System Administration Commands in.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
in.rdisc remains part of the software distribution of the
Solaris Operating Environment. It is, however, not used by
default. in.routed(1M) includes the functionality provided
by in.rdisc. See routeadm(1M) for details of how to specify
the IPV4 routing 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 mes-
sages. Normally, in.rdisc only accepts (and
enters in the kernel routing tables) the
router or routers with the highest prefer-
ence.
-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
overridden with the -f option.
-p preference Set the preference transmitted in the soli-
citation 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), routeadm(1M), ioctl(2), gateways(4), attri-
butes(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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