H3C Technologies H3C S7500E Series Switches - Manual (Page 138)

10-5
VRRP preemption delay timer
To avoid frequent state changes among members in a VRRP group and provide the backups
enough time to collect information (such as routing information), each backup waits for a period
of time (the preemption delay time) after it receives an advertisement with the priority lower
than the local priority, 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 10-3
shows the format of a VRRPv2 packet and Figure 10-4 shows the format of a VRRPv3 packet.
Figure 10-3 Format of a VRRPv2 packet
...
Figure 10-4 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: