Networks
·
ADSL Broadband
(Asymmetric
Digital Subscriber Line)
ADSL broadband is a connection
provided over home telephone lines. BT owns all of the UK's landline cables, so
when you have an ADSL connection you need to pay BT for your phone line. If you
already have an existing phone line, the broadband is added onto the package
and has to be paid monthly.
·
ISDN
Integrated Services for Digital
Network (ISDN) is a set of communication devices for digital communication of
voice, video, data, and other forms of data over the traditional circuits of
the public switched telephone network. It was first defined in 1988 in the
CCITT red book.
·
Packet switches
Packet switching is a networking method
that groups all transmit data – regardless of content, type, or structure.
Packet-switched networks
move data in different, small blocks ‘packets’ based on the destination address
in each packet. When received, packets are put together in the proper sequence
to make up the message.
Wireless Access protocol
Wireless Application Protocol (WAP)
is a technical standard for accessing information over a mobile device
wirelessly. A WAP browser is a web browser for mobile devices such as mobile
phones and tablets that uses the protocol.
Benefits
·
Broadband:
A broadband connection is "always on"
You do not have to wait for dial-up connectivity if
you use the same route to the Internet. This means that you are able to get on
the internet quicker and as a result be more productive without having to wait
for a connection.
·
As
broadband comes at a fixed price, you can budget effectively.
Many websites now contain different types of media. This
means that they don't just have large amounts of writing and limited images,
but have interactive features like streaming sound and video and other media.
They are designed to be used via broadband connection.
Packet
Switches:
·
It makes very effective and quick use of the network -
no tied-up lines.
·
It can easily get around broken sections of the network.
·
As customers increase, the network can be expanded
slowly compared to circuit switching that has to be done quickly.
ISDN:
·
Like the telephone network you only pay for the time
you use during your phone call, and a monthly access charge.
·
Switched service flexibility meaning you can change
provider much easier.
·
ISDN is an update of the public telephone network it
is a switched service. You can call anyone who has ISDN access in any country.
You can also make standard voice calls on the telephone network, or data calls
to people who use modems.
·
ISDN calls are digital from end to end, so you get
higher speeds, quality of sound and reliability of the signal being sent and
faster call set-up than on the telephone network.
·
A single access line can carry voice, image, data and
video applications.
·
Perfect for video conference calls with both quality
service and the high transmission speeds required for video.
·
WAP opens a host of opportunities for carriers to
generate on-going revenue streams, secure customer loyalty and develop unique
services that will allow differentiation from the competition.
·
One worldwide standard that is device-independent and
bearer-independent assures developers of a broad, ever-expanding market for
content and applications.
·
The increasing popularity of WAP will generate
tremendous demand for new devices to accommodate WAP's capabilities, new
infrastructure to handle the increased demands on operator's systems and more
gateways to handle the information flow between Internet and wireless operator
networks.
·
WAP offers an easy-to-use and highly portable
communications and information tool. Devices using WAP-based micro browsers can
access an array of innovative, value-added services, which are rapidly coming
to market.
When/Where?
· ADSL
o When: ADSL
broadband should be used when there is no separate internet connection in the
area or if you have a phone package with the provider.
o Where: ADSL
broadband can be used in homes across the UK, but quality can drop the further
from a telephone exchange you are.
·
ISDN
o When: ISDN
Can be used if a faster internet connection is required, offering up to double
the speeds of a standard connection.
o Where: ISDN
is commonly used in urban areas in the USA and Europe, ISDN is not recommended
in rural areas.
·
Packet
Switches
o When:
Packet switches are better used in businesses which send and receive lots of
data and need to space it out to avoid slowing the network when large amounts
of data is sent.
o Where: In
businesses which send and receive large amounts of data through a bottlenecked
system
·
Wireless
Access Protocol
o When:
Wireless Access Protocol is used to convert standard web pages to be viewed on
mobile devices like a phone, IPod or tablet which has access to the internet
o Where: In
public places like stations or airports, where there are no desktop PCs
available for use
Limitations
·
Packet
switches
o The time to
do the process changes every time.
o Not good to
carry small data packages.
o The data
has to be reassembled again.
·
ISDN
o It is very
expensive than a telephone system.
o It requires
specialised devices to do this.
o This is
slow when compared to newer technology.
·
Wireless
Access Protocol
o Low
bandwidth
o Small
displays, mostly monochrome
o Limited
memory
o Can’t use
it to transfer large amounts of data
o It is
expensive to use
·
ASDL
o Signal
strength decreases with distance
o Can’t
handle VPN (Virtual Private Networking) very well, but it will work.
o Not good
for things like web conferences
References
ADSL diagram: http://www.freezone.co.uk/images/adsl.jpg
ISDN network diagram: http://www.hw-server.com/obrazek/network_topology
Packet Switch diagram: http://www.dcs.bbk.ac.uk/~mick/academic/networks/bsc/data-link-layer/wan-technology/packet-switch.gif
Wireless Access Protocol diagram: http://www.althos.com/sample_diagrams/ag_WML_WAP_Server_Operation_low_res.jpg
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