• Both devices must be from the same product family and running the same TOS version.
• Each device must have a secure connection to the network and to the other device in the Transparent HA pair.
• Both devices must have SSLv3 capability (HTTPS server enabled, which is the default setting) and be able to communicate on TCP port 9591.
• A device configured with Transparent HA can only connect and communicate with a partner configured to talk to other IPS devices configured with TRHA. In other words, both machines participating must point to each other. Each device must be configured with the partner serial number and IP address.
• After the communication channel is active, the IPS will synchronize the following tables:
  • Blocked Streams
  • Trusted Streams
  • Rate Limited Streams
  • Quarantined IP Addresses

Note 1: If your system has two IPS devices communicating through Transparent HA, a change to the global timeout for the connection table at one IPS device will not propagate to the other IPS, you must make this change on each device accordingly.

Note 2: The SSLv3 tunnel relies on the HTTPS daemon of the IPS. If you enabled HTTP instead of HTTPS the communication will fail.

Note 3: With TRHA active, both IPS will still be stand-alone IPS. They do not synchronize configurations. The benefit in Transparent HA in the ability of each IPS to understand what actions have occurred on their partner IPS so that in the event of network convergence to the alternate path, blocks and rate limits will already be in place.