Digi TX54, User Manual

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Interfaces Wide Area Networks (WANs)
TX54 User Guide 64
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 TX54 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 TX54 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 TX54 device to regularly probe connections through the
WAN to determine if the WAN has failed.
Required configuration items
n
Enable SureLink.
SureLink can be enabled for both IPv4 and IPv6 configurations. By default, SureLink is enabled
for IPv4 for the preconfigured WAN (
WAN1 ) and WWANs ( WWAN1 and, for dual-cellular models,
WWAN2 ). 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
TX54 device to automatically recover the modem in the event that it cannot obtain an IP
address. See
Configure a Wireless Wide Area Network (WWAN) for details about SIM failover .
n
The type of probe test to be performed, one of:
l
Test another interface's status: Used to create a failover or coupled relationship between
two interfaces. Requires the name of the alternate interface, the IP version to be tested,
and the expected status of the alternate interface (either up or down).
l
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
configured for the WAN.
l
HTTP test: Requires the URL of the host to be tested.
l
Test DNS servers configured for this interface: Tests communication with this interface's
DNS servers that are either provided by DHCP, or statically configured.
l
Interface status: Determines if the interface has an IP address assigned to it, that the
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
n
The behavior of the TX54 device upon test failure:
l
The default behavior, which is to restart the interface and fail over to the next priority
WAN/WWAN.