In continuing our commentary on TCP/IP's 25th birthday, today we'll look at a few more of the reasons why TCP/IP has had a gradual growth curve to become the de facto networking standard.

In the second part of the series, we gave a brief description of the connection/connectionless debate, to which Vint Cerf responded by mentioning that Larry Roberts rejected TCP/IP for use in Telenet “…on the grounds that he could not sell a datagram service. He thought he could only sell ‘virtual circuits’ to replace real circuits at a lower price.” And, as it turns out, Larry Roberts was probably right – for the time.

Twenty years ago, 5 years ago, and, to a lesser extent, even now, the telecommunications departments for most corporations were broken into two seldom-intersecting worlds: the LAN world and the WAN world. And while the LAN world adopted TCP/IP rather quickly (after a couple of minor skirmishes with competing protocol sets), the WAN world was firmly entrenched in SNA, DECNet, and other protocols that were much more circuit-oriented.

And the two worlds also had a different fundamental world-view. In the LAN world, having essentially unlimited, free bandwidth was a reasonable assumption. Consequently, the packet overhead was of little concern. In the WAN world, the opposite was true. Bandwidth was an extremely precious commodity, being limited and expensive. In fact, it was so expensive (relatively speaking) that there was great debate as to whether ATM was too overhead-intensive with its “cell tax” on the header of each packet.

As further evidence of this technology “turf war,” even though VoIP has now become a staple of the telecommunications diet, this was not an instant success either. While part of the issue with VoIP was that people did not see a compelling reason to rip out their existing voice systems that were working so well, the issues of bandwidth per call, the variation in delay, and the use of UDP (TCP’s datagram twin) led to technical debates. But the technical debates still had an undertone of the telecommunications folks’ traditional telephony world view (and turf) vs. the data folks’ “just another application” world view. And both had legitimate points.

Steve Taylor is president of Distributed Networking Associates and publisher/editor-in-chief of Webtorials. Jim Metzler is vice president of Ashton, Metzler & Associates.