Search by keyword:
Astronomy
Chemistry
Classical Physics
Climate Change
Cosmology
Finance and Accounting
General Relativity
Lagrangian and Hamiltonian Mechanics
Macroeconomics
Mathematics
Microeconomics
Particle Physics
Probability and Statistics
Programming and Computer Science
Quantum Field Theory
Quantum Mechanics
Semiconductor Reliability
Solid State Electronics
Special Relativity
Statistical Mechanics
String Theory
Superconductivity
Supersymmetry (SUSY) and Grand Unified Theory (GUT)
test
The Standard Model
Topology
Units, Constants and Useful Formulas
Open Systems Interconnection (OSI) Standard - TCP/IP Protocol
-------------------------------------------------------------
Virtually all networks in use today are based in some fashion on OSI. The core of this standard
is the OSI Reference Model, a set of seven layers that define the different stages that data must
go through to travel from one device to another over a network.
Application Set
Transport Set
The OSI Reference Model is really just a guideline. Actual protocol stacks often combine one or more of the OSI layers into a single layer. A protocol stack is a group of protocols that all work together to allow software or hardware to perform a function. The TCP/IP protocol stack is a good example. It uses four layers that map to the OSI model as follows:
A TCP packet consist of:
IP is an Internet protocol (layer 2) that handles the address part of each packet so that it gets to the right destination. Basically, IP is responsible for managing the sending and receiving of data packets over the Internet. An IP packet consists of:
The whole process can be summarized as follows:
IP Routers
-----------
After the IP datagram has been assembled, the local machine ships it down the wire to a router that picks up
the frame. Routers are very smart. They can look at the network type and,
if necessary, reformat the Data layer information before passing the data onto
the destination or another router. The router has a map of the local internet
in its memory and each frame is sent off to its destination via the best available
route. In the process the IP datagrams are just re-framed with different headers and frame source and frame destination addresses.
The router uses the technique of packet switching and all of the packets
in the message may or may not take the same route. In this way the network
can dynamically balance the load across various pieces of equipment. If there is
a problem with one piece of equipment in the network while a message is being
transferred, packets can be routed around the problem, ensuring the delivery
of the entire message. The routers that make up the main part of the Internet
can reconfigure the paths that packets take because they look at the information
surrounding the data packet, and they tell each other about line conditions, such
as delays in receiving and sending data and traffic on various pieces of the network.