The IPNGN vision provides the SP community an architectural framework within which to rationalize networking solutions. The great thing about the IPNGN framework is its simplicity, neatly summarizing in a logically layered 3 dimensioned model all the functionality required for supporting NGN services. But this apparent simplicity hides the intricate complexity of all the interfaces and protocols that need to be implemented to enable any specific IPNGN service. An inkling of this complexity can be gleaned from the NGN Protocol Reference Model (PRM), shown below. This is a”Rubik’s Cube” of Layers and Planes and, most importantly, the complex interplay between them. In effect, the PRM encapsulates ALL the essence of the IPNGN – in a cube!Each Plane- Transport, Management, Control – is a world in itself, but relies on the others to be effective. The separations may be more virtual than real, but they help us understand the whole as more than the sum of its parts. Revenue generating services are created from the interplay of control and management messages, knitted together by applications embedded on either side of the user-to-network interfaces. The IP suite of protocols forms the”common element” in the NGN PRM framework. The use of IP as the common packet transfer mode dictates how the desirable NGN attributes, such as QoS, Security, Survivability, etc., are implemented.So how does this cubic NGN PRM abstraction help us build better networks, and by implication, more profitable services? Consider security for example. Every operator wants security as an essential element of their network. The IPNGN cube shows us that in order to deliver security in all its facets, we have to consider the security aspects in all the Layers and Planes of the IPNGN. The question is, if we disregard any one of these aspects, do we end up with a potential”Achilles heel”?The same is true for the elusive notion of QoS, much talked about and desired, but hard to achieve in practical terms. In its broadest sense, QoS capabilities rely on functions that are spread over many Layers and Planes of the NGN PRM cube. A bottleneck in one Layer could lead to impairments elsewhere. The cube encourages us to take into account the complex inter-dependencies. Whoever said ubiquitous QoS was going to be easy!As transport plane capabilities become increasingly commoditized, the IPNGN cube raises the question as to how we can more effectively leverage control and management plane capabilities to generate profitable services?And what of the need to interwork with existing services and networks? How are the legacy services to be accommodated in this IPNGN vision? The IPNGN vision provides a very useful tool to conceptualize networking solutions. The IPNGN cube helps get to a deeper understanding, another conceptual tool that illustrates inter-dependencies between the protocols we must rely on, and helps us build better networks.Rajiv KapoorDirector, Standards & Architectures MarketingCisco Systems, Inc.