Router advertisements

An IPv6 router periodically transmits RAs on the VLANs to which it belongs to notify other devices of its presence. The switch uses these advertisements for purposes such as:
  • Learning the MAC and link-local addresses of IPv6 routers on the VLAN. (For devices other than routers, the switch must use ND to learn these addresses.)

  • Building a list of default (reachable) routers, along with router lifetime and prefix lifetime data

  • Learning the prefixes and the valid and preferred lifetimes to use for stateless (autoconfigured) global unicast addresses. (It is required for autoconfiguration of global unicast IPv6 addresses.)

  • Learning the hop limit for traffic leaving the VLAN interface

  • Learning the MTU (Maximum Transmission Unit) to apply to frames intended to be routed