By far this is the simplest form of addressing, as the numbers remain static and generally
remain with a subscription for a long time. I am sure you are well accustomed
to telephone numbers and how they are used within the switched network, so we won??™t
go into a lot of detail here.
One thing I will mention here about telephone numbers concerns security and authentication.
In a fixed-line network, authentication takes place when the subscriber
orders telephone service. There is no need, therefore, for the network to know if the
subscriber is legitimate; the line is associated with a subscription and a fixed physical
address. The wiring used to connect to the subscriber address further ensures that the
subscription need not be authenticated. The wiring always goes to the same address
used when the service was ordered.
This is not the case with IP. A subscriber may be using his or her laptop to access the
network from anyplace; therefore, it is impossible to ascertain if the user accessing the
network is the same user associated with the subscription being used. Authentication
is a challenge in these networks.
The physical address is dynamic, assigned by the access network when the subscriber
connects to the Internet (or to the local IP network). This means that the identity of the
subscriber cannot be authenticated without additional mechanisms where credentials
can be exchanged between the network and the subscriber device.
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