Hello and thank you for your question.
As you probably know, the International Standards Organization (ISO)
Open Systems Interconnect (OSI) is a standard set of rules describing
the transfer of data between each layer in a network operating system.
Each layer has a specific function.
The OSI Model defines the interfaces between each layer. This allows
different network operating systems and protocols to work together by
having each manufacturer adhere to the standard interfaces. There are
seven layers in the OSI model:
· 7. Application Layer (Top Layer)
· 6. Presentation Layer
· 5. Session Layer
· 4. Transport Layer
· 3. Network Layer
· 2. Data Link Layer
· 1. Physical Layer (Bottom Layer)
http://www.thelinuxreview.com/howto/intro_to_networking/index.lxp?lxpwrap=x150%2ehtm
There are many good diagrams for the OSI 7-layer model that you can
access and reproduce from the Internet. You can use the diagram and
related explanation presented at:
Network Data Transmission, and the OSI model
http://www.hub-tech.net/article1.html
The diagram that goes with this article appears alone at
http://www.hub-tech.net/osi.gif
To match the device to the layer, you need to consider the job that
the device does.
See:
http://www.itexamprep.com/china/cisco/article/o_device.htm
and also
http://www.geocities.com/SiliconValley/Monitor/3131/ne/osimodel.html
And here are the answers:
a.) Hub
The hub operates at the Physical layer of the OSI model.
The physical layer:
*transmits raw bit stream over physical cable
*defines cables, cards, and physical aspects
*defines NIC attachments to hardware, how cable is attached to NIC
*defines techniques to transfer bit stream to cable
A hub does not have any processing power, it's just a box where you
plug cables.
b.) Repeater
Like hubs, repeaters operate at the Physical layer of the OSI model.
Repeaters are physical hardware devices. They have a primary function
to regenerate the electrical signal by reshaping the waveform,
amplifying the waveform and retiming the signal.
c.) switch
A switch works at the Datalink layer of the OSI model.
The Datalink layer:
*turns packets into raw bits 100101 and at the receiving end turns
bits into packets.
*handles data frames between the Network and Physical layers
*defines the methods used to transmit and receive data on the
network.
A switch examines the destination MAC addresses of the packer to
decide where the packet should be forwarded. By doing that, the data
is not broadcasted to all computers on the segment. Using the switch
dramatically reduces the broadcast traffic and saves the bandwidth.
d.) bridge
A bridge also works at the Datalink layer of the OSI model.
A bridge segments a network and reduces network traffic by examining
the source and destination hardware address of the packet.
e.) gateway
A gateway principally operates at the application layer of the OSI
model, although it can also be found at other layers.
The application layer:
*is used for applications specifically written to run over the
network
*allows access to network services that support applications;
*directly represents the services that directly support user
applications
*handles network access, flow control and error recovery
A gateway connects networks with different protocols like TCP/IP
network and IPX/SPX networks. Email gateways are used to connect
different email systems. Gateways operate at layers above the network
layer of the OSI model Email
f.) Router
Routers operate at the Network layer of the OSI model.
The network layer translates logical network address and names to
their physical address and is responsible for
*addressing
*determining routes for sending
*managing network problems such as packet switching, data
congestion and routing
Routers route packets to remote networks by examining the packet's
network source and destination address. The destination address of the
packet must match an entry in the routing table of the router;
otherwise, the packet is discarded.
Search terms used:
"osi model" hub layer
hub "physical layer" osi
Thank you again for giving me the chance to help you with this
material.
If you find any of my answer unclear, please request clarification. I
would appreciate it if you would hold off on rating my answer until I
have a chance to reply.
Sincerely,
Google Answers Researcher
Richard-ga |
