MCSE : Security Specialist
Identify the basic characteristics (e.g., speed, capacity, media)
of the following WAN technologies:
Packet switching vs. circuit switching
WAN
technologies use either circuit switching or packet switching as a
connection method.
With
circuit switching, data travels over a fixed path that is
established at the beginning of the connection and remains open
until the connection is terminated. A telephone call is an example
of a circuit switched link. When you dial a number the
telecommunication provider, establishes an open circuit between your
phone and the phone of the person you are calling. No other calls
can be placed over this circuit until you hang up.
Packet switching offers more efficient use of a telecommunication
provider's network bandwidth. With packet switching, the switching
mechanisms on the network route each data packet from switch to
switch individually over the network using the best-available path.
Any one physical link in a packet-switched network can carry packets
from many different senders and for many different destinations.
Where as in a circuit switched connection, the bandwidth is
dedicated to one sender and receiver only.
ISDN
Integrated Services Digital Network adapters can be used to send
voice, data, audio, or video over standard telephone cabling. ISDN
adapters must be connected directly to a digital telephone network.
ISDN adapters are not actually modems, since they neither modulate
nor demodulate the digital ISDN signal.
Like
standard modems, ISDN adapters are available both as internal
devices that connect directly to a computer's expansion bus and as
external devices that connect to one of a computer's serial or
parallel ports. ISDN can provide data throughput rates from 56 Kbps
to 1.544 Mbps using a T1 service.
ISDN
hardware requires a NT (network termination) device, which converts
network data signals into the signaling protocols used by ISDN. Some
times, the NT interface is included, or integrated, with ISDN
adapters and ISDN-compatible routers. In other cases, an NT device
separate from the adapter or router must be implemented.
ISDN
works at the physical, data link, network, and transport layers of
the OSI Model.
|
