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The Out Of Band (OOB) connection is a connection established by a pair of Steelhead appliances optimizing traffic. Steelhead appliances use this unique connection to maintain and communicate the internal information for traffic optimization.

As I mentioned previously, RiOS 5.0 provides a WAN visibility options for optimization traffic to enhance the traffic through a router or device. But, it still uses port 7800 to communicate to each other by OOB connection. In some cases, this might cause OOB can't be established due to a NAT device between Steelhead appliances. Therefore, RiOS 5.0 provides alternative options for OOB connections which can be done in CLI.

There are three modes for OOB connections, Correct Addressing, Destination, and Full.

1. Correct Addressing: This is the default mode of Steelhead appliance. The same as WAN acceleration default mode, it uses the IP address and port number of client-side and server-side Steelhead appliances to establish OOB connection. Nothing is changed in this mode. The CLI for this mode is: in-path peering oobtransparency mode none
2. Destination: In this mode, a client-side Steelhead appliance uses it's own IP address and temporary port number to establish a OOB connection with server-side Steelhead appliance using the IP address and port number of a server. The server IP address and port number are taken from the first connection optimized by the pair of Steelhead appliances. The CLI for this mode is: in-path peering oobtransparency mode destination
3. Full: The client-side Steelhead appliance uses a pre-determined port number and IP address of a client, and server IP address and port number to establish OOB connections. The client IP address, and the server IP address and port number are taken from the first connection optimized by the pair of Steelhead appliances. The CLI command for this mode is: in-path peering oobtransparency mode full

The transparent addressing modes, destination and full, are only used to integrate with specific types of network configurations. That is not necessary for a regular topology.