3Com S7902E, Руководство по настройке

Страница: 2083 / 2621

1-10
z
The MAC address obtained by Host B is the virtual MAC address of Router B, and thus to ensure
that the packets from Host B are forwarded by Router B.
z
The MAC address obtained by Host C is the virtual MAC address of Router C, and thus to ensure
that the packets from Host C are forwarded by Router C.
Virtual Forwarder
When working in the load balancing mode, VRRP uses VFs to realize load balancing. Each VF
associates with a virtual MAC address of the VRRP group and forwards packets destined to this virtual
MAC address.
The master allocates virtual MAC addresses to all routers (including the master and the backups) in the
VRRP group. After obtaining its virtual MAC address, a router in the VRRP group will create a VF
corresponding to this MAC address, and then the router becomes the owner of this VF.
VF weight and priority
The weight of a VF indicates the forwarding capability of a router: the higher the weight, the higher the
forwarding capability. When the weight is lower than a specified value which is the lower limit of failure,
the router will not be capable of forwarding packets for the hosts.
The priority of a VF decides the VF state: a VF with the highest priority is in the active state and is known
as the active virtual forwarder (AVF), which forwards packets; other VFs are in the listening state and
are known as the listening virtual forwarders (LVFs), which listen to the state of the AVF. The priority
value of a VF ranges from 0 to 255, where 255 is reserved for the VF owner.
The priority value of a VF is calculated based on its weight.
VF backup
If the weight of the VF owner is no less than the lower limit of failure, the priority of the VF owner is the
highest value 255. Therefore, the VF owner is the AVF and forwards packets destined to the MAC
address of the AVF. After receiving the advertisements sent by the AVF, other routers in the VRRP
group create their own VFs, which are in the listening state. Figure 1-8 illustrates the VF information on
each router in the VRRP group.