RAdv: Documentation for more specific routes

networks. These packets contain basic information about a local network (e.g. a

list of network prefixes), which allows network hosts to autoconfigure network

addresses and choose a default route. BIRD implements router behavior as defined

in <rfc id="4861"> and also the DNS extensions from <rfc id="6106">.

in <rfc id="4861">, router preferences and specific routes (<rfc id="4191">),

and DNS extensions (<rfc id="6106">).

<sect1>Configuration

<label id="radv-config">

	definitions may also be interface-specific when used inside interface

	options. By default, interface uses both global and interface-specific

	options, but that can be changed by <cf/rdnss local/ option.

dsc-iface

	<tag><label id="radv-dnssl">dnssl { <m/options/ }</tag>

	DNSSL definitions allow to specify a list of advertised DNS search

	domains together with their options. Like <cf/rdnss/ above, multiple

	default router. <cf/preferred lifetime/ and <cf/valid lifetime/ could

	also be configured as <cf/sensitive/ for a prefix, which would cause

	autoconfigured IPs to be deprecated or even removed.

	<tag><label id="radv-propagate-routes">propagate routes <m/switch/</tag>

	This option controls propagation of more specific routes, as defined in

	<rfc id="4191">. If enabled, all routes exported to the RAdv protocol,

	with the exception of the trigger prefix, are added to advertisments as

	additional options. The lifetime and preference of advertised routes can

	be set individually by <cf/ra_lifetime/ and <cf/ra_preference/ route

	attributes, or per interface by <cf/route lifetime/ and

	<cf/route preference/ options. Default: disabled.

	Note that the RFC discourages from sending more than 17 routes and

	recommends the routes to be configured manually.

</descrip>

<p>Interface specific options:

	hosts. Valid values are 0-255, 0 means unspecified. Default: 64

	<tag><label id="radv-iface-default-lifetime">default lifetime <m/expr/ [sensitive <m/switch/]</tag>

	This option specifies the time (in seconds) how long (after the receipt

	This option specifies the time (in seconds) how long (since the receipt

	of RA) hosts may use the router as a default router. 0 means do not use

	as a default router. For <cf/sensitive/ option, see <ref id="radv-trigger" name="trigger">.

	Default: 3 * <cf/max ra	interval/, <cf/sensitive/ yes.

	<tag><label id="radv-iface-linger-time">linger time <m/expr/</tag>

	When a prefix disappears, it is advertised for some time with 0

	lifetime, to inform clients the prefix is no longer usable. This option

	sets the time for how long it is advertised (in seconds). Maximum is

	3600, 0 means disabled. Default: 300.

	<tag><label id="radv-iface-default-preference-low">default preference low|medium|high</tag>

	<tag><label id="radv-iface-default-preference">default preference low|medium|high</tag>

	This option specifies the Default Router Preference value to advertise

	to hosts. Default: medium.

	<tag><label id="radv-iface-route-lifetime">route lifetime <m/expr/ [sensitive <m/switch/]</tag>

	This option specifies the default value of advertised lifetime for

	specific routes; i.e., the time (in seconds) for how long (since the

	receipt of RA) hosts should consider these routes valid. A special value

	0xffffffff represents infinity. The lifetime can be overriden on a per

	route basis by the <ref id="rta-ra-lifetime" name="ra_lifetime"> route

	attribute. Default: 3 * <cf/max ra interval/, <cf/sensitive/ no.

	For the <cf/sensitive/ option, see <ref id="radv-trigger" name="trigger">.

	If <cf/sensitive/ is enabled, even the routes with the <cf/ra_lifetime/

	attribute become sensitive to the trigger.

	<tag><label id="radv-iface-route-preference">route preference low|medium|high</tag>

	This option specifies the default value of advertised route preference

	for specific routes. The value can be overriden on a per route basis by

	the <ref id="rta-ra-preference" name="ra_preference"> route attribute.

	Default: medium.

	<tag><label id="radv-prefix-linger-time">prefix linger time <m/expr/</tag>

	When a prefix or a route disappears, it is advertised for some time with

	zero lifetime, to inform clients it is no longer valid. This option

	specifies the time (in seconds) for how long prefixes are advertised

	that way. Default: 3 * <cf/max ra interval/.

	<tag><label id="radv-route-linger-time">route linger time <m/expr/</tag>

	When a prefix or a route disappears, it is advertised for some time with

	zero lifetime, to inform clients it is no longer valid. This option

	specifies the time (in seconds) for how long routes are advertised

	that way. Default: 3 * <cf/max ra interval/.

	<tag><label id="radv-iface-rdnss-local">rdnss local <m/switch/</tag>

	Use only local (interface-specific) RDNSS definitions for this

	interface. Otherwise, both global and local definitions are used. Could

	<cf/sensitive/ no.

</descrip>

<p>RDNSS specific options:

<descrip>

	RDNSS <cf/lifetime/ option above. Default: 3 * <cf/max ra interval/.

</descrip>

<sect1>Attributes

<label id="radv-attr">

<p>RAdv defines two route attributes:

<descrip>

	<tag><label id="rta-ra-preference">enum ra_preference/</tag>

	The preference of the route. The value can be <it/RA_PREF_LOW/,

	<it/RA_PREF_MEDIUM/ or <it/RA_PREF_HIGH/. If the attribute is not set,

	the <ref id="radv-iface-route-preference" name="route preference">

	option is used.

	<tag><label id="rta-ra-lifetime">int ra_lifetime/</tag>

	The advertised lifetime of the route, in seconds. The special value of

	0xffffffff represents infinity. If the attribute is not set, the

	<ref id="radv-iface-route-lifetime" name="route lifetime">

	option is used.

</descrip>

<sect1>Example

<label id="radv-exam">

<p><code>

table radv_routes;			# Manually configured routes go here

protocol static {

	table radv_routes;

	route 2001:0DB8:4000::/48 unreachable;

	route 2001:0DB8:4010::/48 unreachable;

	route 2001:0DB8:4020::/48 unreachable {

		ra_preference = RA_PREF_HIGH;

		ra_lifetime = 3600;

	};

}

protocol radv {

	propagate routes yes;		# Propagate the routes from the radv_routes table

	table radv_routes;

	export all;

	interface "eth2" {

		max ra interval 5;	# Fast failover with more routers

		managed yes;		# Using DHCPv6 on eth2