RA basics

  • Enabling IPv6 unicast routing on a routing switch initiates transmission of RAs on active, IPv6-enabled VLANs unless RA transmission has been suppressed.

  • RAs are not routed.

  • A host response to an RA depends on how the host implements IPv6. Generally, settings in an RA received by a host replaces settings received from an earlier RA. Settings configured directly on a host by an operator may override values received in an RA for the same settings.

  • When a host receives a default "unspecified" value in an RA, the host applies either its own current setting for that value, or the defaults specified in RFC 4861 or other applicable RFCs, depending on how IPv6 is implemented in the host.

  • The M-bit and O-bit flags enable RAs to be configured either to act as the sole source of host addressing and related settings, or to direct the host to use a DHCPv6 server for some or all such settings.