VRRP Overview 153
■The virtual router IP addresses and the real IP addresses used by the member
switches in the backup group must belong to the same network segment. If they
are not in the same network segment, the backup group will be in initial state.
■A backup group is removed if its last virtual router IP address is removed from the
backup group. If a backup group is removed, all its configurations 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. In this case, 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.
Before enabling VRRP feature on an SWITCH 5500 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.
Mapping Virtual IP Addresses to MAC Addresses
You can map MAC addresses to virtual router IP addresses as needed. The MAC
address can be a virtual MAC address or the real MAC address of a Layer 3 switch
routing interface.
You need to map the IP addresses of the backup group to the MAC addresses before
enabling VRRP feature on an SWITCH 5500 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.
Due to the chips installed, you can configure only one backup group on a VLAN
interface of some switches when mapping the virtual IP addresses to the virtual MAC
addresses.
Due to the chips installed, you can configure up to 14 backup groups on a VLAN
interface of some switches if you map the virtual IP addresses to the real MAC address
of a switch.
You can configure on some switches 14 backup groups under both of the above
mentioned circumstances.
Introduction to Backup
Group
VRRP can group switches in a LAN into a virtual router, which is also known as a
backup group.
You can perform the following configuration on an SWITCH 5500 series switch that
belongs to a backup group.
■Configuring switch priority
■Configuring preemptive mode for a switch in a backup group
■Configuring authentication type and authentication key for a switch in a backup
group
■Configuring VRRP timer
■Configuring the VLAN interfaces to be tracked for a backup group