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 MTU - the minimum link MTU of all the links in a path between
a source node and a destination node.
Note: it is possible, though unusual, for a device with multiple
interfaces to be configured to forward non-self-destined packets
arriving from some set (fewer than all) of its interfaces, and to
discard non-self-destined packets arriving from its other interfaces.
Such a device must obey the protocol requirements for routers when
receiving packets from, and interacting with neighbors over, the
former (forwarding) interfaces. It must obey the protocol
requirements for hosts when receiving packets from, and interacting
with neighbors over, the latter (non-forwarding) interfaces.
RFC 1883 IPv6 Specification December 1995
3. IPv6 Header Format
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Version| Prio. | Flow Label |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Payload Length | Next Header | Hop Limit |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| |
+ Source Address +
| |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| |
+ Destination Address +
| |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Version 4-bit Internet Protocol version number = 6.
Prio. 4-bit priority value. See section 7.
Flow Label 24-bit flow label. See section 6.
Payload Length 16-bit unsigned integer. Length of payload,
i.e., the rest of the packet following the
IPv6 header, in octets. If zero, indicates that
the payload length is carried in a Jumbo Payload
hop-by-hop option.
Next Header 8-bit selector. Identifies the type of header
immediately following the IPv6 header. Uses
the same values as the IPv4 Protocol field
[RFC-1700 et seq.].
Hop Limit 8-bit unsigned integer. Decremented by 1 by
each node that forwards the packet. The packet
is discarded if Hop Limit is decremented to
zero.
Source Address 128-bit address of the originator of the
packet. See [RFC-1884].
RFC 1883 IPv6 Specification December 1995
Destination Address 128-bit address of the intended recipient
of the packet (possibly not the ultimate
recipient, if a Routing header is present).
See [RFC-1884] and section 4.4.
4. IPv6 Extension Headers
In IPv6, optional internet-layer information is encoded in separate
headers that may be placed between the IPv6 header and the upper-
layer header in a packet. There are a small number of such extension
headers, each identified by a distinct Next Header value. As
illustrated in these examples, an IPv6 packet may carry zero, one, or
=3= |
