HP 4800G Series Configuration Manual page 1451

The IP address of the virtual router can be either an unused IP address on the segment where the
VRRP group resides or the IP address of an interface on a router in the VRRP group. In the latter
case, the router is called the IP address owner.
In a VRRP group, you can configure only one IP address owner.
VRRP priority
VRRP determines the role (master or backup) of each router in the VRRP group by priority. A router with
a higher priority has more opportunity to become the master.
VRRP priority is in the range of 0 to 255. A bigger number means a higher priority. Priorities 1 to 254 are
configurable. Priority 0 is reserved for special uses and priority 255 for the IP address owner. When a
router acts as the IP address owner, its running priority is always 255. That is, the IP address owner in a
VRRP group acts as the master as long as it works properly.
If two routers are both in the master state and have the same priority, the router with a higher IP address
becomes the master.
Working mode
A router in a VRRP group works in one of the following two modes:
Non-preemptive mode
When a router in the VRRP group becomes the master, it stays as the master as long as it operates
normally, even if a backup is assigned a higher priority later.
Preemptive mode
When a backup finds its priority higher than that of the master, the backup sends VRRP advertisements
to start a new master election in the VRRP group and becomes the master. Accordingly, the original
master becomes a backup..
Authentication mode
VRRP provides two authentication modes:
simple: Simple text authentication
You can adopt the simple text authentication mode in a network facing possible security problems. A
router sending a packet fills an authentication key into the packet, and the router receiving the packet
compares its local authentication key with that of the received packet. If the two authentication keys are
the same, the received VRRP packet is considered real and valid; otherwise, the received packet is
considered invalid.
md5: MD5 authentication
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