NBT Manual

Glossary
NBT Manual—424773-001
Glossary-9
header token
header token. In an SPI message, a token that provides information pertaining to the
message as a whole. Header tokens differ from other tokens in several ways: they exist
in the buffer at initialization and their values are usually set by SSINIT, they can occur
only once in a buffer, they are never enclosed in a list, they cannot be moved to another
buffer with SSMOVE, and programs cannot position to them or retrieve their values
using the NEXTCODE or NEXTTOKEN operation. Programs retrieve the values of
header tokens by passing appropriate token codes to SSGET and can change the values
of some header tokens by passing their token codes to SSPUT.
Examples of header tokens for commands are the command number, the object type, the
maximum-response token, the server-version token, the maximum-field-version token,
and the checksum token. Command and response messages contain a specified set of
header tokens; event messages, a different set with some overlap. See also SPI message
.
hierarchical routing. Routing based on a hierarchical addressing scheme. Most Internet
routing is based on a two-level hierarchy in which an Internet address is divided into a
network portion and a host portion. Gateways use only the network portion until the
datagram reaches a gateway that can deliver it directly. Subnetting introduces additional
levels of hierarchical routing.
hop count. A measure of distance between two points in the Internet. A hop count of n means
that n gateways separate the source destination.
ICMP. See Interior Gateway Protocol (IGP)
.
IEEE. See Institute of Electrical and Electronics Engineers (IEEE)
.
IEEE 802.3. A local area network protocol suite commonly known as Ethernet. Ethernet has
either a 10Mbps or 100Mbps throughput and uses Carrier Sense Multiple Access bus
with Collision Detection (CSMA/CD. This method allows users to share the network
cable. However, only one station can use the cable at a time. A variety of physical
medium dependent protocols are supported.
IEE 802.5. A local area network protocol suite commonly known as token ring. A standard
originated by IBM for a token-passing ring network that can be configured in a star
topology. Versions supported are 4Mbps and 16 Mbps.
IEN. See Internet Engineering Note (IEN)
.
IGP. See Interior Gateway Protocol (IGP)
.
Information Xchange Facility (IXF). Compaq software product that provides file transfer
support between a Compaq system and IBM-compatible PCs.
Interior Gateway Protocol (IGP). The generic term applied to any protocol used to
propagate network reachability and routing information within an autonomous system.
Although no standard Internet IGP exists, RIP is among the most popular.
Institute of Electrical and Electronics Engineers (IEEE). An international industry group
that develops standards for many areas of electrical engineering and computers.