This document contains generic and specific requirements for the IOS interfaces. The document contains the generic protocol descriptions that are used through all of the IOS interfaces. In addition@ protocol stack and transport network requirements for each IOSinterface are contained in this document. Details of the IOS application and signalinglayer messages are contained in the respective interface documents [14]@ [15]@ [16]@ and [17]. Purpose The purpose of this document is to describe the transport protocols and protocol stacks used on the interfaces@ which make up the logical network model@ and to indicate any unique aspects of these protocols that are relevant to the Interoperability Specification (IOS).