To optimize your HotStandby setup, use a single logical network access (IP address) in each HSB server for all communications. The servers can use different port numbers for different purposes.

You can use multiple, or redundant, lower-level network components (network interface cards, cables and switches), that are transparent at the network interface API level.

When only one logical network access is used, HAC (with ERE) detects network breaks that affect both the HSB transaction replication and the database client applications. If separate interfaces are used, HAC cannot detect failures in database client communications because HAC monitors the health of the HSB link only.

However, regardless of the underlaying network access implementation, the ERE feature of HAC can be used if the network access is regarded unreliable for whatever reason.