H3C S5810 Series, Руководство по эксплуатации

Страница: 764 / 820

1-4
VRRP advertisement interval timer
The master in a VRRP group sends VRRP advertisements periodically to inform the other routers in the
VRRP group that it operates properly.
You can adjust the interval for sending VRRP advertisements by setting the VRRP advertisement
interval timer. If a backup receives no advertisements in a period three times the interval, the backup
regards itself as the master and sends VRRP advertisements to start a new master election.
VRRP preemption delay timer
To avoid members in a VRRP group from changing their states frequently and make backups have
enough time to collect information (such as routing information), each backup waits for a period of time
(the preemption delay time) after it receives an advertisement with the priority lower than the local
priority, then sends VRRP advertisements to start a new master election in the VRRP group and finally
becomes the master.
Packet Format
The master multicasts VRRP packets periodically to declare its existence. VRRP packets are also used
for checking the parameters of the virtual router and electing the master.
Figure 1-3 Format of a VRRPv2 packet
...
As shown in Figure 1-3 , an IPv4-based VRRP packet consists of the following fields:
z
Version: Version number of the protocol, 2 for VRRPv2.
z
Type: Type of the VRRPv2 packet. Only one VRRP packet type is present, that is, VRRP
advertisement, which is represented by 1.
z
Virtual Rtr ID (VRID): Serial number of the virtual router, that is, serial number of the VRRP group.
It ranges from 1 to 255.
z
Priority: Priority of the router in the VRRP group, in the range 0 to 255. A greater value represents
a higher priority.
z
Count IP Addrs: Number of virtual IP addresses for the VRRP group. A VRRP group can have
multiple virtual IP addresses.
z
Auth Type: Authentication type. 0 means no authentication, 1 means simple text authentication,
and 2 means MD5 authentication.
z
Adver Int: Interval for sending advertisement packets, in seconds. The default is 1.
z
Checksum: 16-bit checksum for validating the data in VRRP packets.
z
IP Address: Virtual IP address entry of the VRRP group. The Count IP Addrs field defines the
number of the virtual IP addresses.