VRRP Authentication

If your interfaces do not use authentication, neither does VRRP. For example, if you configure your device interfaces to use an MD5 password to authenticate traffic, VRRP uses the same MD5 password, and VRRP packets that do not contain the password are dropped.

In summary, if the interfaces on which you configure the virtual router use authentication, the VRRP or VRRP Extended (VRRP-E) packets on those interfaces must use the same authentication. The following VRRP and VRRP-E authentication types are supported:

• No authentication: The interfaces do not use authentication. This authentication type is the default for VRRP and VRRP-E.
• Simple: The interfaces use a simple text string as a password in packets that they send. If the interfaces use simple password authentication, the virtual router configured on the interfaces must use the same authentication type and the same password.
• MD5: This method of authentication ensures that the packet is authentic and cannot be modified in transit. Syslog and SNMP traps are generated when a packet is dropped due to MD5 authentication failure. MD5 authentication is supported only in VRRP-E, and the device configuration is unique on a per-interface basis. The MD5 authentication configuration on an interface takes effect for all VRRP-E virtual routers configured on a particular interface.