rdisc(1M)
NAME
in.rdisc, rdisc - network router discovery daemon
SYNOPSIS
/usr/sbin/in.rdisc [-a] [-f] [-s] [send-address] [receive-
address]
/usr/sbin/in.rdisc -r [-p preference] [-T interval] [send-
address] [receive-address]
DESCRIPTION
The functionality provided by the in.rdisc daemon is now
included in in.routed(1M). in.rdisc remains part of the
software distribution of the Solaris Operating Environment.
However, the system startup scripts in /etc/init.d start
in.routed and do not start in.rdisc. If you want to custom-
ize router discovery behavior, consult gateways(4). See
in.routed(1M) for information on that daemon.
in.rdisc implements the ICMP router discovery protocol. The
first form of the command is used on hosts and the second
form is used on routers.
in.rdisc can be invoked in either the first form (host mode)
or second form (router mode).
On a host, in.rdisc populates the network routing tables
with default routes. On a router, advertises the router to
all the hosts.
Host (First Form)
On a host, in.rdisc listens on the ALL_HOSTS (224.0.0.1)
multicast address for ROUTER_ADVERTISE messages from
routers. The received messages are handled by first ignoring
those listed router addresses with which the host does not
share a network. Among the remaining addresses, the ones
with the highest preference are selected as default routers
and a default route is entered in the kernel routing table
for each one of them.
Optionally, in.rdisc can avoid waiting for routers to
announce themselves by sending out a few ROUTER_SOLICITATION
messages to the ALL_ROUTERS (224.0.0.2) multicast address
when it is started.
A timer is associated with each router address. The address
will no longer be considered for inclusion in the routing
tables if the timer expires before a new advertise message
is received from the router. The address will also be
excluded from consideration if the host receives an adver-
tise message with the preference being maximally negative or
with a lifetime of zero.
Router (Second Form)
When in.rdisc is started on a router, it uses the
SIOCGIFCONF ioctl(2) to find the interfaces configured into
the system and it starts listening on the ALL_ROUTERS multi-
cast address on all the interfaces that support multicast.
It sends out advertise messages to the ALL_HOSTS multicast
address advertising all its IP addresses. A few initial
advertise messages are sent out during the first 30 seconds
and after that it will transmit advertise messages approxi-
mately every 600 seconds.
When in.rdisc receives a solicitation message, it sends an
advertise message to the host that sent the solicitation
message.
When in.rdisc is terminated by a signal, it sends out an
advertise message with the preference being maximally nega-
tive.
OPTIONS
-a Accept all routers independent of the preference they
have in their advertise messages. Normally, in.rdisc
only accepts (and enters in the kernel routing tables)
the router or routers with the highest preference.
-f Run in.rdisc forever even if no routers are found.
Normally, in.rdisc gives up if it has not received any
advertise message after soliciting three times, in
which case it exits with a non-zero exit code. If -f
is not specified in the first form then -s must be
specified.
-r Act as a router, rather than a host.
-s Send three solicitation messages initially to quickly
discover the routers when the system is booted. When
-s is specified, in.rdisc exits with a non-zero exit
code if it can not find any routers. This can be over-
ridden with the -f option.
-p preference
Set the preference transmitted in the solicitation
messages. The default is zero.
-T interval
Set the interval between transmitting the advertise
messages. The default time is 600 seconds.
ATTRIBUTES
See attributes(5) for descriptions of the following attri-
butes:
____________________________________________________________
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
|_____________________________|_____________________________|
| Availability | SUNWroute |
|_____________________________|_____________________________|
SEE ALSO
in.routed(1M), ioctl(2), gateways(4), attributes(5),
icmp(7P), inet(7P)
Deering, S.E., editor, ICMP Router Discovery Messages, RFC
1256, Network Information Center, SRI International, Menlo
Park, California, September 1991.
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