FoxGate S63 series, Руководство по настройке

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IPv6 VRRPv3 Configuration
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60. IPv6 VRRPv3 Configuration
60.1
Introduction to VRRPv3
VRRPv3 is a virtual router redundancy protocol for IPv6. It is designed based on
VRRP (VRRPv2) in IPv4 environment. The following is a brief introduction to it.
In a network based on TCP/IP protocol, in order to guarantee the communication
between the devices which are not physically connected, routers should be specified. At
present there are two most commonly used methods to specify routers: one is to study
dynamically via routing protocols (such as internal routing protocols RIP and OSPF); the
other is to configure statically. Running dynamical routing protocol on each terminal is
unrealistic, since most operating systems for client end do not support dynamical routing
protocol, even if they do, they are limited by the overheads of management, convergence,
security and many other problems. So the common method is to adopt static routing
configuration on terminal IP devices, which usually means specify one or more default
gateway for terminal devices. Static routing simplifies the management of network and
reduces the communication overheads of terminal devices, but it still has a disadvantage:
if the router acting as the default gateway breaks, the communication of all the hosts
which use this gateway as their next hop host. Even if there are more than one default
gateways, before rebooting the terminal devices, they can not switch to the new gateway.
Adopting virtual router redundancy protocol (VRPR) can effectively avoid the flaws of
statically specifying gateways.
In VRRP protocol, there are two groups of import concepts: VRRP routers and virtual
routers, master routers and backup routers. VRRP routers are routers running VRRP,
which are physical entities; virtual routers are the ones created by VRRP, which are logical
concepts. A group of VRRP routers cooperate to comprise a virtual router, which acts
outwardly as a logical router with a unique fixed IP address and MAC address. The
routers belonging to the same VRRP group play two mutually exclusive roles at the same
time: master routers and backup routers. One VRRP group can only have one master
router other but one or more backup routers. VRRPv3 protocol uses selection policy to
select a master router from the router group to take charge of responding ND(Neighbor
Discovery) neighbor request messages(ARP in IPv4) and forwarding IP data packets,
while the other routers in the group will be in a state of waiting as backups. When the
master router has a problem for some season, the backup router will be updated to the
master router after a delay of a few seconds. Since this switch is very fast and does not
need to change IP address or MAC address, it will be transparent to terminal user