R3721-F3210-F3171-HP High-End Firewalls High Availability Configuration Guide-6PW101

7
Packet format
The master multicasts VRRP packets periodically to declare its existence. VRRP packets are also used for
checking the parameters of the virtual router and electing the master.
VRRP packets are encapsulated in IP packets, with the protocol number being 112. Figure 3 sh
ows the
format of a VRRPv2 packet and Figure 4
shows the format of a VRRPv3 packet.
Figure 3 Format of a VRRPv2 packet
Figure 4 Format of a VRRPv3 packet
A VRRP packet comprises the following fields:
• Version—Version number of the protocol, 2 for VRRPv2 and 3 for VRRPv3.
• Type—Type of the VRRPv2 or VRRPv3 packet. Only one VRRP packet type is present, that is, VRRP
advertisement, which is represented by 1.
• Virtual Rtr ID (VRID)—ID of the virtual router, that is, ID of the VRRP group. It ranges from 1 to 255.
• Priority—Priority of the router in the VRRP group, in the range 0 to 255. A greater value represents
a higher priority.
...
Version Type Virtual Rtr ID Priority Count IPv6 Addrs
Auth Type Adver Int Checksum
IPv6 address 1
Authentication data 1
Authentication data 2
IPv6 address n
0 7 15 23 313