Summary

Chapter 8: Fundamental Networks 41Transport ProtocolsTransport layer protocols provide end-to-end management of the data. One of the functionsof these protocols is to divide the data into manageable segments for easier transport acrossthe network. Here are the two transport protocols that operate at the TCP/IP transportlayer:■■Transmission Control Protocol (TCP) is the primary Internet protocol for the reliabledelivery of data. TCP includes facilities for end-to-end connection establishment, errordetection and recovery, and metering the rate of data flow into the network. Many standardapplications, such as e-mail, web browser, file transfer, and Telnet, depend on theservices of TCP.User Datagram Protocol (UDP) offers a connectionless service for delivery of data.UDP uses lower overhead than TCP and doesn’t handle issues of reliability. Networkmanagement applications, network file system, and simple file transport use UDP.Internet ProtocolsInternet layer protocols operate at the third layer from the top in the TCP/IP model. Internetprotocols are used to provide connectivity between hosts in the network. Here are some ofthe protocols that operate at the TCP/IP Internet layer:■■■■Internet Protocol (IP) provides source and destination addressing, much like theaddress and return address on a postal envelope. In conjunction with routing protocols,IP provides packet-forwarding information from one network to another.Internet Control Message Protocol (ICMP) is used for network testing and troubleshooting.It enables diagnostic and error messages. The ping application uses ICMPecho messages to test if a remote device can be reached.Routing information Protocol (RIP) operates between router devices to discover pathsbetween networks. In an intranet, routers depend on a routing protocol to build andmaintain information about how to forward packets toward the destination. RIP choosesroutes based on the distance or hop count to the destination.Address Resolution Protocol (ARP) is used to map the MAC address of a node on thenetwork when its IP address is known. End stations as well as routers use ARP to discoverMAC addresses.Network Access ProtocolsNetwork access protocols describe the standards that hosts use to access the physicalmedia. The IEEE 802.3 Ethernet standards and technologies, such as CSMA/CD and10BASE-T, are defined at this layer.