M2M
Cellular
Gateway
Index
skipping
is
used
to
reserve
slots
for
new
function
insertion,
when
required.
260
Scenario
Application
Timing
Above
diagram
illustrates
the
Security
Gateway
2
or
the
mobile
device
playing
the
PPTP
VPN
client
role.
The
PPTP
tunnel
is
established
by
the
PPTP
client
making
the
tunnel
connection
request
initiation
and
the
Security
Gateway
1
in
Network
‐
A
of
headquarters
serves
as
the
PPTP
VPN
server
responding
to
the
request.
Once
the
tunnel
has
been
established,
all
client
hosts
behind
the
Security
Gateway
2
or
the
mobile
device
can
access
the
resources
in
the
Intranet
of
Network
‐
A
at
headquarters
via
this
established
PPTP
tunnel.
Usually,
these
hosts
at
PPTP
client
peer
access
the
Internet
directly
via
the
WAN
interface
of
Security
Gateway
2.
Only
the
packets
whose
destination
is
in
the
dedicated
subnet
to
Network
‐
A
will
be
transferred
via
the
PPTP
tunnel.
But
if
PPTP
client
peer
is
configured
to
all
packets
are
delivered
via
the
PPTP
tunnel,
as
shown
in
the
diagram
by
configuring
the
PPTP
tunnel
is
the
default
gateway
at
PPTP
client
peer,
the
Internet
accessing
packets
will
be
also
sent
to
the
Security
Gateway
1
in
Network
‐
A
and
be
re
‐
transferred
to
the
Internet.
That
means
the
Internet
accessing
of
PPTP
Client
peer
is
also
controlled
by
the
Security
Gateway
1,
the
PPTP
VPN
server.
Scenario
Description
PPTP
Tunneling
is
a
Client
and
Server
based
tunneling
technology.
