On a SIM7100A the PPPD connection fails (modem hangup) with nm-ppp-plugin, but a custom pppd script works
Simon Rijk
s.rijk at viriciti.com
Tue May 11 11:06:04 UTC 2021
Hi all,
We have some strange behavior (on a SIM7100A) where NetworkManager (using
the nm-ppp-plugin) needs to initiate a connection with Vodafone (private
APN). The modem gets registered successfully on the network (roaming over
the available T-Mobile or AT&T networks), but receives a modem hangup (the
modem gives a "NO CARRIER" error) which leads to pppd disconnecting.
However, when using a custom pppd script (and without using ModemManager &
NetworkManager), we are able to setup a data connection.
* MM version is 1.14.10
* NM version is 1.28.0
* pppd version is 2.4.9
When using NetworkManager the pppd options that seem to be used (from
evaluating debug output of NetworkManager) are:
ttyUSB2
debug
idle 0
ipparam
lcp-echo-failure 0
lcp-echo-interval 0
lock
noauth
nodefaultroute
nodetach
noipdefault
noipv6
usepeerdns
and this results into the following pppd output:
Serial connection established.
using channel 23
Using interface ppp0
Connect: ppp0 <--> /dev/ttyUSB3
sent [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0x8e804837> <pcomp>
<accomp>]
rcvd [LCP ConfReq id=0x3f <asyncmap 0x0> <auth chap MD5> <magic
0x88528a77> <pcomp> <accomp>]
No auth is possible
sent [LCP ConfRej id=0x3f <auth chap MD5>]
rcvd [LCP ConfAck id=0x1 <asyncmap 0x0> <magic 0x8e804837> <pcomp>
<accomp>]
rcvd [LCP ConfReq id=0x40 <asyncmap 0x0> <magic 0x88528a77> <pcomp>
<accomp>]
sent [LCP ConfAck id=0x40 <asyncmap 0x0> <magic 0x88528a77> <pcomp>
<accomp>]
sent [IPCP ConfReq id=0x1 <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-dns2
0.0.0.0>]
sent [IPV6CP ConfReq id=0x1 <addr fe80::9095:1777:829f:47a0>]
rcvd [LCP DiscReq id=0x41 magic=0x88528a77]
Modem hangup
Connection terminated.
We do get good results when just running manual pppd script manually (no
ModemManager and NetworkManager active), but with quite different options
from the NetworkManager defaults. From the manual pppd script (a script
taken from Quectel) the options are:
debug
defaultroute
dump
hide-password
ipcp-accept-local
ipcp-accept-remote
ipcp-max-failure 30
ipparam 3gppp
lock
modem
noauth
noccp
nocrtscts
nodetach
noipdefault
novj
novjccomp
remotename 3gppp
usepeerdns
And that gives a good result (shortened pppd output a bit):
$ pppd debug call gprs
pppd options in effect:
debug debug
nodetach
dump
noauth
remotename 3gppp
/dev/ttyUSB3
115200
lock
connect chat -s -v -f /data/ppp/chatscripts/quectel-chat-connect -T
vf-viriciti
disconnect chat -s -v -f /data/ppp/chatscripts/quectel-chat-disconnect
nocrtscts
modem
hide-password
novj
novjccomp
ipcp-accept-local
ipcp-accept-remote
ipparam 3gppp
noipdefault
ipcp-max-failure 30
defaultroute
usepeerdns
noccp
abort on (BUSY)
abort on (NO CARRIER)
abort on (NO DIALTONE)
abort on (ERROR)
abort on (NO ANSWER)
timeout set to 30 seconds
send (AT^M)
expect (OK)
AT^M^M
OK
-- got it
send (ATE0^M)
expect (OK)
^M
ATE0^M^M
OK
-- got it
send (ATI;+CSUB;+CSQ;+COPS?;+CGREG?;&D2^M)
expect (OK)
^M
^M
Manufacturer: SIMCOM INCORPORATED^M
Model: SIMCOM_SIM7100A^M
Revision: SIM7100A_V4.5^M
IMEISV: 014339000429148/05^M
+GCAP: +CGSM^M
^M
+CSUB: B03V03^M
+CSUB: MDM9x15_AP_S_V1.63_161010^M
^M
+CSQ: 26,99^M
^M
+COPS: 1,0,"T-Mobile DATA ONLY",7^M
^M
+CGREG: 0,5^M
^M
OK
-- got it
send (AT+COPS=1,2,310260^M)
expect (OK)
^M
^M
OK
-- got it
send (AT+CGDCONT=1,"IP","vf-viriciti",,0,0^M)
expect (OK)
^M
^M
OK
-- got it
send (ATDT*99***1#^M)
expect (CONNECT)
^M
^M
CONNECT
-- got it
Script chat -s -v -f /data/ppp/chatscripts/quectel-chat-connect -T
vf-viriciti finished (pid 11933), status = 0x0
Serial connection established.
using channel 25
Using interface ppp0
Connect: ppp0 <--> /dev/ttyUSB3
sent [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0xfb7fbc11> <pcomp>
<accomp>]
rcvd [LCP ConfReq id=0x0 <asyncmap 0x0> <auth chap MD5> <magic
0x8856fba8> <pcomp> <accomp>]
No auth is possible
sent [LCP ConfRej id=0x0 <auth chap MD5>]
rcvd [LCP ConfAck id=0x1 <asyncmap 0x0> <magic 0xfb7fbc11> <pcomp>
<accomp>]
rcvd [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0x8856fba8> <pcomp>
<accomp>]
sent [LCP ConfAck id=0x1 <asyncmap 0x0> <magic 0x8856fba8> <pcomp>
<accomp>]
sent [IPCP ConfReq id=0x1 <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-dns2
0.0.0.0>]
sent [IPV6CP ConfReq id=0x1 <addr fe80::64c5:e93a:eca7:5409>]
rcvd [LCP DiscReq id=0x2 magic=0x8856fba8]
rcvd [IPCP ConfReq id=0x0]
sent [IPCP ConfNak id=0x0 <addr 0.0.0.0>]
rcvd [IPCP ConfNak id=0x1 <addr 10.141.107.204> <ms-dns1 10.1.2.199>
<ms-dns2 10.1.2.200>]
sent [IPCP ConfReq id=0x2 <addr 10.141.107.204> <ms-dns1 10.1.2.199>
<ms-dns2 10.1.2.200>]
rcvd [IPCP ConfReq id=0x1]
sent [IPCP ConfAck id=0x1]
rcvd [IPCP ConfAck id=0x2 <addr 10.141.107.204> <ms-dns1 10.1.2.199>
<ms-dns2 10.1.2.200>]
Could not determine remote IP address: defaulting to 10.64.64.64
not replacing default route to eth0 [192.168.1.254]
local IP address 10.141.107.204
remote IP address 10.64.64.64
primary DNS address 10.1.2.199
secondary DNS address 10.1.2.200
sent [IPV6CP ConfReq id=0x1 <addr fe80::64c5:e93a:eca7:5409>]
sent [IPV6CP ConfReq id=0x1 <addr fe80::64c5:e93a:eca7:5409>]
What we would like of course is for NetworkManager and the nm-ppp-plugin to
basically also just get the connection up and running. At the moment we are
clueless why the combination of ModemManager & NetworkManager is not able
to obtain an active data sessions, but the manual pppd script is.
More (debug) info if attached in a pdf!
I hope someone has any clue on the particular case, how to debug better, or
can give an idea if this is a network operator sided issue.
Thanks in advance!
--
Best regards, Met vriendelijke groet,
*Ir. Simon Rijk | CTO*
Kabelweg 57 | 1014 BA Amsterdam
T: +31 207 717 817 | www.viriciti.com <https://viriciti.com> | See what we
do in 1 minute <https://www.youtube.com/watch?v=eXD791LkMmQ>
<https://www.facebook.com/ViriCiti/>
<https://www.linkedin.com/company/viriciti/>
<https://twitter.com/ViriCiti>
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