Wireless Wide Area Networks (Wwans); Configure Surelink Active Recovery To Detect Modem Failures - Digi IX10 User Manual

Interfaces

Wireless Wide Area Networks (WWANs)

A Wireless Wide Area Network (WWAN) provides connectivity to the internet or a remote network
through a cellular connection. A WWAN configuration consists of the following:
A cellular modem.
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Several networking parameters for the WAN, such as firewall configuration and IPv4 and IPv6
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support.
Several parameters controlling failover.
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Configure SureLink active recovery to detect modem failures

Problems can occur beyond the immediate modem connection that prevent some IP traffic from
reaching its destination. Normally this kind of problem does not cause the IX10 device to detect that
the modem 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 IX10 device to regularly probe connections through the
modem to determine if the modem connection has failed.
Required configuration items
By default, SureLink is enabled for the preconfigured Modem interface. The default
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configuration tests the DNS servers configured for the interface.
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 IX10
device to automatically recover the modem in the event that it cannot obtain an IP address.
See Configure a Wireless Wide Area Network (WWAN)
The type of tests to be performed:
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Ping test: Uses ICMP to determine connectivity. The default behavior is to ping the
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interface gateway, which means that an initial traceroute is sent to the hostname or IP
address configured in the SureLink advanced settings, and then the first hop in that route
is used for the ping test.
DNS test: Performs a DNS query to the named DNS server.
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HTTP test: Uses HTTP(s) GET requests to determine connectivity to the configured web
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server.
Test DNS servers configured for this interface: Tests communication with DNS servers
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that are either provided by DHCP, or statically configured for this interface.
Test the interface status: Tests the current status of the interface. The test fails if the
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interface is down. Failing this test infers that all other tests fail.
Custom test: Tests the interface with custom commands.
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TCP connection test: Tests that the interface can reach a destination port on the
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configured host.
Test another interface's status: Tests the status of another interface.
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The actions to take to recover connectivity in the event of failed tests:
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Change default gateway: Increases the interface's metric to change the default gateway.
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This recovery action is enabled by default for the preconfigured WWAN interface.
IX10 User Guide
Wireless Wide Area Networks (WWANs)
for details about SIM failover.
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