Router Advertisements

RAs are described in RFC 4861#section-4.6.2. They are part of what is known as SLAAC.

Supported interface types:

bonding

bridge

ethernet

geneve

l2tpv3

openvpn

pseudo-ethernet

tunnel

vxlan

wireguard

wireless

wwan

Configuration

Field	VyOS Option	Description
Cur Hop Limit	hop-limit	Hop count field of the outgoing RA packets
“Managed address configuration” flag	managed-flag	Tell hosts to use the administered stateful protocol (i.e. DHCP) for autoconfiguration
“Other configuration” flag	other-config-flag	Tell hosts to use the administered (stateful) protocol (i.e. DHCP) for autoconfiguration of other (non-address) information
MTU	link-mtu	Link MTU value placed in RAs, exluded in RAs if unset
Router Lifetime	default-lifetime	Lifetime associated with the default router in units of seconds
Reachable Time	reachable-time	Time, in milliseconds, that a node assumes a neighbor is reachable after having received a reachability confirmation
Retransmit Timer	retrans-timer	Time in milliseconds between retransmitted Neighbor Solicitation messages
Default Router Preference	default-preference	Preference associated with the default router
Interval	interval	Min and max intervals between unsolicited multicast RAs
DNSSL	dnssl	DNS search list to advertise
Name Server	name-server	Advertise DNS server per https://tools.ietf.org/html/rfc6106

Advertising a Prefix

Note

You can also opt for using ::/64 as prefix for your RAs. This will take the IPv6 GUA prefix assigned to the interface, which comes in handy when using DHCPv6-PD.

VyOS Field	Description
decrement-lifetime	Lifetime is decremented by the number of seconds since the last RA - use in conjunction with a DHCPv6-PD prefix
deprecate-prefix	Upon shutdown, this option will deprecate the prefix by announcing it in the shutdown RA
no-autonomous-flag	Prefix can not be used for stateless address auto-configuration
no-on-link-flag	Prefix can not be used for on-link determination
preferred-lifetime	Time in seconds that the prefix will remain preferred (default 4 hours)
valid-lifetime	Time in seconds that the prefix will remain valid (default: 30 days)

Advertising a NAT64 Prefix

Enable PREF64 option as outlined in RFC 8781.

NAT64 prefix mask must be one of: /32, /40, /48, /56, /64 or 96.

Note

The well known NAT64 prefix is 64:ff9b::/96

VyOS Field	Description
valid-lifetime	Time in seconds that the prefix will remain valid (default: 65528 seconds)

Disabling Advertisements

To disable advertisements without deleting the configuration:

Example

Your LAN connected on eth0 uses prefix 2001:db8:beef:2::/64 with the router beeing 2001:db8:beef:2::1

set interfaces ethernet eth0 address 2001:db8:beef:2::1/64

set service router-advert interface eth0 default-preference 'high'
set service router-advert interface eth0 name-server '2001:db8::1'
set service router-advert interface eth0 name-server '2001:db8::2'
set service router-advert interface eth0 other-config-flag
set service router-advert interface eth0 prefix 2001:db8:beef:2::/64