H3C Technologies H3C SR8800 - Manual (Page 64)

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Specifying the VRRP control VLAN
With VLAN termination, after a port receiving a VLAN packet, it removes its VLAN tag(s) and then
forwards it at Layer 3 or processes it in other ways. VLAN termination falls in the following categories:
• Unambiguous termination—Terminates VLAN packets from a specified VLAN only. In other words,
after receiving a packet from the specific VLAN, a port 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. In other words, after receiving a packet from a VLAN in the specified range, a
port configured with ambiguous VLAN termination removes its VLAN tag.
By default, an ambiguous termination-enabled Layer 3 subinterface or VLAN interface drops broadcast
and multicast packets they receive, instead of transmitting them.
You can enable a Layer 3 Ethernet subinterface, or a VLAN interface configured with ambiguous
termination to transmit broadcast/multicast packets within all VLANs whose VLAN packets are
configured to be terminated by the subinterface or VLAN interface.
Figure 20 VRRP control VLAN
As shown in Figure 20 , configure ambiguous VLAN termination for VLAN 10 and VLAN 20 on the Layer
3 Ethernet subinterfaces on routers. To make sure that the master can periodically multicast VRRP
advertisements to the backups, be sure to enable the subinterfaces configured with VLAN termination to
transmit broadcast/multicast packets. Then, the master sends VRRP advertisements within all VLANs
whose VLAN packets are configured to be terminated by the subinterfaces. If the Layer 3 Ethernet
subinterfaces are configured to terminate packets from many VLANs, there will be many VRRP
advertisements to be transmitted through the subinterfaces, and the performance of the router will be
seriously affected.
To solve this problem, you can configure a VRRP control VLAN to allow the master to send VRRP
advertisements only within the control VLAN when the subinterfaces configured with VLAN termination
are disabled from transmitting broadcast or multicast packets.
VRRP control VLAN falls into the following categories:
• Specifying a single VLAN tag—For subinterfaces configured with ambiguous Dot1q termination,
this type of control VLAN should be specified.