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Interfaces
Note
If your device is operating on a private APN or on wired network with firewall restrictions,
ensure that the DNS servers on your private network allow DNS lookups for
my.devicecloud.com; otherwise, the SureLink DNS query test will fail and the Connect IT 16/48
device will determine that the interface is down.
By default, these tests will be performed every 15 minutes, with a response timeout of 15 seconds. If
the tests fail three consecutive times, the device will reset the network interface to attempt to
recover the connection.
Configure SureLink active recovery to detect WAN/WWAN failures
Problems can occur beyond the immediate WAN/WWAN connection that prevent some IP traffic from
reaching its destination. Normally this kind of problem does not cause the Connect IT 16/48 device to
detect that the WAN has failed, because the connection continues to work while the core problem
exists somewhere else in the network.
Using Digi SureLink, you can configure the Connect IT 16/48 device to regularly probe connections
through the WAN to determine if the WAN has failed.
Required configuration items
Enable SureLink.
n
SureLink can be enabled for both IPv4 and IPv6 configurations. By default, SureLink is enabled
for IPv4 for the preconfigured WAN (ETH1) and WWAN (WWAN). It is disabled for IPv6.
When SureLink is configured for Wireless WANs, SureLink tests are only run if the cellular
modem is connected and has an IP address. Use the SIM failover options to configure the
Connect IT 16/48 device to automatically recover the modem in the event that it cannot obtain
an IP address. See
failover.
The type of probe test to be performed, either:
n
Ping: Requires the hostname or IP address of the host to be pinged.
l
DNS query: You can perform a DNS query to a named DNS server, or to the DNS servers
l
configured for the WAN.
HTTP or HTTPS test: Requires the URL of the host to be tested.
l
Interface status: Determines if the interface has an IP address assigned to it, that the
l
physical link is up, and that a route is present to send traffic out of the network interface.
The preconfigured WAN is configured by default to use SureLink to both test the interface
status and perform a test DNS query.
Additional configuration items
The behavior of the Connect IT 16/48 device upon test failure:
n
The default behavior, which is to fail over to the next priority WAN/WWAN.
l
Restart the WAN interface.
l
Reboot the device.
l
The interval between connectivity tests.
n
The number of probe attempts before the WAN is considered to have failed.
n
Digi Connect IT® 16/48 User Guide
Configure a Wireless Wide Area Network (WWAN)
Wide Area Networks (WANs)
for details about SIM
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