H3C Technologies H3C MSR 50 - Manual (Page 71)

63
Figure 26 Sending packets to different routers for forwarding
Virtual forwarder
1. Creating a virtual forwarder
Virtual MAC addresses enable traffic distribution across the routers in a VRRP group. To enable the
routers in the VRRP group to forward the packets, be sure to create virtual forwarders (VFs) on the
routers. Each VF associates with a virtual MAC address in the VRRP group and forwards packets
sent to this virtual MAC address.
VFs are created on the routers in a VRRP group, as follows:
a. The master assigns virtual MAC addresses to all routers in the VRRP group. Each member
router creates a VF for this MAC address and becomes the owner of this VF.
b. Each router advertises its VF information to the other member routers.
c. After receiving the VF advertisement, each of the other routers creates the advertised VF.
Eventually, every member router maintains one VF for each virtual MAC address in the VRRP
group.
2. VF weight and priority
The weight of a VF indicates the forwarding capability of a router. A higher weight means higher
forwarding capability. When the weight is lower than the lower limit of failure, the router cannot
forward packets.
The priority of a VF determines the VF state. Among the VFs created on different member routers for
the same virtual MAC address, the VF with the highest priority, known as the active virtual
forwarder (AVF), is in the active state to forward packets. All other VFs listen to the state of the AVF
are known as the listening virtual forwarders (LVFs). VF priority ranges from 0 to 255, where 255
is reserved for the VF owner. When the weight of a VF owner is higher than or equal to the lower
limit of failure, the priority of the VF owner is 255.
The priority of a VF is calculated based on its weight:
{
On the router that owns the VF, if the weight of the VF is higher than or equal to the lower limit
of failure, the priority of the VF is 255.