rdisc — network router discovery daemon
rdisc [
-abdfrstvV
] [
-p
] [
preference-T
] [send_address] [receive_address]max_interval
rdisc implements client side of the ICMP Internet Router Discovery Protocol (IRDP). rdisc is invoked at boot time to populate the network routing tables with default routes.
rdisc listens on the ALL_HOSTS (224.0.0.1) multicast address (or receive_address if it is provided) 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, 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 (or send_address if it is provided) when it is started.
A timer is associated with each router address and 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 received advertise message has a preference of maximum negative.
Server side of router discovery protocol is supported by Cisco IOS and by any more or less complete UNIX routing daemon, for example gated. If compiled with ENABLE_RDISC_SERVER, rdisc can act as responder.
-a
Accept all routers independently of the preference they have in their advertise messages. Normally rdisc only accepts (and enters in the kernel routing tables) the router or routers with the highest preference.
-b
Opposite to
-a, i.e. install only router with the
best preference value. This is the default behaviour.
-d
Send debugging messages to syslog.
-f
Keep
rdisc running in the background even
if no routers are found. Normally
rdisc gives up if it has not received
any
advertise message after
soliciting three times. In this case it exits with
a non-zero exit code. If
-f is not specified in the first form
then
-s must be specified.
-r
Responder mode, available only if compiled with ENABLE_RDISC_SERVER.
-s
Send three
solicitation messages
initially to quickly discover the routers when the system
is booted. When
-s is specified
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 preference in advertisement messages. Available only with -r option.
-T
max_interval
Set maximum advertisement interval in seconds. Default is 600. Available only with -r option.
-t
Test mode. Do not go to background.
-v
Be verbose and send lots of debugging messages to syslog.
-V
Print version and exit.
This program was developed by Sun Microsystems (see
copyright notice in source file). It was ported to Linux by
Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>.