IPv6用経路MTU探索（用語）

   node        - a device that implements IPv6.

   router      - a node that forwards IPv6 packets not explicitly
                 addressed to itself.

   host        - any node that is not a router.

   upper layer - a protocol layer immediately above IPv6.  Examples are
                 transport protocols such as TCP and UDP, control
                 protocols such as ICMP, routing protocols such as OSPF,
                 and internet or lower-layer protocols being "tunneled"
                 over (i.e., encapsulated in) IPv6 such as IPX,
                 AppleTalk, or IPv6 itself.

   link        - a communication facility or medium over which nodes can
                 communicate at the link layer, i.e., the layer
                 immediately below IPv6.  Examples are Ethernets (simple
                 or bridged); PPP links; X.25, Frame Relay, or ATM
                 networks; and internet (or higher) layer "tunnels",
                 such as tunnels over IPv4 or IPv6 itself.

   interface   - a node's attachment to a link.

   address     - an IPv6-layer identifier for an interface or a set of
                 interfaces.

   packet      - an IPv6 header plus payload.

   link MTU    - the maximum transmission unit, i.e., maximum packet
                 size in octets, that can be conveyed in one piece over
                 a link.

   path        - the set of links traversed by a packet between a source
                 node and a destination node

   path MTU    - the minimum link MTU of all the links in a path between
                 a source node and a destination node.

   PMTU        - path MTU

   Path MTU
   Discovery   - process by which a node learns the PMTU of a path

   flow        - a sequence of packets sent from a particular source
                 to a particular (unicast or multicast) destination for
                 which the source desires special handling by the
                 intervening routers.

   flow id     - a combination of a source address and a non-zero
                 flow label.