User's Manual

Configuration Guide of XGS-5240-Series
61-3
e the virtual IPv6 address of the virtual router.
Fig 2-1 VRRPv3 message
61.1.2 VRRPv3 Working Mechanism
The working mechanism of VRRPv3 is the same with that of VRRPv2, which is m
ainly implemented via the interaction of VRRP advertisement messages. It will be briefly
described as follows:
Each VRRP router has a unique ID: VRIP, ranging from 1 to 255. This router has
a unique virtual MAC address outwardly, and the format of which is 00-00-5E-00-02-{V
RID} (the format of virtual MAC address in VRRPv2 is 00-00-5E-00-01-{VRID}). Master
router is in charge of using this MAC address to respond to ND neighbor request (it is
ARP request in VRRPv2). Thus, no matter what switch is made, the terminal devices
will get the same IP and MAC address all the time, reducing the affection that the swit
ch causes on terminal devices.
There is only one kind of VRRP control message: VRRP advertisement. It uses IP
multicast data packets to encapsulate, and the format of multicast addresses is FF02:0:
0:0:0:0:XXXX:XXXX. In order to keep a consistence with the multicast address in VRRP
v2 (224.0.0.18), the multicast addresses used by VRRPv3 advertisement messages can
be FF02:0:0:0:0:0:0:12, and the advertisement is limited within the same LAN. Thus, di
fferent VRID are guaranteed to be used repeatedly in different networks. In order to re
duce the overheads of network bandwidth, only master routers can send VRRP advertis
ement messages regularly. Backup routers will start a new round of VRRP selection if i
t hasn’t received a VRRP advertisement in 3 advertisement intervals in a row or if it re
ceives an advertisement with a priority of 0.
In a VRRP router group, the master router is selected according to priority. The ra
nge of priority in VRRP protocol is 0-255. If the IP address of a VRRP router is the sa
me to that of the virtual router interface, then the virtual router will be called the IP ad