M2M
Cellular
Gateway
Index
skipping
is
used
to
reserve
slots
for
new
function
insertion,
when
required.
282
The
"Configuration"
window
is
to
enable
the
GRE
VPN
function
by
checking
the
Enable
box.
GRE
Tunnel
List
"GRE
Tunnel
List"
window
shows
all
your
defined
GRE
tunnel
profiles
and
parameters
include
Tunnel
Name,
Interface,
Operation
Mode,
IP
address
of
local
peer,
IP
address
of
remote
peer,
Key,
TTL,
if
keep
alive
or
not,
tunnel
as
the
Default
Gateway
or
specifying
the
remote
subnet
to
flow
through
the
tunnel,
and
tunnel
activation.
GRE
Rule
Configuration
"GRE
Rule
Configuration"
window
can
let
you
specify
all
parameters
for
a
GRE
VPN
tunnel.
Take
a
GRE
tunnel
between
the
gateway
in
headquarters
and
the
one
in
branch
office
as
an
example
fo
following
description.
GRE
Tunnel
at
HQ
Peer
Scenario
Application
Timing
Above
diagram
illustrates
the
security
gateway
in
headquarters
playing
the
GRE
server
role.
In
fact,
the
GRE
tunnel
establishment
can
be
started
from
either
site.
The
GRE
tunnel
is
established
by
starting
from
GRE
client,
the
Security
Gateway
2
in
Network
‐
B.
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
GRE
tunnel.
Usually,
these
hosts
at
GRE
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
GRE
tunnel.
Scenario
Description
