Physical IP Addresses versus Virtual IP Addresses Redundancy

Administering and Monitoring AppDirector > Redundancy > Physical IP Addresses versus Virtual IP Addresses Redundancy

Physical IP Addresses versus Virtual IP Addresses Redundancy

In redundancy configurations, both primary and backup AppDirectors must be configured to work with virtual and physical addresses. The primary platform ensures that the backup AppDirector supports virtual addresses. These addresses are defined on the backup AppDirector just like the primary AppDirector. Different physical IP addresses are used for the primary and backup platforms, and often, another configuration is required on the redundant AppDirector to support backup for physical IP addresses of the primary platform.

When a physical interface of the primary AppDirector platform is set as the default gateway of a server, and the backup AppDirector takes over, the server works using the backup platform as a Next Hop Router. However, in this situation the server cannot ping its default gateway IP address because the primary platform is down. To avoid this, you can use Virtual IP addresses as the default gateways of servers and other platforms around AppDirector. To use Virtual IP addresses, you need to create a Virtual IP Interface address for each local subnet of AppDirector, and use this address in the relevant routing tables for hosts on that subnet. Ensure that the same Virtual IP Interface addresses are set as backup on the redundant platform. To create a Virtual IP address, see Layer 4 Policies.