© 2005 Cisco Systems, Inc. All rights reserved. INTRO v Module Summary TCP/IP is the most widely used networking protocol, with functions that can be described in terms of layers, much like the layers of the OSI model. TCP/IP includes several protocols and supports a number of applications, including FTP, TFTP, and Telnet. IP delivers packets of data (datagrams) across a network, using specific packet header fields that contain information about the packet and the sending and receiving hosts. IP uses information in the packet header to identify to which of the many upper-layer protocols the datagram will be passed. ARP maps IP addresses to physical addresses on a network and maintains them dynamically in an ARP cache, or table, adding and changing address relationships as they are used on the local host. Routers are network devices that use routing tables to determine the path (or optimal path if alternatives exist) for transmitting data from one network to another and to forward packets of data.

© 2005 Cisco Systems, Inc. All rights reserved. INTRO v2.14-2