- Clear Datagram -
- The unmodified IP datagram in the User Space before Encapsulation.
- Clear Header -
- The header portion of the Clear Datagram before Encapsulation. This header includes the IP header and possibly part or all of the next layer protocol header, i.e., the TCP header.
- Decapsulation -
- The stripping of the Encapsulation Header and forwarding of the Clear Datagram by the Decapsulator.
- Decapsulator -
- The entity responsible for receiving an Encapsulated Datagram, decapsulating it, and delivering it to the destination User Space. Delivery may be direct, or via Encapsulation. A Decapsulator may be a host or a gateway.
- Encapsulated Datagram -
- The datagram consisting of a Clear Datagram prepended with an Encapsulation Header.
- Encapsulation -
- The process of mapping a Clear Datagram to the Encapsulation Space, prepending an Encapsulation Header to the Clear Datagram and routing the Encapsulated Datagram 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.
- Source Route -
- A complete end-to-end route which is computed at the source and enumerates transit gateways.
- User Space -
- The address and routing space within which the users reside. Routing within this space provides reachability between all address pairs within the space. User Spaces do not overlap, that is, a given User Address is unique in all User Spaces.
Glossary
