Specifications
66 / 80
It is always best first to check the Network Æ Summary for existence of GPRS and VPN
interfaces in Arctics, if the Arctic GUIs are accessible.
16.2.3. Pinging the VPN peer on the other side of the tunnel
A good method of knowing that the VPN tunnel is established and the VPN peer is alive is to ping
the other end of the VPN tunnel. Use VPN peer IPs for testing.
Note: In Arctic, the ping command with only IP address as an argument will cause the Arctic to
endlessly ping the target. This is typically unwanted since the ping command may be accidentally
left running thus causing high billing for GPRS connection. Always use –c option (restrict the
count of ICMP echo messages sent) as in the following example:
In M2M GW:
ping –c5 172.16.0.2
Test 4: Test that the M2M GW is able to ping the Arctic’s VPN peer IP
In Arctic:
ping –c5 172.16.0.1
Test 5: Test that the Arctic is able to ping the M2M GW’s VPN peer IP
If the system is not properly configured, there is a danger that the target for pinging is not in the
opposite end of VPN tunnel, but there is a local host with the same IP. The local host will answer
the ping very fast (within some milliseconds) and this is a good indicator that the setup is not
correct. The ping roundtrip time over GPRS should be several hundreds of milliseconds, at least.
If respectively configured, you can also ping the hosts in Arctic’s LAN from a host in M2M GW’s
LAN (remember to check that a possible firewall in target host is not blocking the ping messages).
This will require that the routing is arranged as e.g. in the example configuration, see Figure 6:
Scenario 1, M2M GW connected with public IP address (with “Tunnel the following network”
settings).
16.2.4. Arctic LAN
If there is a LAN behind the Arctic as in the example configuration the 10.10.10.0/24 LAN, it should
be tested that the Arctic is able to connect to devices in the LAN.
In the example, there is an Ethernet device with IP 10.10.10.2. Ping the Arctic and Ethernet device
from each others. Note that if the Ethernet device is a computer, it may probably have a firewall
configured, which blocks the ICMP echo (=ping) messages. Consider shutting down the firewall or
making an exception for ICMP messages, while testing.
Test 6: Test the Arctic’s connectivity to devices in Arctic’s LAN (if present).
16.2.5. M2M GW’s WAN
The M2M GW needs an access to the Internet or another TCP/IP connected network for
establishing a VPN connection to the Arctic. Test that the M2M GW is able to ping the default
gateway of M2M GW’s eth0 (WAN) interface.
Test 7: Test the M2M GW’s connection to eth0 default gateway.
16.2.6. M2M GW’s LAN
The M2M GW may also be connected to the LAN. Typically this is the LAN where the SCADA or
other controlling/monitoring server is residing. Test the connection from SCADA server to M2M GW
by pinging the M2M GW’s eth1 LAN address (192.168.0.1 in this example configuration) from
SCADA server (192.168.0.2 in this example).