Image Processing Reference
In-Depth Information
19.4
ISDN Connections
The next advance in performance beyond the 56K modems is an ISDN line. This is a
digital connection using the same cables as a 56K modem, but the equipment at the
exchange needs to be configured properly. You also have to have an ISDN termination at
your premises.
ISDN delivers a dual-channel connection. This provides two simultaneous 64K bit
streams, although each connection is charged as a separate call. Therefore, if you duplex
them to get a 128K connection you will be charged twice as much. But then your call will
last half as long. This is good for when you have a large, bulky file to transfer but not great
if you normally only make short calls. ISDN includes voice circuits as well.
It is a good idea to connect a router to an ISDN line so that all your systems can share
the connection. This can form the basis of your office network because it will probably
have an integral network hub. The other major benefit is that it can block incoming con-
nections and act as a barrier to virus infections.
19.5
Broadband Connections
Broadband technologies provide novel and sometimes more effective solutions to propo-
sitions that previously required a broadcast infrastructure. The peer-to-peer distribution
model is an example that is normally only suited to downloading files. The protocols
could be extended to pass on a stream as long as the connectivity is assured. One feed
could be delivered to a household and the receiver could route it onward through the local
LAN to multiple client players. This model would also work for schools, hospitals, cam-
pus settings, and corporate environments.
Using a router to share a broadband connection is a good thing to do. Like the ISDN
router/hub concept, hardware is available for broadband connections with all the same
advantages of sharing and virus protection if the router is properly configured.
Fast network connections like this are beginning to be tested by companies such as
Netflix and TiVo, which are both perfectly positioned to take advantage of networked
rentable video as a commercial possibility. This might result in services being offered to
the public during 2005 or 2006.
Be wary of running beta versions of software unless they provide features
that you absolutely MUST have.
This kind of networking is also where the IPTV services will grow from. Prototype
H.264 set-top boxes are already in evidence, as seen at the National Association of
Broadcasters conference in 2004. The DG2L Neuron and the MediaReady 4000 unit are
typical examples.
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