3com S7906E 설치 설명서
1-11
Figure 1-8 VF information
Host A
Host B
Host C
Router A
Master
Router B
Backup
Router C
Backup
Virtual IP address:
10.1.1.1/24
10.1.1.2/24
10.1.1.3/24
10.1.1.4/24
Network
VF
Virtual
MAC address VF priority State
000f-e2ff-0011
VF 1
255
AVF
000f-e2ff-0012
VF 2
127
LVF
000f-e2ff-0013
VF 3
127
LVF
VF
Virtual
MAC address VF priority State
000f-e2ff-0011
VF 1
127
LVF
000f-e2ff-0012
VF 2
255
AVF
000f-e2ff-0013
VF 3
127
LVF
VF
Virtual
MAC address VF priority State
000f-e2ff-0011
VF 1
127
LVF
000f-e2ff-0012
VF 2
127
LVF
000f-e2ff-0013
VF 3
255
AVF
LVFs listen the AVF. When the AVF fails, the LVFs elect a new AVF with the highest priority value among
the LVFs.
A VF always works in the preemption mode. When an LVF finds its priority higher than that in the
advertisement sent by the AVF, the LVF declares itself as the AVF.
VF tracking
The AVF forwards packets destined to the MAC address of the AVF. If the uplink of the AVF fails and no
LVF is notified to take over the AVF's work, hosts (on the LAN) that take the MAC address of the AVF as
their gateway MAC address cannot access the external network.
You can solve this problem through the VF tracking function. You can monitor the uplink state by using
network quality analyzer (NQA) and bidirectional forwarding detection (BFD), and establish the
collaboration between the VF and the NQA or between the VF and the BFD through the tracking
function. When the uplink fails, the state of the monitored Track object changes to negative and the
weight of the VF decreases by a specified value. After that, the VF with a higher priority becomes the
AVF and forwards packets.
Packet Types
VRRP standard protocol mode defines only one type of packet: the VRRP advertisement. Only the
master in a VRRP group sends VRRP advertisements periodically, and the backups do not send VRRP
advertisements.
To realize load balancing, VRRP load balancing mode defines four types of packets:
z
Advertisement: VRRP uses the advertisements to notify the VRRP group state on the local router
and the information of the VF that is in the active state. Both the master and the backups send
VRRP advertisements periodically.
z
Request: If a backup router is not the VF owner, it sends a request to ask the master for virtual
MAC address.