Network Working Group S. Deering, Editor
Request for Comments: 1256 Xerox PARC
September 1991
ICMP Router Advertisement Message
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Num Addrs |Addr Entry Size|
Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Router Address[1] |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Preference Level[1] |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Router Address[2] |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Preference Level[2] |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| . |
| . |
| . |
Source Address An
IP address belonging to the interface
from which this message is sent.
Destination Address The configured AdvertisementAddress or the
IP address of
a neighboring host.
Time-to-Live 1
if the Destination Address is an
IP multicast address; at least 1 otherwise.
ICMP Fields:
Checksum The 16-bit one's complement of the one's
complement sum of the ICMP message, start-
ing with the ICMP
Type. For computing the
checksum, the Checksum field is set to 0.
Num Addrs The number of router addresses advertised
in this message.
Addr Entry Size The number of 32-bit words of information
per each router address (2, in the version
of the protocol described here).
Lifetime The maximum number of seconds that the
router addresses may be considered valid.
Router Address[i], The sending router's IP address(es) on the
i = 1..Num Addrs interface from which this message is sent.
Preference Level[i], The preferability of each Router Address[i]
i = 1..Num Addrs as a default router address, relative to
other router addresses on the same subnet.
A signed, twos-complement value; higher
values mean more preferable.
static struct stru_802_11_Phy_Parameters_HT a
void IP(uint state[], uchar in[])
unsigned short int Lifetime
1.9.5