H3C Technologies H3C S7500E Series Switches - Manual (Page 135)

10-2
Figure 10-1 LAN networking
Gateway
Network
Host A
Host B
Host C
Configuring a default route for network hosts facilitates your configuration, but also requires
high performance stability of the device that acts as the gateway. Using more egress gateways
is a common way to improve system reliability, but introduces the problem of routing among the
egresses.
Virtual Router Redundancy Protocol (VRRP) is designed to address this problem. VRRP adds a
group of routers that can act as network gateways to a VRRP group, which forms a virtual router.
Routers in the VRRP group elect a master through the VRRP election mechanism to act as a
gateway, and hosts on a LAN only need to configure the virtual router as their default network
gateway.
VRRP is an error-tolerant protocol, which improves the network reliability and simplifies
configurations on hosts. On a multicast and broadcast LAN such as Ethernet, VRRP provides
highly reliable default links without configuration changes (such as dynamic routing protocols,
route discovery protocols) when a router fails, and prevent network interruption due to a single
link failure.
For the S7500E series Ethernet switches, VRRP works in standard protocol mode.
Standard protocol mode includes two versions VRRPv2 and VRRPv3 based on RFCs. 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 .
VRRP Standard Protocol Mode
Introduction to VRRP Group
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 features the following:
z A virtual router has a 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.
z Every host on the LAN communicates with external networks through the virtual router.