If it is not configured, the cellular interface is presented on the interface list either by modem USB address, or if serial modem is used, by modem name. This 'fake' interface name is replaced by 'proper' interface name (e.g., ppp0) when the first modem configuration is submitted.
The cellular interface should be configured by first enabling it in the TCP/IP tab, and then setting the Cellular tab. Note that the cellular interface can only be set as WAN using DHCP. The cellular interface configuration options are described below.
The Cellular tab contains the following configuration parameters:
Model: specifies the modem model.
Network Technology: describes the network technology used by this modem.
Modem Identifier: provides a unique name for this modem.
Interface #: provides a unique number for the modem interface (e.g., an interface # of 0 would name the modem interface ppp0).
Dial String: instructs how the modem should attempt to connect. Typical dial strings are as follows:
- HSPA modem: atd*99***1#
- EVDO/CDMA modem: atd#777
APN: defines the modem access point name (HSPA modems only).
Auth Type: specifies the authentication type (HSPA modems only).
Username: supplies the username; disabled if no authentication method is specified.
Password: supplies the password; disabled if no authentication method is specified.
Modem Reset Timeout: sets the modem reset timeout in minutes. If set to a non-zero value, the modem is reset after n consecutive minutes of unsuccessful connection attempts. If set to zero, the modem keeps trying to establish a PPP connection without resetting. The default value is 5 minutes.
Reopen Connection on Termination: sets the persist option of the PPP daemon that specifies if PPP daemon should exit after connection is terminated. Note that the maxfail option still has an effect on persistent connections.
Connection Attempts: sets the maxfail option of the PPP daemon that limits the number of consecutive failed PPP connection attempts. The default value is 5 connection attempts. A value of zero means no limit. The PPP daemon terminates after the specified number of failed PPP connection attempts and restarts by the ModemMonitor thread.
Disconnect if Idle: sets the idle option of the PPP daemon, which terminates the PPP connection if the link is idle for a specified number of seconds. The default value is 95 seconds. To disable this option, set it to zero.
Active Filter: sets the active-filter option of the PPP daemon. This option specifies a packet filter (filter-expression) to be applied to data packets in order to determine which packets are regarded as link activity, and thereby, reset the idle timer. The filter-expression syntax is as described for tcpdump(1); however, qualifiers that do not apply to a PPP link, such as ether and arp, are not permitted. The default value is inbound. To disable the active-filter option, leave it blank.
LCP Echo Interval: sets the lcp-echo-interval option of the PPP daemon. If set to a positive number, the modem sends LCP echo request to the peer at the specified number of seconds. To disable this option, set it to zero. This option may be used with the lcp-echo-failure option to detect that the peer is no longer connected.
LCP Echo Failure: sets the lcp-echo-failure option of the PPP daemon. If set to a positive number, the modem presumes the peer to be dead if a specified number of LCP echo-requests are sent without receiving a valid LCP echo-reply. To disable this option, set it to zero.
Enable GPS: enables GPS with the following conditions:
- One modem port will be dedicated to NMEA data stream.
- This port may not be used to send AT commands to the modem.
- PositionService should be enabled. Serial settings of PositionService should not be changed; it will be redirected to the modem GPS port automatically.
Cellular Linux Configuration
This section describes the changes applied by Kura at the Linux networking configuration. Please read the following note before proceeding with manual changes of the Linux networking configuration.
It is NOT recommended performing manual editing of the Linux networking configuration files when the gateway configuration is being managed through Kura. While Linux may correctly accept manual changes, Kura may not be able to interpret the new configuration resulting in an inconsistent state.
When the cellular configuration is submitted, Kura generates peer and chat scripts used by the PPP daemon to establish a PPP connection. Examples of these scripts for HSPA and EVDO modems are shown below.
Example Peer Script for HSPA Modem
connect 'chat:v:f /etc/ppp/scripts/chat_HE910-D_2-1.5'
disconnect 'chat:v:f /etc/ppp/scripts/disconnect_HE910-D_2-1.5'
Example Chat Script for HSPA Modem
Example Peer Script for EVDO Modem
connect 'chat:v:f /etc/ppp/scripts/chat_DE910-DUAL_1-1.5'
disconnect 'chat:v:f /etc/ppp/scripts/disconnect_DE910-DUAL_1-1.5'