RFC 922 (rfc922) - Page 2 of 12
Broadcasting Internet datagrams in the presence of subnets
Alternative Format: Original Text Document
RFC 922 October 1984
Broadcasting Internet Datagrams in the Presence of Subnets
When a datagram is broadcast, it imposes a cost on every host that
hears it. Therefore, broadcasting should not be used
indiscriminately, but rather only when it is the best solution to a
problem.
2. Terminology
Because broadcasting depends on the specific data link layer in use
on a local network, we must discuss it with reference to both
physical networks and logical networks.
The terms we will use in referring to physical networks are, from the
point of view of the host sending or forwarding a broadcast:
Local Hardware Network
The physical link to which the host is attached.
Remote Hardware Network
A physical network which is separated from the host by at least
one gateway.
Collection of Hardware Networks
A set of hardware networks (transitively) connected by gateways.
The IP world includes several kinds of logical network. To avoid
ambiguity, we will use the following terms:
Internet
The DARPA Internet collection of IP networks.
IP Network
One or a collection of several hardware networks that have one
specific IP network number.
Subnet
A single member of the collection of hardware networks that
compose an IP network. Host addresses on a given subnet share an
IP network number with hosts on all other subnets of that IP
network, but the local-address part is divided into subnet-number
Mogul