FUJITSU PSWITCH User’s Guide
138 December/2018
joined router takes over the role of the VRRP master. Preemption delay controls the
amount of time that high priority backup routers wait to determine whether to
preempt lower priority masters.
The backup router may not be able to receive advertisements from the master,
such as during network congestion. This can cause flaps that frequently change the
state of members in the VRRP group. This problem can be avoided by setting the
VRRP preemption delay timer to an appropriate value.
3.1.9.17.4. VRRP Accept Mode
In accept mode, the switch can respond to a ping (ICMP echo request) sent to the
VRRP virtual IP address. With the VRRP specification (RFC 3768), the router can
accept IP packets sent to the virtual router IP address only if the router is the
address owner. In practice, this restriction makes it more difficult to troubleshoot
network connectivity problems. If the host cannot communicate, it is common to
ping the host's default gateway to determine if the problem is on the first hop to
the destination. However, this troubleshooting method cannot be used in the case
of the default gateway is a virtual router that does not respond to pings.
You can enable the system to respond to the ping sent to the virtual IP address by
enabling the accept mode of the VRRP function. This feature allows for response to
pings for virtual routers, but does not allow VRRP masters to accept other types of
packets. The VRRP master responds to both fragmented ICMP echo request packets
and unfragmented ICMP echo request packets.
The VRRP master responds to echo requests sent to the primary or secondary
address of the virtual router.
A member of the virtual router in the backup state discards the ping packet
addressed to the VRRP address, just as discarding the Ethernet frame sent to the
VRRP MAC address.
When the VRRP master responds with an echo reply, the source IPv4 address is the
VRRP address and the source MAC address is the MAC address of the virtual router.
3.1.9.17.5. VRRP Route and Interface Tracking
The VRRP route/interface tracking feature extends the VRRP feature so that it can
track specific routes and interface IP state in routers that can change the priority of
a virtual router in a VRRP group.
VRRP interface tracking monitors the specific interface IP state within the router.
Depending on the state of the tracked interface, you can change the VRRP priority
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