Link integrity test options

There are several link integrity tests available:

You can use these tests to demonstrate that two-way communication is working over the mobile connection. Several tests are provided because different mobile networks or firewalls may allow or block Internet packets for various services. Select the appropriate test according to the mobile network constraints and your preferences.

The link integrity tests are only performed while the mobile connection is established. If the mobile connection is disconnected, the link integrity tests are suspended until the connection is established again.

For the link integrity tests to provide meaningful results, the remote or target hosts must be accessible over the mobile connection and not through the LAN interface of the device (if it has one). That is, you should configure the settings to guarantee that the mobile connection is actually being tested.

You can modify the link integrity test settings at any time. These changes go into effect at the start of the next test interval.

Ping Test

Enables or disables the use of “ping” (ICMP) as a test to verify the integrity of the mobile connection. The test is successful if a valid ping reply is received in response to the ping request sent. The ping test sends 1 ping request and waits up to 30 pings for a reply. When a valid reply is received, the test completes successfully and immediately.

You can configure destination hosts for this test. If the first host fails to reply to the ping request, the same test is attempted to the second host. If neither host replies to any of the ping requests sent, the test fails. The primary and secondary addresses may be either IP addresses or fully qualified domain names.

TCP Connection Test

Enables or disables the creation of a new TCP connection as a test to verify the integrity of the mobile connection. A successful test establishes a TCP connection to a specified remote host and port number. If the remote host actively refuses the connection request, the test fails. The TCP connection test waits up to 30 seconds for the connection to be established or refused. When the TCP connection is established, the test completes successfully, and the TCP connection is closed immediately.

You can configure two destination hosts for this test. If the first host fails to establish (or refuse) the TCP connection, the same test is attempted to the second host. If neither host successfully establishes (or refuses) the TCP connection, the test fails. The primary and secondary addresses may be either IP addresses or fully qualified domain names.

DNS Lookup Test

nables or disables the use of a Domain Name Server (DNS) lookup as a test to verify the integrity of the mobile connection. The test is successful if the DNS server sends valid reply. Typically, this means the hostname is successfully “resolved” to an IP address by a DNS server. But even a reply such as “not found” or “name does not exist” is acceptable as a successful test result, because that demonstrates successful two-way communication over the mobile connection. When a valid reply is received, the test completes successfully and immediately.

This test uses the primary and secondary DNS server obtained from the mobile network when the PPP connection is first established. You can view these addresses on the Administration > Mobile Status page.

Note The LTE modem does not use a PPP connection.

Device Cloud Connection Test

Enables or disables verification of the Remote Manager connection. The test is successful if you can establish a connection to the configured Remote Manager server, and if you can exchange keep-alive messages with the server. The test fails if you cannot establish a connection or if keep-alive messages stop. You can configure the Remote Manager server on the Advanced Configuration > Device Cloud Connectivity page.