R3204P16-HP Load Balancing Module High Availability Configuration Guide-6PW101

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protocols, route discovery protocols) when a router fails, and prevent network interruption due to failure
of a single link.
VRRP works in one of the following two modes:
• Standard protocol mode—Includes two versions based on RFCs: VRRPv2 and VRRPv3. VRRPv2 is
based on IPv4, and VRRPv3 is based on IPv6. The two versions implement the same functions but
are applied in different network environments. For more information, see “VRRP standard protocol
mode.”
• Load balancing mode—Extends the standard protocol mode and realizes load balancing. For
more information, see “VRRP load balancing mode.”
VRRP standard protocol mode
VRRP group overview
VRRP combines a group of routers (including a master and multiple backups) on a LAN into a virtual
router called VRRP group.
A VRRP group has the following features:
• A virtual router has an IP address, called virtual IP address. A host on the LAN only needs to know
the IP address of the virtual router and uses the IP address as the next hop of the default route.
• Every host on the LAN communicates with external networks through the virtual router.
• Routers in the VRRP group elect the gateway according to their priorities. The other routers function
as the backups. When the master acting as the gateway fails, to ensure that the hosts in the network
segment can communicate with the external networks uninterruptedly, the backups in the VRRP
group elect a new gateway to undertake the responsibility of the failed master.
Figure 2 Network diagram for VRRP
As shown in Figure 2, Router A, Router B, and Router C form a virtual router, which has its own IP address.
Hosts on the Ethernet use the virtual router as the default gateway.
The router with the highest priority of the three routers is elected as the master to act as the gateway, and
the other two are backups.