VRRP Address Support for IPv6

IPv6 VRRP router advertisements are always sent using the VRRP virtual link-local address as the source address.

Hosts on the LAN can use this link-local address as their default route gateway. If no VRRP link-local address is configured, a default value is derived as follows:


VRID is the VRRP instance identifier.


The host portion of this address corresponds to the virtual MAC address associated with the VRRP router.

When a backup VRRP router assumes the role of master, it must use the same link-local address in router advertisements as the previous master. Therefore, when configuring a backup VRRP router, you must either configure a virtual link local address that matches the link local address on the IP address owner or allow the virtual link local address to default to the derived value in the same manner as on the master.

Router advertisement prefixes are configured based on the VRRP IP addresses. The mask used for the prefix will be the smallest mask used by all VRRP IP addresses on a VLAN interface. The ExtremeXOS software supports multiple IPv6 addresses on an interface that can overlap. For example, you can add both 200d::1/48 and 200d::2/96 to a VLAN. IPv6 VRRP routers advertise the smallest mask that applies to all VRRP IP addresses. In this example, if VRRP IP address 200d::100 is added, the mask is 48.

The VRRP MAC address for an IPv6 VRRP router instance is an IEEE 802 MAC address in the following hexadecimal format (in Internet-standard bit-order):


The first three octets are derived from the IANA OUI. The next two octets (00-02) indicate the address block assigned to the VRRP router for IPv6 protocol, and VRID is the VRRP instance identifier. This mapping provides for up to 255 IPv6 VRRP routers on a network.

When a VRRP router assumes the role of master, it issues an unsolicited neighbor discovery (ND) neighbor advertisement message for each of the VRRP router IP addresses.

The master also always responds to ND neighbor solicitations with ND neighbor advertisements using the VRRP MAC address.