GLOSSARY

1822

BBN Report 1822, "The Specification of the Interconnection of a Host and an IMP". The specification of interface between a host and the ARPANET.

ARPANET leader

The control information on an ARPANET message at the host-IMP interface.

ARPANET message

The unit of transmission between a host and an IMP in the ARPANET. The maximum size is about 1012 octets (8096 bits).

ARPANET packet

A unit of transmission used internally in the ARPANET between IMPs. The maximum size is about 126 octets (1008 bits).

Destination

The destination address, an internet header field.

DF

The Don't Fragment bit carried in the flags field.

Flags

An internet header field carrying various control flags.

Fragment Offset

This internet header field indicates where in the internet datagram a fragment belongs.

GGP

Gateway to Gateway Protocol, the protocol used primarily between gateways to control routing and other gateway functions.

header

Control information at the beginning of a message, segment, datagram, packet or block of data.

ICMP

Internet Control Message Protocol, implemented in the internet module, the ICMP is used from gateways to hosts and between hosts to report errors and make routing suggestions.

Identification

An internet header field carrying the identifying value assigned by the sender to aid in assembling the fragments of a datagram.

IHL

The internet header field Internet Header Length is the length of the internet header measured in 32 bit words.

IMP

The Interface Message Processor, the packet switch of the ARPANET.

Internet Address

A four octet (32 bit) source or destination address consisting of a Network field and a Local Address field.

internet datagram

The unit of data exchanged between a pair of internet modules (includes the internet header).

internet fragment

A portion of the data of an internet datagram with an internet header.

Local Address

The address of a host within a network. The actual mapping of an internet local address on to the host addresses in a network is quite general, allowing for many to one mappings.

MF

The More-Fragments Flag carried in the internet header flags field.

module

An implementation, usually in software, of a protocol or other procedure.

more-fragments flag

A flag indicating whether or not this internet datagram contains the end of an internet datagram, carried in the internet header Flags field.

NFB

The Number of Fragment Blocks in a the data portion of an internet fragment. That is, the length of a portion of data measured in 8 octet units.

octet

An eight bit byte.

Options

The internet header Options field may contain several options, and each option may be several octets in length.

Padding

The internet header Padding field is used to ensure that the data begins on 32 bit word boundary. The padding is zero.

Protocol

In this document, the next higher level protocol identifier, an internet header field.

Rest

The local address portion of an Internet Address.

Source

The source address, an internet header field.

TCP

Transmission Control Protocol: A host-to-host protocol for reliable communication in internet environments.

TCP Segment

The unit of data exchanged between TCP modules (including the TCP header).

TFTP

Trivial File Transfer Protocol: A simple file transfer protocol built on UDP.

Time to Live

An internet header field which indicates the upper bound on how long this internet datagram may exist.

TOS

Type of Service

Total Length

The internet header field Total Length is the length of the datagram in octets including internet header and data.

TTL

Time to Live

Type of Service

An internet header field which indicates the type (or quality) of service for this internet datagram.

UDP

User Datagram Protocol: A user level protocol for transaction oriented applications.

User

The user of the internet protocol. This may be a higher level protocol module, an application program, or a gateway program.

Version

The Version field indicates the format of the internet header.