HP VPN Firewall Appliances High Availability Configuration Guide

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Figure 89 Work flow of firewall load balancing
Firewall load balancing operates in the following way:
1. LB device A receives the traffic from the source.
2. LB device A forwards the traffic to a firewall based on the destination IP address range and the
pre-configured load balancing rules of the traffic.
3. The firewall forwards the traffic to LB device B.
4. As a level 2 LB device, LB device B records the firewall that forwards the traffic and then forwards
the traffic to the destination.
5. LB device B receives the traffic sent from the destination.
6. LB device B forwards the traffic to the firewall recorded in step 4.
7. The firewall forwards the traffic to LB device A.
8. LB device A forwards the traffic back to the source.
The load balanced firewalls between two LB devices perform network traffic load balancing, and thus
network performance is increased. This load balancing mode is also called sandwich load balancing.
Firewall load balancing can be used together with server load balancing, as shown in Figure 90.
(1) Traffic from source
LB device A
Firewall
(3) Forward
LB device B
(2)
Scheduler & Forward
(4) Record &
Forward to destination
(5) Traffic from destination
(7) Forward
(8) Forward to source
(6) Forward