VRRPv2 and VRRPv3 Advertisement Packets
VRRP Advertisement packets are sent by the master to notify all backups in the VRRP group of the master's priority and status.
VRRP Advertisement packets are encapsulated into IP packets with the VRRP virtual IP address as the destination address. In the IP packet header, the source address is the primary IP address of the interface that sends the packets (not the virtual IP address), the destination address is 224.0.0.18, the TTL is 255, and the protocol number is 112.
The primary IP address is selected from one of the actual IP addresses of the interfaces. Usually, it is the first configured IP address.
VRRP has two versions: VRRPv2 and VRRPv3. VRRPv2 applies only to the IPv4 network, and VRRPv3 applies to both IPv4 and IPv6 networks.
VRRP is classified into VRRP for IPv4 (VRRP) and VRRP for IPv6 (VRRP6) by network type.
VRRPv2 and VRRPv3 Advertisement Packet Formats
Figure 1 shows the VRRPv2 Advertisement packet format, and Figure 2 shows the VRRPv3 Advertisement packet format.
| Field | Description | |
|---|---|---|
| VRRPv2 | VRRPv3 | |
| Version | VRRP protocol version. The value is 2. | VRRP protocol version. The value is 3. |
| Type | VRRP Advertisement packet type. The value 1 indicates an Advertisement packet. | |
| Virtual Rtr ID | Virtual router ID. The value ranges from 1 to 255. | |
| Priority | Priority of the master in a VRRP group. The value ranges from 0 to 255. The value 0 indicates that the device stops participating in the VRRP group so that the backup with the highest priority immediately becomes the master. The value 255 is reserved for the IP address owner. The default value is 100. | |
| Count IP Addrs/Count IPvX Addr | Number of virtual IPv4 addresses in the VRRP group. | Number of virtual IPv4 or IPv6 addresses in the VRRP group. |
| Auth Type | Authentication mode. There are three authentication modes:
|
- |
| Adver Int/Max Adver Int | Interval at which VRRP Advertisement packets are sent, in seconds. The default value is 1. | Interval at which VRRP Advertisement packets are sent, in centiseconds. The default value is 100 (1 second). |
| Checksum | 16-bit checksum, which is used to verify data integrity in VRRP Advertisement packets. | |
| IP Address/IPvX Address(es) | Virtual IPv4 address in the VRRP group. The Count IP Addrs field determines the number of virtual IPv4 addresses in the VRRP group. | Virtual IPv4 or IPv6 address in the VRRP group. The Count IPvX Addrs field determines the number of virtual IPv4 or IPv6 addresses in the VRRP group. |
| Authentication Data | Authentication key. This field is used only in simple authentication and MD5 authentication modes. In non-authentication mode, this field is set to 0. | - |
| rsvd | - | Reserved. This field has a fixed value of 0. |