HP VPN Firewall Appliances High Availability Configuration Guide

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• Cluster—A cluster that provides network traffic load balancing, consisting of an LB device, physical
links, and local DNS servers.
• LB device—Operating as an authoritative name server of the domain name to be resolved, an LB
device is used to select an optimal path for the traffic from the internal network to the external
network.
• Physical links—Links provided by carriers.
• Local DNS server—A local DNS server that resolves the DNS requests sent by a host.
Figure 94 Work flow of inbound link load balancing
Inbound link load balancing operates in the following way:
1. An external user sends a DNS request to its local DNS server for DNS resolution before resource
access.
2. The local DNS server converts the source IP address of the DNS request to its own IP address, and
forwards it to the authoritative name server (the LB device).
3. The LB device resolves the domain name according to the domain name of the DNS request and
the configured inbound link load balancing rules.
4. The LB device sends the DNS response to the local DNS server according to the DNS resolution
result.
5. The local DNS server forwards the DNS resolution result to the user.
6. The user uses the selected link to access the LB device.
Configuring server/firewall load balancing
IPv4 firewall load balancing and Layer 4 server load balancing are configured in the same way. This
section describes how to configure Layer 4 server load balancing.
configuration considerations
The server load balancing module comprises a real service group consisting of real services and a virtual
service, as shown in Figure 95.