Network Categories

TDP/IP includes a wide range of protocols which are used for a variety of purposes on the network. The set of protocols that are a part of TCP/IP is called the TCP/IP protocol stack or the TCP/IP suite of protocols. Considering the many protocols, message types, levels, and services that TCP/IP networking supports, I believe it would be very helpful to categorize the various protocols that support TCP/IP networking and define their respective contribution to the operation of networking. Unfortunately I have never seen this done to any real extent, but believe it would be worthwhile to help those learning networking understand it faster and better. I cannot guarantee that experts will agree with the categorizations that will be provided here, but they should help the reader get the big picture on the various protocols, and thus clarify what the reason or need is for each protocol. As mentioned previously, there are four TCP/IP layers. They are link, network, transport, and application. The link layer is the hardware layer that provides ability to send messages between multiple locations. In the case of this document, Ethernet provides this capability. Below I define several categories some of which fit into the 4 layer protocol levels described earlier. I also define a relative fundamental importance to the ability of the network to function at all. Importance includes essential, critical, important, advanced, useful. Essential - Without this all other categories are irrelevant. Critical - The network, as designed, is useless without this ability. Important - The network could function, but would be difficult to use and manage. Advanced - Includes enhancements that make the network easier to use and manage. Useful - Functionality that you would like to be able to use as a network user. Applications or some functionality is supported here. Without this, why build a network? The categories are:

Name(layer)	Importance	Names of protocols	What it does
Hardware(link)	Essential	ethernet, SLIP, PPP, Token Ring, ARCnet	Allows messages to be packaged and sent between physical locations.
Package management(network)	Essential	IP, ICMP	Manages movement of messages and reports errors. It uses message protocols and software to manage this process. (includes routing)
Inter layer communication	Essential	ARP	Communicates between layers to allow one layer to get information to support another layer. This includes broadcasting
Service control(transport)	Critical	TCP, UDP	Controls the management of service between computers. Based on values in TCP and UDP messages a server knows what service is being requested.
Application and user support	Important	DNS, RPC	DNS provides address to name translation for locations and network cards. RPC allows remote computer to perform functions on other computers.
Network Management	Advanced	RARP, BOOTP, DHCP, IGMP, SNMP,RIP, OSPF, BGP, CIDR	Enhances network management and increases functionality
Utility(Application)	Useful	FTP, TFTP, SMTP, Telnet, NFS, ping, Rlogin	Provides direct services to the user.