Reconnection 819 Router after connection failure

[casper999]

Hi all,

I have a Cisco 819 WAN Router (C819 Secure M2M GW (non-US) 3.7G HSPA+ R7 w/SMS/GPS).

Software: Cisco IOS Software, C800 Software (C800-UNIVERSALK9-M), Version 15.2(2)T, RELEASE SOFTWARE (fc1)

For dialing in at my Provider (T-mobile Germany), I use the following chat-script:

chat-script gsm "" ATZ "" AT+CGDCONT=1 "OK" "AT!SCACT=1,1" TIMEOUT 60 "OK" "ATD*99#" "CONNECT"

Dial-In is successful after Reboot.

Now, i want to simulate a conenction fault, e.g. termination by mobile provider.

So I used the command "clear int cellular 0".

After that, The router can't dial in again.

Debug shows:

Dec  7 11:04:03: %LINEPROTO-5-UPDOWN: Line protocol on Interface Virtual-Access1, changed state to down

Dec  7 11:04:14: CHAT3: Attempting async line dialer script

Dec  7 11:04:14: CHAT3: Dialing using Modem script: gsm & System script: none

Dec  7 11:04:14: CHAT3: process started

Dec  7 11:04:14: CHAT3: Asserting DTR

Dec  7 11:04:14: CHAT3: Chat script gsm started

Dec  7 11:04:14: CHAT3: Sending string: ATZ

Dec  7 11:04:14: CHAT3: Sending string: AT+CGDCONT=1

Dec  7 11:04:14: CHAT3: Expecting string: OK

Dec  7 11:04:19: CHAT3: Timeout expecting: OK

Dec  7 11:04:19: CHAT3: Chat script gsm finished, status = Connection timed out; remote host not responding

Is the "clear interface cellular 0" the wrong way to test this, or why can't the Router reconnect?

The only solution is a reboot, but that is not the best option. The router should automatically redial.

Any ideas?

Thanks in advance!

[aidacruises]

Hello casper999,

would you be so kind and share your cellular config? I do have the same router (C819 with HSPA+/R7) and try to connect to T-Mobile with the same error (Timeout Expecting OK).

Thank you in advance.

Regards

Mathias

[casper999]

Hello Mathias,

my solution is to manually reset the modem with the command

    test cellular 0 modem-reset

To enable such reset-commands, you need to configure "service internal" previosly in your router-configuration.

But I am still not sure, whether this test-scenario with "clear int cellular 0" is realistic.

Regards,

Carsten

[aidacruises]

Hi Carsten,

thanks - same is "working" for me. As soon as the cellular connection is down it will only come up again after a device reload or your described procedure via modem-reset.

What is your intention, is this a software/firmware issue (upgrade needed?) or a bug or configuration issue?

Here my config lines:

cellular 0 gsm profile create 1 internet.t-mobile chap dummy dummy

chat-script hspaplus "" ATZ "" AT+CGDCONT=1 "OK" "AT!SCACT=1,1" TIMEOUT 60 "OK" "ATD*99#" "CONNECT"

interface Cellular0

ip address negotiated

encapsulation slip

dialer in-band

dialer string hspaplus

dialer-group 1

async mode interactive

ip route 0.0.0.0 0.0.0.0 Cellular0

dialer-list 1 protocol ip permit

line 3

exec-timeout 0 0

script dialer hspaplus

modem InOut

Regards

Mathias

[casper999]

I upgraded to the newset firmware, but it's still the same.

Did you simulate an error with "clear int cellular 0" or did you experience connection problems during normal operation?

If this error is only together with "clear int cellular 0" this might be a bad mechanism to test a failure.

[aidacruises]

I do have the issue after every normal lost connection - meaning I do not do any clear, just waiting for the next 3G connection loss...

[aidacruises]

Good Morning Carsten,

I'm now working with following IPSLA + EEM script to work around the issue:

ip sla 1
 icmp-echo X.X.X.X
 frequency 5
ip sla schedule 1 life forever start-time now
ip sla reaction-configuration 1 react timeout threshold-type consecutive  action-type trapAndTrigger
ip sla logging traps
!
event manager applet IPSLA1_EEM_SCRIPT
 event snmp oid 1.3.6.1.4.1.9.9.42.1.2.9.1.6.1 get-type exact entry-op lt entry-val "2" poll-interval 60
 trigger occurs 1 period 60
 action 01.0 syslog msg "IPSLA1 timeout, reset 3G modem via EEM script"
 action 02.0 cli command "enable"
 action 03.0 cli command "test cellular 0 modem-reset"

SMNP OID needs to be in the form 1.3.6.1.4.1.9.9.42.1.2.9.1.6.x, where x is the ip sla ID.

Regards

Mathias

[casper999]

Hi Mathias,

thank for the script. A colleague in my company developed the following script as a workaround.

ip sla 1

icmp-echo xx.xx.xx.xx source-ip yy.yy.yy.yy

frequency 120

ip sla schedule 1 life forever start-time now

event manager applet EnableCHATDebugging

event syslog occurs 1 pattern "%SYS-5-RESTART"

action 1.0 cli command "enable"

action 2.0 cli command "debug chat"

event manager applet EEM-Watchdog-modem-reset

event syslog occurs 3 pattern "Chat script gsm finished, status = Connection timed out; remote host not responding" period 300

action 1.0 cli command "enable"

action 2.0 cli command "test cellular 0 modem-reset"

action 3.0 info type routername

action 4.0 syslog priority informational msg "EEM Watchdog cellular modem reset on $_info_routername"

It seems, that not many people are using this router in such a configuration, especially with tcom.

Perhaps we can exchange further experiences with this router in the future directly???

[Stefan Tiefel · Accepted solution]

Hi,

i think i have a solution for your problem.

You need another chat script.

chat-script gsm "" "AT!SCACT=1,1" TIMEOUT 60 "OK"

This Solution works fine with the german t-mobile.

https://supportforums.cisco.com/docs/DOC-18957

Kind regards

Stefan

[casper999]

Hi Stefan,

thank you.

This works for german t-mobile as like as german vodafone.

Kind regards

Carsten

[ted reese]

I have this same interfaces in my 2911 ISR and when there is cell maintenace from my provider AT&T and my SIM becomes un-registered the only way I can bring it back is a reload.  I've debugged and my cel 0/2/0 interfaces shows as not responding:

%CELLWAN-2-SEND_TIMEOUT: Cellular0/2/0 not responding

The chat string is getting initiated but keeps show the connection times out:

CHAT0/2/0: Chat script HSPA finished, status = Connection timed out; remote host not responding

I can still send SMS to this interface but none of the solutions above seem to restart my connection.  Any thoughts on this one?

If we find something to restart the connection than I could use EEM to run the script.  It seems like the dialer doesn't know how to reach AT&T:

Ce0/2/0 - dialer type = IN-BAND ASYNC NO-PARITY

Idle timer (30 secs), Fast idle timer (20 secs)

Wait for carrier (30 secs), Re-enable (15 secs)

Dialer state is enabling

Dial reason: ip (s=99.0.0.0, d=0.240.0.212)

Time until interface enabled 9 secs

Dial String      Successes   Failures    Last DNIS   Last status

HSPA                     1        248    00:01:05           failed   Default

Thank you,

Ted