The TCP/IP Family of Protocols
The protocols that make up the TCP/IP family can be divided into groups of similar functionality for convenience.
Figure 108 shows the TCP/IP family tree.
Protocols that control the movement of data between two machines.
TCP (Transport Control Protocol): A connection-based service, meaning that the sending and receiving machines are communicating with each other at all times.
UDP (User Datagram Protocol): A connection-less service, meaning that the two machines are not communicating with each other.
Protocols that handle the addressing of data and determine the best routing to the destination. They also handle the breaking up and reassemble of larger messages.
IP (Internet Protocol): Handles the actual transmission of data.
ICMP (Internet Control Message Protocol): Handles status messages for IP, such as errors and network changes that can affect routing.
RIP (Routing Information Protocol): One of several protocols that determines the best routing method.
OSPF (Open Shortest Path First): An alternate protocol for determining routing.
These protocols handle the way machines are addressed, both by a unique number and a more common symbolic name.
ARP (Address Resolution Protocol): Determines the unique numeric addresses of the machine on the network.
DNS (Domain Name System): Determines numeric addresses from machine names.
RARP (Reverse Address Resolution Protocol): Determines addresses of machines on the network, but in a manner backward from ARP.
These are applications to which users have direct access.
BOOTP (BOOT Protocol): Starts up a network machine by reading the boot information from a server.
FTP (File Transfer Protocol): Transfers files from one machine to another without excessive overhead. Uses TCP as the transport.
TFTP (Trivial File Transfer Protocol): A simple file transfer method that uses UDP as the transport.
Telnet: Enables remote logins so that users on one machine can connect to another machine and behave as if they are sitting at the remote machine's keyboard.
These protocols help the network communicate routing and status information.
EGP (Exterior Gateway Protocol): Transfers routing information for external networks.
GGP (Gateway-to-Gateway Protocol): Transfers routing information between Internet gateways
IGP (Interior Gateway Protocol): Transfer routing information for internal networks.
Services that don't fall into any of the preceding categories.
NFS (Network File System): Enables directories on one machine to be mounted on another machine, then accessed by users as if they were on the local machine.
NIS (Network Information Service): Maintains user accounts across networks simplifying logins and password maintenance.
RPC (Remote Procedure Call): Enables remote applications to communicate with each other using function calls.
SMTP (Simple Mail Transfer Protocol): A protocol for transferring electronic mail between machines.
NTP (Network Time Protocol): Used to synchronise clocks of machines on a network.
SNMP (Simple Network Management Protocol): An administrator's service that sends status messages about the network and devices attached to it.