rfc2461.txt
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TXT
1,451 行
Hop Limit 255
Authentication Header
If a Security Association for the IP Authentication
Header exists between the sender and the
destination address, then the sender SHOULD include
this header.
Narten, et. al. Standards Track [Page 21]
RFC 2461 Neighbor Discovery for IPv6 December 1998
ICMP Fields:
Type 135
Code 0
Checksum The ICMP checksum. See [ICMPv6].
Reserved This field is unused. It MUST be initialized to
zero by the sender and MUST be ignored by the
receiver.
Target Address
The IP address of the target of the solicitation.
It MUST NOT be a multicast address.
Possible options:
Source link-layer address
The link-layer address for the sender. MUST NOT be
included when the source IP address is the
unspecified address. Otherwise, on link layers
that have addresses this option MUST be included in
multicast solicitations and SHOULD be included in
unicast solicitations.
Future versions of this protocol may define new option types.
Receivers MUST silently ignore any options they do not recognize
and continue processing the message.
Narten, et. al. Standards Track [Page 22]
RFC 2461 Neighbor Discovery for IPv6 December 1998
4.4. Neighbor Advertisement Message Format
A node sends Neighbor Advertisements in response to Neighbor
Solicitations and sends unsolicited Neighbor Advertisements in order
to (unreliably) propagate new information quickly.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Code | Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|R|S|O| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| |
+ Target Address +
| |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Options ...
+-+-+-+-+-+-+-+-+-+-+-+-
IP Fields:
Source Address
An address assigned to the interface from which the
advertisement is sent.
Destination Address
For solicited advertisements, the Source Address of
an invoking Neighbor Solicitation or, if the
solicitation's Source Address is the unspecified
address, the all-nodes multicast address.
For unsolicited advertisements typically the all-
nodes multicast address.
Hop Limit 255
Authentication Header
If a Security Association for the IP Authentication
Header exists between the sender and the
destination address, then the sender SHOULD include
this header.
Narten, et. al. Standards Track [Page 23]
RFC 2461 Neighbor Discovery for IPv6 December 1998
ICMP Fields:
Type 136
Code 0
Checksum The ICMP checksum. See [ICMPv6].
R Router flag. When set, the R-bit indicates that
the sender is a router. The R-bit is used by
Neighbor Unreachability Detection to detect a
router that changes to a host.
S Solicited flag. When set, the S-bit indicates that
the advertisement was sent in response to a
Neighbor Solicitation from the Destination address.
The S-bit is used as a reachability confirmation
for Neighbor Unreachability Detection. It MUST NOT
be set in multicast advertisements or in
unsolicited unicast advertisements.
O Override flag. When set, the O-bit indicates that
the advertisement should override an existing cache
entry and update the cached link-layer address.
When it is not set the advertisement will not
update a cached link-layer address though it will
update an existing Neighbor Cache entry for which
no link-layer address is known. It SHOULD NOT be
set in solicited advertisements for anycast
addresses and in solicited proxy advertisements.
It SHOULD be set in other solicited advertisements
and in unsolicited advertisements.
Reserved 29-bit unused field. It MUST be initialized to
zero by the sender and MUST be ignored by the
receiver.
Target Address
For solicited advertisements, the Target Address
field in the Neighbor Solicitation message that
prompted this advertisement. For an unsolicited
advertisement, the address whose link-layer address
has changed. The Target Address MUST NOT be a
multicast address.
Narten, et. al. Standards Track [Page 24]
RFC 2461 Neighbor Discovery for IPv6 December 1998
Possible options:
Target link-layer address
The link-layer address for the target, i.e., the
sender of the advertisement. This option MUST be
included on link layers that have addresses when
responding to multicast solicitations. When
responding to a unicast Neighbor Solicitation this
option SHOULD be included.
The option MUST be included for multicast
solicitations in order to avoid infinite Neighbor
Solicitation "recursion" when the peer node does
not have a cache entry to return a Neighbor
Advertisements message. When responding to unicast
solicitations, the option can be omitted since the
sender of the solicitation has the correct link-
layer address; otherwise it would not have be able
to send the unicast solicitation in the first
place. However, including the link-layer address in
this case adds little overhead and eliminates a
potential race condition where the sender deletes
the cached link-layer address prior to receiving a
response to a previous solicitation.
Future versions of this protocol may define new option types.
Receivers MUST silently ignore any options they do not recognize
and continue processing the message.
Narten, et. al. Standards Track [Page 25]
RFC 2461 Neighbor Discovery for IPv6 December 1998
4.5. Redirect Message Format
Routers send Redirect packets to inform a host of a better first-hop
node on the path to a destination. Hosts can be redirected to a
better first-hop router but can also be informed by a redirect that
the destination is in fact a neighbor. The latter is accomplished by
setting the ICMP Target Address equal to the ICMP Destination
Address.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Code | Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| |
+ Target Address +
| |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| |
+ Destination Address +
| |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Options ...
+-+-+-+-+-+-+-+-+-+-+-+-
IP Fields:
Source Address
MUST be the link-local address assigned to the
interface from which this message is sent.
Destination Address
The Source Address of the packet that triggered the
redirect.
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