Saturday, 17 May 2014

The TCP/IP Protocol Suite

The TCP/IP Protocol Suite consists of many different protocols, each designed for a specific task in a TCP/IP network. The protocols are each known by an acronym.

The three basic protocols are:
ProtocolAcronymTask
Internet ProtocolIPHandles the actual transmissions: the packets of data with sender and receiver in each
Transmission Control ProtocolTCPHandles receiving and sending out communications. It is designed to work cohesive messages or data, checking received packets and sorting them into their designated order, forming the original message. Data sent out is broken into separate , order-designated packets.
User Datagram ProtocolUDPHandles receiving and sending out packets of data, but does not check their order.
The TCP and IP protocols are designed to provide stable and reliable connections that ensure that all data is reorganized into it's original order.

The UDP protocol is designed to send as much data as possible with no guarantee that packets will be received, or placed in their correct order. It is used for transmitting large amounts of data that can survive the loss of a few packets - for example, temporary images, videos and banners displayed on the internet.

Other protocols provide various network and user services. These protocols make use of either TCP or UDP protocol to send and receive packets, which, in turn, use the IP protocol to transmit the packets.

A complete list of protocols is:
ProtocolAcronymTask
Transport
Internet ProtocolIPHandles the actual transmissions: the packets of data with sender and receiver in each
Transmission Control ProtocolTCPHandles receiving and sending out communications. It is designed to work cohesive messages or data, checking received packets and sorting them into their designated order, forming the original message. Data sent out is broken into separate , order-designated packets.
User Datagram ProtocolUDPHandles receiving and sending out packets of data, but does not check their order.
Internet Control Message ProtocolICMPStatus messages for IP.
Routing
Routing Information ProtocolRIPDetermines routing.
Open Shortest Path FirstOSPFDetermines routing.
Network Address
Address Resolution ProtocolARPDetermines unique IP address of systems.
Domain Name ServiceDNSTranslates hostnames into IP addresses.
Reverse Address Resolution ProtocolRARPDetermines addresses of systems.
User Service
File Transfer ProtocolFTPTransmits files from one system to another using TCP.
Trivial File Transfer ProtocolTFTPTransfers files from one system to another using UDP.
TelnetRemote login to another system on the network.
Simple Mail Transfer ProtocolSMTPTransfers email between systems.
Remote Procedure CallRPCAllow programs on remote systems to communicate.
Gateway
Exterior Gateway ProtocolEGPProvides routing for external networks.
Gateway-to-Gateway ProtocolGGPProvides routing between internet gateways.
Interior Gateway ProtocolIGPProvides routing for internal networks.
Network Service
Network File SystemNFSAllows mounting of file systems on remote machines.
Network Information ServiceNISMaintains user accounts across a network.
Boot ProtocolBOOTPStarts system using boot information on server for network.
Simple Network Management ProtocolSNMPProvides status messages on TCP/IP configuration.
Dynamic Host Configuration ProtocolDHCPAutomatically provides network configuration information to host systems.
In a TCP/IP network, messages are broken into small components called datagrams. These are then transmitted through various routes and reassembled into their original message at the destination computer.

Datagrams can in turn be broken down into smaller components, called packets. These are the physical units that are actually transmitted. Sending messages as small components is faster and more reliable than sending them as one single large transmission. If one component is lost or corrupted, only that component must be resent. With a single large transmission, the whole message must be resent.

Configuring and Managing TCP/IP Networks

TCP/IP networks are configured and managed with a set of utilities, ifconfig, route and netstat.
UtilityDescription
ifconfigEnables full configuration of network interfaces, adding new ones and modifying others.
routeEnables full configuration of the routing tables, adding new entries and modifying others.
netstatProvides information about the status of network connections.