Tutorial:Internet
too. E commerce will drive the world's
charges whenever you connect. Unless
process requires very little adaptation
economy in the next millennium and
your ISP offers global roaming (or, like
to provide roaming access to your own
it is already a force to be reckoned with.
AOL and CompuServe, has access
virtual private network. In principle,
There seems little point in simply using
points all over the world).
you simply need to connect your own
your Web site to advertise your wares
Global roaming is a new concept,
corporate network to the Internet.
when it can also be used to actively sell
and as such you may have heard of it
Then, when working from home or
them. And if you're selling goods over
under a different name (some people
travelling, you use a local ISP to pro
the Internet, perhaps you should also
simply call it roaming service ). The
vide access to the Internet and from
be buying them. And if your company
two primary providers are iPass
there to your corporate Net. This can
is big enough, and your products and
(http://www.ipass.com) and Aim
be done with tunnelling.
needs are multifarious and repetitive,
quest's Global Reach Internet Connec
then perhaps you should be allowing
tion (http://www.aimquest.com). A
Tunnelling
both your major customers and suppli
description of the iPass service will
ers to order from and supply to your
show how it works and its value to the
Tunnelling, also known as encapsu
stock systems. It makes a lot of sense.
VPN.
lation, is not a new technology. It is the
It would be efficient and excellent for
The iPass system is actually a net
process of encapsulating or enclosing
good customer relations. This is best
work of ISPs. Provided that your own
one type of data packet (as used by
done via a virtual private network,
ISP delivers the iPass service, you can
your own LANs) inside the packet of
where major suppliers and customers
access the Internet via the nearest point
another protocol, in this case TCP/IP
(and partners and contractors) can di
of presence of any other iPass ISP any
as used by the Internet. Once the data
rectly access their accounts on your
where in the world. For example, an
has been enclosed within TCP/IP, it
systems (suitably secured, of course).
Australian user visiting the UK would
can be transmitted across the Internet.
So there is little doubt that the argu
be able to use a UK ISP offering local
But encapsulation is not all that is
ments in favour of implementing a
call dial up to get on to the Internet and
needed for a VPN. You also need user
VPN are growing. If they are not yet
thence to his own ISP to collect or send
authentication to ensure that only au
overwhelming, they soon will be.
any email. The cost would simply be
thorised users can log onto your pri
the local call charge plus any charge
vate network, and encryption to
How To Do It
levied for the service by his Australian
ensure the privacy of your data across
ISP. It would undoubtedly be cheaper
the Internet. There are many proprie
The Internet is the obvious choice of
than dialling Australia from the UK.
tary products that can help you
transmission medium because of its
The iPass system itself claims to
achieve this. Some use their own tech
universal availability. This is where
have more than 2500 Points Of Pres
nologies, but the two standards are Mi
global roaming comes in. If your ISP's
ence (POPs) in more than 150 different
crosoft's PPTP (Point to Point Tunne
only access point is in Sydney and
countries and this number is increas
lling Protocol) and Microsoft/Cisco's
you're visiting California, you are still
ing all the time. The service is transpar
L2TP (Layer 2 Tunnelling Protocol).
faced with long distance telephone
ent. You can use any platform, and can
PPTP is an extension of the remote
use the browser and email system of
access Point to Point Protocol (PPP
your own choice. Your ISP or company
which is defined and documented by
provides you with the iPass Dial Wiz
the Internet Engineering Task Force in
ard or the Microsoft Connection Man
RFC 1171). PPTP technology encapsu
ager to install on your laptop. This is a
lates PPP packets into IP datagrams for
simple client software tool that con
transmission over TCP/IP based net
tains an international phone book of
works. It is packaged with NT 4 server
iPass access numbers.
and workstation, and also within
From anywhere in the world, you
Win95's Dial Up Networking so it has
need just point and click with the iPass
the advantage of being widely avail
client software to connect to a local
able.
Internet access number. You would
Data is transmitted in IP datagrams
then log in with the same userid and
containing PPP packets. The IP data
password that you usually use, but in
gram is created using a modified ver
cluding your domain name after your
sion
of
the
Generic
Routing
userid (eg, yourname@yourdomain).
Encapsulation (GRE) protocol (GRE is
The local ISP recognises that you are an
defined in RFC 1701 and 1702). The
alien and forwards your user name
structure of the IP datagram is shown
and password (encrypted) to your
in Figure 1.
own ISP. Provided that everything is
Three systems would be involved in
correct, you are then logged on to your
such a point to point VPN: the client,
Figure 1 The structure
own ISP account.
an ISP (for the Internet), and an In
of the IP datagram.
It is relatively easy to see that this
ternet server on your private network.
File: T1807.2
Issue 97 (July 1998) page 10
PC Network Advisor
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