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Protocols for Interworking: XNFS, Version 3W
Copyright © 1998 The Open Group



(Address Resolution Protocol) The protocol used to bind a high-level Internet Address to a low-level physical hardware address. It can only be used on networks that support hardware broadcast. The protocol is only across a single physical network.


(Advanced Research Project Agency) Part of the U.S. Department of Defense. This agency funded the ARPANET and DARPA Internet. Its present name is DARPA. They are located at 1400, Wilson Blvd, Arlington, VA, U.S.A.


A network built by BBN (Bolt, Beranek and Newman, Incorporated) and funded by ARPA. It was one of the first largescale packet switched networks, and was used to link academic institutes involved with ARPA work. It helped with the early network research and formed a basis for Internet.


The name of a particular byte order (coined by Danny Cohen). When looking at addresses in increasing order, the most significant byte comes first. The Internet protocols use Big-Endian byte order.


To broadcast a packet is the function of delivering a given packet to all hosts that are attached to the broadcasting delivery system. Broadcasting is implemented both at the hardware and the software levels.


8 bits.


Common Applications Environment.


The distributed system model where a requesting program (the client) interacts with a program that can satisfy the request (the server). The client initiates the interaction and may wait for the server to respond.

connection-oriented service

A service provided between two endpoints along which data is passed in a sequenced and reliable way.

connectionless service

In a connectionless service each packet is a separate entity containing a source and destination address; therefore packets may be dropped or delivered out of sequence. The delivery service offered by the Internet Protocol (IP) is a connectionless service.


(Cyclic Redundancy Check) An integer calculated from a sequence of octets used to check that errors have not occurred during their transmission. The CRC is calculated and transmitted with the octets. At the receiving end the CRC is recalculated and compared with the value sent. If the values are identical the data is assumed to be error free.


(Defense Advanced Projects Research Agency) Formerly ARPA.

data encapsulation

The way a lower-level protocol accepts a message from a higher-level protocol and places it in the data portion of the low-level frame.


A process that is not associated with any user. This sort of process performs system-wide functions; for example, administration, control of networks and execution-dependent activities.


A packet sent independently of the others in the network. It contains the source and destination addresses as well as the data.

distributed database

A distributed database which is split up into several components, with each component on a different computer. The end-user, however, is given the impression that only a single local database is used.

effective group ID

An attribute of a process that is used in determining various permissions, including file access permissions. This value is subject to change during the process lifetime.

effective user ID

An attribute of a process that is used in determining various permissions, including file access permissions. This value is subject to change during the process lifetime.


A local area network developed by Digital Equipment Corporation, Intel Corporation and Xerox Corporation. The Ethernet is a passive coaxial cable with the interconnections containing all the active components.


The XSI system call that is used to start a process running.


The XSI system call which is used to create a new process. The process created is a duplicate of the calling process.


A transmission channel that can carry signals in both directions simultaneously.


(Internet Control and Monitoring Protocol) Part of the Internet Protocol Suite. ICMP is used to provide network layer management facilities, providing an error reporting facility and routing suggestions. ICMP also includes an echo request/reply, used to test whether a destination is reachable and responding.


A large virtual network made up of a series of networks interconnected by routers.

Internet, The

The cooperative virtual network that uses the TCP/IP protocol and includes the ARPANET, MILNET and NSFnet. It provides universal connectivity and reaches many universities, government and military establishments.


The ability of software and hardware on multiple machines and from multiple vendors to communicate effectively.


A system call which allows a process to specify control information to control a device. This function exists in both XSI and DOS.


(Internet Protocol) The protocol from the Internet Protocol Suite that provides the basis for internet communications.


(Interworking Protocol) The OSI protocol which supports the interconnection of separate OSI networks.


(Inter-Process Communication) Methods by which two or more processes can communicate; for example, formatted data streams or shared memory.


(Local Area Network) A physical network that operates at a high speed over short distances; for example, Ethernet.


The name of a particular byte order (coined by Danny Cohen). When looking at addresses in increasing order, the least significant byte comes first.

Mount Protocol

This protocol obtains a file handle from the server for the root of a file system which will then be available through NFS.

Multi-component Lookup

The filename used in a lookup request that uses a public filehandle may contain a slash-separated pathname. The server is required to evaluate this pathname (crossing intermediate mountpoints and evaluating symbolic links if necessary) and return the filehandle for the final component.


(Network File System) A protocol which allows a set of computers access to each others file systems. NFS was developed by Sun Microsystems, Inc. and is used primarily on UNIX systems.


(Network Lock Manager) An RPC based service which provides advisory DOS file locking and access control synchronisation across the network. This service is used in conjunction with NFS.


(National Science Foundation NETwork) The collection of networks across the United States sponsored by NSF.


Network Status Monitor.


(Open Systems Interconnect) ISO standards for the interconnection of cooperative (open) computer systems.


A block of data sent across a packet switching network.


(Personal Computer NFS Daemon) The daemon that provides personal computer NFS clients with authentication and printing services which are usually available in larger and more capable systems.


(Process ID) The number assigned to a process so that it can be uniquely identified.

port mapper

The port mapper is a program that maps RPC program and version numbers to transport-specific port numbers thus providing a dynamic binding capability for remote programs.

Public Filehandle

A filehandle with a known value associated with a specific directory on the server. A "version 2" public filehandle has 32 zero bytes. A "version 3" public filehandle has zero length.

remote mount

The process by which one machine can mount a file system that exists on a remote machine so it can be accessed as if it were a local file system.


(Request For Comments) The name of a series of notes that contain surveys, measurements, ideas, techniques and observations, as well as proposed and accepted Internet protocol standards.

root (of file system)

The top directory in the directory hierarchical structure.


A mechanism for interconnection of two or more networks at the network layer (see bridge, gateway).


(Remote Procedure Call) A mechanism allowing a client to call a procedure that a remote server executes.


A program-defined endpoint for network communication between processes. Sockets are a particular paradigm used for interprocess communication.

stateful server

A stateful server is a server that maintains information about the state of the transactions it has processed, for example whether or not a file is currently open.

stateless server

A stateless server is a server that does not maintain state information from one transaction to another.


(To Be Defined) Further detail will be provided at a later time.


(Transmission Control Protocol) The Internet standard transport level connection-oriented protocol. It provides a full duplex, reliable stream service which allows a process on one machine to send a stream of data to a process on another. Part of the Internet Protocol Suite.


(Time To Live) Used to stop the existence of endlessly looping packets. Each packet is assigned an integer which is decremented each time it passes through a router. If the integer reaches zero the router discards the packet.


(User Datagram Protocol) The Internet connectionless protocol. Part of the Internet Protocol Suite.


The XSI process's file mode creation mask used during file and directory creation. Bit positions that are set in the umask are cleared in the mode of the newly created file or directory. The umask is set using the umask() call.


(Virtual Circuit) The path between two communicating systems that provides a reliable, sequenced data delivery service.

working directory

A directory, associated with a process, that is used in pathname resolution for pathnames that do not begin with a slash.


(External Data Representation) A machine-independent data representation scheme developed by Sun Microsystems, Inc.


The name given to the X/Open Specification for file-sharing services based upon the NFS architecture developed by Sun Microsystems, Inc.
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