RFC 1241 (rfc1241) - Page 2 of 17
Scheme for an internet encapsulation protocol: Version 1
Alternative Format: Original Text Document
RFC 1241 Internet Encapsulation July 1991
to a Decapsulator.
Encapsulation Header -
The header for the Encapsulation Protocol prepended to the
Clear Datagram during Encapsulation. This header consists
of an IP header followed by an Encapsulation Protocol
Header.
Encapsulation Protocol Header -
The Encapsulation Protocol specific portion of the
Encapsulation Header.
Encapsulation Space -
The address and routing space within which the
Encapsulators and Decapsulators reside. Routing within
this space is accomplished via Flows. Encapsulation
Spaces do not overlap, that is, the address of any
Encapsulator or Decapsulator is unique for all
Encapsulation Spaces.
Encapsulator -
The entity responsible for mapping a given User Space
datagram to the Encapsulation Space, encapsulating the
datagram, and forwarding the Encapsulated Datagram to a
Decapsulator. An Encapsulator may be a host or a gateway.
Flow -
Also called a "tunnel." A flow is the end-to-end path in
the Encapsulation Space over which Encapsulated Datagrams
travel. There may be several Encapsulator/Decapsulator
pairs along a given flow. Note that a Flow does not
denote what User Space gateways are traversed along the
path.
Flow ID -
A 32-bit identifier which uniquely distinguishes a flow in
a given Encapsulator or Decapsulator. Flow IDs are
specific to a single Encapsulator/Decapsulator Entity and
are not global quantities.
Mapping Function -
This is the function of mapping a Clear Header to a
particular Flow. All encapsulators along a given Flow are
required to map a given Clear Header to the same Flow.
User Address -
The address or identifier uniquely identifying an entity
within a User Space.
Woodburn & Mills