1.what is networking topology?
Network topology is the physical interconnections of the elements (links, nodes, etc.) of a computer network.[1][2] A local area network (LAN) is one example of a network that exhibits both a physical topology and a logical topology. Any given node in the LAN has one or more links to one or more other nodes in the network and the mapping of these links and nodes in a graph results in a geometrical shape that may be used to describe the physical topology of the network. Likewise, the mapping of the data flows between the nodes in the network determines the logical topology of the network.
2.
>Bus Topology
In local area networks where bus topology is used, each machine is connected to a single cable. Each computer or server is connected to the single bus cable through some kind of connector. A terminator is required at each end of the bus cable to prevent the signal from bouncing back and forth on the bus cable. A signal from the source travels in both directions to all machines connected on the bus cable until it finds the MAC address or IP address on the network that is the intended recipient. If the machine address does not match the intended address for the data, the machine ignores the data. Alternatively, if the data does match the machine address, the data is accepted.
Star Topology
The star topology is considered the easiest topology to design and implement. An advantage of the star topology is the simplicity of adding additional nodes. The primary disadvantage of the star topology is that the hub represents a single point of failure.
Ring Topology
In local area networks where the ring topology is used, each computer is connected to the network in a closed loop or ring. Each machine or computer has a unique address that is used for identification purposes. The signal passes through each machine or computer connected to the ring in one direction. Ring topologies typically utilize a token passing scheme, used to control access to the network. By utilizing this scheme, only one machine can transmit on the network at a time.
Mesh Topology
The value of fully meshed networks is proportional to the exponent of the number of subscribers, assuming that communicating groups of any two endpoints, up to and including all the endpoints, is approximated by Reed's Law
Tree Topology
The type of network topology in which a central 'root' node (the top level of the hierarchy) is connected to one or more other nodes that are one level lower in the hierarchy (i.e., the second level) with a point-to-point link between each of the second level nodes and the top level central 'root' node, while each of the second level nodes that are connected to the top level central 'root' node will also have one or more other nodes that are one level lower in the hierarchy (i.e., the third level) connected to it, also with a point-to-point link, the top level central 'root' node being the only node that has no other node above it in the hierarchy (The hierarchy of the tree is symmetrical.) Each node in the network having a specific fixed number, of nodes connected to it at the next lower level in the hierarchy, the number, being referred to as the 'branching factor' of the hierarchical tree
. What is OSI Layer?
- Open System Interconnection, an ISO standard for worldwide communications that defines a networking framework for implementing protocols in seven layers. Control is passed from one layer to the next, starting at the application layer in one station, proceeding to the bottom layer, over the channel to the next station and back up the hierarchy.
At one time, most vendors agreed to support OSI in one form or another, but OSI was too loosely defined and proprietary standards were too entrenched. Except for the OSI-compliant X.400 and X.500 e-mail and directory standards, which are widely used, what was once thought to become the universal communications standard now serves as the teaching model for all other protocols.
4. Examples of OSI Layer, their definition in order.
Application Layer 7
It is employed in software packages which implement client-server software. When an application on one computer starts communicating with another computer, then the Application layer is used. The header contains parameters that are agreed between applications. This header is often only sent at the beginning of an application operation.
Presentation Layer 6
This provides function call exchange between host operating systems and software layers. It defines the format of data being sent and any encryption that may be used, and makes it presentable to the Application layer.
Session Layer 5
The Session layer defines how data conversations are started, controlled and finished. The Session layer manages the transaction sequencing and in some cases authorisation. The messages may be bidirectional and there may be many of them, the session layer manages these conversations and creates notifications if some messages fail. Indications show whether a packet is in the middle of a conversation flow or at the end. Only after a completed conversation will the data be passed up to layer.
Transport Layer 4
This layer is resonsible for the ordering and reassembly of packets that may have been broken up to travel across certain media. Some protocols in this layer also perform error recovery. After error recovery and reordering the data part is passed up to layer 5.
Network Layer 3
This layer is responsible for the delivery of packets end to end and implements a logical addressing scheme to help accomplish this. This can be connectionless or connection-oriented and is independent of the topology or path that the data packets travel. Routing packets through a network is also defined at this layer plus a method to fragment large packets into smaller ones depending on MTUs for different media (Packet Switching). Once the data from layer 2 has been received, layer 3 examines the destination address and if it is the address of its own end station, it passes the data after the layer 3 header to layer 4.
Data Link Layer 2
This layer deals with getting data across a specific medium and individual links by providing one or more data link connections between two network entities. End points are specifically identified, if required by the Network layer Sequencing. The frames are maintained in the correct sequence and there are facilities for Flow control and Quality of Service parameters such as Throughput, Service Availability and Transit Delay.
Physical Layer 1
This layer deals with the physical aspects of the media being used to transmit the data. The electrical, mechanical, procedural and functional means This defines things like pinouts, electrical characteristics, modulation and encoding of data bits on carrier signals. It ensures bit synchronisation and places the binary pattern that it receives into a receive buffer. Once it decodes the bit stream, the physical layer notifies the data link layer that a frame has been received and passes it up.
What is Networking?
Networking
- In the world of computers, networking is the practice of linking two or more computing devices together for the purpose of sharing data. Networks are built with a mix of computer hardware and computer software.
6. Example of Networking, Post at least 5 examples with picture.
7. Example of networking devices and their functions, post at least 10 w/ picture.
device sitting at a network node for interfacing with another network that uses different protocols. Works on OSI layers 4 to 7.
Router: a specialized network device that determines the next network point to which to forward a data packet toward its destination. Unlike a gateway, it cannot interface different protocols. Works on OSI layer 3.
Bridge: a device that connects multiple network segments along the data link layer. Works on OSI layer 2.
Switch: a device that allocates traffic from one network segment to certain lines (intended destination(s)) which connect the segment to another network segment. So unlike a hub a switch splits the network traffic and sends it to different destinations rather than to all systems on the network. Works on OSI layer 2.
Hub: connects multiple Ethernet segments together making them act as a single segment. When using a hub, every attached device shares the same broadcast domain and the same collision domain. Therefore, only one computer connected to the hub is able to transmit at a time. Depending on the network topology, the hub provides a basic level 1 OSI model connection among the network objects (workstations, servers, etc). It provides bandwidth which is shared among all the objects, compared to switches, which provide a dedicated connection between individual nodes. Works on OSI layer 1.
Repeater: device to amplify or regenerate digital signals received while setting them from one part of a network into another.
Multilayer Switch: a switch which, in addition to switching on OSI layer 2, provides functionality at higher protocol layers.
Protocol Converter: a hardware device that converts between two different types of transmissions, such as asynchronous and synchronous transmissions.
Bridge Router(Brouter): Combine router and bridge functionality and are therefore working on OSI layers 2 and 3.
Digital media receiver: Connects a computer network to a home theatre
Hardware or software components that typically sit on the connection point of different networks, e.g. between an internal network and an external network:
Proxy: computer network service which allows clients to make indirect network connections to other network services
Firewall: a piece of hardware or software put on the network to prevent some communications forbidden by the network policy
8. Example of networking cables and their functions, post at least 10 w/ picture.
video cables
like S-Video cables, are dedicated to one task; the task of transmitting video between home theater components. These video cables look similar to composite cables in that component video cables are also split into three separate lines with RCA connectors at the ends of each.
audio cables
used to connect those components.
network adapter
These adapters connect
to a standard USB port
available on
the back of most
newer computers. In general,
USB network adapters
are not much larger
in size than PC Card adapters.
Two LED lights on
the adapter indicate
its power and network link status.
USB cable
USB to mini-USB cable
to connect between
the PC to the PSP.
Video Extension cable
is used to extend
the length
of a VGA monitor cable.
Most CRT monitors
have built-in VGA cables
which cannot be disconnected,
so this is the best way
to relocate such displays
as you need them.
Power Connector
This cable
is used
for powering
serial drives.
Serial drives,
unlike standard drives,
do not use
the four pin molex connector
that comes off
of your power supply.
This cable
converts the power supply's
four pin molex connector
to a 15 pin male serial connector,
used for powering up
the serial device.
PC Joystick Extension Cable
can be
used with
a PC's DB15
joystick port.
Male to Male
configurations
will connect
a joystick port
with the appropriate
switch box
while a Female
to Male will
extend the
existing cable.
Crossover cable
is used for
networking and
data transfer.
For use from
a DSL/cable
modem directly
to the PC and
for a direct
link from PC
to PC. All our
CAT-5E cables
are 100%
tested for
performance
and continuity
in accordance
with industry
standards.
We offer
a wide selection
of colors.
IDE cables
it is a standard type of
connection for storage devices
in a PC. Generally,
it refers to the types of
cables and ports
used to connect
some hard drives
andoptical drives
to each other
and to the
motherboard.
SATA cable
This cable is
superior in
data transfer
in that it is significantly
faster, however SATA cables
can only
be used to
connect a
single device.
Wednesday, February 10, 2010
Sunday, February 7, 2010
Subscribe to:
Posts (Atom)
