Configuring IPv6 RAs

When IPv6 unicast routing is enabled on the routing switch, RAs are transmitted on all IPv6-enabled VLANs unless explicitly suppressed globally or per-VLAN.

The following steps provide a general outline of the steps for configuring the routing switch for nondefault RA operation on all IPv6-enabled VLANs:

Procedure
  1. Enable IPv6 routing on your network.
  2. Enable IPv6 unicast routing. (This must be enabled to allow configuration of other routing protocols).

    Switch(config)# ipv6 unicast–routing

    (This command enables RA transmission on any VLAN where RAs are not specifically suppressed.)

  3. Configure the desired per-VLAN RA operation:
    1. Use the M-bit and O-bit settings to specify the source for IPv6 host configuration; see page VLAN context Neighbor Discovery (ND) configuration:
      1. M-bit setting:

        • Get configuration from RAs (default).

        • Get configuration from DHCPv6.

      2. O-bit setting (applies only if M-bit setting is left in default state):

        • Use RA source for global unicast prefixes (default).

        • Do not use the RA for nonprefix configuration.

    2. Configure global unicast prefix assignments; see Configuring the global unicast prefix and lifetime for hosts on a VLAN:

      1. Specify any prefixes not configured on the routing switch VLAN interface that should be transmitted in RAs to IPv6 hosts on the VLAN.

      2. Deny any prefixes configured on the routing switch VLAN interface that should not be transmitted in RAs to IPv6 hosts on the VLAN. (Default: Global unicast prefixes configured on the routing switch VLAN interface are included in RAs.)

    3. Configure the maximum and minimum interval for transmitting RAs on the VLAN; see page Configuring the range for intervals between RA transmissions on a VLAN.
      NOTE:

      The routing switch also transmits RAs when it receives router solicitations from a host. Autoconfiguration must be enabled on the host before it will generate router solicitations on the VLAN.

    4. Configure the ND policy for hosts on the VLAN to use:

      1. hop-limit (default: 64; see page Setting or changing the hop-limit for host-generated packets)

      2. Default router lifetime (default: 1800 seconds; see page Setting or changing the default router lifetime)

      3. Reachable time duration to advertise for confirmed neighbors (default: unspecified (0); see page Changing the reachable time duration for neighbors)

      4. Retransmit time to advertise for neighbor solicitations (default: unspecified (0); see page Setting or changing the neighbor discovery retransmit timer)

    5. Configure per-VLAN RA suppression for any VLAN on which you do not want the routing switch to transmit RAs. (See Viewing the RA configuration.) Switch(vlan–1)# ipv6 nd ra suppress