TCP option 76 is only carried in the SYN and SYN-ACK packets of each TCP connection. This is used for autodiscovery.
TCP option 78 is carried in every TCP segment of a connection. This is necessary to allow the Steelheads distinguish full transpareny packets.
There are no other TCP option numbers used by Riverbed that I'm aware of. Note that the above 76 and 78 option numbers are the default values, and that they can be changed through the Steelhead configuration.
