RADVD.CONF(5)

NAME
radvd.conf - configuration file of the router advertisement daemon radvd

DESCRIPTION
This file describes the information which is included in the router advertisement (RA) of a specific interface.

The file contains one or more interface definitions of the form:

interface name {
	list of interface specific options
	list of prefix definitions
};

All the possible interface specific options are detailed below. Each option has to be terminated by a semicolon.

Prefix definitions are of the form:

prefix prefix/length {
	list of prefix specific options
};

Prefix can be network prefix or the address of the inferface. The address of interface should be used when using Mobile IPv6 extensions.

All the possible prefix specific options are described below. Each option has to be terminated by a semicolon.

Decimal values are allowed only for MaxRtrAdvInterval and MinRtrAdvInterval. Decimal values should be used only when using Mobile IPv6 extensions.

INTERFACE SPECIFIC OPTIONS

AdvSendAdvert on|off

    A flag indicating whether or not the router sends periodic router advertisements and responds to router solicitations.

    This option no longer has to be specified first, but it needs to be on to enable advertisement on this interface.

    Default: off

UnicastOnly on|off

    Indicates that the interface link type only supports unicast. This will prevent unsolicited advertisements from being sent, and will cause solicited advertisements to be unicast to the soliciting node. This option is necessary for non-broadcast, multiple-access links, such as ISATAP.

    Default: off

MaxRtrAdvInterval seconds

    The maximum time allowed between sending unsolicited multicast router advertisements from the interface, in seconds.

    Must be no less than 4 seconds and no greater than 1800 seconds.

    Minimum when using Mobile IPv6 extensions: 1.5.

    Default: 600 seconds

MinRtrAdvInterval seconds

    The minimum time allowed between sending unsolicited multicast router advertisements from the interface, in seconds.

    Must be no less than 3 seconds and no greater than 0.75 * MaxRtrAdvInterval.

    Minimum when using Mobile IPv6 extensions: 0.05.

    Default: 0.33 * MaxRtrAdvInterval

AdvManagedFlag on|off

    When set, hosts use the administered (stateful) protocol for address autoconfiguration in addition to any addresses autoconfigured using stateless address autoconfiguration. The use of this flag is described in RFC 2462.

    Default: off

AdvOtherConfigFlag on|off

    When set, hosts use the administered (stateful) protocol for autoconfiguration of other (non-address) information. The use of this flag is described in RFC 2462.

    Default: off

AdvLinkMTU integer

    The MTU option is used in router advertisement messages to insure that all nodes on a link use the same MTU value in those cases where the link MTU is not well known.

    If specified, i.e. not 0, must not be smaller than 1280 and not greater than the maximum MTU allowed for this link (e.g. ethernet has a maximum MTU of 1500. See RFC 2464).

    Default: 0

AdvReachableTime milliseconds

    The time, in milliseconds, that a node assumes a neighbor is reachable after having received a reachability confirmation. Used by the Neighbor Unreachability Detection algorithm (see Section 7.3 of RFC 2461). A value of zero means unspecified (by this router).

    Must be no greater than 3,600,000 milliseconds (1 hour).

    Default: 0

AdvRetransTimer milliseconds

    The time, in milliseconds, between retransmitted Neighbor Solicitation messages. Used by address resolution and the Neighbor Unreachability Detection algorithm (see Sections 7.2 and 7.3 of RFC 2461). A value of zero means unspecified (by this router).

    Default: 0

AdvCurHopLimit integer

    The default value that should be placed in the Hop Count field of the IP header for outgoing (unicast) IP packets. The value should be set to the current diameter of the Internet. The value zero means unspecified (by this router).

    Default: 64

AdvDefaultLifetime seconds

    The lifetime associated with the default router in units of seconds. The maximum value corresponds to 18.2 hours. A lifetime of 0 indicates that the router is not a default router and should not appear on the default router list. The router lifetime applies only to the router's usefulness as a default router; it does not apply to information contained in other message fields or options. Options that need time limits for their information include their own lifetime fields.

    Must be either zero or between MaxRtrAdvInterval and 9000 seconds.

    Default: 3 * MaxRtrAdvInterval

AdvSourceLLAddress on|off

    When set, the link-layer address of the outgoing interface is included in the RA.

    Default: on

AdvHomeAgentFlag on|off

    When set, indicates that sending router is able to serve as Mobile IPv6 Home Agent. When set, minimum limits specified by Mobile IPv6 are used for MinRtrAdvInterval and MaxRtrAdvInterval.

    Default: off

AdvHomeAgentInfo on|off

    When set, Home Agent Information Option (specified by Mobile IPv6) is included in Router Advertisements. AdvHomeAgentFlag must also be set when using this option.

    Default: off

HomeAgentLifetime seconds

    The length of time in seconds (relative to the time the packet is sent) that the router is offering Mobile IPv6 Home Agent services. A value 0 must not be used. The maximum lifetime is 65520 seconds (18.2 hours). This option is ignored, if AdvHomeAgentInfo is not set.

    If both HomeAgentLifetime and HomeAgentPreference are set to their default values, Home Agent Information Option will not be sent.

    Default: AdvDefaultLifetime

HomeAgentPreference integer

    The preference for the Home Agent sending this Router Advertisement. Values greater than 0 indicate more preferable Home Agent, values less than 0 indicate less preferable Home Agent. This option is ignored, if AdvHomeAgentInfo is not set.

    If both HomeAgentLifetime and HomeAgentPreference are set to their default values, Home Agent Information Option will not be sent.

    Default: 0

AdvIntervalOpt on|off

    When set, Advertisement Interval Option (specified by Mobile IPv6) is included in Router Advertisements. When set, minimum limits specified by Mobile IPv6 are used for MinRtrAdvInterval and MaxRtrAdvInterval.

    Default: off

PREFIX SPECIFIC OPTIONS

AdvOnLink on|off

    When set, indicates that this prefix can be used for on-link determination. When not set the advertisement makes no statement about on-link or off-link properties of the prefix. For instance, the prefix might be used for address configuration with some of the addresses belonging to the prefix being on-link and others being off-link.

    Default: on

AdvAutonomous on|off

    When set, indicates that this prefix can be used for autonomous address configuration as specified in RFC 2462.

    Default: on

AdvRouterAddr on|off

    When set, indicates that the address of interface is sent instead of network prefix, as is required by Mobile IPv6. When set, minimum limits specified by Mobile IPv6 are used for MinRtrAdvInterval and MaxRtrAdvInterval.

    Default: off

AdvValidLifetime seconds|infinity

    The length of time in seconds (relative to the time the packet is sent) that the prefix is valid for the purpose of on-link determination. The symbolic value infinity represents infinity (i.e. a value of all one bits (0xffffffff)). The valid lifetime is also used by RFC 2462.

    Default: infinity

AdvPreferredLifetime seconds|infinity

    The length of time in seconds (relative to the time the packet is sent) that addresses generated from the prefix via stateless address autoconfiguration remain preferred. The symbolic value infinity represents infinity (i.e. a value of all one bits (0xffffffff)). See RFC 2462.

    Default: 604800 seconds (7 days)

Base6to4Interface name

    If this option is specified, this prefix will be combined with the IPv4 address of interface name to produce a valid 6to4 prefix. The first 16 bits of this prefix will be replaced by 2002 and the next 32 bits of this prefix will be replaced by the IPv4 address assigned to interface name at configuration time. The remaining 80 bits of the prefix (including the SLA ID) will be advertised as specified in the configuration file. See the next section for an example.

    If interface name is not available at configuration time, a warning will be written to the log and this prefix will be disabled until radvd is reconfigured.

    This option enables systems with dynamic IPv4 addresses to update their advertised 6to4 prefixes simply by restarting radvd or sending a SIGHUP signal to cause radvd to reconfigure itself.

    Note that 6to4 prefixes derived from dynamically-assigned IPv4 addresses should be advertised with a significantly shorter lifetime (see the AdvValidLifetime and AdvPreferredLifetime options).

    For more information on 6to4, see RFC 3056.

    Default: 6to4 is not used

EXAMPLES

interface eth0
{
        AdvSendAdvert on;
        prefix fec0:0:0:1::/64
        {
                AdvOnLink on;
                AdvAutonomous on;
        };
};

It says that router advertisement daemon should advertise (AdvSendAdvert on;) the prefix fec0:0:0:1:: which has a lenght of 64 on the interface eth0. Also the prefix should be marked as autonomous (AdvAutonomous on;) and as on-link (AdvOnLink on;). All the other options are left on their default values.

To support movement detection of Mobile IPv6 Mobile Nodes, the address of interface should be used instead of network prefix:

interface eth0
{
        AdvSendAdvert on;
        prefix fec0:0:0:1::4/64
        {
                AdvOnLink on;
                AdvAutonomous on;
                AdvRouterAddr on;
        };
};

For 6to4 support, include the Base6to4Interface option in each prefix section. When using a dynamic IPv4 address, set small prefix lifetimes to prevent hosts from retaining unreachable prefixes after a new IPv4 address has been assigned.

interface eth0
{
        AdvSendAdvert on;

        # Advertise at least every 30 seconds
        MaxRtrAdvInterval 30;

        prefix 0:0:0:5678::/64
        {
                AdvOnLink on;
                AdvAutonomous on;
                Base6to4Interface ppp0;

                # Very short lifetimes for dynamic addresses
                AdvValidLifetime 300;
                AdvPreferredLifetime 120;
        };
};

Since 6to4 is enabled, the prefix will be advertised as 2002:WWXX:YYZZ:5678::/64, where WW.XX.YY.ZZ is the IPv4 address of ppp0 at configuration time. (IPv6 addresses are written in hexadecimal whereas IPv4 addresses are written in decimal, so the IPv4 address WW.XX.YY.ZZ in the 6to4 prefix will be represented in hex.)

FILES

/usr/sbin/radvd
/etc/radvd.conf
/var/run/radvd.pid
/var/log/radvd.log

CREDIT
The description of the different flags and variables is in large parts taken from RFC 2461.

RFCS
Narten, T., E. Nordmark, W. Simpson, "Neighbor Discovery for IP Version 6 (IPv6)", RFC 2461, December 1998

Thomson, S., and T. Narten, "IPv6 Stateless Address Autoconfiguration", RFC 2462, December 1998.

Deering, S., and R. Hinden, Editors, "IP Version 6 Addressing Architecture", RFC 2373, July 1998.

Conta, A., and S. Deering, "Internet Control Message Protocol (ICMPv6) for the Internet Protocol Version 6 (IPv6)", RFC 2463, December 1998.

Crawford, M., "Transmission of IPv6 Packets over Ethernet Networks", RFC 2464, December 1998.

Carpenter B., Moore K., "Connection of IPv6 Domains via IPv4 Clouds", RFC 3056, February 2001. (6to4 specification)

SEE ALSO

radvd(8), radvdump(8)