Electrical computers and digital processing systems: multicomput – Computer network managing – Computer network access regulating
Reexamination Certificate
1998-12-04
2001-09-04
Wiley, David (Department: 2155)
Electrical computers and digital processing systems: multicomput
Computer network managing
Computer network access regulating
Reexamination Certificate
active
06286048
ABSTRACT:
FIELD OF THE INVENTION
The present invention is related to network protocols. In particular, the present invention relates to a protocol for discovering relative states for processors.
BACKGROUND OF THE INVENTION
A network is a communication system that allows users to access resources on other computers and exchange messages with other users. A network is typically a data communication system that links two or more computers and peripheral devices. It allows users to share resources on their own systems with other network users and to access information on centrally located systems or systems that are located at remote offices. It may provide connections to the Internet or the networks of other organizations. The network typically includes a cable that attaches to network interface cards (NIC) in each of the devices within the network. Users may interact with network-enabled software applications to make a network request (such as to get a file or print on a network printer). The application may also communicate with the network software and network software then may interact with the network hardware to transmit information to other devices attached to the network.
A local area network (LAN) is a network that is located in a relatively small area, such as a department or building. A LAN typically includes a shared medium to which workstations attach and communicate with one another by using broadcast methods. With broadcasting, any device on the LAN can transmit a message that all other devices on the LAN can listen to. The device to which the message is addressed actually receives the message. Data is typically packaged into frames for transmission on the LAN.
FIG. 1
is a block diagram illustrating a network connection between a user
10
and a particular web page
20
. This Figure is an example which may be consistent with any type of network, including a LAN, a wide are network (WAN), or a combination of networks, such as the Internet.
When a user
10
connects to a particular destination, such as a requested web page
20
, the connection from the user
10
to the web page
20
is typically routed through several routers
12
A-
12
D. Routers are internetworking devices. They are typically used to connect similar and heterogeneous network segments into Internetworks. For example, two LANs may be connected across a dial-up, integrated services digital network (ISDN), or a leased line via routers. Routers may also be found throughout the Internet. End users may connect to a local Internet service provider (ISP) (not shown), which are typically connected via routers to regional ISPs, which are in turn typically connected via routers to national ISPs.
If a router, such as router
12
C, fails and is no longer able to route the desired connection, then the desired connection between the user
10
the desired web page
20
may be significantly delayed or unable to connect at all.
To avoid this problem, a solution has been implemented by router manufacturers, such as Cisco Systems, that include two processors, a primary processor and a secondary processor, such that the secondary processor may take over as the main processor if the primary processor has either a hardware or software failure. Accordingly, such a solution provides redundancy to avoid failure of the router.
Although this solution works well, it may be desirable for many companies to avoid buying a specialized router with built in redundancy and simply use their existing routers for the same purpose. The present invention addresses such a need.
SUMMARY OF THE INVENTION
According to an embodiment of the present invention, two routers coupled through a network, such as a local access network (LAN), may be used to serve the function of redundancy to avoid the failure of a connection. The LAN may be used as a backplane to substitute for a bus between two processors. According to an embodiment of the present invention, the two routers may send their medium access control (MAC) addresses to each other and compare these MAC addresses. The router associated with the MAC address that meets a predetermined criteria may be deemed as a primary router and the other router can be deemed as a secondary router. An example of meeting the predetermined criteria is the router associated with the lower MAC address. Once processor states, such as stand alone, primary, and secondary, are established for the two routers, the primary router may serve the function of a standard router, while the secondary router monitors the health of the primary router and becomes a primary router should the original primary router have a failure.
A method according to an embodiment of the present invention for determining a state of a processor is presented. The method comprises providing a first criteria and a second criteria, wherein the first criteria is associated with a first device and the second criteria is associated with a second device, and wherein the first device and second device are coupled to each other. the method also compares the first criteria and the second criteria; and determines a first state for the first device.
A system according to an embodiment of the present invention for determining a state of a processor is also presented. The system comprises a first device providing a first criteria. The system also includes a second device coupled with the first device, the second device providing a second criteria. A processor is coupled with the first device. The processor is configured to compare the first criteria and the second criteria; and the processor is also configured to determine a first state for the first device.
Another system according to an embodiment of the present invention for determining a state of a processor is presented. The system comprises a processor that is configured to provide a first criteria and receive a second criteria. The first criteria is associated with a first device and the second criteria is associated with a second device. The processor is also configured to compare the first criteria and the second criteria, and determine a first state for the first device. A memory is coupled to the processor for providing instructions to the processor.
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Jack Jenney, “Dual RSP—High System Availability SW Functional Spec”, Oct. 6, 1995, Cisco Systems, Inc.
Cisco Technology Inc.
Van Pelt & Yi LLP
Wiley David
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