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 U2FsdGVkX1/1fGrMYm2Dyr+UEQJmibhJ7vm8zqmp2Cs=
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

May 14 11:16:20.350003 osdx systemd-journald[62163]: Runtime Journal (/run/log/journal/938c25d0e4c641f3a8cd84f49e64cd65) is 1.0M, max 8.5M, 7.4M free.
May 14 11:16:20.352176 osdx systemd-journald[62163]: Received client request to rotate journal, rotating.
May 14 11:16:20.352371 osdx systemd-journald[62163]: Vacuuming done, freed 0B of archived journals from /run/log/journal/938c25d0e4c641f3a8cd84f49e64cd65.
May 14 11:16:20.374095 osdx sudo[207613]: pam_limits(sudo:session): invalid line '@200:215        hard        maxlogins        ' - skipped
May 14 11:16:20.442309 osdx OSDxCLI[206185]: User 'admin' executed a new command: 'system journal clear'.
May 14 11:16:40.648155 osdx OSDxCLI[206185]: User 'admin' executed a new command: 'system journal show | cat'.
May 14 11:16:40.848153 osdx OSDxCLI[206185]: User 'admin' executed a new command: 'system journal show | cat'.
May 14 11:16:42.060156 osdx OSDxCLI[206185]: User 'admin' executed a new command: 'system journal show | cat'.
May 14 11:16:43.272167 osdx OSDxCLI[206185]: User 'admin' executed a new command: 'system journal show | cat'.
May 14 11:16:44.512162 osdx OSDxCLI[206185]: User 'admin' executed a new command: 'system journal show | cat'.
May 14 11:16:45.744153 osdx OSDxCLI[206185]: User 'admin' executed a new command: 'system journal show | cat'.
May 14 11:16:46.992178 osdx OSDxCLI[206185]: User 'admin' executed a new command: 'system journal show | cat'.
May 14 11:16:48.264161 osdx OSDxCLI[206185]: User 'admin' executed a new command: 'system journal show | cat'.
May 14 11:16:49.528175 osdx OSDxCLI[206185]: User 'admin' executed a new command: 'system journal show | cat'.
May 14 11:16:50.808164 osdx OSDxCLI[206185]: User 'admin' executed a new command: 'system journal show | cat'.
May 14 11:16:50.912274 osdx wwan-module[207342]: [Core/cell0] Info: Signal '12' received to reconnect device.
May 14 11:16:50.912319 osdx wwan-module[207342]: [Device/cell0] Info: Stopping network connection...
May 14 11:16:50.930335 osdx wwan-module[207711]: Network cancelled... releasing resources
May 14 11:16:51.067832 osdx wwan-module[207711]: [/dev/cdc-wdm0] Network stopped
May 14 11:16:51.067832 osdx wwan-module[207711]: [/dev/cdc-wdm0] Client ID not released:
May 14 11:16:51.067832 osdx wwan-module[207711]:         Service: 'wds'
May 14 11:16:51.067832 osdx wwan-module[207711]:             CID: '21'
May 14 11:16:51.069657 osdx wwan-module[207342]: [Device/cell0] Info: Network connection was stopped!
May 14 11:16:51.071738 osdx wwan-module[207342]: [Network/cell0] Info: Stopping accessibility control...
May 14 11:16:51.071937 osdx wwan-module[207342]: [Network/cell0] Info: Accessibility control was stopped!
May 14 11:16:51.074880 osdx kernel: net cell0: link_state 0x1 -> 0x0
May 14 11:16:51.085306 osdx modulelauncher[207718]: stop DHCP client for cell0
May 14 11:16:51.086704 osdx dhclient[207433]: receive_packet failed on cell0: Network is down
May 14 11:16:51.088967 osdx wwan-module[207342]: [Device/cell0] Info: Checking registration state...
May 14 11:16:51.095860 osdx dhclient[207722]: Killed old client process
May 14 11:16:51.195798 osdx wwan-module[207342]: [Device/cell0] Info: Device registered and PS attached successfully
May 14 11:16:51.195820 osdx wwan-module[207342]: [Device/cell0] Info: Establishing network connection...
May 14 11:16:51.227320 osdx dhclient[207722]: DHCPRELEASE of 5.205.223.64 on cell0 to 5.205.223.65 port 67
May 14 11:16:51.227349 osdx dhclient[207722]: send_packet: Network is down
May 14 11:16:51.227361 osdx dhclient[207722]: dhclient.c:3146: Failed to send 300 byte long packet over cell0 interface.
May 14 11:16:51.520717 osdx wwan-module[207342]: [Device/cell0] Info: Network connection was successfully started: PDH=[2175544928]
May 14 11:16:51.647031 osdx kernel: net cell0: link_state 0x0 -> 0x1
May 14 11:16:51.648442 osdx wwan-module[207342]: [Network/cell0] Info: Starting accessibility control...
May 14 11:16:51.648850 osdx wwan-module[207342]: [Network/cell0] Info: Accessibility control was started!
May 14 11:16:51.817769 osdx modulelauncher[207771]: start DHCP client for cell0