H3C Technologies H3C S10500 Series Switches - Manual (Page 136)

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then sends VRRP advertisements to start a new master election in the VRRP group and becomes the
master.
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 33 shows the
format of a VRRPv2 packet and Figure 34 shows the format of a VRRPv3 packet.
Figure 33 Format of a VRRPv2 packet
...
Figure 34 Format of a VRRPv3 packet
...
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
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.