The SteelHead makes a connection to its peers using the Out of Band splice.

An OOB splice is an independent, separate TCP connection made on the first connection between two peer Steelhead appliances used to transfer version, licensing and other OOB data between peer Steelhead appliances. An OOB connection must exist between two peers for connections between these peers to be optimized. If the OOB splice dies all optimized connections on the peer Steelhead appliances will be terminated.

References:

http://ccie11440.blogspot.se/2009/12/out-of-band-oob-splice.html