Electrical computers and digital processing systems: multicomput – Computer-to-computer protocol implementing
Reexamination Certificate
1999-07-20
2003-12-16
Powell, Mark (Department: 2142)
Electrical computers and digital processing systems: multicomput
Computer-to-computer protocol implementing
C709S220000, C709S222000
Reexamination Certificate
active
06665724
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention concerns the use of a software protocol stack within a network interface device in which initialization of the protocol stack is delayed until the automatic detection of a network communication conforming to the specific protocol supported by the protocol stack. More particularly, the present invention includes a network interface device which has the capability of communicating with other network devices by using a plurality of different protocol stacks and which has the capability of delaying the initialization process for a given protocol stack until such time that a network communication supported by the protocol stack is automatically detected, thereby reducing transmissions of unwanted and unnecessary initialization-related network communication from the network interface device.
2. Description of the Related Art
Local area networks (LANs) are widely used for the purpose of connecting a plurality of computers and computer related devices including printers, copiers and other peripherals and devices. On a given LAN wiring architecture, such as Ethernet, a plurality of different communication protocols may be utilized for communication between the different devices on the LAN. A LAN which is capable of supporting a plurality of different communication protocols is commonly referred to as a “heterogeneous” or “multiprotocol” LAN. Examples of such communication protocols include, but are not limited to, TCP/IP, IPX/SPX, NetBIOS, NETBEUI and AppleTalk.
A computer or electronic device may communicate on a LAN via hardware known as a network interface device. A network interface device can be a network expansion board locally attached to the computer or device, a network expansion device locally attached to the computer or device, or a network interface board locally attached to the computer or device. In the alternative, the network interface device may comprise a network interface board or a network expansion board that is embedded within the computer or device and locally attached thereto. Alternatively, for some electronic devices such as network-ready smart appliances (digital cameras, digital sound recorders, personal organizers, etc.), a network interface device is implemented directly within the processor and/or circuitry of the electronic device without the need for a separate network interface board or network expansion board attached to, or embedded within the electronic device. In this manner, a network may be utilized to inter-connect a diversity of devices such as personal computers, printers, scanners, copiers, digital cameras, and other smart appliances. A network interface device such as an embedded network expansion board within a network printer can communicate with other devices on a heterogeneous LAN by containing an appropriate protocol stack corresponding to each of the protocols being utilized by the other devices. A protocol stack is a software module that processes packets of network data pursuant to a specific protocol. The packets of network data are either received from or transmitted to the LAN by devices connected to the LAN. The protocol stack ensures that the data communication between two or more devices on the LAN is in compliance with the preset rules of the corresponding protocol.
In the case of a heterogeneous LAN, a network interface device should support each of the protocols in use on the LAN in order for the device to be accessible to the other computers and devices on the LAN. For example, a network printer with an embedded network expansion board must be capable of supporting the protocols in use on the LAN so as to facilitate service of print requests from the other computers and devices on the LAN.
A network interface device is commonly configured to support a plurality of protocols by loading the corresponding protocol stacks within the network interface device. Software modules commonly referred to as a network interface driver and a protocol multiplexer are also loaded in the network interface device. The network interface driver is a low-level software that communicates directly with the network interface hardware, which is connected to the LAN. The protocol multiplexer provides a common interface between each of the loaded protocol stacks and the network interface driver. After being loaded, each of the loaded protocol stacks establishes an interface with the protocol multiplexer. Establishing this interface is commonly referred to as “binding” the protocol stack to the protocol multiplexer. Binding a protocol stack to the protocol multiplexer enables the protocol multiplexer to (i) receive packets from the LAN that are supported by the protocol stack and then pass them to the protocol stack, and (ii) transmit packets to the LAN as directed by the protocol stack.
The initialization process for a protocol stack is commonly performed immediately after the protocol stack is loaded within the network interface device. The initialization process for certain protocol stacks may include the transmission of at least one packet on the LAN in order to obtain information from another device on the LAN that is necessary for the configuration of the protocol stack, such as address and other network-related information. For example, an AppleTalk protocol stack typically broadcasts at least one packet over the network during its initialization process in order to obtain the specific network address and zone information required to configure the protocol stack for appropriate communication with other devices on the LAN which are also utilizing the AppleTalk protocol.
Multi-protocol devices, such as network printers and copiers, typically configure themselves to support a plurality of protocols even if one or more of the protocols are not currently being utilized on the LAN. For example, it is common for a network printer that supports AppleTalk in addition to other protocols, such as TCP/IP or IPX, to load and initialize the AppleTalk protocol stack even though the network printer resides on a LAN that is currently only utilizing the TCP/IP and IPX protocols. In this manner, the network printer blindly loads all protocol stacks that it is capable of supporting without regard to the protocols that are currently being utilized on the LAN.
As mentioned above, during initialization of a protocol stack for a protocol such as AppleTalk, the network interface device transmits at least one initialization-related broadcast packet, even when that protocol is not currently being utilized by any other device on the LAN. This results in the unexpected or unwanted transmission of packets of a particular protocol on a network that is not currently utilizing that protocol. These unexpected or unwanted packets may be confusing or distracting to network administrators who may be totally unfamiliar with the particular protocol because it is not currently being utilized on the network. Additionally, these unnecessary or unwanted packet transmissions may result in increased traffic on the LAN, thereby potentially affecting the throughput capacity for other network devices on the LAN. Protocol stacks for protocols other than AppleTalk may transmit multicast, instead of broadcast, packets during initialization in a similar manner.
One solution to this problem, as described in U.S. Pat. No. 5,699,350 to Kraslavsky, is to prevent the network interface device from loading any protocol stack at all until a PRESCAN software module residing within the network interface device detects network traffic on the LAN conforming to a protocol that is supported by one of the corresponding protocol stacks. Upon such detection, the corresponding protocol stack is loaded and initialized for use by the network interface device. For example, on a heterogeneous LAN which is not currently utilizing the AppleTalk protocol, the AppleTalk protocol stack would not be loaded and initialized until the PRESCAN software module residing within the network interface device detects the presence of AppleTalk network traffic
Powell Mark
Vaughn, Jr. William C.
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