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Interfaces
Active detection uses Digi SureLink
n
the status of the interface. The WAN/WWAN is considered to be down if there are no responses
for a configured amount of time. See
failures
for more information about active failure detection.
Passive detection involves detecting the WAN going down by monitoring its link status by some
n
means other than active detection. For example, if an Ethernet cable is disconnected or the
state of a cellular interface changes from on to off, the WAN is down.
Default Digi SureLink configuration
Beginning with firmware version 20.2.x, Surelink is enabled by default for IPv4 on all WAN and WWAN
interfaces, and is configured to perform two tests on these interfaces:
Interface connectivity.
n
DNS query to the DNS servers for interface's the network connection.
n
DNS servers are typically received as part of the interface's DHCP client connection, although
you can manually configure the DNS servers that will be used by SureLink.
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 Mini
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 Mini 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 Mini 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 (ETH) and WWAN (Modem). It is disabled for IPv6.
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.
Digi Connect IT® Mini User Guide
TM
technology to send probe tests to a target host or to test
Configure SureLink active recovery to detect WAN/WWAN
Wide Area Networks (WANs)
45
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