H3C Technologies H3C SecBlade LB Cards - Manual (Page 15)

7
Packet format
The master periodically multicasts VRRP packets to declare its presence. 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 shows the
VRRPv2 packet format and Figure 4 shows the VRRPv3 packet format.
Figure 3 VRRPv2 packet format
Figure 4 VRRPv3 packet format
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. It must be VRRP advertisement, represented by 1.
• Virtual Rtr ID (VRID)—ID of the virtual router. 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.
• Count IP Addrs/Count IPv6 Addrs—Number of virtual IPv4 or IPv6 addresses for the VRRP group.
A VRRP group can have multiple virtual IPv4 or IPv6 addresses.
...
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 31 3