IPv6 Router Advertisements

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Router Advertisements

Router advertisements are described in https://tools.ietf.org/html/rfc4861#section-4.2 . They are part of what is known as SLAAC (Stateless Address Autoconfiguration).

Supported interface types:

  • bonding
  • bridge
  • ethernet
  • l2tpv3
  • openvpn
  • psuedo-ethernet
  • tunnel
  • vxlan
  • wireless
  • wirelessmodem

To enable or disable, use

set interfaces <interface> ipv6 router-advert send-advert <true or false>

To set the options described in "Router Advertisement Message Format", start from

set interfaces <interface> ipv6 router-advert

With sub-options:

RFC Field VyOS Config Option Description
Cur Hop Limit cur-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
Router Lifetime default-lifetime
Reachable Time reachable-time
Retrans Timer retrans-timer
MTU link-mtu
Prefix Information See below

Prefix Information

Prefix information is described in https://tools.ietf.org/html/rfc4861#section-4.6.2

To set the fields described, start from

set interfaces <interface> ipv6 router-advert prefix <h:h:h:h:h:h:h:h/x>

With sub-options:

RFC Field VyOS Config Option
Prefix Length 'x' in <h:h:h:h:h:h:h:h/x>
on-link flag on-link-flag
autonomous address-configuration flag autonomous-flag
Valid Lifetime valid-lifetime
Preferred Lifetime preferred-lifetime

Miscellaneous Options

Starting from

set interfaces <interface> ipv6 router-advert

There are the following additional options:

Receiving Router Advertisements

To receive and accept RAs on an interface, you need to enable it via sysctl with the following command (as root):

sysctl -w net.ipv6.conf.eth0.accept_ra=2

The change is not reboot-persistent, so it either needs to be redone every time or added to rc.d.