Transcript Computer Networks

Computer Networks
Coordonator: Mr. Dr. Z. Pólkowski
Siposs Arnold Konrad
Computer Network standards
Network standards are also ground rules that are set by commissions so
that hardware is compatible among similar computers and assures
interoperability. This is done to ensure that backwards compatibility and
compatibility from vendor to vendor. It is necessary to have standards
because if each company had its own protocol standards and didn't allow
it to talk with other protocols there would be a lack of communication from
different machines and would result in one company being hugely
successful and the other running out of business due to lack of being able
to communicate with other machines. So this is why its necessary to have
network standards and protocols because they are what allow different
computers from different companies running different software to
communicate with each-other making networking possible.
In this presentation is written about the LAN connection types: Token ring,
Arcnet, Ethernet and FDDI.
Source: https://sites.google.com/site/computernetworksassignment1/different-network-standards-and-protocols
Token ring
Description:
A Token Ring network is a local area network (LAN) in
which all computers are connected in a ring or star topology and
a bit- or token-passing scheme is used in order to prevent the
collision of data between two computers that want to send
messages at the same time.
Token-Ring Lan Technology was developed by IBM in the middle
1980s as a fast and reliable alternative to Ethernet.
Photo of device(MAU):
Source: http://www.trynci.com/cat/tok26.htm
Arcnet Network
Description:
Short for Attached Resource Computer network, Arcnet is one
of the oldest, simplest, and least expensive types of local-area
network. Arcnet was introduced by Datapoint Corporation in 1977. It
uses a token-ring architecture, supports data rates of 2.5Mbps, and
connects up to 255 computers. A special advantage of Arcnet is that
it permits various types of transmission media (twisted-pair
wire, coaxial cable, and fiber optic cable) to be mixed on the
same network.
Photo of device:
Source: http://www.danpex.com/products/nics/an520bt.htm
Arcnet active hub
Description:
Active hubs are much more complicated; they are powered and
contain electronics to amplify the signal and send it to other
segments of the net. They usually have eight connectors. Active
hubs come in two variants - dumb and smart. The dumb variant just
amplifies, but the smart one decodes to digital and encodes back all
packets coming through. This is much better if you have several
hubs in the net, since many dumb active hubs may worsen the
signal quality.
Photo of device:
Source: http://www.temesonline.de/index.php/en/products/arcnet-hub-8-connect
Arcnet passive hub
Description:
Passive hubs are small boxes with four BNC connectors
containing four 47 Ohm resistors.
Passive hubs cannot amplify signals. Each hub has four connectors.
Because of the characteristics of passive hubs, unused ports must
be equipped with a terminator, a connector containing a resistor that
matches the ARCnet cabling characteristics. A port on a passive hub
can only connect to an active device (an active hub or an NIC).
Passive hubs can never be connected to passive hubs.
Photo of device:
Source: http://www.cwc-group.com/pahub4p.html
Ethernet Network
Description:
Ethernet is a family of computer networking technologies
for local area network (LAN) and metropolitan area network (MAN).
It was commercially introduced in 1980 and first standardized in
1983 as IEEE 802.3 and has since been refined to support higher bit
rates and longer link distances. Over time, Ethernet has largely
replaced competing wired LAN technologies such as Token
ring,FDDI, and ARCNET. The primary alternative for contemporary
LAN is not a wired standard, but instead a wireless LAN
standardized asIEEE 802.11 and also known as Wi-Fi.
Photo of device:
Source: http://searchnetworking.techtarget.com/definition/Ethernet
Ethernet Hub
Description:
An Ethernet hub is the basic building block of a twisted-pair
Ethernet network. Hubs do little more than act as a physical
connection. They link PCs and peripherals and enable them to
communicate over a network. All data coming into the hub travels to
all stations connected to the hub. Because a hub doesn’t use
management or addressing, it simply divides the 10- or 100-Mbps
bandwidth among users. If two stations are transferring high
volumes of data between them, the network performance of all
stations on that hub will suffer.
Photo of device:
Source: http://www.elec-intro.com/cms/plus/view.php?aid=10484
Ethernet Switch
Description:
An Ethernet switch, on the other hand, provides a central
connection in an Ethernet network in which each connected device
has its own dedicated link with full bandwidth. Switches divide LAN
data into smaller, easier-to-manage segments and send data only to
the PCs it needs to reach. They allot a full 10 or 100 Mbps to each
user with addressing and management features. As a result, every
port on the switch represents a dedicated 10- or 100-Mbps pathway.
Because users connected to a switch do not have to share
bandwidth, a switch offers relief from the network congestion a
shared hub can cause.
Photo of device:
Source: http://www.ethernet-serialconverter.com/china-5_port_industrial_ethernet_switches_10_100_base_tx-457583.html
FDDI Network
Description:
FDDI stands for Fiber Distributed Data Interface. In a nutshell,
FDDI is a 100 Mbps LAN technology which can run over fiber optic
or copper cable. It is the oldest 100 Mbps network type commonly
available, and is widely used as a backbone technology to
interconnect several smaller Ethernet or Token Ring networks. It is
also used whenever high reliability and/or high speed are required
for a specific application that can extend in range up to 200 km.
Connection Diagram:
Source: http://searchnetworking.techtarget.com/definition/FDDI