H3C Technologies H3C S3600 Series Switches - Manual (Page 579)

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z Virtual router IP address-to-real MAC address mapping. When there is an IP address owner in the
VRRP group, a virtual router IP address may correspond to two MAC addresses, a real MAC
address of the IP address owner and a virtual MAC address created by default. In this case, you
can map virtual router IP addresses to the real MAC address. Then hosts send packets to the IP
address owner for layer 3 forwarding according to the real MAC address.
z You need to configure the mapping between the IP addresses of the VRRP group and the MAC
address before enabling VRRP feature on an S3600 Ethernet switch. If VRRP is already enabled,
the system does not support this configuration.
z The number of virtual router IP addresses that can be mapped with the virtual router MAC address
is determined by the chips of the switches in the VRRP group.
z A switch can belong to multiple VRRP groups. However, the number of VRRP groups supported by
a switch is determined by the chip it uses. Refer to device specification for details.
VRRP Timer
There are two types of VRRP timer, the VRRP advertisement interval timer and the VRRP preemption
delay timer.
VRRP advertisement interval timer
z The master advertises its normal operation state to the switches within the VRRP group by sending
VRRP packets once in each specified interval (determined by the adver-interval argument).
z You can adjust the interval for a master to send VRRP advertisements by setting the VRRP
advertisement interval timer. If a backup does not receive the VRRP advertisements from the
master after a period three times of the specified interval, it considers itself as the master and
sends out VRRP advertisements to reelect the master.
VRRP preemption delay timer
z The backup may not receive a VRRP advertisement within a period three times of the specified
interval due to excessive network traffic or network instability. In this case, you can configure the
VRRP preemption delay for backups.
z If you configure the preemption delay for a backup, the switch preempts the master if it does not
receive a VRRP advertisement from the master after it waits for a period three times of the
advertisement interval and the period specified by the preemption delay.
VRRP Tracking