2.1 The OSI Model
*NOTE*
The OSI model graphical explanation is available at this link
http://www.4shared.com/file/37894066/
cbcacee0/The_OSI_Model__1_.html
2.2 Networking Devices
Internetworking devices offer communication between
local area network (LAN) segments. There are five
primary types of internetworking devices:
repeaters, bridges, routers, brouters, and gateways.
The OSI layer at which they establish the LAN-to-LAN
connection can differentiate these devices very generally.
Each device offers the functionality found at its layer(s)
of connection and uses the functionality of all lower layers.
-Repeater (Physical) A network device used to regenerate or
replicate a signal. Repeaters are used in transmission systems
to regenerate analog or digital signals distorted by
transmission loss. Analog repeaters frequently can
only amplify the signal while digital repeaters can
reconstruct a signal to near its original quality.
In a data network, a repeater can relay messages
between subnetworks that use different protocols or
cable types. Hubs can operate as repeaters by
relaying messages to all connected computers. A
repeater cannot do the intelligent routing performed
by bridges and routers.
-Bridge (Data Link) A device that connects two
local-area networks (LANs), or two segments of
the same LAN .
The two LANs being connected can be alike or
dissimilar. For example, a bridge can connect an
Ethernet with a Token-Ring network.
Unlike routers, bridges are protocol independent.
They simply forward packets without analyzing and
re-routing messages. Consequently, they're faster
than routers, but also less versatile.
-Router (Network) A device that connects two LANs.
Routers are similar to bridges, but provide additional
functionality, such as the ability to filter messages
and forward them to different places based on
various criteria.
The Internet uses routers extensively to forward
packets from one host to another.
Brouter Data Link/Network Short for bridge router,
a device that functions as both a router and a bridge.
A brouter understands how to route specific types of packets,
such as TCP/IP packets. Any other packets it receives are
simply forwarded to other network(s) connected to
the device (this is the bridge function).
-Gateway (Top 4 layers) In networking, a combination of
hardware and software that links two different types of networks.
Gateways between e-mail systems, for example,
allow users on different e-mail systems to exchange
messages.
The Open System Interconnection (OSI) Model is a seven
layer model that helps designers of network operating
systems and software to create relatively standardized software.
This is useful when trying to get different operating systems to talk
to each other. Although the model is only a blueprint, it is
almost universally followed.
layer model that helps designers of network operating
systems and software to create relatively standardized software.
This is useful when trying to get different operating systems to talk
to each other. Although the model is only a blueprint, it is
almost universally followed.
*NOTE*
The OSI model graphical explanation is available at this link
http://www.4shared.com/file/37894066/
cbcacee0/The_OSI_Model__1_.html
2.2 Networking Devices
Internetworking devices offer communication between
local area network (LAN) segments. There are five
primary types of internetworking devices:
repeaters, bridges, routers, brouters, and gateways.
The OSI layer at which they establish the LAN-to-LAN
connection can differentiate these devices very generally.
Each device offers the functionality found at its layer(s)
of connection and uses the functionality of all lower layers.
-Repeater (Physical) A network device used to regenerate or
replicate a signal. Repeaters are used in transmission systems
to regenerate analog or digital signals distorted by
transmission loss. Analog repeaters frequently can
only amplify the signal while digital repeaters can
reconstruct a signal to near its original quality.
In a data network, a repeater can relay messages
between subnetworks that use different protocols or
cable types. Hubs can operate as repeaters by
relaying messages to all connected computers. A
repeater cannot do the intelligent routing performed
by bridges and routers.
-Bridge (Data Link) A device that connects two
local-area networks (LANs), or two segments of
the same LAN .
The two LANs being connected can be alike or
dissimilar. For example, a bridge can connect an
Ethernet with a Token-Ring network.
Unlike routers, bridges are protocol independent.
They simply forward packets without analyzing and
re-routing messages. Consequently, they're faster
than routers, but also less versatile.
-Router (Network) A device that connects two LANs.
Routers are similar to bridges, but provide additional
functionality, such as the ability to filter messages
and forward them to different places based on
various criteria.
The Internet uses routers extensively to forward
packets from one host to another.
Brouter Data Link/Network Short for bridge router,
a device that functions as both a router and a bridge.
A brouter understands how to route specific types of packets,
such as TCP/IP packets. Any other packets it receives are
simply forwarded to other network(s) connected to
the device (this is the bridge function).
-Gateway (Top 4 layers) In networking, a combination of
hardware and software that links two different types of networks.
Gateways between e-mail systems, for example,
allow users on different e-mail systems to exchange
messages.
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