Huawei Quidway S3900 Series Operation Manual page 537

Operation Manual – VRRP
Quidway S3900 Series Ethernet Switches-Release 1510
A backup group is established if it is assigned an IP address for the first time. If you
then add other IP addresses to the backup group, the IP addresses are added to
the virtual router IP address list of the backup group.
The virtual router IP address and the IP addresses used by the member switches
in a backup group must belong to the same network segment. If not, the backup
group will be in the initial state (the state before you configure the VRRP on the
switches of the group). In this case, VRRP does not take effect.
A backup group is removed if all its virtual router IP addresses are removed. In this
case, all the configurations performed for the backup group get ruined.
According to the standard VRRP, you will fail to use the ping command to ping the IP
address of a virtual router. So the hosts connected to a switch in a backup group cannot
judge with ping command whether an IP address is used by the backup group. If the IP
address of a host is also used by the virtual router, all packets destined for the network
segment will be forwarded to the host. In this case, data in this network segment cannot
be forwarded properly.
Before enabling VRRP feature on an S3900 series switch, you can enable the switches
in a backup group to respond the ping operations destined for the virtual router IP
addresses. Therefore the above incident can be avoided. If VRRP is already enabled,
the system does not support this configuration.
II. Mapping Virtual IP Addresses to MAC Addresses
An S3900 series switch provides the following functions in addition to forwarding data
correctly.
You can map multiple virtual IP addresses of the backup group to a virtual MAC
address as needed. You can also map virtual IP addresses to the MAC address of
a switch routing interface.
You need to map the IP addresses of the backup group to the MAC addresses
before enabling VRRP feature on an S3900 series switch. If VRRP is already
enabled, the system does not support this configuration.
By default, virtual router IP addresses are mapped to the virtual MAC address of a
backup group.
Note:
When you map a virtual IP address to the virtual MAC address on an S3900 series
switch, the number of backup groups that can be configured on a VLAN interface is
determined by the chips used. Refer to device specification for detail.
Huawei Technologies Proprietary
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Chapter 1 VRRP Configuration