<s>
A	O
mediated	B-Architecture
VPN	I-Architecture
is	O
a	O
virtual	B-Application
private	I-Application
network	I-Application
topology	B-Architecture
where	O
two	O
or	O
more	O
participants	O
connect	O
to	O
a	O
central	O
switchboard	O
server	O
managed	O
typically	O
by	O
a	O
third	O
party	O
in	O
order	O
to	O
create	O
a	O
virtual	B-Application
private	I-Application
network	I-Application
between	O
them	O
,	O
as	O
distinct	O
from	O
a	O
typical	O
VPN	B-Application
arrangement	O
whereby	O
clients	O
of	O
an	O
organisation	O
connect	O
to	O
a	O
VPN	B-Application
concentrator	O
managed	O
by	O
the	O
same	O
organization	O
.	O
</s>
<s>
Typically	O
a	O
switchboard	O
server	O
(	O
referred	O
to	O
as	O
a	O
mediator	O
)	O
will	O
manage	O
several	O
VPNs	B-Application
,	O
identifying	O
each	O
individually	O
by	O
authentication	O
credentials	O
(	O
such	O
as	O
username	O
,	O
network	O
name	O
and	O
passwords	O
)	O
.	O
</s>
<s>
The	O
mediator	O
's	O
role	O
is	O
to	O
assign	O
IP	B-Protocol
addresses	I-Protocol
to	O
each	O
participant	O
in	O
a	O
VPN	B-Application
,	O
and	O
to	O
encrypt	O
data	O
through	O
the	O
switchboard	O
server	O
in	O
order	O
to	O
keep	O
it	O
secure	O
from	O
other	O
participants	O
in	O
other	O
VPNs	B-Application
.	O
</s>
