IP App Revolution Means Changes in Networks

Carl Weinschenk

The very act of sending an e-mail (not to mention a song or a video) from point A to point B is incredibly complicated. This complexity is exacerbated when the core techniques used to push the bits and bytes changes after the underlying network infrastructure has been built.


Most emerging applications and services today are based on Internet Protocol. And vendors and service providers are falling over themselves in transforming existing applications -- such as television and telephone -- to less expensive, more flexible and highly portable IP.


The sticking point is the lag time between the emergence of the new applications and the evolution of the networks on which they travel. Special steps must be taken, for instance, to carry IP voice traffic on a legacy distribution architecture known as Frame Relay. Distributing IP traffic on networks that are not optimized for the protocol is a different task than if the network and the application speak the same language.


And there is a second layer of complexity: riding herd over the relationship between networks that exchange traffic. A VoIP call made in San Francisco must traverse many networks before it reaches its destination in Kansas City.


Networks use the Open Systems Interconnection (OSI) model to ensure that the data one network is sending can be recognized and used on another. For those of you who have had the good fortune of avoiding the OSI protocol stack until now, suffice it to say that it is a seven-layer hierarchy of protocols that provide networking information on everything from the physical media (fiber, copper or coaxial cable) to subtle features of the application being ferried about (e.g., assigning time-sensitive VoIP packets priority over packets carrying e-mail).


If two networks use the same protocol, there is no problem (at least theoretically). But if the two are different, communications must occur at a lower and more basic level of the OSI protocol stack. Complexity equals less functionality, higher expense and less flexibility.


The Vertical Systems Group says that legacy networks, such as Frame Relay and Systems Network Architecture (SNA), are carrying more IP traffic than ever. The good news is that this rather cumbersome situation -- in which different types of networks are trading data in a format that neither was originally meant to carry -- will eventually fade as the world focuses on IP both for the applications and for the underlying plumbing.


The move toward IP is inexorable. On the application level, it's manifest in the growth of VoIP, streaming and other services. Perhaps more subtly, it shows up at the networking layer in the growth of carrier Ethernet, an IP-optimized platform that extends protocols traditionally seen in the LAN into the wide-area sector run by telecommunications companies.

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