Check Accessibility Control

This scenario shows how to configure a cellular interface, enabling the accessibility control mechanism that triggers reconnections when network connectivity is lost.

Test Reconnection By Accessibility Control

Description

In DUT0, the cell0 cellular interface is configured with a cellular profile for which accessibility control is enabled. Once connectivity with Google’s DNS public server has been verified, a situation where 100% of the packets received by the network are lost is emulated to verify that the accessibility control mechanism triggers a reconnection.

Scenario

Step 1: Set the following configuration in DUT0 :

set cellular logging level info
set cellular profile CELPROFILE accessibility-control ping address 8.8.8.8
set cellular profile CELPROFILE accessibility-control ping interval 10
set cellular profile CELPROFILE apn movistar.es
set interfaces cellular cell0 address dhcp
set interfaces cellular cell0 encrypted-pin U2FsdGVkX1/pqvj0fS0Z07XkHlwWfg2Ta+2zsFxm5PA=
set interfaces cellular cell0 profile CELPROFILE
set system login user admin authentication encrypted-password '$6$GSjsCj8gHLv$/VcqU6FLi6CT2Oxn0MJQ2C2tqnRDrYKNF8HIYWJp68nvXvPdFccDsT04.WtigUONbKYrgKg8d6rEs8PjljMkH0'

Note

Once the cellular interface is configured, it can be verified that there is network connectivity by pinging Google’s DNS public server.

Step 2: Ping IP address 8.8.8.8 from DUT0:

admin@DUT0$ ping 8.8.8.8 count 1 size 56 timeout 1

Note

The accessibility control is a mechanism where pings are sent at an interval, and to the IP address, configured by the user. The mechanism then waits for a response within this interval. If no response is received before it times out, a second ping is sent and a response is expected within 10 seconds. If there is still no response, two more pings are sent at 5-second intervals. Finally, if there is still no response, the device reconnects to the network.

Note

As a result, you can verify that no reconnection has been recorded in the system logs if you wait long enough.

Step 3: Run command system journal clear at DUT0.

Step 4: Run command system journal show | cat at DUT0 and check if output does not contain the following tokens:

[Core/cell0] Info: Signal '12' received to reconnect device
[Device/cell0] Info: Stopping network connection
[Device/cell0] Info: Establishing network connection

Note

However, when traffic control is applied, it is possible to prove the ‘ping’ command is failing because ICMP packets are being dropped.

Step 5: Modify the following configuration lines in DUT0 :

set interfaces cellular cell0 traffic control in PLOSS
set traffic control PLOSS type network-emulator packet-loss 100

Step 6: Expect a failure in the following command: Ping IP address 8.8.8.8 from DUT0:

admin@DUT0$ ping 8.8.8.8 count 1 size 56 timeout 1

Note

You can verify that a reconnection has been recorded in the system logs if you wait long enough.

Step 7: Run command system journal clear at DUT0.

Step 8: Run command system journal show | cat at DUT0 and check if output does not contain the following tokens:

[Core/cell0] Info: Signal '12' received to reconnect device
[Device/cell0] Info: Stopping network connection
[Device/cell0] Info: Establishing network connection

Step 9: Run command system journal show | cat at DUT0 and check if output contains the following tokens:

[Core/cell0] Info: Signal '12' received to reconnect device
[Device/cell0] Info: Stopping network connection
[Device/cell0] Info: Establishing network connection

Show output

Mar 14 16:20:55.080024 osdx systemd-journald[23576]: Runtime Journal (/run/log/journal/07899dbd53234fe1814fb1b6c546c242) is 1.0M, max 8.5M, 7.4M free.
Mar 14 16:20:55.082220 osdx systemd-journald[23576]: Received client request to rotate journal, rotating.
Mar 14 16:20:55.082414 osdx systemd-journald[23576]: Vacuuming done, freed 0B of archived journals from /run/log/journal/07899dbd53234fe1814fb1b6c546c242.
Mar 14 16:20:55.172056 osdx OSDxCLI[508887]: User 'admin' executed a new command: 'system journal clear'.
Mar 14 16:21:03.674834 osdx cfgd[1317]: Could not parse bandwidth for traffic-control network-emulator 'PLOSS'
Mar 14 16:21:13.740546 osdx cfgd[1317]: Could not parse bandwidth for traffic-control network-emulator 'PLOSS'
Mar 14 16:21:15.421993 osdx OSDxCLI[508887]: User 'admin' executed a new command: 'system journal show | cat'.
Mar 14 16:21:15.689998 osdx OSDxCLI[508887]: User 'admin' executed a new command: 'system journal show | cat'.
Mar 14 16:21:16.973993 osdx OSDxCLI[508887]: User 'admin' executed a new command: 'system journal show | cat'.
Mar 14 16:21:18.230030 osdx OSDxCLI[508887]: User 'admin' executed a new command: 'system journal show | cat'.
Mar 14 16:21:19.517996 osdx OSDxCLI[508887]: User 'admin' executed a new command: 'system journal show | cat'.
Mar 14 16:21:20.798011 osdx OSDxCLI[508887]: User 'admin' executed a new command: 'system journal show | cat'.
Mar 14 16:21:22.121997 osdx OSDxCLI[508887]: User 'admin' executed a new command: 'system journal show | cat'.
Mar 14 16:21:23.425992 osdx OSDxCLI[508887]: User 'admin' executed a new command: 'system journal show | cat'.
Mar 14 16:21:23.806591 osdx cfgd[1317]: Could not parse bandwidth for traffic-control network-emulator 'PLOSS'
Mar 14 16:21:24.296306 osdx wwan-module[510348]: [Core/cell0] Info: Signal '12' received to reconnect device.
Mar 14 16:21:24.296357 osdx wwan-module[510348]: [Device/cell0] Info: Stopping network connection...
Mar 14 16:21:24.314483 osdx wwan-module[510653]: Network cancelled... releasing resources
Mar 14 16:21:24.447086 osdx wwan-module[510653]: [/dev/cdc-wdm0] Network stopped
Mar 14 16:21:24.447086 osdx wwan-module[510653]: [/dev/cdc-wdm0] Client ID not released:
Mar 14 16:21:24.447086 osdx wwan-module[510653]:         Service: 'wds'
Mar 14 16:21:24.447086 osdx wwan-module[510653]:             CID: '21'
Mar 14 16:21:24.448939 osdx wwan-module[510348]: [Device/cell0] Info: Network connection was stopped!
Mar 14 16:21:24.451003 osdx wwan-module[510348]: [Network/cell0] Info: Stopping accessibility control...
Mar 14 16:21:24.451554 osdx wwan-module[510348]: [Device/cell0] Info: Accessibility control was stopped!
Mar 14 16:21:24.452717 osdx kernel: net cell0: link_state 0x1 -> 0x0
Mar 14 16:21:24.465926 osdx dhclient[510412]: receive_packet failed on cell0: Network is down
Mar 14 16:21:24.466226 osdx modulelauncher[510660]: stop DHCP client for cell0
Mar 14 16:21:24.467869 osdx wwan-module[510348]: [Device/cell0] Info: Establishing network connection...
Mar 14 16:21:24.476140 osdx dhclient[510665]: Killed old client process
Mar 14 16:21:24.609107 osdx dhclient[510665]: DHCPRELEASE of 88.31.21.123 on cell0 to 88.31.21.124 port 67
Mar 14 16:21:24.609145 osdx dhclient[510665]: send_packet: Network is down
Mar 14 16:21:24.609158 osdx dhclient[510665]: dhclient.c:3146: Failed to send 300 byte long packet over cell0 interface.