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Computer Networks and Internet - Coggle Diagram
Computer Networks and Internet
introduction
A network is defined as the interconnection of a set of devices capable of communication.
A device can be a
host
(or an
end system
): large computer, desktop, laptop, workstation, cellular phone, or security system.
A device can be also be a connecting device such as a
router
which connects the network to other networks
These devices in a network are connected using wired or wireless transmission media such as cable or air.
NETWORKS
Local Area Network (LAN)
A LAN is usually privately owned and connects some hosts in a single office, building, or campus.
Wired LANS: ethernet
A
group of bits are packaged
together and are referred to as a
frame
Wireless LANS
The standard defines two kinds of services:
the basic service
set (BSS) and
the extended service
set (ESS)
Each host in a LAN has an
identifier, an address,
that uniquely defines the host in the LAN.
A
packet
sent by a host to another host
carries both the source host’s
and the
destination host’s addresses.
Wired LANS: ethernet
Wide Area Network (WAN)
A WAN is also an interconnection of devices capable of communication.
A WAN interconnects connecting devices such as
switches, routers, or modems
A
point-to-point WAN
is a network that connects two communicating devices through a
transmission medium
(cable or air).
A
switched
WAN is a network with more than two ends.. A switched WAN is
a combination of several point-to-point WANs that are connected by switches
the Internet
An Internet is two or more networks that can communicate with each other and is composed of thousands of interconnected networks.
The Internet
is as several
backbones, provider networks, and customer networks
Backbones
at top level are large networks
owned by some communication companies
Provider networks
at second level use the services of the backbones for a fee.
Customer networks
actually
use the services
provided by the Internet
Backbones and provider networks
are also called
Internet Service Providers (ISPs).
TCP/IP
Protocol Layering A protocol defines the rules that both the sender and receiver and all intermediate devices need to follow to be able to communicate effectively in Internet
The TCP/IP (Transmission Control Protocol / Internet Protocol)
only
four
because the physical layer (data exchange is a bit) does not need addresses.
the address used in that layer, and the packet name at that layer.
source and destination addresses
application layer:
NAMES
they
only receive services
from the protocols in the transport layer.
application programs be able to
request services
and
provide services
the client-server paradigm
World Wide Web (WWW)
and its
vehicle HyperText Transfer Protocol (HTTP)
,
file transfer protocol
(FTP),
secure shell
(SSH),
email
, and so on.
the peer-to-peer paradigm
No need
for a server process to be
running all the time
and
waiting for the client processes to connect
transport layer:
PORT NUMBERS
The transport layer acts as a liaison between a client program and a server program.
It
provides services to the application layer
and
receives services from the network layer.
client program
greater than 1023
server process
define itself with a port number.
the
User Datagram Protocol (UDP)
(nhanh, không đáng tin cậy)
video calls
UDP packets
, called
user **
datagrams **
the
Transmission Control Protocol (TCP)
(chậm, đáng tin cậy)
TCP adds a header to each segment and delivers the segment
gmail
network layer:
LOGICAL ADDRESSES
The network layer in the TCP/IP protocol suite is responsible for the
host-to-host delivery
of messages
The network layer
accepts a packet from a transport layer
,
encapsulates
the packet in a datagram, and
delivers the packet to the data-link layer.
(IP
ver 4(32bits
) dotted decimal and IP
ver 6(128 bits
) dotted hexa )
At the
destination host
, the datagram is
de-capsulated
, the packet is extracted and delivered to the corresponding transport layer.
data-link layer:
LINK-LAYER ADDRESS
This layer is the
territory of networks
that when connected make up the Internet.
These networks, wired or wireless,
receive services and provide services to the network layer.
node-to-node
two end hosts
and
the routers
as
nodes
and the
networks
in between as
links
.
DNS in the Internet
generic domains(define registered hosts
) , country domains, and the inverse domain
Data and signals
Major function: to route bits between nodes by converting these bits into
electromagnetic signals
ANALOG AND DIGITAL
Analog data
refers to information that is
continuous
. Analog data, such as the
sounds
made by a
human voice
, take on continuous values.
Digital data
take on
discrete values
Signals
can be either analog or digital. An
analog signal
has infinitely many levels of intensity over a period of time.
A digital signal
can have only a limited number of defined values.