HP VPN Firewall Appliances High Availability Configuration Guide

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DR-mode server load balancing
Figure 86 Network diagram
DR mode is different from NAT mode in that NAT is not used in load balancing. This means that besides
its local IP address, a server must have the VSIP configured.
DR-mode server load balancing comprises the following elements:
• Cluster—A cluster consists of an LB device, a general device, and multiple servers to provide
specific services.
• LB device—A device that distributes different service requests to multiple servers.
• General device—A device that forwards data according to general forwarding rules.
• Server—A server that responds to and processes different service requests.
• VSIP—Virtual service IP address of the cluster, used for users to request services. Besides configuring
the VSIP on the LB device, you need to configure it on servers. (Because the VSIP on the server
cannot be contained in an ARP request and response, you can configure the VSIP on a loopback
interface.)
• Server IP—IP address of a server, used by the LB device to distribute requests.
Figure 87 Work flow of DR-mode Layer 4 server load balancing
DR-mode Layer 4 server load balancing operates in the following way:
Host
IP network
LB device
Server A
VSIP/IP A
Server B
VSIP/IP B
Server C
VSIP/IP C
Cluster
VSIP
General device