant network nodes send over a network.

3. The method of claim 2, wherein the network address information that is sent comprises Internet Protocol Address Resolution Protocol packets (IP ARP

packets).

4. The method of claim 2, wherein determining the network on which each non- fault-tolerant network node exists comprises determining which network interface received the network address information sent from each non-fault-tolerant network node.

5. The method of claim 1, wherein storing the data comprises populating a non-

fault-tolerant network node address table.

6. The method of claim 1, further comprising sending data intended for a non-

fault-tolerant network node over both the primary and redundant network if the

network on which the non-fault-tolerant network node exists has not been

determined.

7. The method of claim 6, wherein determination of whether the network on which

the non-fault-tolerant network node exists has been determined comprises:

searching an address table for the stored data;

determining the network on which the non-fault-tolerant network node

exists has been determined if the address table contains an entry for the non-fault-

tolerant network node; and

determining the network on which the non-fault-tolerant network node

exists has not been determined if the address table does not contain an entry for the

non-fault-tolerant network node.

8. A method of managing communication with non-fault tolerant network nodes in

a fault-tolerant computer network, comprising:

transmitting data from a transmitting node to a non-fault tolerant network node over a primary network; and

transmitting data from the transmitting node to the non-fault tolerant

network node over a redundant network.

9. The method of claim 8, further comprising receiving and retransmitting the data

via an intermediate node when the transmitting node is unable to communicate

with both the primary and redundant networks, such that if the intermediate node

receives the data via the redundant network it retransmits the data on the primary

network and if the intermediate node receives the data via the primary network it

retransmits the data on the redundant network.

10. A fault-tolerant network node interface operable to communicate with non-

fault-tolerant network nodes, the interface operable to: determine the network addresses of network nodes present in a plurality of

determine the network on which each non-fault tolerant network node

exists;

store the detected network address data of the non-fault tolerant network nodes and to store associated network data comprising the network on which the

non-fault tolerant network node exists therewith; and

send data intended for a non-fault tolerant network node over only the

network on which the non-fault tolerant network node has been determined to exist.

11. The interface of claim 10, wherein determining the network addresses of non- fault-tolerant network nodes comprises detection of network address information

that the non-fault-tolerant network nodes send over a network.

12. The interface of claim 11 , wherein the network address information that is sent

comprises Internet Protocol Address Resolution Protocol packets (IP ARP

packets).

13. The interface of claim 11, wherein determining the network on which each

non-fault-tolerant network node exists comprises determining which network

interface received the network address information sent from each non-fault-

tolerant network node.

14. The interface of claim 10, wherein storing the data comprises populating a

non-fault-tolerant network node address table.

15. The interface of claim 10, wherein the network interface is further operable to

send data intended for a non-fault-tolerant network node over both the primary and

redundant network if the network on which the non-fault-tolerant network node

exists has not been determined.

16. The interface of claim 15, wherein determination of whether the network on

which the non-fault-tolerant network node exists has been determined comprises:

searching an address table for the stored data; determining the network on which the non-fault-tolerant network node exists has been determined if the address table contains an entry for the non-fault- tolerant network node; and

determining the network on which the non-fault-tolerant network node

non-fault-tolerant network node.

17. A fault-tolerant network node interface operable to communicate with non-

fault-tolerant network nodes, the interface operable to:

transmit data to a non-fault-tolerant network node over a primary network;

and

transmit data to a non-fault-tolerant network node over a redundant

network.

18. The interface of claim 17, wherein transmitting data to a non-fault tolerant

network node comprises receiving and retransmitting the data via an intermediate

node when the transmitting node is unable to communicate with both the primary

and redundant networks, such that if the intermediate node receives the data via the

redundant network it retransmits the data on the primary network and if the

intermediate node receives the data via the primary network it retransmits the data

on the redundant network.

19. A machine-readable medium with instructions stored thereon, the instructions

when executed on a computerized system operable to cause the computerized

system to: determine the network addresses of network nodes present in a plurality of networks that are not fault-tolerant and are connected to only a single network; determine the network on which each non-fault tolerant network node exists;

store the detected network address data of the non-fault tolerant network nodes and to store associated network data comprising the network on which the non-fault tolerant network node exists therewith; and send data intended for a non-fault tolerant network node over only the network on which the non-fault tolerant network node has been determined to exist.

20. The machine-readable medium of claim 19, wherein determining the network addresses of non-fault-tolerant network nodes comprises detection of network address information that the non-fault-tolerant network nodes send over a network.

21. The machine-readable medium of claim 20, wherein the network address information that is sent comprises Internet Protocol Address Resolution Protocol packets (IP ARP packets).

22. The machme-readable medium of claim 20, wherein determining the network on which each non-fault-tolerant network node exists comprises determining which network interface received the network address information sent from each non- fault-tolerant network node.

23. The machine-readable medium of claim 19, wherein storing the data comprises

populating a non-fault-tolerant network node address table.

24. The machine-readable medium of claim 19, the instructions when executed

further operable to cause a computerized system to send data intended for a non-

fault-tolerant network node over both the primary and the redundant network if the

network on which the non-fault-tolerant network node exists has not been

determined.

25. The machme-readable medium of claim 24, wherein determination of whether

the network on which the non-fault-tolerant network node exists has been

determined comprises:

searching an address table for the stored data;

determining the network on which the non-fault-tolerant network node

tolerant network node; and

determining the network on which the non-fault-tolerant network node

non-fault-tolerant network node.

26. A machine-readable medium with instructions stored thereon, the instructions

when executed on a computerized system operable to cause the computerized

system to: transmit data to a non-fault-tolerant network node over a primary network; and

transmit data to the non-fault-tolerant network node over a redundant network.

27. The machine-readable medium of claim 26, the instructions when executed

further operable to cause a computerized network of nodes to receive and

retransmit the data via an intermediate node when the transmitting node is unable

to communicate with both the primary and redundant networks, such that if the

intermediate node receives the data via the redundant network it retransmits the

data on the primary network and if the intermediate node receives the data via the

primary network it retransmits the data on the redundant network.