TCP/IP Configuration and Management Manual

Glossary
TCP/IP Configuration and Management Manual—427132-004
Glossary-2
ATM
ATM. See Asynchronous Transfer Mode (ATM).
bridge. A router that connects two or more networks and forwards packets among them.
Usually, bridges operate at the physical network level. For example, an Ethernet bridge
connects two physical Ethernet cables and forwards from one cable to the other
exactly those packets that are not local. Bridges differ from repeaters; bridges store
and forward complete packets, while repeaters forward electrical signals.
broadcast. A packet delivery system that delivers a copy of a given packet to all hosts that
attach to it is said to broadcast the packet. Broadcast may be implemented with
hardware or software.
BSD. Berkeley Software Distribution.
Class A. The network number is 1 through 127 (1 octet); that is, the first octet is in the
range 1-127. The remaining three octets in the address are used for the subnet
number and host number.
Class B. The network number is 128 through 191.255 (2 octets); that is, the first octet is in
the range 128-191, the second octet is in the range 0-255. The remaining two octets
are used for the subnet number and host number.
Class C. The network number is 192.0.0 through 255.255.255 (3 octets); that is, the first
octet is in the range 192-255, the second octet is in the range 0-255, and the third
octet is in the range 0-255. The remaining octet is used for the subnet number and
host number. The subnet number varies in length. The subnet number's width is
typically represented by a bit mask. The rest of the available bits uniquely identify the
host connected to the subnetwork. LANs connected by way of a gateway to the
Internet get their subnet class from the DCA's NIC (Network Information Center). The
address classes of standalone, or entirely private, LANs are administered by the LAN
administrator. Typical usage calls for all CLASS A addresses to have private LANs.
Class D. A Class D address is a 4-octet multicast group address. The four high-order bits of
the address are always 1110; therefore, the first octet is a number in the range 224
through 239 (%HE0 through %HEF). This means that an Internet can have a total of
268,435,456 multicast groups.
collector. An EMS process that accepts event messages from subsystems and logs them in
the event log. See also Event Management Service (EMS)
. Compare distributor.
command message. A SPI message, containing a command, sent from an application
program to a subsystem. See also SPI message
. Compare response message or
event message
.
common definition. In DSM programmatic interfaces, a definition (data declaration) used in
several commands, responses, or event messages in an SPI interface to a subsystem.
See also definition
.