Transcript Communication Network Protocols ---

Communication
Network
Protocols
----Krishna Priyanka Chebrolu
~ Given a Network Architecture, some
rules and standards must be set up to
govern the communication i.e.;
communication protocols.
~ Ensures secure, fast and error-free data
delivery.
Division of protocols:
~ Connection-oriented and connectionless
~ Circuit-switching and Packet-Switching
~ Virtual circuit and datagram
Circuit and Packet Switching
Protocol Hierarchies:
~ Most networks are organized as stack of
layers, each one built upon the one below
it.
~ Number of layers, Name, Content and
Function of each layer varies from
network to network.
Reference Models:
1. OSI Reference Model
2. TCP/IP Reference Model
OSI Reference Model
The OSI model has seven layers. The principles that were
applied to arrive at the seven layers can be briefly
summarized as follows:
1. A layer should be created where a different
abstraction is needed.
2. Each layer should perform a well-defined function.
3. The function of each layer should be chosen with an
eye toward defining internationally standardized protocols.
4. The layer boundaries should be chosen to minimize the
information flow across the interfaces.
5. The number of layers should be large enough that
distinct functions need not be thrown together in the
same layer out of necessity and small enough that the
architecture does not become unwieldy.
•
The Physical Layer
~ The
physical layer is concerned with
transmitting of raw bits over a
communication channel.
Definition of Hardware Specifications
Encoding and Signaling
Data Transmission and Reception
Topology and Physical Network Design
The data link layer
~ Link Layer
~ DLL = Logical Link Layer + Media
Access Control
Data Framing
Addressing
Error Detection and handling
The Network Layer
The network layer is the lowest one in the
OSI model that is concerned with actually
getting data from one computer to
another even if it is on a remote network;
in contrast, the data link layer only deals
with devices that are local to each other.
Logical Addressing
Routing
Datagram Encapsulation
Fragmentation and Reassembly
Error handling and Diagnostics
The Transport Layer
~Accepts data from above and splits into
smaller units
~ Determines what type of service to
provide to the session layer.
~ Primary goal is create reliable end to
end communication.
~ The OSI protocol suite implements two
types of services at the transport layer:
connection-oriented transport service and
connectionless transport service.
The Session Layer
Session service provides four basic services to SS-users.
Establishes and terminates connections between SSusers and synchronizes the data exchange between
them.
Performs various negotiations for the use of session
layer tokens, which the SS-user must possess to begin
communicating.
Inserts synchronization points in transmitted data that
allow the session to be recovered in the event of errors
or interruptions.
Enables SS-users to interrupt a session and resume it
later at a specific point.
The Presentation Layer
the presentation layer is charged with
taking care of any issues that might arise
where data sent from one system needs to
be viewed in a different way by the other
system. It also takes care of any special
processing that must be done to data
from the time an application tries to send
it until the time it is sent over the
network.
Translation
Compression
Encryption
The Application Layer
The application layer contains a variety of protocols that
are commonly needed by users. One widely-used
application protocol is HTTP (HyperText Transfer
Protocol), which is the basis for the World Wide Web.
When a
browser wants a Web page, it sends the name of the
page it wants to the server using HTTP. The server then
sends the page back. Other application protocols are
used for file transfer, electronic mail, and network
news.
TCP/IP Reference Model
The host-network layer
The Internet Layer
The Transport Layer
The Application Layer
Comparison
OSI vs TCP/IP
References
Andrew S. Tenenbaum ,Computer Networks ,4th
edition. Pearson Education, 2003
http://www.tcpipguide.com/free/t_TCPIPInternetArchit
ectureandProtocolSuite.htm
Jim Kurose, Keith Ross, Computer Networking: A Top Down Approach
Featuring the Internet, 3rd edition. Addison-Wesley, July 2004.