Specifying an IPv4 VRRP control VLAN
VLAN termination enables an interface to remove the VLAN tags of a packet and deliver the packet to Layer 3 forwarding or other processing pipelines. The following VLAN termination categories are available:
Unambiguous termination—Terminates VLAN packets from a specified VLAN only. After receiving a packet from the VLAN, the interface that is configured with unambiguous VLAN termination removes its VLAN tag.
Ambiguous termination—Terminates VLAN packets from multiple VLANs whose VLAN IDs are in the specified range. After receiving a packet from a VLAN in the specified range, the interface that is configured with ambiguous VLAN termination removes its VLAN tag.
By default, an ambiguous termination-enabled Layer 3 subinterface drops broadcast and multicast packets that it receives. You can enable the interface to transmit broadcast packets and multicast packets as needed. The packets are transmitted within all VLANs whose VLAN packets are configured to be terminated by the subinterface.
Figure 21: VRRP control VLAN
As shown in Figure 21, ambiguous VLAN termination is configured for VLAN 10 and VLAN 20 on the Layer 3 Ethernet subinterfaces on routers. To allow the master to regularly send VRRP advertisements in multicast to the backups, enable the VLAN termination-enabled subinterfaces to transmit broadcast packets and multicast packets. Then, the master can send VRRP advertisements within all VLANs whose VLAN packets are configured to be terminated by the subinterfaces. If ambiguous VLAN termination is configured on the Layer 3 Ethernet subinterfaces for a large range of VLANs, the VRRP advertisements might overload the subinterfaces. This adversely affects the performance of the routers.
To solve this problem, perform the following tasks:
Disable the VLAN termination-enabled subinterfaces from transmitting broadcast packets and multicast packets.
Configure a VRRP control VLAN to allow the master to send VRRP advertisements only within the control VLAN.
The following categories of VRRP control VLANs are available:
VLANs with a single VLAN tag—Specified for ambiguous Dot1q termination-enabled subinterfaces.
VLANs with both inner and outer VLAN tags—Specified for ambiguous QinQ termination-enabled subinterfaces.
For more information about VLAN termination, see Layer 2—LAN Switching Configuration Guide.
Configuration guidelines
When VRRP is operating in load balancing mode, you cannot specify the VRRP control VLAN.
As a best practice, configure the arp send-gratuitous-arp command on the routers in a VRRP group after you specify a VRRP control VLAN. This command enables the routers to periodically send gratuitous ARP packets. The devices in the VLAN terminated ambiguously can then update MAC address entries after a master switchover. For more information about the arp send-gratuitous-arp command, see Layer 3—IP Services Command Reference.
Configuration procedure
To specify a VRRP control VLAN:
Step | Command | Remarks |
|---|---|---|
1. Enter system view. | system-view | N/A |
2. Enter Layer 3 Ethernet subinterface view or Reth subinterface view. | interface interface-type interface-number | N/A |
3. Specify a VRRP control VLAN. |
| By default, no VRRP control VLAN is specified. The master sends VRRP advertisements within all VLANs whose VLAN packets are configured to be terminated by the subinterface. |