TCP/IP Part I
Hello fellas,
Part - I
Today, the Internet and World Wide Web are familiar terms to millions of people all over
the world. Many people depend on apps enabled by the Internet, such as electronic mail and
Web acsess. In addition, the increase in popularity of business applicatioons places
additional emphasis on the Internet.
The Transmission Control Protocol/Internet Protocol (TCP/IP) protocol suite is the engine
for the internet and networks worldwide. Its simplicity and power has led to its becoming
the single network protocol of choice in the world today.
TCP/IP architectural model
The TCP/IP protocol suite is so named for two of its most important protocols:
Transmission Control Protocol (TCP) and Internet Protocol (IP). A less used name for it
is the Internet Protocol Suite, which is the phrase used in official
Internet statndards documents. AKA "RFCs"
Internetworking
The main design goal of TCP/IP was to build an interconnection of networks,
referred to as an internetwork, or internet, that provided universal communication
services over heterogeneous physical networks. The clear benefit of such an internetwork
is the enabling of communication between hosts on different networks, perharps separated
by a large geographical area.
The TCP/IP protocol layers
Like most networking software, TCP/IP is modeled in layers. This layered
representation leads to the term protocol stack, which refers to the stack of
layers in the protocol suite. It can be used for positioning(but not for functionally
comparing) the TCP/IP protocol suite againts other, such as Systems Network Architecture
and the Open System Interconection (OSI) model.
Functional comparisons cannot easily be extracted from this, because there are basic
differences in the layered models used by the different protocol suites.
By dividing the communication software into layers, the protocol stack allows for divsion
of labor, ease of implementation and code testing, and the ability to develop alternative
layer implementations. Layers communication with those above and below via concise
interfaces, n this regard, a layer provided by the layer directly below it. For exemple,
the IP layer provides the ability to transfer data from one host to another without any
guarantee to reliable delivery or duplicate suppression. Transport protocol such as TCP
make use of this service to provide applications with reliable, in order, data strem delivery
Application layer:
The Application layer is provided by the program that uses TCP/IP for communication.
An Application is a user process cooperating with another process usually on a different
host (there is a benefit to Application communication within a single host). Examples of
Applications include Telnet and the File transfer Protocol (FTP). The interface between
the Application and transport layers is defined by port numbers and sockets.
Transport layer:
The transport layer provides the end-to-end data transfer by delivering data from an
Application to its remote peer. Multiple Applications can be supported simultaneously.
The most-used transport layer protocol is the Transmission Control Protocol (TCP),
which provides connection-oriented reliable data delivery, and flow control.
Another transport layer protocol is the User Datagram Protocol. It provides connectionless,
unreliable, best effort service. As, a result, Application using UDP as the transport have
to provide their own end-to-end integrity, flow control, and congestion control, if desired.
usually, UDP is used by Applications that need a fast transport mechanism and can tolerate
the loss of some data.
Internetwork layer:
The internetwork layer, also called the internet layer or the network layer, provides the
"virtual network" image of an internet (this layer shields the higher levels from physcal
network architecture below it). Internet Protocol (IP) is most important protocol in this
layer. It is a connectionless protocol that does not assume reliability from lower layers.
IP does not provide reliability, flow control, or error recovery. These functions must
be provided at a higher level.
Ip provides a routing function dat attempts to deliver transmitted messages to their
destination. A message unit in an IP network is called an IP datagram. This is the basic
unit of information transmitted across TCP/IP network.
Network interface layer:
The network interface layer, also called the link layer or data-link layer, is the interface
to the actual network hardware. This interface may or may not provide reliable delivery, and
may be packet or stream oriented. In fact, TCP/IP does not specify any protocol here, but
can use almost any network interface available, which illustrates the flexibility of the IP
layer.