Advantech ICR-1601G Configuration Manual page 162

GRE Tunnel Scenario
through the established GRE tunnel. That means the remote GRE server peer controls the flow of any
packets from the GRE client peer. Certainly, those packets come through the GRE tunnel.
If the GRE server supports DMVPN Hub function, like Cisco router as the VPN concentrator, the GRE
client can active the DMVPN spoke function here since it is implemented by GRE over IPSec tunneling.
GRE Setting
Go to Security > VPN > GRE tab.
The GRE setting allows user to create and configure GRE tunnels.
Enable GRE
Enable GRE Window
Item Value setting
Unchecked by
GRE Tunnel
default
Max. Concurrent Depends on Product
GRE Tunnels
specification.
To set up a GRE tunnel, each peer needs to
setup its global IP as tunnel IP and fill in the
other's global IP as remote IP.
Besides, each peer must further specify the
Remote Subnet item. It is for the Intranet of
GRE server peer. So, at GRE client peer, the
packets whose destination is in the
dedicated subnet will be transferred via the
GRE tunnel. Others will be transferred based
on current routing policy of the gateway at
GRE client peer. But, if you entered 0.0.0.0/0
in the Remote Subnet field, it will be treated
as a "Default Gateway" setting for the GRE
client peer, all packets, including the
Internet accessing of GRE client peer, will go
Description
Click the Enable box to enable GRE function.
The specified value will limit the maximum number of simultaneous GRE
tunnel connection. The default value can be different for the purchased
model.
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ICR-1601