The switch also supports VRRPv2 for IPv4. If you configure VRRP IPv6 on an interface, it runs independently of the IPv4 version. Configure the version of the VRRP IPv4 on the interface before you configure any other IPv4 VRRP attributes. By default, the version is not configured to a particular value. However, when sourcing older configuration files that do not have the version saved, the router configures the version to VRRPv2 by default. If you change the version, all IPv4 configuration under that interface is automatically removed, and you are prompted for a confirmation before this operation.
Perform the CLI configuration through ip vrrp or ipv6 vrrp nodes; CLI commands for IPv4 are common for version 2 and version 3.
The following list identifies the features that make both IPv4 and IPv6 VRRPv3 features compliant to RFC 5798:
Advertisement vs Fast-advertisement — Prior to RFC 5798, the minimum advertisement interval was 1 second, with Fast-advertisement a sub-second interval could be configured. When this feature is enabled, the VRRP ADVERTISEMENT packets are sent with type 7 instead of 1. With RFC 5798 the sub-second interval is standardised, and the switch sends all packets for VRRPv3 with type 1. The use of Fast-advertisement remains the same. VRRPv2 packets send with type 7, if Fast-advertisement is enabled.
Add Master-advertisement-interval — Prior to RFC 5798 compliance, all virtual routers on the same VLAN had the same Advertisement-Interval configured. RFC 5798 states that you can use different Advertisement Intervals on the Master and Backup. On the Master, the Master-advertisement-interval and the Advertisement-Interval have the same value. On the Backup, the Master-advertisement-interval is used to calculate the timers, and the locally configured Advertisement-Interval is ignored until the Backup transitions to Master. The Master-advertisement-interval value is put in the advertisement packet type sent by the Master
Transition to master as specified in RFC 5798 — Prior to RFC 5798, if a Backup receives an advertisement with a lower priority (or same priority but lower IP), it immediately sends its own advertisement and transitions to Master. However, RFC 5798 states that such packets must be discarded, which means it will transition to Master after the Master_Down_Timer expires
Add skew-time — RFC 5798 states that skew-time is calculated depending on the priority, and Master-advertisement-interval assures that the Backup with highest priority sends the first advertisement when the Master goes down
Skew time is calculated using the formula: (((256 - priority) * Master_Adver_Interval) / 256).
Add preempt-mode — Preempt-mode is different from the ipv6 vrrp <vrid> action preempt command, which is an operational command issued when you want to stop the hold-down timer. RFC 5798 states that preempt-mode should be set to false when you do not want a higher priority Backup to transition to Master. By default, it is set to true
Note
Accept-mode is not fully implemented for IPv4 VRRPv3. You can only ping the virtual IP address, the same way as it is for IPv4 VRRPv2.