# DIGITAL TCP/IP Services for OpenVMS
Concepts and Planning

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proxy database: The database that provides OpenVMS identities for remote NFS clients and UNIX-style identities for local NFS client users; provides proxy accounts for remote processes.

pseudodevice: A software device used to implement special-purpose transports and not directly associated with hardware.

public domain: Intellectual property available to people without paying a fee.

RARP: See Reverse Address Resolution Protocol.

RCD: See RMT/RCD.

RCP: See remote copy program.

reachable node: The node to which the local node has a usable communications path.)

read access: The access right that grants the ability to view data.

reassembly: The process of piecing together datagram fragments to reproduce the original datagram based upon the fragmentation data in the IP header of the datagram.

Record Management Services (RMS): The OpenVMS data management subsystem that defines the rules that govern the internal organization of and the methods of accessing file data, including how files are named and cataloged in directories.

reliability: The ability of a protocol to recover data that is damaged, lost, duplicated, or delivered out of order.

relative path name : A path name that does not start at the root; default directory is merged with the relative path name to form the absolute path name.

remote boot (BOOTP): The software that supports the downloading of system images and other types of files to requesting clients.

remote copy program (RCP): The program based on the Berkeley UNIX (see BSD) rcmd protocol that permits files to be copied from one computer to another by an extension to the syntax of the UNIX cp (copy) command. (RCP) does not provide the word-length adaptability and flexibility that the FTP protocol does.

remote line printing (LPR/LPD): The remote printing services for UNIX and OpenVMS client hosts.

remote node: A node in the network other than the local node.

remote procedure call (RPC): A programming interface for implementing the client/server model of distributed computing. In general, a request is sent to a remote system to execute a designated procedure, using arguments supplied, and the result returned to the caller. See also Sun RPC.

remote shell: A program that sends a command, shell, script, or command procedure to a remote host for execution.

remote task: A task either executing at a remote host or originating there.

repeater: A bidirectional device that amplifies or resynchronizes signals into standard voltages, currents, and timing; propagates electrical signals from one Ethernet to another without making routing decisions or providing packet filtering; Physical layer intermediate system. See also bridge and router.

Request for Comments (RFC): A series of documents, begun in 1969, that describes the Internet suite of protocols and related experiments. Very few RFCs describe Internet standards, but all Internet standards are written as RFCs.

resolver: A mechanism or process to correlate a network host name into an appropriate network address in support of network applications---a network name resolver. See BIND resolver.

reserved port: An assigned port that provides services to unknown callers by providing a service contact point; reserved port numbers range from 1 to 255.

resynchronization: A process that enables the recovery of user information lost or corrupted during transfer across an association. Sets the association back to the state it was in at a specified point in the transfer.

retransmission: A method of error recovery in which stations receiving messages acknowledge the receipt of correct messages and, on receipt of incorrect messages, either do not acknowledge or acknowledge in the negative. The lack of acknowledgment or receipt of a negative acknowledgment indicates to the sending station that it should transmit the failed message again.

Reverse Address Resolution Protocol (RARP): The TCP/IP protocol that provides the reverse function of ARP. This protocol maps a physical (hardware) address to an IP address. Often used by diskless nodes when they first initialize to find their Internet address.

reverse domain: An Internet domain that BIND servers use to map IP addresses to domain names.

RFC: See Request for Comments.

RFC 822: The TCP/IP standard format for electronic mail message headers; often referred to as "822 messages". The name comes from RFC 822 that contains the specification; previously known as 733 format.

RIP: See Routing Information Protocol.

rlogin: Remote login: The Berkeley 4.3 BSD service that allows users of one machine to connect to other systems across the Internet and interact as if their terminals are connected the machines directly.

RMS: See Record Management Services.

RMT/RCD: Remote command that allows remote users to access magnetic tapes and CD drives.

root: The top level directory in a UNIX-style file system; also used to indicate a user (the superuser) who has special privileges. See superuser.

root mode: The file protection placed on a container file when it is created.

root name: The element of a path name that identifies the target file system.

root server: An Internet name server that knows about all of the top-level domains on the Internet network; the master servers for the Internet root zone.

round-trip delay: The total time during communications that implement a protocol with positive acknowledgments, for a message to be transmitted, arrive at its destination, and its corresponding acknowledgment to be sent and subsequently received by the sender of the original message.

round-trip time (RTT): A variable computed during TCP sessions that indicates the total time required to send a TCP segment to a remote host and receive a reply.

route: The path over the network that information takes to get from one source to its destination.

route through: Data packets not destined for the local node.

routes database: The UCX database that specifies Internet gateways.

routed: See Route Daemon.

Route Daemon (routed): A program that runs under 4.2BSD/4.3BSD UNIX systems (and derived operating systems) to propagate routes among machines on a local area network using the Routing Information Protocol; pronounced "route-d."

router: A node that can send and receive data and also forward data to other nodes.

routing: A Network layer function, implemented in intermediate systems, that determines the path along which data travels to its destination and the movement of that data. See also decision.

routing database: The database that contains routing information, including destination host names, IP addresses for the hosts, gateway host names, and IP addresses for the gateways. There are two route databases: the static route database that is maintained on disk and the volatile database in memory.

routing domain: A set of hosts and routers within a single administrative domain that operates according to the same routing procedures.

Routing Information Protocol (RIP): The protocol that enables gateways to broadcast their current routing database to hosts and networks that are connected directly to them. UCX software implements the RIP through its dynamic routing server.

Routing Protocol: A protocol sent between routers by which routers exchange information on how to route to various parts of the network. The TCP/IP family of protocols has many of this type of protocol, such as RIP, EGP, BGP, OSPF, and dual IS-IS.

RPC: See remote procedure call and Sun RPC.

rshell: Remote shell; a remote utility that gives the user with a shell session on a remote host.

RTL: See Run-Time Library.

RTT: See round-trip time.

Run-Time Library (RTL): A collection of OpenVMS procedures available to native mode images at run time; provide support routines for high-level language compilers.

SCALE: A TCP window scaling option; allows window information to be interpreted as being scaled by 1 to 16 powers of 2, thus increasing the size of the effective window.

secondary server: A master BIND server that receives authoritative database information from a primary server. See also BIND server, cache server, forwarder server, and primary server.

segment: A unit of data exchanged by the TCP modules.

segment length: The amount of sequence number space occupied by a segment, including controls that occupy sequence space.

sequence number: A 32-bit field in the TCP header that contains the sequence number of a sequenced control flag, the first byte of data, or empty segments (the sequence number of the next data octet to be sent).

Serial Line Internet Protocol(SLIP): A protocol designed to allow a host to connect to another host over serial lines, such as telephone circuits or RS-232 cables.

server: A process that offers a service to another process over the network and accepts requests from other processes, known as clients.

service: (1) A task that an application can carry out. (2) The interface provided by a service element or layer for accessing one or more function.

service interface: The boundary at which a layer provides a service to the adjacent higher layer in the network architecture; may vary between implementations.

service parameter: The means by which a service user and a service provider exchange information.

service provider: In network architecture, the service element or layer that provides a set of services to the layer immediately above.

service specification: An international standard that describes the functions and service parameters of every service of a service provider.

service user: An application program, service element, or Network layer that uses the services of a service provider.

services database: The UCX database created by default that contains one entry for each UCX service configured.

Simple Mail Transfer Protocol (SMTP): An Internet standard protocol for transferring electronic mail messages from one machine to another; specifies how two mail systems interact and the format of control messages they exchange to transfer mail.

Simple Network Management Protocol (SNMP): The network management protocol of choice for TCP/IP-based internets; allows remote monitoring and management of network devices (particularly routers and servers) from across an Internet.

slave server: A name server that has no access to the Internet and relies on forwarder servers to resolve queries that it cannot resolve locally. As slave servers receive information from forwarder servers, they store that information in their cache. See also cache server, forwarder server, primary server, and secondary server.

SLIP: Serial Line Internet Protocol---a protocol designed to allow a host to connect to a TCP/IP internetwork over a telephone connection.

SMI: See Structure of Management Information.

SMTP: See Simple Mail Transfer Protocol.

SNMP: See Simple Network Management Protocol.

socket: The end point of communication to which an IP address and port may be bound. When writing a UCX application, it is a data structure that is part of the Internet pseudodevice created every time an OpenVMS process assigns a communication channel. The other part of the Internet pseudodevice is the device socket.

source: The IP header field that contains the IP address of the datagram's point of origin.

source port: A 2-octet value in the TCP or UDP header field that identifies the upper-level application or protocol associated with the data in the segment.

spanning tree: A logical arrangement created by bridges in an extended LAN in which all LANs are connected and there are no loops.

split horizon: When a router (or group of routers work together) accepts routing information from multiple external networks, but does not pass on information learned from one external network to others. This is an attempt to prevent false routes to a network from being propagated because of gossip or counting to infinity.

splitting: The process of mapping one transport connection to several network connections.

stream-oriented: The type of transport service that allows its client to send data in a continuous stream; guarantees that all data will be delivered to the other end in the same order as sent and without duplicates. Also known as a reliable transport service.

Structure of Management Information (SMI): The rules used to define the objects that can be accessed by means of a network management protocol. See also Management Information Base.

subnet: An organization of hosts within a network into logical groups. A network can be comprised of several subnets. The portion of a network, which might be a physically independent network, that shares a network address with other portions of the network and is distinguished by a subnet number. A subnet is to a network what a network is to an internet.

subnet address: A part of the Internet addressing scheme. If a site uses a single IP address for multiple physical networks, there is one subnet address for each physical network. Each such address is composed of the network part of the full address and part of the local part (host).

subnet field: A bit field in an IP address that denotes the subnet number. The bits making up this field are not necessarily contiguous in the address.

subnet mask: A method of representing the portion of the IP network address that is devoted to subnet address. Each bit that is turned on (binary one) in the mask is interpreted as part of the network and subnet address. Synonymous with network mask. See address mask.

Sun RPC: An easy and popular paradigm for implementing the client/server model of distributed computing. In general, a request is sent to a remote system to execute a designated procedure, using arguments supplied, and the result returned to the caller.

superuser: A UNIX user who has been granted special privileges; has an effective UID of 0.

symbiont: (1) A process that transfers record-oriented data to and from a mass storage device; for example, from disks to printers. (2) Synonym for daemon.

symbolic link: A file that contains the name of the file to which it is linked. The referenced file is used whenever the symbolic link file is opened.

synchronous transmission: Data transmission in which characters are transmitted at a fixed rate. The transmitter and receiver are synchronized, gaining greater efficiency than in asynchronous transmission. Synchronous transmissions send a predetermined group of "sync" characters ahead of a long stream of data. The sync characters enable the communicating devices to synchronize with each other in accordance with a time clock at each end. Contrast with asynchronous transmission.

syntax: The rules for formatting/interpreting data.

TAC: See terminal access controller.

target system: The intended destination of messages.

TCP: See Transmission Control Protocol.

TCP/IP: An Internet suite of protocols. See also Transmission Control Protocol and Internet Protocol.

TELNET: An Internet protocol for remote terminal connection. TELNET allows a user at one site to interact with remote timesharing systems at another site as if the user's terminal were directly connected to the remote host.

terminal access controller (TAC): A program and hardware that connects terminals to the Internet, usually using dialup modem connections.

terminal emulator: A program that allows a computer to emulate a terminal; a workstation thus appears as a terminal to the host.

terminal server: A device that handles terminal operations for host nodes on a LAN; can be used to connect terminal users to nodes on the same LAN and to users on nodes located off the LAN. Off-loads the terminal connection and I/O responsibilities from host nodes, and reduces the number of direct terminal connections to each host, thus saving substantial power, packaging, and cabling expense.

terminating packet: A packet whose destination is the local node.

TFTP: See Trivial File Transport Protocol.

thread: (1) A request from an NFS client to the NFS server. (2) A single unit of execution within a program.

throughput: A measure of how much data is sent, or can be sent, between two points in a specified unit of time; often used in either of two contexts:

- Rated throughput, which refers to the bandwidth or capacity of a component
- Real throughput, which refers to actual measured throughput.

time to live (TTL): A field in the IP header that indicates how long this packet should be allowed to be forwarded to other routers before being discarded.

timeo: A timeout option for the NFS mount command.

TN3270: TELNET options that allows TELNET users to connect to hosts that support 3270 model terminals.

token ring: A type of LAN that has stations wired in a ring, where each station constantly passes a special message (a "token") on to the next; technically referred to as IEEE 802.5.

topology: The architecture of a network. A network topology shows the computers and the links between them within a network.

traffic: The measurement of data flow, volume, and velocity over a communications link.

transceiver: Transmitter-receiver; a physical device required in baseband networks that takes the digital signal from a computer or terminal and imposes it on the baseband medium; connects a host interface to a LAN, such as Ethernet.

transient information: Network management information carried in an operation; is meaningful only while the operation is being performed.

transit network: A network that passes traffic between networks in addition to carrying traffic for its own hosts; must have multiple connections to the internet.

Transmission Control Protocol (TCP): A Transport layer protocol that provides the reliable, full-duplex, stream service on which many application protocols depend. TCP allows a process on one host to send a stream of data to a process on another. It is connection-oriented in the sense that before transmitting data, participants must establish a connection.

Transmission Control Protocol/Internet Protocol (TCP/IP): The acronym for the suite of application and transport protocols that run over IP, for example, FTP, TELNET, and UCP as well as TCP and IP themselves.

Transport layer: The layer in the TCP/IP architecture model where network traffic is passed between an application on one host and an application on another host.

Trivial File Transport Protocol (TFTP): The Internet protocol for file transfer with minimal capability and minimal overhead. The simple design of the facility is intended for use in application environments that do not require complex interactions among clients and servers. TFTP is a simple service running on top of UDP, using timeout and retransmission to ensure that data arrives. The sending side transmits a 512-byte, fixed-size file, and awaits an acknowledgment for each block before sending the next. The receiver acknowledges each block. See also File Transfer Protocol.

TTL: See time to live.

tunneling: The encapsulation of protocol A within protocol B such that A treats B as though it were a Network Interface layer. Used to get data between administrative domains that use a protocol not supported by the internet connecting those domains.

UAF: See user authorization file.

UCP: See UCX Control Program.

UCX: The widely used name that refers to the DIGITAL TCP/IP Services for OpenVMS product. Originally stood for "ULTRIX Connection."

UCX Control Program (UCP): The UCX network management control software; includes a command-line interface.

UDP: See User Datagram Protocol.

UID: See user identification.

UNIX-style file system: An organization of files based on the UNIX operating system.

UNIX-to-UNIX Copy Program (UUCP): A program that allows one UNIX system to copy files to or from another UNIX system.

Universal Time Coordinated (UTC): Greenwich Mean Time

user authorization file (UAF): An OpenVMS file that contains account names and their associated attributes.

User Datagram Protocol (UDP): An Internet transport protocol. A connectionless, unreliable Transport layer protocol for the exchange of requests and replies between networked hosts. UDP, like TCP, uses IP for message delivery from one host to another; however, unlike TCP, UDP provides for exchange of datagrams without acknowledgments or guaranteed delivery of data. Each UDP message contains the data sent by a user process, a destination port number, and a source port number.

user identification (UID): The UNIX identification code for a user.

UUCP: See UNIX-to-UNIX Copy Program.

virtual circuit: The network service that allows two processes to communicate as if they were directly connected, regardless of the structure of the underlying subnet.

WAN: See wide area network.

well-known port: A port number assigned for use by a specific network application for connections made with either UDP or TCP.

wide area network (WAN): A network, usually constructed with serial lines, which covers large geographic areas.

wildcarding: A method for generalizing parts of a OpenVMS file designation to encompass a set of files by substituting a symbol to represent one or more characters. OpenVMS wildcarding symbols are % (for one character) and * (for a character string of any length, including zero).

window: A 2-octet field in a TCP header indicating the number of data octets (relative to the acknowledgment number in the header) that the sender is currently willing to accept.

write access: An Access right that grants users the ability to change data.

zone: A subdivision of the Internet hierarchy that starts at a domain and extends down to leaf domains (individual host names) or to domains where other zones begin; usually represents an administrative boundary. Contrast with domain.

zone file: A master name server file that describes the domain names for which the server has authority.

# G.2 Acronyms

Table 1 shows DIGITAL TCP/IP Services for OpenVMS acronyms and other acronyms related to open networking.

Table 1 Acronyms
Acronym | Meaning
--- | ---
ACK | acknowledgment
ACL | access control list
ACP | ancillary control process
ANSI | American National Standards Institute
API | application programming interface
ARP | Address Resolution Protocol
ASCII | American Standard Code for Information Interchange
ATM | asynchronous transfer mode
BBS | Bulletin Board System
BGP | Border Gateway Protocol
BIND | Berkeley Internet Name Domain
BOOTP | Bootstrap Protocol
bps | bits per second
BSD | Berkeley Software Distribution
CFS | container file system
CFSRTL | container file system run-time library
CSLIP | Compressed Serial Line Internet Protocol
DCE | Distributed Computing Environment
DCL | Digital Command Language
DEK | data encryption key
DES | data encryption standard
DNS | Domain Name Service
eSNMP | extensible Simple Network Management Protocol
EGP | External Gateway Protocol
FDDI | Fiber Distributed Data Interface
EOF | end of file
EOL | end of line
FQDN | fully qualified domain name
FTP | File Transfer Protocol
GID | group identification (UNIX)
IAB | Internet Architecture Board
ICMP | Internet Control Message Protocol
IGP | Internal Gateway Protocol
InterNIC | Internet Network Information Center
IP | Internet Protocol
ISDN | Integrated Services Digital Networks
IVP | installation verification procedure
Kbps | kilobits per second
LAN | local area network
LPD | line printer daemon
LPR | remote line printing
MBUF | memory buffer
MFD | master file directory
MIB | Management Information Base
MIBII | Management Information Base II
MTU | maximum transmission unit
MX | mail exchanger
NAK | negative acknowledgment
NFS | Network File System
NIS | Network Information Service
NOC | Network Operations Center
NTP | Network Time Protocol
PDU | protocol data unit
PING | packet internet groper
POP | Post Office Protocol
PPP | Point-to-Point Protocol
PSDN | Packet Switching Data Network
PWIP | PATHWORKS Internet Protocol
RARP | Reverse Address Resolution Protocol
RCP | remote copy
REXEC | remote execute
RFC | Request for Comments
RLOGIN | remote login
RIP | Routing Information Protocol
RMS | Record Management Services
RPC | remote procedure call
RSH | remote shell
RTL | run-time library
RTT | round-trip time
SLIP | Serial Line Internet Protocol
SMI | structure of management information
SMTP | Simple Mail Transfer Protocol
SNMP | Simple Network Management Protocol
TAC | terminal access controller
TCP | Transmission Control Protocol
TCP/IP | Transmission Control Protocol/Internet Protocol
TFTP | Trivial File Transport Protocol
TP | Time Protocol
TTL | time to live
UAF | user authorization file
UCP | UCX Management Control Program
UCX | DIGITAL TCP/IP Services for OpenVMS
UDP | User Datagram Protocol
UID | user identification (UNIX)
UTC | Universal Coordinated Time
UUCP | UNIX-to-UNIX Copy Program
WAN | wide area network
WKS | Well Known Server
XDR | external data representation

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