H3C Technologies H3C SecPath F1000-E - Manual (Page 831)

2
VRRP is an error-tolerant protocol, which improves the network reliability and simplifies configurations on
hosts. Deploying VRRP on multicast and broadcast LANs such as Ethernet, you can ensure that the system
can still provide highly reliable default links without changing configurations (such as dynamic routing
protocols, route discovery protocols) when a router fails, and prevent network interruption due to failure
of a single link.
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
Host A
Host B
Host C
Router A
Router B
Router C
Virtual router
Network
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.
NOTE:
•
A virtual IP address 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.
• Status of a router in a VRRP group includes master, backup, and initialize.