Download computer networking

Al AlBayt University
Computer Networking
Presented by:
Eng. Gader Al-khawaldeh
Network Engineer
Computer Center
[email protected]
COMPUTER NETWORKING:
A computer network, often simply referred to as a network, is a collection of
computers and devices connected by communications channels that
facilitates communications among users and allows users to share resources
with other users. Networks may be classified according to a wide variety of
characteristics. This article provides a general overview of types and
categories and also presents the basic components of a network.
History:
Back the beginnings of the Internet to the year 1969, when I felt and
Advanced Research Projects Agency at the Pentagon Defense Advanced
Research Projects Agency (DARPA) and the need to develop a means for the
exchange of information between the secret research institution researchers
scattered in places as far apart.
The solution was to establish a computer network linking they by four
computers, called a large network Apranet, and number of nodes of the
network is rising rapidly to become a computer 37 node.
After a brief set up another network called the military network Milnet to
follow up on military research secret, as has the U.S. National Science
National Science Foundation (NSF) in 1984, the establishment of centers of
computers high-performance supercomputers and put at the disposal of
universities to take advantage of the resources of those universities and take
advantage of these universities the capacity of supercomputers in academic
research.
There is a need then to link these centers with each other on the one hand and
universities on the other hand, it was not necessary to use the network Apranet
or equivalent for this purpose, but this use is not possible, prompting the body
to create its own network I called «Network Authority National Science
»NSFNET.
In 1987, relied on telephone lines for communication between networks instead
of a network the National Science NSF, and has since begun the process of
opening the network for users other than academics. And the increasing breadth
of this network has become even at the beginning of the nineties of the
twentieth century, a global network known today as the «Internet».
Network Devices:Network devices are components used to connect computers or other electronic
devices together so that they can share files or resources like printers or fax
machines.
1-Router
2-Switche
3-Firewall
4-Cabling
5- Network card
Router :• In packet-switched networks such as the Internet, a router is a device or, in
some cases, software in a computer, that determines the next network point to
which a packet should be forwarded toward its destination.
• The router is connected to at least two networks and decides which way to send
each information packet based on its current understanding of the state of the
networks it is connected to.
• A router is located at any gateway (where one network meets another),
including each point-of-presence on the Internet
• A router may create or maintain a table of the available routes and their
conditions and use this information along with distance and cost algorithms to
determine the best route for a given packet.
• Typically, a packet may travel through a number of network points with routers
before arriving at its destination.
• Routing is a function associated with the Network layer (layer 3) in the standard
model of network programming
IP: Internet Protocol
Short for Internet Protocol, IP is an address of a computer or other network
device on a network using IP or TCP/IP. For example, the number "166.70.10.23"
is an example of such an address.
These addresses are similar to an addresses used on a house and is what allows
data to reach the appropriate destination on a network.
There are five classes of available IP ranges: Class A, Class B, Class C, Class D and
Class E, while only A, B and C are commonly used. Each class allows for a range of
valid IP addresses.
Class
Address Range
Subnet Masking
Supports
Class A
1.0.0.1 to
126.255.255.254
255.0.0.0
Supports 16 million hosts on
each of 127 networks.
Class B
128.1.0.1 to
191.255.255.254
255.255.0.0
Supports 65,000 hosts on each
of 16,000 networks.
Class C
192.0.1.1 to
223.255.254.254
255.255.255.0
Supports 254 hosts on each of 2
million networks.
Private and Public IP Addresses
Private IP: Is IP address space for private internets (local networks):
Class A :10.0.0.0 - 10.255.255.255
Class B :172.16.0.0 - 172.31.255.255
Class C :192.168.0.0 - 192.168.255.255
Firewall :• A firewall is a set of related programs, located at a network gateway server, that
protects the resources of a private network from users from other networks.
(The term also implies the security policy that is used with the programs.)
• An enterprise with an intranet that allows its workers access to the wider
Internet installs a firewall to prevent outsiders from accessing its own private
data resources and for controlling what outside resources its own users have
access to.
• Basically, a firewall, working closely with a router program, examines each
network packet to determine whether to forward it toward its destination.
• A number of companies make firewall products. Features include logging and
reporting, automatic alarms at given thresholds of attack, and a graphical user
interface for controlling the firewall.
Switch :• In a telecommunications network, a switch is a device that channels incoming
data from any of multiple input ports to the specific output port that will take
the data toward its intended destination.
• On an Ethernet local area network (LAN), a switch determines from the physical
device (Media Access Control or MAC) address in each incoming
message frame which output port to forward it to and out of.
• In a wide area packet-switched network such as the Internet, a switch
determines from the IP address in each packet which output port to use for the
next part of its trip to the intended destination.
• In the Open Systems Interconnection (OSI) communications model, a switch
performs the Layer 2 or Data-link layer function.
Network Connection Media used in the university:-
•UTP Cable
•Fiber Optic Cable
UTP cable:• UTP cable is also the most common cable used in computer networking.
Modern Ethernet, the most common data networking standard, utilizes UTP
cables.
• Twisted pair cabling is often used in data networks for short and medium
length connections because of its relatively lower costs compared to optical
fiber and coaxial cable.
• UTP is also finding increasing use in video applications, primarily in security
cameras.
Most common cable categories
Category
Bandwidth
Applications
Notes
Cat1
0.4 MHz
Telephone and modem lines
Not described in EIA/TIA
recommmendations. Unsuitable for
modern systems.
Cat2
? MHz
Older terminal systems, e.g. IBM 3270
Not described in EIA/TIA
recommmendations. Unsuitable for
modern systems.
Cat3
16MHz
10BASE-T and 100BASE-T4 Ethernet
Described in EIA/TIA-568. Unsuitable for
speeds above 16 Mbit/s.
Cat4
20MHz
16 Mbit/s Token Ring
Cat5
100MHz
100BASE-TX & 1000BASE-T Ethernet
Cat5e
100MHz
100BASE-TX & 1000BASE-T Ethernet
Enhanced Cat5. Practically the same as
Cat5, but with better testing standards
so Gigabit Ethernet works reliably.
Cat6
250MHz
1000BASE-T Ethernet
Most commonly installed cable in
Finland according to the 2002 standard.
SFS-EN 50173-1
Cat6e
250MHz (500MHz according to some)
10GBASE-T (under
development) Ethernet
Not a standard; a cable maker's own
label.
Cat6a
500MHz
10GBASE-T (under
development) Ethernet
Standard under development (ISO/IEC
11801:2002 Amendment 2).
Cat7
600MHz
No applications yet.
Four pairs, U/FTP (shielded pairs).
Standard under development.
1000MHz
Telephone, CATV, 1000BASE-T in the
same cable.
Four pairs, S/FTP (shielded pairs, braidscreened cable). Standard under
development.
1200MHz
Four pairs, S/FTP (shielded pairs, braidUnder development, no applications yet. screened cable). Standard under
development.
Cat7a
Cat8
UTP cable:- (cont)
Optical Fiber
• Optical fiber are mainly used to transmit information over long distances and
with high bit rates. Their benefits are numerous: the signal transmitted on the
fiber is not disturbed by any electromagnetic wave created by power cables or
electric machines.
• It also provides more security, as these cables can be fully dielectric. Besides,
they provide a weight and space saving due to their small diameter, only 250
μm.
• An optical fiber is made up of three main parts: the core, the cladding and the
coating. In the center, the “core” is made of doped silica and is surrounded by
the “cladding”, made of natural silica.
• The light signal propagates along the core and the signal is reflected on the
surface between the core and the cladding.
Different fiber types
• Multimode fiber are used for Local Area Networks (LAN) where the network links
can be up to 2,000 meters. Two standard sizes of core are offered: 62.5 μm and 50
μm (with better performances). Multimode fiber have a graded index profile to
reduce the dispersion of the signal during the transmission. The high size of the
core is interesting for easy connection and does not require high cost test
equipment.
• Single mode fiber are able to transmit over longer distances. The installation is
more delicate as they have a smaller core of 9 μm. This implies more precise
connectors and test equipment.
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MT-RJ
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proxy server:• A server that sits between a client application, such as a Web browser, and a
real server. It intercepts all requests to the real server to see if it can fulfill the
requests itself. If not, it forwards the request to the real server.
• an enterprise that uses the Internet, a proxy server is a server that acts as an
intermediary between a workstation user and the Internet so that the
enterprise can ensure security, administrative control, and caching service.
• A proxy server is associated with or part of a gateway server that separates the
enterprise network from the outside network and a firewall server that
protects the enterprise network from outside intrusion.
proxy server:-
DHCP Server:• Short for Dynamic Host Configuration Protocol, a protocol for assigning
dynamic IP addresses to devices on a network.
• With dynamic addressing, a device can have a different IP address every time it
connects to the network. In some systems, the device's IP address can even
change while it is still connected. DHCP also supports a mix of static and
dynamic IP addresses.
• Dynamic addressing simplifies network administration because the software
keeps track of IP addresses rather than requiring an administrator to manage
the task. This means that a new computer can be added to a network without
the hassle of manually assigning it a unique IP address. Many ISPs use dynamic
IP addressing for dial-up users.
DHCP Server:-
DNS Server:• Short for Domain Name System (or Service or Server), an Internet service that
translates domain names into IP addresses. Because domain names are
alphabetic, they're easier to remember. The Internet however, is really based
on IP addresses.
• Every time you use a domain name, therefore, a DNS service must translate the
name into the corresponding IP address.
• For example, the domain name www.example.com might translate to
198.105.232.4
• The DNS system is, in fact, its own network. If one DNS server doesn't know how
to translate a particular domain name, it asks another one, and so on, until the
correct IP address is returned.
DNS Server:-
Thank You