RFC 1662 (rfc1662) - Page 2 of 25
PPP in HDLC-like Framing
Alternative Format: Original Text Document
RFC 1662 HDLC-like Framing July 1994
1.1. Specification of Requirements
In this document, several words are used to signify the requirements
of the specification. These words are often capitalized.
MUST This word, or the adjective "required", means that the
definition is an absolute requirement of the specification.
MUST NOT This phrase means that the definition is an absolute
prohibition of the specification.
SHOULD This word, or the adjective "recommended", means that there
may exist valid reasons in particular circumstances to
ignore this item, but the full implications must be
understood and carefully weighed before choosing a
different course.
MAY This word, or the adjective "optional", means that this
item is one of an allowed set of alternatives. An
implementation which does not include this option MUST be
prepared to interoperate with another implementation which
does include the option.
1.2. Terminology
This document frequently uses the following terms:
datagram The unit of transmission in the network layer (such as IP).
A datagram may be encapsulated in one or more packets
passed to the data link layer.
frame The unit of transmission at the data link layer. A frame
may include a header and/or a trailer, along with some
number of units of data.
packet The basic unit of encapsulation, which is passed across the
interface between the network layer and the data link
layer. A packet is usually mapped to a frame; the
exceptions are when data link layer fragmentation is being
performed, or when multiple packets are incorporated into a
single frame.
peer The other end of the point-to-point link.
silently discard
The implementation discards the packet without further
processing. The implementation SHOULD provide the
capability of logging the error, including the contents of
the silently discarded packet, and SHOULD record the event
in a statistics counter.
Simpson