re detail later in this book. IPsec-compliant routers, IPsec-compliant firewalls, and IPsec-compliant switches are now available. Although VPNs still have the same underlying principle of a certain degree of communications security, they acquired a different dimension altogether with the arrival of the layer 3 switching tech- niques. It especially changed after the concerted consolidation of major rival approaches from Ipsilon/Nokia (IP switching), Cisco (tag switching), IBM (ARIS), and Toshiba (CSR) into MPLS. MPLS-enabled carriers, as a direct result of the technology they possess, are able to offer VPNs as one of several value-added services they can provide to their customers. SECURITY CO-PROCESSORS In the mid-1990s, router and switch manufacturers realized that security was important. The competi- tion provided by traditional security companies with previous experience serving the military and intel- ligence markets was too intense. Network equipment manufacturers understood that they had to offer security inside their products or the solidity of their base would erode. The trend started as security 63. Naganand Doraswamy and Dan Harkins, IPsec: The New Security Standard for the Internet, Intranets, and Virtual Private Networks (Upper Saddle River, New Jersey: Prentice-Hall, 1999). 64. Elizabeth Kaufman and Andrew Neuman, Implementing IPsec: Making Security Work on VPNs, Intranets, and Extranets (New York: John Wiley, 1999). 65. Carlton Davis, IPsec: Securing VPNs, (New York: McGraw-Hill Professional Publishing, 2001). 66. Peter Loshin, Big Book of IPsec RFCs: Internet Security Architecture (San Francisco: Morgan Kaufmann Publishers, 1999). Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. THE EVOLUTION OF NETWORK TECHNOLOGY: DISTRIBUTED COMPUTING AND THE CONVERGENCE OF NETWORKS THE EVOLUTION OF NETWORK TECHNOLOGY 27 software (encryption,