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DSL is
fairly easy to distribute within a network. Indeed, an entire
industry has formed to provide devices or software for distributing
broadband access. For those networks without proxy servers,
DSL can be distributed and firewalled by software routers
such as Wingate or Sygate; or DSL hardware router boxes such
as the Infinilink 1500, or the Linksys BEFSR41, can be used.
The current price point for the Infinilink or Linksys devices
are $150. Upgrading to the server level, a number of DSL-ready
server appliances, such as the Cobalt Qube or IBM Whistle
InterJet are available in the $1,500-1,800 range. All these
solutions utilize NAT (Network Address Translation) to allow
the distribution of private IPs through a network, while using
only one public IP address from the ISP.
First
of all, let's go over what your DSL connection looks like
from the outside:
A. Over
the Wire: At the other end of the phone line--18,000 feet
away at most--is another ADSL modem, located at the phone
company's central office. This modem also has a POTS splitter,
which separates the voice calls from the data.
B. Telephone
Calls: Voice calls are routed to the phone company's public
switched telephone network (PSTN) and proceed on their way
as usual.
C. Internet
Requests: Data coming from your PC passes from the ADSL modem
to the digital subscriber line access multiplexer (DSLAM).
The DSLAM links many ADSL lines to a single high-speed asynchronous
transfer mode (ATM) line, which in turn connects to the Internet
at speeds up to 1Gbps.
D. Back
at You: The data you request is retrieved from the Internet
and routed back through the DSLAM and ADSL modem at the phone
company's central office before coming back to your PC.
Here is
a non-networked DSL configuration:
At the
most basic level, you can establish a working home network
using Windows ICS, or Internet Connection Sharing. ICS is
a simplistic version of more robust software routers such
as Wingate or Sygate, and isn't much good in our experience
beyond 2-3 workstations--but it does have the virtue of being
free, as it comes bundled with Windows. This configuration
requires a classic server/client, or "master/slave"
relationship.
The Pros
of this configuration is low cost. The Cons are that it isn't
much good for more than a few PCs, is very slow, and the worst
- if the master PC goes offline for any reason (turned off
for the night, needs repair, etc.), the rest of the network
is offline as well.
In order
to be "online," every computer needs an IP (Internet
Protocol) address. Your ISP usually gives only one IP address
without additional charge. To continue to use the one free
IP that comes with your DSL account and still give IP addresses
to all the PCs in your network, you need a router of some
kind. ISPs usually provide public IP addresses either as dynamic
(non-routable), or static. Both dynamic and static IPs are
networkable, and generally a static IP is only required for
advanced customer services such as a mail server on the customer's
site, or an HTTP (Web) servier ont he DSL line.
To move
to the next level, then, requires a software router such as
Wingate
or Sygate.
Such routers are shareware and sell in the $50/single user
range.
Software
routers provide what is called NAT, or Network Address Translation,
to give each workstation in your network its own "private"
IP address, while still using the one "public" IP
address (that is, visible to the Internet) you ISP gives you.
This enables you to connect up to 255 workstations in your
network with Net access from one connection. NAT also provides
a firewall to help keep out unwanted visitors from your always-on
Internet connection.
For more
details on NAT, check out the NAT
Page here
The Pros
of this configuration are relatively low cost and more sophisticated
features. The Cons are that such software tends to be more
complicated for the user unfamiliar with networks, and doesn't
solve the "master/slave" problem. One PC is still
in charge of the others.
The best
overall method for distributing broadband access across a
network is the hardware router. The hardware provides all
the services of a software router, including NAT, firewall,
and sophistication, but also adds ease of setup and the elimination
of the master/slave problem. They don't add much to the cost,
either--about $150-$180.
While
there are many brands of hardware routers, we recommend three:
The Infinilink
i500
The Linksys
BEFSR41
The Ugate-
3000
Or, if
you prefer a wireless LAN:
The Linksys
BEFW11S4
The BuffaloTech
WLAR-L11-L
Please
contact us for additional consultation if you're new to networking.
We will help you develop a configuration that is right for
you.
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