issue in connection's status

[Dan Williams]

On Tue, 2016-08-30 at 10:40 +0300, alexander.sorvin at shbp.ru wrote:
> Hello!
> I'm waiting for the connection status to change for more then 5 min.
> I use load balancing and that timeout is very critical for me (even
> 30 sec. is too long for me). How can I change it?

In the past, we've seen two indications of disconnect behavior:

1) WDS Packet Service Status "connection status" reports disconnected

2) NAS Serving System indications report no selected network as such:

ModemManager[15426]: [/dev/cdc-wdm1] Received message (translated)...
>>>>>> QMUX:
>>>>>>   length  = 33
>>>>>>   flags   = 0x80
>>>>>>   service = "nas"
>>>>>>   client  = 61
>>>>>> QMI:
>>>>>>   flags       = "indication"
>>>>>>   transaction = 0
>>>>>>   tlv_length  = 21
>>>>>>   message     = "Serving System" (0x0024)
>>>>>> TLV:
>>>>>>   type       = "Detailed Service Status" (0x22)
>>>>>>   length     = 5
>>>>>>   value      = 00:03:00:00:00
>>>>>>   translated = [ status = 'none' capability = 'cs-ps' hdr_status = 'none' hdr_hybrid = 'no' forbidden = 'no' ]
>>>>>> TLV:
>>>>>>   type       = "Data Service Capability" (0x11)
>>>>>>   length     = 1
>>>>>>   value      = 00
>>>>>>   translated = {}
>>>>>> TLV:
>>>>>>   type       = "Serving System" (0x01)
>>>>>>   length     = 6
>>>>>>   value      = 02:01:01:00:01:00
>>>>>>   translated = [ registration_state = 'not-registered-searching' cs_attach_state = 'attached' ps_attach_state = 'attached' selected_network = 'unknown' radio_interfaces = '{ [0] = 'none '}' ]

Note that even though the registration state is "searching", there is
no selected network and no radio interface listed, and other stuff like
"data service capability" is QMI_NAS_DATA_CAPABILITY_NONE instead of
something like QMI_NAS_DATA_CAPABILITY_LTE.

So, what do you get for "qmicli --nas-get-serving-system" when you
remove antennas?  Note that some searching is normal if you're on
marginal signal, so if Serving System does provide the right state when
you disconnect antennas, you'd want to start a short timer that was
cleared when the device re-registered, but if the timer expired then
you'd know to fail over.

Dan

> 29.08.2016, 20:01, "Dan Williams" <dcbw at redhat.com>:
> > 
> > On Mon, 2016-08-29 at 17:00 +0300, alexander.sorvin at shbp.ru wrote:
> > > 
> > >  Hello!
> > > 
> > >  We use a modem Sierra MC7304 (at!udusbcomp=6  at!scact=1,1) .
> > > Connect
> > >   with the command: qmicli -d /dev/cdc-wdm0 --client-no-release-
> > > cid
> > >  To get ip address: dhclient wwan0
> > >  Then I remove the antenna from the modem in order to achieve a
> > >  connection loss. The response from the ping stops flowing, but
> > > the
> > >  status still shows that there is a connection. Where is a fault?
> > How long are you waiting for the connection status to change?
> >  Modems
> > often have large timeouts to paper over network dropouts like
> > insufficient coverage, short tunnels, etc and not drop the packet
> > data
> > connection and thus IP address and such.  If it doesn't drop after
> > an
> > hour then I'd say there's an issue, but I would expect at least 30
> > seconds or so of no signal without reporting a disconnect.
> > 
> > Dan
> > 
> > > 
> > >  sudo qmicli -d /dev/cdc-wdm0 --wds-get-packet-service-status
> > >  [/dev/cdc-wdm0] Successfully got serving system:
> > >  Registration state: 'registered'
> > >  CS: 'attached'
> > >  PS: 'attached'
> > >  Selected network: '3gpp'
> > >  Radio interfaces: '1'
> > >  [0]: 'lte'
> > >  Roaming status: 'off'
> > >  Data service capabilities: '1'
> > >  [0]: 'lte'
> > >  Current PLMN:
> > >  MCC: '250'
> > >  MNC: '2'
> > >  Description: 'MegaFon'
> > >  Roaming indicators: '1'
> > >  [0]: 'off' (lte)
> > >  3GPP location area code: '65534'
> > >  3GPP cell ID: '253764101'
> > >  Detailed status:
> > >  Status: 'available'
> > >  Capability: 'cs-ps'
> > >  HDR Status: 'power-save'
> > >  HDR Hybrid: 'yes'
> > >  Forbidden: 'no'
> > >  LTE tracking area code: '9913'
> > >  Full operator code info:
> > >  MCC: '250'
> > >  MNC: '2'
> > >  MNC with PCS digit: 'no'
> > > 
> > >  sudo qmicli -d /dev/cdc-wdm0 --nas-get-serving-system
> > > 
> > >  [/dev/cdc-wdm0] Successfully got system info:
> > >  GSM service:
> > >  Status: 'none'
> > >  True Status: 'none'
> > >  Preferred data path: 'no'
> > >  WCDMA service:
> > >  Status: 'none'
> > >  True Status: 'none'
> > >  Preferred data path: 'no'
> > >  LTE service:
> > >  Status: 'limited'
> > >  True Status: 'available'
> > >  Preferred data path: 'no'
> > >  Domain: 'cs-ps'
> > >  Service capability: 'cs-ps'
> > >  Roaming status: 'off'
> > >  Forbidden: 'yes'
> > >  Cell ID: '197157636'
> > >  MCC: '250'
> > >  MNC: '99'
> > >  Tracking Area Code: '3877'
> > >  Voice support: 'no'
> > >  eMBMS coverage info support: 'no'
> > >  SIM reject info: 'vailable'
> > > 
> > >  sudo qmicli -d /dev/cdc-wdm0 --wds-get-packet-service-status
> > > 
> > >  [/dev/cdc-wdm0] Connection status: 'connected'
> > >  _______________________________________________
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