ay machines (actually these are routers) that move data anywhere in the world. TCP Responsible for verifying the correct delivery of data from client to server. Data can be lost in the intermediate network. TCP detects errors or lost data and triggers retransmission requests until the data is correctly and completely received. Sockets The name given to a package of subroutines that provide access to TCP/IP on most systems. The OSI Stack The Internet Stack Figure 7-15 The many protocols X.500 Others TELNET Others X.400 in the TCP/IP comparison. X.208:ASN.1 X.209:BER X.226 & X.216 Generally, not defined, but ASN.1 is used in some systems X.225 & X.215 Not defined TP, classes 0-4 or TP CL TCP or UDP OSPF, IS-IS Q.2931 Q.931 BGP,RIP ES-IS ARP and RARP Generally, not defined, except like PPP Phys. SONET Not defined OSI and Internet Protocol Stacks 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. X.25, Internets, Intranets, and Extranets Chapter 7 Internet Protocols (IPs) The IP was developed to provide internetworking. Individual machines are first connected to a LAN. TCP/IP shares the LAN with other uses (a Novell file server, Windows 95, or Windows NT). A router provides the TCP/IP con- nection between the LAN and the rest of the world. To ensure that all types of systems from all vendors can communicate, TCP/IP is absolutely stan- dardized on the LAN. Larger networks based on long distances and phone lines are more volatile. Many organizations want to reuse large internal networks based on IBM's Systems Network Architecture (SNA). In Europe, the national phone companies traditionally standardized on X.25. However, the explosion of high-speed microprocessors, fiber optics, and digital phone systems has created a burst of new options: Integrated Services Data Net- work (ISDN), Frame Relay, and Asynchronous Transfer Mode (ATM). New technologies co