NimbeLink Skywire NL-LTE-TNAG User manual

Configuring Linux ‘pppd’ for a
Skywire® 4G LTE CAT3 GSM Modem
NimbeLink Corp
Updated: November 2016
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Table of Contents
Table of Contents 2
1. Introduction 3
1.1 Applies to the Following Part Numbers: 3
1.2 Prerequisites 3
2. PPP – 4G LTE Modems 4
2.1 Overview 4
2.2 Elevate to root 4
2.3 Check for Updates 4
2.4 Install the “ppp” Package 4
2.5 Verify The Modem is Connected 4
2.6 Ubuntu Only: Load the “option” Driver 5
2.7 Write PPP Scripts 5
2.8 Take Down the Ethernet Interface 6
2.9 Bring Up the PPP Interface 7
2.10 Troubleshooting 7
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1. Introduction
1.1 Applies to the Following Part Numbers:
Orderable Device
Description
Carrier
Network Type
NL-SWDK
Skywire Development Kit
Any
Any
NL-AB-BBBC
Skywire BeagleBone Black Cape
Any
Any
NL-AB-MPCIE
Mini-PCI Express Adapter Board
Any
Any
NL-SW-LTE-TNAG
LTE without Fallback, GPS, GLONASS
AT&T/T-Mobile
GSM
1.2 Prerequisites
This document assumes you have completed the initial setup
of your modem and development kit. If you have not
completed those steps, refer to the Skywire® Development Kit
User Manual and complete the modem setup before
proceeding.
If you are using a device that is communicating via SSH,
Telnet, or any other type of Ethernet interface, you must
connect to it via USB or serial. Section 2.8 requires the
Ethernet interface to be taken down.
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2. PPP – 4G LTE Modems
2.1 Overview
This example has been tested on the following distributions of Linux:
- Ubuntu Linux 14.04 LTS
- BeagleBone Black Debian 8.x
using a Skywire® NL-LTE-TNAG GSM 4G LTE modem.
This example is written using Debian and Ubuntu. Some additional steps are necessary
to get PPP working on Ubuntu, and those steps will be covered in their respective
sections.
This example is also using AT&T a carrier.
2.2 Elevate to root
In order to make the changes necessary, it is necessary to login to the root account. To
do so, type the following command into the Terminal:
For Debian:
$ su -
For Ubuntu:
$ sudo -i
followed by the Enter key. You will be prompted to enter your password: enter it,
followed by the Enter key.
2.3 Check for Updates
Make sure that your Debian or Ubuntu system is up to date using the following
commands:
# apt-get update
# apt-get upgrade
2.4 Install the “ppp” Package
To install the ppp package, type the following command:
# apt-get install ppp
2.5 Verify The Modem is Connected
To verify that our system can see the Skywire modem, type the following command:
# lsusb
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followed by the enter key, and you should have an entry similar to the one below:
Bus 001 Device 002: ID 1bc7:1201 Telit
If so, the modem is connected properly. If not, verify the modem is connected properly
and run the command again.
2.6 Ubuntu Only: Load the “option” Driver
The Skywire modem does not properly enumerate automatically, if at all, under Ubuntu.
To enumerate the device, we need to load the “option” driver.
To get our device’s ID, type the following command:
# lsusb
followed by the Enter key. There should be a device listed according to the following
format that says “Telit”:
Bus 001 Device 002: ID 1bc7:1201 Telit
Make note of the eight-character hex code right before “Telit”. In the case of a
SW-LTE-TSVG, it is “1bc7:1201”.
To load the option driver, type the following into the Terminal:
# modprobe option
# echo 1bc7 1201 > /sys/bus/usb-
serial/drivers/option1/new_id
2.7 Write PPP Scripts
We need to write two scripts for PPP to reference when initializing the connection.
Note: We have a GitHub page with the necessary PPP files available for
customers to use located here:
https://github.com/NimbeLink/skywire-ppp-scripts
We highly recommend downloading that repo and following the instructions in
the files related to your modem. The other recommended option is to click on the
file you want and copy and paste directly from GitHub.
First, clone the repo and navigate to the cloned repo. Next, as superuser (root) copy the
file:
att-TNAG
to:
/etc/ppp/peers/
or copy-and-paste the contents of:
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att-TNAG
from the GitHub repo to
/etc/ppp/peers/att-TNAG
The contents of att-TNAG are shown below:
Next, copy:
att-TNAG-chat
to:
/etc/ppp/peers/
or copy-and-paste the contents of
att-TNAG-chat
from the GitHub repo to
/etc/ppp/peers/att-TNAG-chat
Make sure to replace [apn] with your APN. The contents of att-TNAG-chat are
shown below:
 
2.8 Take Down the Ethernet Interface
A PPP connection requires that any existing Ethernet connection be taken down. To
bring down the Ethernet connection, type the following command:
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# ifconfig eth0 down
(Optional) To verify that the Ethernet connection is down, type:
# ifconfig
followed by the enter key. eth0 should not be listed.
2.9 Bring Up the PPP Interface
To enable the PPP interface, type the following commands:
For Debian:
# pon att-TNAG
For Ubuntu:
# pppd call att-TNAG
followed by the enter key. You will see the second script you wrote appear on the
screen, followed by the network communication the Skywire modem is going through to
get connected.
Once the process is complete, test the connection:
#ping –c 2 www.google.com
and you should receive a response similar to this:
PING www.google.com (216.58.216.196) 56(84) bytes of data.
64 bytes from ord31s21-in-f4.1e100.net (216.58.216.196): icmp_seq=1 ttl=50 time=47.8 ms
64 bytes from ord31s21-in-f4.1e100.net (216.58.216.196): icmp_seq=2 ttl=50 time=90.6 ms
--- www.google.com ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1001ms
rtt min/avg/max/mdev = 47.818/69.237/90.656/21.419 ms
This indicates that your PPP connection is up and connected to the network.
2.10 Troubleshooting
- If your PPP fails with the error 0x1 in Section 2.9, chances are your att-TNAG
file cannot see your att-TNAG-chat file. Ensure that the last part of line 3 of
the att file:
.../att-TNAG-chat
has the same name as your att-TNAG-chat file. The tool xxd may be
beneficial to ensure that there are no extra characters in the file and that the files
are named the same:
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$ xxd att-TNAG
If you are still having issues, rename the last part of line 3 in the att-TNAG file
to:
.../attchat
and rename att-TNAG-chat to attchat and try again.
- If your PPP fails with the error 0x3 in Section 2.9, you may have poor signal
strength. Move the unit closer to a window for a better signal strength.
- If your PPP still fails with error 0x3 in Section 2.9, your APN may be incorrect.
Verify that your APN is correct in your att-TNAG-chat file.
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