If you configure VRRP and IP routing protocols on the same IP physical interface, you cannot select the interface address as the VRRP virtual IP address (logical IP address). You must use a separate dedicated IP address for VRRP.
After you create a VRRP interface, you can add Secondary IP Interfaces, which are the equivalent of IPv6 VRRP global addresses. Secondary virtual IP addresses must be in the same subnet as a Secondary IP Interface on the VLAN.
You can replace a primary virtual IP only if no secondary virtual IPs exist on the VRRP interface.
Do not configure the virtual address as a physical interface that is used on the routing switches. Instead, use a third address, for example:
Interface IP address of VLAN A on Switch 1 = x.x.x.2
Interface IP address of VLAN A on Switch 2 = x.x.x.3
Virtual IP address of VLAN A = x.x.x.1
Note
The VRRP virtual IP address can be the same as the local IP address or Primary IP address of the interface on which VRRP is enabled. In this case, the router is the VRRP address owner on that interface and the priority is configured to the maximum value of 255.Configure the VRRP holddown timer with enough time that the Interior Gateway Protocol (IGP) routing protocol has time to update the routing table. In some cases, configuring the VRRP holddown timer to a minimum of 1.5 times the IGP convergence time is sufficient. For OSPF, as a best practice, use a value of 90 seconds if you use the default OSPF timers.
Implement VRRP BackupMaster for an active-active configuration (BackupMaster works across multiple switches that participate in the same VRRP domain).
Configure VRRP priority as 200 to configure VRRP Master.
Stagger VRRP Masters between switches in the core to balance the load between switches.
If you implement VRRP Fast, you create additional control traffic on the network and also create a greater load on the CPU. To reduce the convergence time of VRRP, the VRRP Fast feature allows the modification of VRRP timers to achieve subsecond failover of VRRP. Without VRRP Fast, normal convergence time is approximately 3 seconds.
When you use the fast advertisement interval option to configure a master and backup device, you must enable the fast advertisement interval option on both systems for VRRP to work correctly. If you configure one device with the regular advertisement interval, and the other device with the fast advertisement interval, it causes an unstable state and drops advertisements.
Do not use VRRP BackupMaster and critical IP at the same time. Use one or the other.